genetics

HLA stands for "human leukocyte antigen" click this icon to hear the preceding term pronounced. homeotic gene click this icon to hear the preceding term pronounced see regulator gene. homologous chromosomes click this icon to hear the preceding term pronounced chromosomes that are paired during the production of of sex cells in meiosis.

Cystic fibrosis occurs as a result of inheriting a recessive allele for it from both parents.

The gene or genes for diabetes are incompletely penetrant. dominant allele an allele that masks the presence of a recessive allele in the phenotype.

Humans have 46 chromosomes in each somatic cell and 23 in each sex cell. codominance click this icon to hear the preceding term pronounced the situation in which two different alleles for a trait are expressed unblended in the phenotype of heterozygous individuals.

The collective group of symptoms known as sickle-cell trait is an example. polygenic trait click this icon to hear the preceding term pronounced an inherited trait that is determined by genes at two or more loci.

HLA stands for "human leukocyte antigen" click this icon to hear the preceding term pronounced. homeotic gene click this icon to hear the preceding term pronounced see regulator gene. homologous chromosomes click this icon to hear the preceding term pronounced chromosomes that are paired during the production of of sex cells in meiosis.

Mendelian genetics click this icon to hear the preceding term pronounced inheritance patterns which can be explained by simple rules of dominance and recessiveness of genes. modifying gene a gene that can alter the expression of another gene in the phenotype of an individual. monozygotic twins click this icon to hear the preceding term pronounced identical twins.

This decoding of the human proteome will be an even more daunting task than the original Human Genome Project.

Since it is an X-linked trait, males more often have it expressed in their phenotypes.

Humans have 46 chromosomes in each somatic cell and 23 in each sex cell. codominance click this icon to hear the preceding term pronounced the situation in which two different alleles for a trait are expressed unblended in the phenotype of heterozygous individuals.

Type AB blood is an example.

The myotonic form of muscular dystrophy is an example.

Through his plant cross-breeding experiments, Gregor Mendel proved that this was wrong Back to Top - C - carrier an individual who is heterozygous for a trait that only shows up in the phenotype of those who are homozygous recessive.

See sex-limited gene. sex-limited gene a gene that can be inherited by both genders but is usually expressed in only males or females.

Such chromosomes are alike with regard to size and also position of the centromere.

Back to Top - D - diabetes click this icon to hear the preceding term pronounced an inherited metabolic disorder in which there are abnormally high blood sugar levels.

Individuals who are homozygous for a trait are referred to as homozygotes.

Back to Top - H - hemophilia click this icon to hear the preceding term pronounced an X-linked genetically inherited recessive disease in which one or more of the normal blood clotting factors is not produced.

The initial stage of discovering all human DNA codons was completed early in 2001 at a cost of 2.7 billion dollars.

However, because they are different, their action may result in different expressions of that trait. amino acids click this icon to hear the preceding term pronounced small molecules that are the components of proteins.

See Human Genome Project. genome imprinting click this icon to hear the preceding term pronounced an inheritance pattern in which a gene will have a different effect depending on the gender of the parent from whom it is inherited.

Usually, the term is used in reference to the crossing of two pure breeding (homozygous) plants. cystic fibrosis click this icon to hear the preceding term pronounced a genetically inherited disease in children that results in chronic fluid development in the lungs, making breathing difficult.

Fraternal twins may look similar but are not genetically identical. multiple-allele series click this icon to hear the preceding term pronounced a situation in which a gene has more than two alleles.

HLA stands for "human leukocyte antigen" click this icon to hear the preceding term pronounced. homeotic gene click this icon to hear the preceding term pronounced see regulator gene. homologous chromosomes click this icon to hear the preceding term pronounced chromosomes that are paired during the production of of sex cells in meiosis.

Meiosis involves two divisions and results in four daughter cells, each containing only half the original number of chromosomes--23 in the case of humans.

This disease is also called Huntington's chorea click this icon to hear the preceding term pronounced. hybrids click this icon to hear the preceding term pronounced offspring that are the result of mating between two genetically different kinds of parents--the opposite of purebred.

Back to Top - T - Tay-Sachs Disease click this icon to hear the preceding term pronounced a genetically inherited condition caused by the inability to produce the enzyme hexosaminidase A. This results in progressively increased fluid pressure on the brain and the subsequent degeneration of the brain and nervous system beginning about 6 months of age and inevitably resulting in death usually by age 2-3.

Back to Top - W - Back to Top - X - X-linked referring to a gene that is carried by an X sex chromosome.

MD is characterized by a gradual, irreversible wasting of skeletal muscle.

albinism click this icon to hear the preceding term pronounced the genetically inherited condition in which there is a marked deficiency of pigmentation in skin, hair, and eyes.

This is the case with hemophilia. cataract click this icon to hear the preceding term pronounced an impairment of vision caused by the lenses of the eyes becoming cloudy.

These modified particles were thought to migrate via blood to the reproductive cells and subsequently could be inherited by the next generation.

Angelman syndrome click this icon to hear the preceding term pronounced a rare genetically inherited form of mental retardation due to the deletion or inactivation of specific genes on chromosome 15.

This disease is also called Huntington's chorea click this icon to hear the preceding term pronounced. hybrids click this icon to hear the preceding term pronounced offspring that are the result of mating between two genetically different kinds of parents--the opposite of purebred.

The inheritance of this syndrome is subject to genome imprinting.

It is a sex-linked trait most often passed on to sons by their mothers.

This is the case with hemophilia. cataract click this icon to hear the preceding term pronounced an impairment of vision caused by the lenses of the eyes becoming cloudy.

See sex-controlled gene. sickle-cell trait a genetically inherited recessive condition in which red blood cells are distorted resulting in severe anemia and related symptoms that are often fatal in childhood.

However, because they are different, their action may result in different expressions of that trait. amino acids click this icon to hear the preceding term pronounced small molecules that are the components of proteins.

Usually, the term is used in reference to the crossing of two pure breeding (homozygous) plants. cystic fibrosis click this icon to hear the preceding term pronounced a genetically inherited disease in children that results in chronic fluid development in the lungs, making breathing difficult.

Humans have 46 chromosomes in each somatic cell and 23 in each sex cell. codominance click this icon to hear the preceding term pronounced the situation in which two different alleles for a trait are expressed unblended in the phenotype of heterozygous individuals.

It is believed that the lack of abundant sun exposure early in life is somehow responsible for the later onset of MS. muscular dystrophy click this icon to hear the preceding term pronounced (MD) any of a group of inherited progressive muscle disorders caused by a defect in one or more genes that control muscle function.

DNA click this icon to hear the preceding term pronounced (deoxyribonucleic acid click this icon to hear the preceding term pronounced) a large organic molecule that stores the genetic code for the synthesis of proteins.

See phenotype. gout click this icon to hear the preceding term pronounced a genetically inherited metabolic disorder in which there is an imbalance of uric acid in the blood which causes a build up of urates in joint areas.

Swollen joints caused by internal bleeding is a common problem for hemophiliacs.

albinism click this icon to hear the preceding term pronounced the genetically inherited condition in which there is a marked deficiency of pigmentation in skin, hair, and eyes.

Usually, the term is used in reference to the crossing of two pure breeding (homozygous) plants. cystic fibrosis click this icon to hear the preceding term pronounced a genetically inherited disease in children that results in chronic fluid development in the lungs, making breathing difficult.

Most fragile-X males have large testes, big ears, narrow faces, and sensory integration dysfunctions that result in learning disabilities.

It is believed that the lack of abundant sun exposure early in life is somehow responsible for the later onset of MS. muscular dystrophy click this icon to hear the preceding term pronounced (MD) any of a group of inherited progressive muscle disorders caused by a defect in one or more genes that control muscle function.

Huntington's disease a severe genetically inherited fatal degenerative nerve disorder.

Angelman syndrome click this icon to hear the preceding term pronounced a rare genetically inherited form of mental retardation due to the deletion or inactivation of specific genes on chromosome 15.

Sickle-cell trait is also known as sickle-cell anemia. somatic cell click this icon to hear the preceding term pronounced any cell in the body except those directly involved with reproduction.

Usually, the term is used in reference to the crossing of two pure breeding (homozygous) plants. cystic fibrosis click this icon to hear the preceding term pronounced a genetically inherited disease in children that results in chronic fluid development in the lungs, making breathing difficult.

Back to Top - H - hemophilia click this icon to hear the preceding term pronounced an X-linked genetically inherited recessive disease in which one or more of the normal blood clotting factors is not produced.

Mendelian genetics click this icon to hear the preceding term pronounced inheritance patterns which can be explained by simple rules of dominance and recessiveness of genes. modifying gene a gene that can alter the expression of another gene in the phenotype of an individual. monozygotic twins click this icon to hear the preceding term pronounced identical twins.

They are visible only under magnification during certain stages of cell division.

The ABO blood type system is an example.

Back to Top - J - Back to Top - K - Back to Top - L - Back to Top - M - meiosis click this icon to hear the preceding term pronounced cell division in specialized tissues of ovaries and testes which results in the production of sperm or ova.

albinism click this icon to hear the preceding term pronounced the genetically inherited condition in which there is a marked deficiency of pigmentation in skin, hair, and eyes.

The next and subsequent generations are referred to as f2, f3, etc. fragile-X syndrome click this icon to hear the preceding term pronounced a relatively common genetically inherited abnormality of the X chromosome which results in mental retardation.

See sex-controlled gene. sickle-cell trait a genetically inherited recessive condition in which red blood cells are distorted resulting in severe anemia and related symptoms that are often fatal in childhood.

Shortly after conception, regulator genes work as master switches orchestrating the timely development of our body parts.

Mendelian genetics click this icon to hear the preceding term pronounced inheritance patterns which can be explained by simple rules of dominance and recessiveness of genes. modifying gene a gene that can alter the expression of another gene in the phenotype of an individual. monozygotic twins click this icon to hear the preceding term pronounced identical twins.

The gene or genes for diabetes are incompletely penetrant. dominant allele an allele that masks the presence of a recessive allele in the phenotype.

It has been most common among the descendents of Eastern European Jews (Ashkenazi Jews). true breeding see purebred.

Such traits are said to be codominant. cross-pollination the mating of two genetically different plants of the same species.

Most fragile-X males have large testes, big ears, narrow faces, and sensory integration dysfunctions that result in learning disabilities.

In large populations, random deviations in allele frequencies in one direction are more likely to be cancelled out by random changes in the opposite direction. genetics click this icon to hear the preceding term pronounced the study of gene structure and action and the patterns of inheritance of traits from parent to offspring.

Most cells in multicellular plants and animals are somatic cells.

It has been most common among the descendents of Eastern European Jews (Ashkenazi Jews). true breeding see purebred.

Angelman syndrome click this icon to hear the preceding term pronounced a rare genetically inherited form of mental retardation due to the deletion or inactivation of specific genes on chromosome 15.

DNA click this icon to hear the preceding term pronounced (deoxyribonucleic acid click this icon to hear the preceding term pronounced) a large organic molecule that stores the genetic code for the synthesis of proteins.

Proteins may be enzymes, hormones, antibodies, structural components, or gas-transporting molecules. proteome click this icon to hear the preceding term pronounced the full complement of proteins produced by an individual (or a species).

See Human Genome Project. psoriasis click this icon to hear the preceding term pronounced an inherited disease characterized by recurring thick, reddish patches of inflamed skin.

Back to Top - D - diabetes click this icon to hear the preceding term pronounced an inherited metabolic disorder in which there are abnormally high blood sugar levels.

This disease is also called Huntington's chorea click this icon to hear the preceding term pronounced. hybrids click this icon to hear the preceding term pronounced offspring that are the result of mating between two genetically different kinds of parents--the opposite of purebred.

This decoding of the human proteome will be an even more daunting task than the original Human Genome Project.

In advanced stages, this often results in blindness from cataracts, nerve damage, gangrene in the feet and legs leading to amputation, heart disease, and kidney failure.

Punnett square click this icon to hear the preceding term pronounced a simple graphical method of showing all of the potential combinations of offspring genotypes that can occur and their probability given the parent genotypes.

Such traits are said to be codominant. cross-pollination the mating of two genetically different plants of the same species.

Angelman syndrome click this icon to hear the preceding term pronounced a rare genetically inherited form of mental retardation due to the deletion or inactivation of specific genes on chromosome 15.

Back to Top - J - Back to Top - K - Back to Top - L - Back to Top - M - meiosis click this icon to hear the preceding term pronounced cell division in specialized tissues of ovaries and testes which results in the production of sperm or ova.

See phenotype. gout click this icon to hear the preceding term pronounced a genetically inherited metabolic disorder in which there is an imbalance of uric acid in the blood which causes a build up of urates in joint areas.

Back to Top - H - hemophilia click this icon to hear the preceding term pronounced an X-linked genetically inherited recessive disease in which one or more of the normal blood clotting factors is not produced.

Such traits are said to be codominant. cross-pollination the mating of two genetically different plants of the same species.

Multiple-allele series only partly follow simple Mendelian genetics. multiple sclerosis click this icon to hear the preceding term pronounced (MS) a genetically inherited progressive disease of the central nervous system.

Genome imprinting is also known as genetic imprinting. genotype click this icon to hear the preceding term pronounced the genetic makeup of an individual.

Usually, only one joint is involved, most commonly the base of a big toe.

See phenotype. gout click this icon to hear the preceding term pronounced a genetically inherited metabolic disorder in which there is an imbalance of uric acid in the blood which causes a build up of urates in joint areas.

Huntington's disease a severe genetically inherited fatal degenerative nerve disorder.

Multiple-allele series only partly follow simple Mendelian genetics. multiple sclerosis click this icon to hear the preceding term pronounced (MS) a genetically inherited progressive disease of the central nervous system.

Back to Top - T - Tay-Sachs Disease click this icon to hear the preceding term pronounced a genetically inherited condition caused by the inability to produce the enzyme hexosaminidase A. This results in progressively increased fluid pressure on the brain and the subsequent degeneration of the brain and nervous system beginning about 6 months of age and inevitably resulting in death usually by age 2-3.

The next and subsequent generations are referred to as f2, f3, etc. fragile-X syndrome click this icon to hear the preceding term pronounced a relatively common genetically inherited abnormality of the X chromosome which results in mental retardation.

People who spend much of their first 16 years in tropical and subtropical regions of the world are much less likely to develop this disease than those who live in far northern and far southern regions of our planet.

Department of Energy.

Back to Top - D - diabetes click this icon to hear the preceding term pronounced an inherited metabolic disorder in which there are abnormally high blood sugar levels.

An individual with these traits is an "albino."

Humans have 46 chromosomes in each somatic cell and 23 in each sex cell. codominance click this icon to hear the preceding term pronounced the situation in which two different alleles for a trait are expressed unblended in the phenotype of heterozygous individuals.

Mendelian genetics click this icon to hear the preceding term pronounced inheritance patterns which can be explained by simple rules of dominance and recessiveness of genes. modifying gene a gene that can alter the expression of another gene in the phenotype of an individual. monozygotic twins click this icon to hear the preceding term pronounced identical twins.

Back to Top - Y - Back to Top - Z - zygote click this icon to hear the preceding term pronounced a "fertilized" ovum.

Back to Top - B - blending theory an incorrect 19th century theory about the inheritance of characteristics.

It is a sex-linked trait most often passed on to sons by their mothers.

albinism click this icon to hear the preceding term pronounced the genetically inherited condition in which there is a marked deficiency of pigmentation in skin, hair, and eyes.

Cystic fibrosis occurs as a result of inheriting a recessive allele for it from both parents.

The most common form, Duchene MD, begins to weaken the legs of boys by age 3 and inevitably gets worse with each passing year.

The genes controlling different traits are inherited independently of one another. principle of segregation Gregor Mendel's first principle of genetic inheritance.

Humans have 46 chromosomes in each somatic cell and 23 in each sex cell. codominance click this icon to hear the preceding term pronounced the situation in which two different alleles for a trait are expressed unblended in the phenotype of heterozygous individuals.

Cystic fibrosis occurs as a result of inheriting a recessive allele for it from both parents.

Mendelian genetics click this icon to hear the preceding term pronounced inheritance patterns which can be explained by simple rules of dominance and recessiveness of genes. modifying gene a gene that can alter the expression of another gene in the phenotype of an individual. monozygotic twins click this icon to hear the preceding term pronounced identical twins.

Genome imprinting is also known as genetic imprinting. genotype click this icon to hear the preceding term pronounced the genetic makeup of an individual.

Through his plant cross-breeding experiments, Gregor Mendel proved that this was wrong Back to Top - C - carrier an individual who is heterozygous for a trait that only shows up in the phenotype of those who are homozygous recessive.

Through his plant cross-breeding experiments, Gregor Mendel proved that this was wrong Back to Top - C - carrier an individual who is heterozygous for a trait that only shows up in the phenotype of those who are homozygous recessive.

Back to Top - J - Back to Top - K - Back to Top - L - Back to Top - M - meiosis click this icon to hear the preceding term pronounced cell division in specialized tissues of ovaries and testes which results in the production of sperm or ova.

Type 1 diabetes melitis (juvenile onset diabetes) is due to decreased production of insulin by the pancreas.

Back to Top - P - pangenesis click this icon to hear the preceding term pronounced Charles Darwin's incorrect theory about the inheritance of traits.

In advanced stages, this often results in blindness from cataracts, nerve damage, gangrene in the feet and legs leading to amputation, heart disease, and kidney failure.

Back to Top - T - Tay-Sachs Disease click this icon to hear the preceding term pronounced a genetically inherited condition caused by the inability to produce the enzyme hexosaminidase A. This results in progressively increased fluid pressure on the brain and the subsequent degeneration of the brain and nervous system beginning about 6 months of age and inevitably resulting in death usually by age 2-3.

This results in prolonged bleeding from even minor cuts and injuries.

Back to Top - D - diabetes click this icon to hear the preceding term pronounced an inherited metabolic disorder in which there are abnormally high blood sugar levels.

Since the gene for albinism is recessive, it only shows up in the phenotype of homozygous recessive people.

This was a variation of Lamarck's incorrect idea of the "inheritance of acquired characteristics." phenotype click this icon to hear the preceding term pronounced the observable or detectable characteristics of an individual organism--the detectable expression of a genotype. pleiotropy click this icon to hear the preceding term pronounced the situation in which a single gene is responsible for a variety of traits.

Multiple-allele series only partly follow simple Mendelian genetics. multiple sclerosis click this icon to hear the preceding term pronounced (MS) a genetically inherited progressive disease of the central nervous system.

See phenotype. gout click this icon to hear the preceding term pronounced a genetically inherited metabolic disorder in which there is an imbalance of uric acid in the blood which causes a build up of urates in joint areas.

Back to Top - B - blending theory an incorrect 19th century theory about the inheritance of characteristics.

This is ultimately a fatal disease, but with modern medical care, about 2/3 of the people with it survive into early adulthood.

HLA stands for "human leukocyte antigen" click this icon to hear the preceding term pronounced. homeotic gene click this icon to hear the preceding term pronounced see regulator gene. homologous chromosomes click this icon to hear the preceding term pronounced chromosomes that are paired during the production of of sex cells in meiosis.

Genes are responsible for the hereditary traits in plants and animals. genetic drift evolution, or change in gene pool frequencies, resulting from random chance.

Twins that come from the same zygote are essentially the same genetically.

Since viruses cannot reproduce without a host cell, they are not strictly speaking living organisms.

Since it is an X-linked trait, males more often have it expressed in their phenotypes.

DNA is composed of sugars, phosphates and bases arranged in a double helix shaped molecular structure.

Symptoms include painfully inflamed joints, especially of the feet and hands, that can become chronic and result in deformity.

In contrast, an acute disease is one with a rapid onset and a short but usually severe course. chromosomes click this icon to hear the preceding term pronounced thread-like, gene-carrying bodies in the nucleus of a cell.

Symptoms range from numbness and tingling to paralysis.

It states that different pairs of genes are passed to offspring independently so that new combinations of genes, present in neither parent, are possible.

They may be inherited or caused by diabetes and environmental factors. photo of a normal eye and another with a cataract chronic disease an illness that lasts for a long period of time or indefinitely.

This was a variation of Lamarck's incorrect idea of the "inheritance of acquired characteristics." phenotype click this icon to hear the preceding term pronounced the observable or detectable characteristics of an individual organism--the detectable expression of a genotype. pleiotropy click this icon to hear the preceding term pronounced the situation in which a single gene is responsible for a variety of traits.

There are 20 different kinds of amino acids in living things.

Viruses are not cells but rather RNA or DNA molecules surrounded by a protein coating.

Research to decode the human genome began in earnest in 1986, funded by the U.S.

In other words, the distribution of one pair of alleles does not influence the distribution of another pair.

Humans have 46 chromosomes in each somatic cell and 23 in each sex cell. codominance click this icon to hear the preceding term pronounced the situation in which two different alleles for a trait are expressed unblended in the phenotype of heterozygous individuals.

Gout is a sex-controlled trait, usually being more severe in men.

In advanced stages, this often results in blindness from cataracts, nerve damage, gangrene in the feet and legs leading to amputation, heart disease, and kidney failure.

The symptoms usually do not appear until early middle age.

Back to Top - B - blending theory an incorrect 19th century theory about the inheritance of characteristics.

Back to Top - I - incomplete penetrance the situation in which an allele is expressed only if certain factors are present in the environment.

In advanced stages, this often results in blindness from cataracts, nerve damage, gangrene in the feet and legs leading to amputation, heart disease, and kidney failure.

Type 1 diabetes melitis (juvenile onset diabetes) is due to decreased production of insulin by the pancreas.

This results in prolonged bleeding from even minor cuts and injuries.

Back to Top - Q - Back to Top - R - recessive allele click this icon to hear the preceding term pronounced an allele that is masked in the phenotype by the presence of a dominant allele.

Amino acids are primarily composed of carbon, oxygen, hydrogen, and nitrogen.

Regulator genes control the timing of production of a variety of chemicals in humans and other organisms.

See Human Genome Project. psoriasis click this icon to hear the preceding term pronounced an inherited disease characterized by recurring thick, reddish patches of inflamed skin.

See phenotype. gout click this icon to hear the preceding term pronounced a genetically inherited metabolic disorder in which there is an imbalance of uric acid in the blood which causes a build up of urates in joint areas.

Usually, the term is used in reference to the crossing of two pure breeding (homozygous) plants. cystic fibrosis click this icon to hear the preceding term pronounced a genetically inherited disease in children that results in chronic fluid development in the lungs, making breathing difficult.

The gene or genes for diabetes are incompletely penetrant. dominant allele an allele that masks the presence of a recessive allele in the phenotype.

The most common form, Duchene MD, begins to weaken the legs of boys by age 3 and inevitably gets worse with each passing year.

Such traits are said to be codominant. cross-pollination the mating of two genetically different plants of the same species.

See Human Genome Project. genome imprinting click this icon to hear the preceding term pronounced an inheritance pattern in which a gene will have a different effect depending on the gender of the parent from whom it is inherited.

Type AB blood is an example.

It has been most common among the descendents of Eastern European Jews (Ashkenazi Jews). true breeding see purebred.

It is likely to occur 1 in 1000 births.

In advanced stages, this often results in blindness from cataracts, nerve damage, gangrene in the feet and legs leading to amputation, heart disease, and kidney failure.

This is the case with hemophilia. cataract click this icon to hear the preceding term pronounced an impairment of vision caused by the lenses of the eyes becoming cloudy.

Back to Top - U - unit inheritance Gregor Mendel's idea that the characteristics of parents are passed on to descendants unchanged as units.

HLA stands for "human leukocyte antigen" click this icon to hear the preceding term pronounced. homeotic gene click this icon to hear the preceding term pronounced see regulator gene. homologous chromosomes click this icon to hear the preceding term pronounced chromosomes that are paired during the production of of sex cells in meiosis.

Department of Energy.

MD is characterized by a gradual, irreversible wasting of skeletal muscle.

Children with Angleman syndrome typically also have small heads, experience seizures, have pronounced speech impairment, are hyperactive, and have balance disorders.

Back to Top - B - blending theory an incorrect 19th century theory about the inheritance of characteristics.

The genes controlling different traits are inherited independently of one another. principle of segregation Gregor Mendel's first principle of genetic inheritance.

Usually, only one joint is involved, most commonly the base of a big toe.

The idea of a Human Genome Project began at a 1984 international conference in Utah.

A gene may be made up of hundreds of thousands of DNA bases.

MS occurs as a consequence of one's own immune system attacking the insulating sheath that normally protects neurons.

Proteins are composed of different combinations of amino acids assembled in chain-like molecules.

However, because they are different, their action may result in different expressions of that trait. amino acids click this icon to hear the preceding term pronounced small molecules that are the components of proteins.

Carriers often do not show any signs of the trait but can pass it on to their offspring.

The mid-range baritone male voice is an example.

Usually, only one joint is involved, most commonly the base of a big toe.

Type AB blood is an example.

Physically, a gene is a sequence of DNA bases that specify the order of amino acids in an entire protein or, in some cases, a portion of a protein.

Approximately 1 in 700 females are carriers of the gene for this trait.

They also have the same genes, but not necessarily the same alleles, at the same locus or location. homozygous click this icon to hear the preceding term pronounced having the same allele at the same locus on both members of a pair of homologous chromosomes.

The idea of a Human Genome Project began at a 1984 international conference in Utah.

albinism click this icon to hear the preceding term pronounced the genetically inherited condition in which there is a marked deficiency of pigmentation in skin, hair, and eyes.

See Human Genome Project. genome imprinting click this icon to hear the preceding term pronounced an inheritance pattern in which a gene will have a different effect depending on the gender of the parent from whom it is inherited.

They may be inherited or caused by diabetes and environmental factors. photo of a normal eye and another with a cataract chronic disease an illness that lasts for a long period of time or indefinitely.

Amino acids are primarily composed of carbon, oxygen, hydrogen, and nitrogen.

Symptoms include painfully inflamed joints, especially of the feet and hands, that can become chronic and result in deformity.

Probability is usually expressed as the ratio of the number of actual occurrences to the number of possible occurrences. proteins click this icon to hear the preceding term pronounced any of a large number of complex organic molecules that are composed of one or more chains of amino acids.

See somatic cell. sex-controlled gene a gene that can be inherited by both genders but is usually expressed differently in males and females.

Back to Top - P - pangenesis click this icon to hear the preceding term pronounced Charles Darwin's incorrect theory about the inheritance of traits.

Back to Top - U - unit inheritance Gregor Mendel's idea that the characteristics of parents are passed on to descendants unchanged as units.

MS occurs as a consequence of one's own immune system attacking the insulating sheath that normally protects neurons.

DNA is composed of sugars, phosphates and bases arranged in a double helix shaped molecular structure.

See sex cell. sperm click this icon to hear the preceding term pronounced a male sex cell or gamete. stuttering alleles defective alleles that have segments which are doubled in their transmission from generation to generation.

Back to Top - B - blending theory an incorrect 19th century theory about the inheritance of characteristics.

He proposed that hereditary particles in the body are affected by the things an individual does during his or her lifetime.

In advanced stages, this often results in blindness from cataracts, nerve damage, gangrene in the feet and legs leading to amputation, heart disease, and kidney failure.

Back to Top - E - evolution click this icon to hear the preceding term pronounced genetic change in a population of organisms that occurs over time.

Humans have 46 chromosomes in each somatic cell and 23 in each sex cell. codominance click this icon to hear the preceding term pronounced the situation in which two different alleles for a trait are expressed unblended in the phenotype of heterozygous individuals.

In the case of genetically inherited diseases, the result is increasingly severe symptoms each generation.

Genes are responsible for the hereditary traits in plants and animals. genetic drift evolution, or change in gene pool frequencies, resulting from random chance.

More precisely, it is the collective genotype of a population. genes click this icon to hear the preceding term pronounced units of inheritance usually occurring at specific locations, or loci, on a chromosome.

HLA system click this icon to hear the preceding term pronounced the body's genetically inherited system for recognizing and rejecting foreign tissues, such as transplanted organs.

Back to Top - D - diabetes click this icon to hear the preceding term pronounced an inherited metabolic disorder in which there are abnormally high blood sugar levels.

A zygote contains the full complement of chromosomes (in humans 46) and has the potential of developing into an entire organism.

Children with Angleman syndrome typically also have small heads, experience seizures, have pronounced speech impairment, are hyperactive, and have balance disorders.

Probability is usually expressed as the ratio of the number of actual occurrences to the number of possible occurrences. proteins click this icon to hear the preceding term pronounced any of a large number of complex organic molecules that are composed of one or more chains of amino acids.

The alleles for a trait occupy the same locus or position on homologous chromosomes and thus govern the same trait.

Usually, the term is used in reference to the crossing of two pure breeding (homozygous) plants. cystic fibrosis click this icon to hear the preceding term pronounced a genetically inherited disease in children that results in chronic fluid development in the lungs, making breathing difficult.

There is a correlation between the amount of sunlight that children are exposed to and the likelihood that they will develop MS later in life.

This is a pleiotropic trait. alleles click this icon to hear the preceding term pronounced alternate forms or varieties of a gene.

The loss or addition of individuals can easily change the gene pool frequencies of both the recipient and donor populations--that is, they can evolve. gene pool all of the genes in all of the individuals in a breeding population.

The symptoms usually do not appear until early middle age.

Carriers often do not show any signs of the trait but can pass it on to their offspring.

In advanced stages, this often results in blindness from cataracts, nerve damage, gangrene in the feet and legs leading to amputation, heart disease, and kidney failure.

Angelman syndrome click this icon to hear the preceding term pronounced a rare genetically inherited form of mental retardation due to the deletion or inactivation of specific genes on chromosome 15.

Since viruses cannot reproduce without a host cell, they are not strictly speaking living organisms.

Carriers often do not show any signs of the trait but can pass it on to their offspring.

DNA is composed of sugars, phosphates and bases arranged in a double helix shaped molecular structure.

Usually, the term is used in reference to the crossing of two pure breeding (homozygous) plants. cystic fibrosis click this icon to hear the preceding term pronounced a genetically inherited disease in children that results in chronic fluid development in the lungs, making breathing difficult.

The triggering of genetically inherited diabetes by obesity and possibly severe emotional stress is an example. intermediate expression the situation in which a heterozygous genotype results in a phenotype that is intermediate between those resulting from the homozygous genotypes.

Meiosis involves two divisions and results in four daughter cells, each containing only half the original number of chromosomes--23 in the case of humans.

See Human Genome Project. genome imprinting click this icon to hear the preceding term pronounced an inheritance pattern in which a gene will have a different effect depending on the gender of the parent from whom it is inherited.

They may be inherited or caused by diabetes and environmental factors. photo of a normal eye and another with a cataract chronic disease an illness that lasts for a long period of time or indefinitely.

Type 2 diabetes melitis is due to increased resistance of cells in the body to insulin.

Genome imprinting is also known as genetic imprinting. genotype click this icon to hear the preceding term pronounced the genetic makeup of an individual.

See sex-controlled gene. sickle-cell trait a genetically inherited recessive condition in which red blood cells are distorted resulting in severe anemia and related symptoms that are often fatal in childhood.

Back to Top - T - Tay-Sachs Disease click this icon to hear the preceding term pronounced a genetically inherited condition caused by the inability to produce the enzyme hexosaminidase A. This results in progressively increased fluid pressure on the brain and the subsequent degeneration of the brain and nervous system beginning about 6 months of age and inevitably resulting in death usually by age 2-3.

Usually, the term is used in reference to the crossing of two pure breeding (homozygous) plants. cystic fibrosis click this icon to hear the preceding term pronounced a genetically inherited disease in children that results in chronic fluid development in the lungs, making breathing difficult.

Human Genome Project a multinational research effort designed to identify and map the location of all human genes.

This is ultimately a fatal disease, but with modern medical care, about 2/3 of the people with it survive into early adulthood.

There is a progressive loss of muscle control that inevitably leads to paralysis and death.

The most common form, Duchene MD, begins to weaken the legs of boys by age 3 and inevitably gets worse with each passing year.

Since the gene for albinism is recessive, it only shows up in the phenotype of homozygous recessive people.

albinism click this icon to hear the preceding term pronounced the genetically inherited condition in which there is a marked deficiency of pigmentation in skin, hair, and eyes.

Human Genome Project a multinational research effort designed to identify and map the location of all human genes.

Mendelian genetics click this icon to hear the preceding term pronounced inheritance patterns which can be explained by simple rules of dominance and recessiveness of genes. modifying gene a gene that can alter the expression of another gene in the phenotype of an individual. monozygotic twins click this icon to hear the preceding term pronounced identical twins.

The initial stage of discovering all human DNA codons was completed early in 2001 at a cost of 2.7 billion dollars.

In humans, it is estimated that each individual possesses approximately 2.9 billion base units in his or her DNA.

Punnett squares are commonly used by genetics counselors to predict the odds of a couple passing on particular inherited traits. illustration of how to set up a Punnett square purebred click this icon to hear the preceding term pronounced offspring that are the result of mating between genetically similar kinds of parents--the opposite of hybrid.

Neither allele is dominant or recessive, so that both appear in the phenotype or influence it.

People who spend much of their first 16 years in tropical and subtropical regions of the world are much less likely to develop this disease than those who live in far northern and far southern regions of our planet.

The initial stage of discovering all human DNA codons was completed early in 2001 at a cost of 2.7 billion dollars.

Differences between monozygotic twins later in life are virtually always the result of environmental influences rather than genetic inheritance.

People who spend much of their first 16 years in tropical and subtropical regions of the world are much less likely to develop this disease than those who live in far northern and far southern regions of our planet.

Such chromosomes are alike with regard to size and also position of the centromere.

Recessive alleles are expressed in the phenotype when the genotype is homozygous recessive (aa). regulator gene a gene that can initiate or block the functions of other genes.

The idea of a Human Genome Project began at a 1984 international conference in Utah.

Shortly after conception, regulator genes work as master switches orchestrating the timely development of our body parts.

Most fragile-X males have large testes, big ears, narrow faces, and sensory integration dysfunctions that result in learning disabilities.

This is the case with hemophilia. cataract click this icon to hear the preceding term pronounced an impairment of vision caused by the lenses of the eyes becoming cloudy.

Genetics is the branch of science that deals with the inheritance of biological characteristics. genome click this icon to hear the preceding term pronounced the full genetic complement of an individual (or of a species).

Since the gene for albinism is recessive, it only shows up in the phenotype of homozygous recessive people.

See sex-controlled gene. sickle-cell trait a genetically inherited recessive condition in which red blood cells are distorted resulting in severe anemia and related symptoms that are often fatal in childhood.

This disease is also called Huntington's chorea click this icon to hear the preceding term pronounced. hybrids click this icon to hear the preceding term pronounced offspring that are the result of mating between two genetically different kinds of parents--the opposite of purebred.

albinism click this icon to hear the preceding term pronounced the genetically inherited condition in which there is a marked deficiency of pigmentation in skin, hair, and eyes.

DNA click this icon to hear the preceding term pronounced (deoxyribonucleic acid click this icon to hear the preceding term pronounced) a large organic molecule that stores the genetic code for the synthesis of proteins.

In advanced stages, this often results in blindness from cataracts, nerve damage, gangrene in the feet and legs leading to amputation, heart disease, and kidney failure.

In other words, the distribution of one pair of alleles does not influence the distribution of another pair.

There are 20 different kinds of amino acids in living things.

It is believed that the lack of abundant sun exposure early in life is somehow responsible for the later onset of MS. muscular dystrophy click this icon to hear the preceding term pronounced (MD) any of a group of inherited progressive muscle disorders caused by a defect in one or more genes that control muscle function.

For instance, a trait that has only one allele (A) can mutate to a new form (a).

DNA is composed of sugars, phosphates and bases arranged in a double helix shaped molecular structure.

In advanced stages, this often results in blindness from cataracts, nerve damage, gangrene in the feet and legs leading to amputation, heart disease, and kidney failure.

This disease also prevents normal absorption of fats and other nutrients from food.

Differences between monozygotic twins later in life are virtually always the result of environmental influences rather than genetic inheritance.

Most fragile-X males have large testes, big ears, narrow faces, and sensory integration dysfunctions that result in learning disabilities.

This disease is also called Huntington's chorea click this icon to hear the preceding term pronounced. hybrids click this icon to hear the preceding term pronounced offspring that are the result of mating between two genetically different kinds of parents--the opposite of purebred.

However, because they are different, their action may result in different expressions of that trait. amino acids click this icon to hear the preceding term pronounced small molecules that are the components of proteins.

Humans have 46 chromosomes in each somatic cell and 23 in each sex cell. codominance click this icon to hear the preceding term pronounced the situation in which two different alleles for a trait are expressed unblended in the phenotype of heterozygous individuals.

See phenotype. gout click this icon to hear the preceding term pronounced a genetically inherited metabolic disorder in which there is an imbalance of uric acid in the blood which causes a build up of urates in joint areas.

It is believed that the lack of abundant sun exposure early in life is somehow responsible for the later onset of MS. muscular dystrophy click this icon to hear the preceding term pronounced (MD) any of a group of inherited progressive muscle disorders caused by a defect in one or more genes that control muscle function.

People who spend much of their first 16 years in tropical and subtropical regions of the world are much less likely to develop this disease than those who live in far northern and far southern regions of our planet.

albinism click this icon to hear the preceding term pronounced the genetically inherited condition in which there is a marked deficiency of pigmentation in skin, hair, and eyes.

It has been most common among the descendents of Eastern European Jews (Ashkenazi Jews). true breeding see purebred.

The term is also frequently used to refer to the appearance of a new species.

Children with Angleman syndrome typically also have small heads, experience seizures, have pronounced speech impairment, are hyperactive, and have balance disorders.

Multiple-allele series only partly follow simple Mendelian genetics. multiple sclerosis click this icon to hear the preceding term pronounced (MS) a genetically inherited progressive disease of the central nervous system.

Viruses are not cells but rather RNA or DNA molecules surrounded by a protein coating.

They are also responsible for changes that occur in our bodies as we grow older.

This disease also prevents normal absorption of fats and other nutrients from food.

However, because they are different, their action may result in different expressions of that trait. amino acids click this icon to hear the preceding term pronounced small molecules that are the components of proteins.

Punnett square click this icon to hear the preceding term pronounced a simple graphical method of showing all of the potential combinations of offspring genotypes that can occur and their probability given the parent genotypes.

Human skin and hair color are polygenic traits.

They may be inherited or caused by diabetes and environmental factors. photo of a normal eye and another with a cataract chronic disease an illness that lasts for a long period of time or indefinitely.

Neither allele is dominant or recessive, so that both appear in the phenotype or influence it.

There are 20 different kinds of amino acids in living things.

Genetic drift occurs most rapidly in small populations.

There are 20 different kinds of amino acids in living things.