genetics

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definitions & notes only words
  1. dominant allele
    an allele that produces the same phenotype whether its paired allele is identical or different
    The Nature of Alleles

    A dominant allele is an allele that is almost always expressed, even if only one copy is present.
  2. coding DNA
    sequence of a gene's DNA that transcribes into protein structures
    Another class of non- coding DNA is the "pseudogene", so named because it is believed to be a remnant of a real gene that has suffered mutations and is no longer functional.
  3. centromere
    a specialized condensed region of each chromosome that appears during mitosis where the chromatids are held together to form an X shape
    The most highly repeated sequences found so far in mammals are called "satellite DNA" because their unusual composition allows them to be easily separated from other DNA. These sequences are associated with chromosome structure and are found at the centromeres (or centers) and telomeres (ends) of chromosomes.
  4. phenotypic
    of or relating to or constituting a phenotype
    These expressed, or phenotypic, traits are attributable to genotypic variation in a person's DNA sequence.
  5. genotypic
    of or relating to or constituting a genotype
    These expressed, or phenotypic, traits are attributable to genotypic variation in a person's DNA sequence.
  6. allele
    any of the forms of a gene that can occupy the same locus
    Methylation also plays an important role in genomic imprinting, which occurs when both maternal and paternal alleles are present but only one allele is expressed while the other remains inactive.
  7. recessive allele
    an allele that produces its characteristic phenotype only when its paired allele is identical
    On the other hand, a recessive allele will be expressed only if there are two identical copies of that allele, or for a male, if one copy is present on the X chromosome.
  8. prokaryote
    a unicellular organism lacking a membrane-bound nucleus
    The location and base sequence of each promoter site vary for prokaryotes (bacteria) and eukaryotes (higher organisms), but they are both recognized by RNA polymerase, which can then grab hold of the sequence and drive the production of an mRNA.
  9. phenotype
    observable characteristics produced by genes and environment
    When two individuals display different phenotypes of the same trait, they are said to have two different alleles for the same gene.
  10. eukaryote
    an organism of one or more cells with membrane-bound nuclei
    The location and base sequence of each promoter site vary for prokaryotes (bacteria) and eukaryotes (higher organisms), but they are both recognized by RNA polymerase, which can then grab hold of the sequence and drive the production of an mRNA.
  11. gamete
    a mature sexual reproductive cell
    This is because mitochondria are only found in the female gametes or "eggs" of sexually reproducing animals, not in the male gamete, or sperm.
  12. gene expression
    conversion of the information encoded in a gene first into messenger RNA and then to a protein
    Genes code for proteins that attach to the genome at the appropriate positions and switch on a series of reactions called gene expression.
  13. mitochondrion
    part of a cell involved in energy production
    Organelle DNA

    Not all genetic information is found in nuclear DNA. Both plants and animals have an organelle-a "little organ" within the cell- called the mitochondrion.
  14. ribosome
    a particle in a cell that helps synthesize proteins
    Because mitochondria have their own DNA, RNA, and ribosomes, this scenario is quite possible.
  15. heterozygous
    having dissimilar alleles at corresponding chromosomal loci
    If the alleles are different, they are said to be heterozygous.
  16. blood type
    human blood cells that have the same antigens
    Then there are the not so obvious genetic variations, such as blood type.
  17. meiosis
    cell division that produces reproductive cells
    Meiosis is the mode of cell replication for the formation of sperm and egg cells in plants, animals, and many other multicellular life forms.
  18. gene
    part of DNA controlling physical characteristics and growth
    The biological information contained in a genome is encoded in its deoxyribonucleic acid (DNA) and is divided into discrete units called genes.
  19. DNA
    a long linear polymer found in the nucleus of a cell
    The biological information contained in a genome is encoded in its deoxyribonucleic acid ( DNA) and is divided into discrete units called genes.
  20. organelle
    a specialized part of a cell; analogous to an organ
    Organelle DNA

    Not all genetic information is found in nuclear DNA. Both plants and animals have an organelle-a "little organ" within the cell- called the mitochondrion.
  21. homozygous
    having identical alleles at corresponding chromosomal loci
    If both alleles are the same, the gene is said to be homozygous.
  22. chromosome
    a threadlike strand of DNA that carries genes
    In 1909, Danish botanist Wilhelm Johanssen coined the word gene for the hereditary unit found on a chromosome.
  23. mutation
    a change or alteration in form or qualities
    There are many diseases caused by mutations in mitochondrial DNA (mtDNA).
  24. recessive
    of or pertaining to a recession
    These factors each exhibit a characteristic dominant, co-dominant, or recessive expression, and those that are dominant will mask the expression of those that are recessive.
  25. mitosis
    the process by which a cell divides into two smaller cells
    Cells that compose tissues in multicellular organisms typically replicate by organized duplication and spatial separation of their cellular genetic material, a process called mitosis.
  26. genetic code
    the ordering of nucleotides in DNA molecules that carries the genetic information in living cells
    The genetic code carried by DNA is what specifies the order and number of amino acids and, therefore, the shape and function of the protein.
  27. cell
    the basic structural and functional unit of all organisms
    Genes instruct each cell type- such as skin, brain, and liver-to make discrete sets of proteins at just the right times, and it is through this specificity that unique organisms arise.
  28. dominant gene
    gene that produces the same phenotype in the organism whether or not its allele identical
    Just how the dominant allele overshadows the other allele depends on the gene, but in some cases the dominant gene produces a gene product that the other allele does not.
  29. dominant
    most frequent or common
    These factors each exhibit a characteristic dominant, co-dominant, or recessive expression, and those that are dominant will mask the expression of those that are recessive.
  30. trait
    a distinguishing feature of your personal nature
    Another way to think of genomic imprinting is as "parent of origin differences" in the expression of inherited traits.
  31. homologous
    similar in position, structure, function, or characteristics
    The term diploid describes a state in which a cell has two sets of homologous chromosomes, or two chromosomes that are the same.
  32. fertilization
    making productive by adding nutrients
    However, when the sperm enters the egg during fertilization, the tail falls off, taking away the father's mitochondria.
  33. inherit
    receive from a predecessor
    Unlike nuclear DNA (the DNA found within the nucleus of a cell), half of which comes from our mother and half from our father, mitochondrial DNA is only inherited from our mother.
  34. inherited
    occurring among members of a family usually by heredity
    Unlike nuclear DNA (the DNA found within the nucleus of a cell), half of which comes from our mother and half from our father, mitochondrial DNA is only inherited from our mother.
Created on August 20, 2010

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