1. A the 1st letter of the Roman alphabet
  2. ATP a nucleotide derived from adenosine that occurs in muscle tissue; the major source of energy for cellular reactions
  3. ADD a condition (mostly in boys) characterized by behavioral and learning disorders
  4. ATM an unattended machine (outside some banks) that dispenses money when a personal coded card is used
  5. 101 being one more than one hundred
  6. ADP an ester of adenosine that is converted to ATP for energy storage
  7. 100 ten 10s
  8. AAA an aneurysm of the abdominal aorta associated with old age and hypertension
  9. ALS thickening of tissue in the motor tracts of the lateral columns and anterior horns of the spinal cord; results in progressive muscle atrophy that starts in the limbs
  10. ABC the elementary stages of any subject (usually plural)
  11. ADA an enzyme found in mammals that can catalyze the deamination of adenosine into inosine and ammonia
  12. ADH hormone secreted by the posterior pituitary gland (trade name Pitressin) and also by nerve endings in the hypothalamus; affects blood pressure by stimulating capillary muscles and reduces urine flow by affecting reabsorption of water by kidney tubules
  13. AIDS a serious (often fatal) disease of the immune system transmitted through blood products especially by sexual contact or contaminated needles
  14. .22 a .22 caliber firearm (pistol or rifle)
  15. 3-D having a three-dimensional form or appearance
  16. ACE proteolytic enzyme that converts angiotensin I into angiotensin II
  17. AFL a federation of North American labor unions that merged with the Congress of Industrial Organizations in 1955
  18. ASL the sign language used in the United States
  19. AMP a nucleotide found in muscle cells and important in metabolism; reversibly convertible to ADP and ATP
  20. 1st indicating the beginning unit in a series