1. Human Genetic Variation Basic terminology

2. What is a gene? A gene is a functional and physical unit of heredity passed from parent to offspring. Genes are pieces of DNA, and most genes contain information for making a specific protein. Genes exist in 2 forms at each location on a chromosome. These are called alleles. Alleles can be dominant or recessive.

3. What is DNA? DNA stands for Deoxyribonucleic Acid. It is the chemical in the nucleus of the cell that carries the genetic instructions for making living organisms.

4. Base Pairs Cytosine and Thymine = pyrimidines Adenine and Guanine = purines A purine always binds with a pyrimidine to form a base pair. A base pair makes up one “rung” on the DNA ladder (double-helix) Adenine-Thymine, Cytosine-Guanine

5. What is an amino acid? An amino acid is one of twenty different kinds of small molecules that link together in long chains to form proteins. Amino acids are referred to as the “building blocks” of proteins.

6. 20 amino acids ** you must memorize these ** Alanine Arginine Asparagine Aspartic acid Cysteine Glutamic acid Glutamine Glycine Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Proline Serine Threonine Tryptophan Tyrosine Valine

7. What is a chromosome? One of the threadlike “packages” composed of proteins, genes, and other DNA in the nucleus of a cell. Different kinds of organisms have different numbers of chromosomes. Humans have 23 pairs of chromosomes, 46 total chromosomes. 1 pair of sex chromosomes, 22 pairs of autosomal chromosomes.

8. Contribution Each parent contributes 1 chromosome to each pair, so children get ½ of their chromosomes from their mother and ½ from their father.

9. Put the following in order from smallest to largest: Gene Chromosome Amino acid DNA Nucleus Cell Protein