Heredity Notes DNA- (Deoxyribonucleic acid)- genetic material that carries the information about an organism and is passed from parent to offspring. Humans contain 23 pairs of chromosomes- a total of 46 chromosomes (23 from mom and 23 from dad). DNA Heredity Heredity-the passing of traits from parents to offspring. Back to Nucleus DNA is loose strands in the nucleus (chromatin), but once a cell gets ready to divide, it produces condensed strands (Chromosomes). Chromosomes must replicate before they can divide. Why? You don’t want to lose half of yourself do you? DNA are made up four different nitrogen bases pairs. Adenine (A), Thymine (T), Guanine (G), Cytosine (C) are the nitrogen bases. Adenine always pairs with Thymine and Guanine always pairs with Cytosine. With these four base pairs, there are 8,000,000 possible outcomes between two parents and the arrangement of chromosomes. Heredity Vocabulary Gene- a set of information that controls a trait; a segment of DNA on a chromosome that codes for a specific trait (hair color, eye color, ear lobes). Traits- characteristics that an organism can be pass on to its offspring through its genes. Heredity Vocab Continued Alleles- the different forms of a gene. Homozygous trait- having two identical alleles for a trait. Heterozygous trait- having different alleles for a trait. Genotype- genetic make up. Phenotype- physical appearance or visible trait.