genetics

the study of heredity and natural variation.

how traits are passed from parents to their children.

• we inherit one set of chromosomes from each parent (how we are similar to them) • because we get different combinations of genes and because small differences (natural variation) which makes each person unique

result of inherited characteristics and the environment. Reason individuals look different.

Traits are passed through genes. Each parent contributes one allele for each gene through their gametes (egg and sperm). The combination of alleles determines the offspring’s traits.

chemical molecule that carries genetic information.

sections of DNA that act as instructions for specific traits or proteins.

long, tightly coiled strands of DNA that contain many genes.

DNA makes up genes, and genes are found on chromosomes.

Genes provide the instructions for a trait, and the environment affects how strongly or how those instructions are expressed, together determining the phenotype.

• double helix • sugar-phosphate backbone • bases (rungs of the ladder) • complementary strands

: Phosphate, Deoxyribose sugar, Nitrogenous base

the rungs are made of pairs of nitrogen bases - adenine (A) - thymine (T) - cytosine (C) - guanine (G)

they pair in a specific way called base pairing A pairs with T C pairs with G

The sequence of bases (A, T, C, G) forms a code. The order determines which protein is made.

DNA base sequence → determines amino acid sequence → amino acids join to form a protein → proteins determine traits.

a package of DNA that carires genes

instructions for traits and how the body works

in the nucleus of a cell

humans have 46 chromosomes in body cells (23 pairs) and 23 sec cells

any cell that has 2 sets of chromosomes. e.g humans 46 in body cells

any cell that has 1 set of chromosomes e.g humans 23 in sex cells

Sister chromatids: Identical copies of a chromosome.

Centromere: The point where sister chromatids are joined.