Genetics Tool Box –Intro. Genetic Variation and Change Segrega-tion pg 99 Mutations pg 93 Beneficial / Harmful Sources of variation Sexual Reproduction Independent assortment pg 101 Crossing over pg 102 Where, when , how? Gene Pools pg 92 Linkage pg 103 Genetics Tool Box –Intro. Genetic Variation and Change Mendelian Genetics Pg 109 Population Genetics pg 123 Changes to allele frequencies Using monohybrid crosses Using dihybrid crosses pg 113 Lethal alleles pg 110 Co-dominance pg 109 Indepen-dent assortment pg 114 Genetic Drift pg 126 Natural selection pg 132 Migration pg 126 Incomplete dominance pg 109 Multiple alleles pg 110 Linkage pg 118

Introduction – Genetics Toolbox Todays keywords: Homologous: refers to chromosomes in which one set comes from the male parent and one set comes from the female parent. Haploid: a cell or organism having two sets of chromosomes; one from each parent. Diploid: a cell or organism having a single set of chromosomes. Chromosome: threadlike structure within the nucleus containing the genetic information that is passed from one generation of cells to the next. Autosome: any chromosome that is not a sex chromosome.

DNA facts Parents and children share 99.5% of the same DNA You share 98% of your DNA with a chimpanzee You share 40% of your DNA with a cabbage If you could type 60 words per minute, eight hours a day, it would take approximately 50 years to type the human genome (all the bases in the DNA in one cell)

DNA Double stranded molecule made from nucleotides (sugar, phosphate + base) Cytosine forms hydrogen bonds with Guanine Thymine forms hydrogen bonds with Adenine Found in the nucleus of all eukaryotic cells, found as a loop in prokaryotic cells. Carries the genetic code – the instructions for joining amino acids into proteins If you put all the DNA molecules in your body end to end, the DNA would reach from the Earth to the Sun and back over 600 times (100 trillion times six feet divided by 92 million miles).

Genes Are sections of DNA made up of many bases which carry the instructions to make a particular protein. Can code for a particular protein or make an enzyme which allows a cellular process to be carried out.

Chromosomes Formed from DNA coiled around proteins. Only visible during mitosis and meiosis when chromosomes condense Each arm of a replicated chromosome is celled a chromatid.

Chromosomes in the human cell We have 46 chromosomes which exist in 23 homologous pairs Each chromosome pair is the same size and contains the same alleles. One of each pair comes from each parent. A cell which contains both pairs of homologous chromosomes (a normal body cell) is called DIPLOID

During meiosis The chromosomes replicate, pair up(crossing over occurs), separate, cells divide, cells divide again (with one of each homologous pair in each cell)  gametes Gametes are haploid

Human Karyotypes = all homologous pairs lined up in size order

Autosomes vs Sex Chromosomes Autosomes are non-sex chromosomes each with the same sized homologous pairs Sex chromosomes determine the sex of an organism and the male and female chromosomes are usually different sizes. Autosomal dominant = a dominant trait found on a normal chromosome

Quiz How many chromosomes are in a haploid human cell? How many cells are produced during meiosis? What can a gene carry instructions for? What is a homologous pair? What is an autosome?