Warm up Pre- Test

Traits What are some traits you inherited? How do you think these traits were passed to you?

Instructions for traits are on Chromosomes Contains DNA Genes Functional unit that controls the expression of an inherited trait Found in the Nucleus

Consist of DNA associated with proteins. Chapter 11 Complex Inheritance and Human Heredity Telomeres Consist of DNA associated with proteins. Ends of Chromosomes Protective function for the structure of the chromosome

Sister Chromatids C H R O M A T I D Centromere Telomere

Homologous Chromosomes Carry genes that control the same traits Same centromere position Same length

XX = Girl XY= Boy Humans Am I a Boy or Girl? 46 Chromosomes 23 Pairs of Chromosomes XX = Girl XY= Boy

How many chromosomes does each parent contribute? 23

Gametes Sex cells How many chromosomes?

Haploid and Diploid Haploid- Half set of chromosomes Diploid- Full set of chromosomes.

Diploid n chromosomes n chromosomes from female 2 n chromosomes n = # of chromosomes haploid- n # of chromosomes diploid- 2n # of chromosomes Gametes combine= Fertilization n chromosomes from female n chromosomes from male 2 n chromosomes Diploid

Recap How did you inherit genes from your parents? Both or one? How many chromosomes from each parent? Haploid vs. Diploid? Which are gametes?

Meiosis Gametes are formed Reduces the number of chromosomes....Why? Provides genetic variation Reduces the number of chromosomes....Why? 2n -> 1n

Two Divisions Meiosis I and Meiosis II Interphase Prophase I Prophase II Metaphase I Metaphase II Anaphase I Anaphase II Telophase I Telophase II

Meiosis I Interphase Growth Chromosome duplication

Meiosis I Prophase I Chromosomes become visible Crossing Over- Homologous Chromosomes exchange segments What’s occurring in this picture?

Meiosis I Metaphase I Homologous pairs line up Chromosome centromeres attach to spindle fibers.

Meiosis I Anaphase I Homologous chromsomes separate and move to opposite poles

Meiosis I Telophase I Homologous Chromosomes reach opposite poles. Cytokinesis takes place Two new cells are formed Each new cell has ½ the original genetic information

Meiosis II Prophase II Metaphase II Spindle Apparatus forms Chromosomes condense Metaphase II Haploid Chromosomes line up

Meiosis II Anaphase II Telophase II Sister chromatids are pulled apart and move toward opposite poles Telophase II Chromosomes reach poles Nuclear membrane and nuclei reform Cytokinesis 4 haploid cells with n chromosomes

Mitosis/ Meiosis Activity Work with a partner. Answer Questions Determine which cards are mitosis and which are meiosis Put the cards for each process in order

Quiz Infer why gametes are haploid? Analyze how traits are passed from one generation to the next.