CCR Biology DSL List 5 of your genetic traits you want to pass on to your children. Why those specific traits?

CCR Biology Agenda DSL Chromosome and Meiosis PowerPoint Meiosis Review Worksheet – Due Monday

CCR Biology Objectives I can compare mitosis and meiosis I can model the phases of meiosis

Chromosomes and Meiosis Genetics LT1 Unit 5: Genetics LT 1: Chromosomes and Meiosis

If stretched and laid end to end, the DNA in just one of your cells would be about 3 meters (10 feet) long. How does it fit inside the nucleus of a microscopic cell?

Condensing our DNA A chromosome is: thread of DNA and proteins in nucleus of eukaryotic cells consists of genes and regulatory information.

Chromosome Structure Pg. 139 DNA condenses tightly during the early stages of mitosis Stage 1: DNA double helix Stage 2: DNA and histones Stage 3: Chromatin Stage 5: Condensed, duplicated chromosome Stage 4: Supercoiled DNA

Region of chromosome that holds sister chromatids together Two identical chromatids that make up 1 chromosome

Exploring your cells and chromosomes You have many specialized cells in your body BUT they can be divided into 2 major groups: Somatic (body) cells Germ cells

Cell types Germ cells: Somatic (body) cells: cells in reproductive organs, the ovaries or testes Develop into gametes: sex cells – eggs in the female and sperm cells in the male DNA in gametes IS passed on to children Divide by MEIOSIS Somatic (body) cells: make up most of body tissue and organs Ex: spleen, kidneys, and eyeballs DNA in body cells is NOT passed on to offspring Divide by MITOSIS

Counting Chromosomes Each of your body cells contains a set of 46 chromosomes, which come in 23 pairs 23 from mom and 23 from dad These cells are genetically identical to each other unless mutations occurred Cells in your body differ because different genes are expressed … NOT because they have different genes

“Homologous pairs” Each pair of chromosomes is referred to a homologous pair Homologous chromosomes: 2 chromosomes – 1 from mom and 1 from dad – that have the same length and general appearance Autosomes: chromosome pairs 1 – 22 Contain genes not directly related to sex or organism Sex chromosomes: 23rd chromosome pair Controls development of sexual characteristics XX = Female XY = Male

TELOPHASE AND CYTOKINESIS Mitosis Review Occurs in somatic cells Consists of 4 stages Produces 2 genetically identical daughter cells PROPHASE METAPHASE ANAPHASE TELOPHASE AND CYTOKINESIS

Meiosis Occurs in germ cells Consists of 8 stages Produces 4 daughter germ cells with ½ the amount of DNA