6.1 Chromosomes and Meiosis Section 6-1: “Chromosomes and Meiosis” Write everything that is underlined

6.1 Chromosomes and Meiosis KEY CONCEPT Gametes (formed by Meiosis) have half the number of chromosomes that body cells have (which are formed by Mitosis).

6.1 Chromosomes and Meiosis In your body there are “body cells” and “gametes”. A.There are two categories of cells in your body. 1. Body cells (are also called somatic cells) - All Cells that are not Sex Cells are body cells Ex: muscle, nerve, liver cells body cells sex cells (sperm) sex cells (egg)

6.1 Chromosomes and Meiosis In your body there are “body cells” and “gametes”. 2. Gametes are sex cells: egg and sperm -Germ cells in the ovaries & testes develop into gametes -Only gametes have DNA that can be passed to offspring body cells sex cells (sperm) sex cells (egg)

6.1 Chromosomes and Meiosis B. All cells have two types of Chromosomes: Autosomes & Sex chromosomes 1. (Somatic Cells) Body cells have 23 pairs of chromosomes - Pairs 1-22 are called “autosomes” - Pair 23 (circled) are the Sex chromosomes, X and Y; they determine gender in Mammals. Your cells have autosomes and sex chromosomes.

6.1 Chromosomes and Meiosis Your cells have autosomes and sex chromosomes. 2. Each pair of chromosomes is “homologous” – they have the same genes For each homologous pair, one comes from each parent.

6.1 Chromosomes and Meiosis Body cells are diploid; gametes are haploid. C. Body cells have 2x as many chromosomes as Sex cells 1. Body cells are “DIPLOID” (2n) and have 2 copies of every chromosome – 44 autosomes and 2 sex chromosomes

6.1 Chromosomes and Meiosis Body cells are diploid; gametes are haploid. 2. Gametes are “HAPLOID” (n) and have one copy of every chromosome - Gametes have 22 autosomes and 1 sex chromosome

6.1 Chromosomes and Meiosis Body cells are diploid; gametes are haploid. - Chromosome number must be maintained in animals (from parent to daughter cells) - Many plants, however, have more than two copies of each chromosome.

6.1 Chromosomes and Meiosis Think Fast!!! Are the following diploid or haploid? Retinal nerve cells in the eye Cardiac muscle cells (heart cells)

6.1 Chromosomes and Meiosis Answer…. They are all Diploid, and have 2 copies of each chromosome

6.1 Chromosomes and Meiosis 1.Mitosis makes diploid body cells. - Takes place all throughout life - Is involved in asexual reproduction D. Mitosis and Meiosis are types of cell division … that make different types of cells for animals.

6.1 Chromosomes and Meiosis 2. Meiosis makes HAPLOID SEX CELLS from diploid cells in the ovaries and testes - Meiosis occurs in ovaries and testes only & makes gametes - Meiosis takes place only at certain times in life - Meiosis is involved in sexual reproduction

6.1 Chromosomes and Meiosis And… Which of the following is/are Haploid?

6.1 Chromosomes and Meiosis Answer … haploid diploid

6.1 Chromosomes and Meiosis Mitosis & Meiosis Graphic Organizer You have 4 minutes and 25 seconds to draw a graphic organizer to show (with words, chart, or a concept map) how these terms/ideas are related:You have 4 minutes and 25 seconds to draw a graphic organizer to show (with words, chart, or a concept map) how these terms/ideas are related: Chromosomes, Body Cells, Gametes, Blood Cells, Egg/Sperm, Mitosis, Meiosis, Diploid, Haploid, 46, 23, Homologous, Unique, Identical

6.1 Chromosomes and Meiosis Graphic Organizer Body Cells - Ex: Blood Cell Gametes - Ex: Egg/ Sperm MitosisMeiosis Chromosomes4623 diploidhaploidIdenticalUnique Homologous