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Section 6-1 “Chromosomes & Meiosis”

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1 Section 6-1 “Chromosomes & Meiosis”
Write everything that is underlined

2 One of Biology’s Essential Questions:
At the end of this unit you will need to be able to answer this question … The Big Question: WHY ARE ALL HUMANS DIFFERENT????? …Look around the room- no one is exactly like you …Your siblings are not exactly like you (unless you have an identical twin) …There is an amazing process that makes us all different … meiosis

3 KEY CONCEPT: Gametes have half the number of chromosomes that body cells have

4 Fill out this chart for reference as we move along in our notes 
Term Definition Somatic Cell Gamete Homologous Chromosome Autosome Sex Chromosome Sexual Reproduction Fertilization Diploid Haploid Meisois

5 A. Body cells and gametes
1. Body cells are also called somatic cells 2. Gametes are sex cells: egg and sperm Gametes have DNA that can be passed to offspring (Psst…Fill out your vocabulary chart…) body cells sex cells (sperm) sex cells (egg)

6 Take a Vote!!!! Is a skin cell a somatic cell or a gamete? -Somatic Is an egg a somatic cell or a gamete? -Gamete What is a liver cell considered- somatic or gamete? What is another type of somatic cell? -Sperm Cell

7 B. Autosomes and sex chromosomes
Your body cells have 23 pairs of chromosomes The first 22 pairs of chromosomes are autosomes Sex chromosomes (X and Y) determine what gender you will be (male or female)

8 Homologous pairs of chromosomes have genes for the same traits
For each homologous pair, one chromosome comes from each parent

9 Think-Pair-Share (2 min.)
Do you believe that homologous chromosomes are identical to each other? Why or why not???

10 Diploid (2n) cells have two copies of every chromosome
C. Diploid and Haploid Diploid (2n) cells have two copies of every chromosome Body cells are diploid Half the chromosomes come from each parent

11 Haploid (n) cells have one copy of every chromosome
Gametes (sex cells) are haploid Gametes have 22 autosomes and 1 sex chromosome

12 Quick Thinking! You can write, draw, diagram, or write a quick song for your answer… Why is it so important that gametes are haploid cells? What would happen if, for some reason, it occurred that one wasn’t?

13 D. Fertilization: When the egg and sperm cell unite
2 haploid cells unite to form a cell (zygote) that once again has the diploid number of chromosomes Chromosome number must be maintained in animals Many plants have more than two copies of each chromosome A zygote grows to be a human

14 Mitosis makes more identical diploid cells
REMEMBER THIS Mitosis and meiosis are types of nuclear division that make different types of cells Mitosis makes more identical diploid cells

15 Meiosis makes haploid cells from diploid cells and:
occurs in sex cells produces gametes

16 Compare and Contrast MITOSIS and MEIOSIS on a separate sheet of paper based on what you already know about both. Turn in at the end of the period before you walk out the door. Differences go HERE Differences go HERE Things they have in common go HERE

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