Chapter 10 Meiosis. Textbook pages 270 - 276. Reproduction. Reproduction - process of producing offspring . Some offspring are produced by two parents . Some offspring are produced by just one parent .
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Chapter 10 Meiosis
Textbook pages 270 - 276
Today were going to talk about sexual reproduction at the cellular level.
All cells contain chromosomes. There are two types of chromosomes found in the nucleus of cells:
Your body cells contain 23 pairs of
Your body cells contain 23 pairs of homologous chromosomes:
For each homologous pair, one chromosome comes from
mom and one comes from dad.
LOOK AT THE KARYOTYPE BELOW:
Chromosome pairs 1-22 are autosomes.
The 23rd pair are the sex chromosomes: X and Y which determinegender:
- diploid (2n)
Diploid (2n) cells – have two copies
of every chromosome
- half the chromosomes come from each parent
- sex cells (sperm and egg)
- have DNA that can be
passed to offspring
- haploid (n)
Haploid (n) cells – have one copy of each chromosome
- gametes have 22 autosomes and 1 sex chromosome
MITOSIS AND MEIOSIS
Mitosis and meiosis are types of nucleardivision that
make different types of cells.
- occurs in sex cells
- Makes 4 haploid cells from diploid cells
- produces gametes
- occurs in somatic cells
- makes more diploid cells
Make a Venn diagram to compare and
Contrast Mitosis and Meiosis!
Meiosis reduces the chromosome number
and creates genetic diversity.
Cells go through two rounds of division in meiosis:
Sounds familiar right???
Crossing Over Creates Genetic diversity
**During Telophase I Cytokinesis occurs at the same time!!**
Haploid cells develop into mature gametes:
Gametogenesis - the production of gametes
- differs between females and males
Sources of Variations and Differences
1. Crossing over
2. Random assortment of chromosomes
EGG = 46 CHROMOSOMES SPERM = 46 CHROM.
ZYGOTE = 46 + 46 = 92 CHROMOSOMES =