1 meiosis 2 Making haploid cells 3 Most
- Slides: 23
1 meiosis
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Making haploid cells 3 • Most body cells are diploid (2 n) and undergo mitosis. • Gamete – reproductive cell is a haploid (n). • In humans these are eggs and sperms. • The gametes are found in organisms which reproduce sexually. • Then fertilization occurs when two gametes fuse to form the first cell of an organism.
4 23 23 46 The gametes form from germ cells through a process known as meiosis
meiosis Two stage form of nuclear division in which the number of chromosomes is halved Meiosis I – first division – reduces the number of chromosomes by half 5
Prophase I is the st 1 stage 6 • Chromosomes condense • The homologous chromosomes pair up. • Matching pairs of chromosomes – one from mom and one from dad. • The nuclear membrane disappears. • Spindle fibers form.
Crossing over occurs • Exchange of DNA segments on homologous chromosomes. • Creates unique chromosomes with each containing genetic material from each parent. • Contributes to evolution and adaptation 7
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Metaphase I Homologous pairs of chromosomes move to the middle of the cell 9
Anaphase I Homologous chromosomes are separated (pulled apart) by the spindle fibers. 10
Telophase I • 2 diploid cells form • Spindle fibers disappear 11
Meiosis II 12 2 nd division that separates copies of the chromosome CHROMOSOMES DO NOT DUPLICATE!
Prophase II • Spindle fibers form • Nuclear membrane disappears • NO CROSSING OVER 13
Metaphase II Chromosomes line up in the middle of the cell 14
Anaphase II Sister chromatids are separated 15
Telophase II • Nucleus reforms • Chromosomes uncoil forming chromatin • Spindle fibers disappear 16
Cytokinesis Cell division Cytoplasm pinches in half Haploid: 23 Chromosomes 17
Results of meiosis. 18 • 4 unique haploid cells • In males – 4 sperms • In females – 1 egg and 3 polar bodies (non-reproductive cell)
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Pg 344 21
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Compare Mitosis & Meiosis: pg 396 - 397 23 Mitosis: Meiosis: Same: Pg 345 - 349 Pg 394 - 395
- Two haploid cells
- Anapjase
- Produces diploid cells
- Homologous chromosome vs sister chromatid
- Telophase def
- Meiosis i vs meiosis ii
- Meiosis and mitosis
- Crossing over occurs during:
- Difference between meiosis 1 and meiosis 2
- Chapter 10 section 1: meiosis
- Chapter 10 meiosis 1 and meiosis 2 answer key
- Telophase
- Are diploid cells produced in meiosis
- How many cells are produced in meiosis? *
- Meiosis
- Whats a gamete
- Metaphase 2
- Sphenoid paranasal sinus
- Transport maximum
- Pineal gland
- Gametic cells vs somatic cells
- Somatic cells vs germ cells
- Red blood cells and white blood cells difference
- Prokaryotic versus eukaryotic