Download presentation
Presentation is loading. Please wait.
Published byDomenic Dawson Modified over 9 years ago
1
Meiosis and Sexual Reproduction Chapter 6 part 2
2
Mini-Quiz (not graded) Name the following steps in the cell cycle: a d b e c
3
Why Sex?
4
Introducing Alleles Sexual reproduction introduces variation in the combinations of traits among offspring Meiosis Process that enables organisms to make special reproductive cells (gametes)
5
Halving the Diploid Number A diploid cell has 2 nonidentical copies of every chromosome The pairs are homologous chromosomes meiosis changes diploid haploid, producing gametes Eggs and sperm have 23 unpaired chromosomes
7
Somatic cell Diploid # Homologous chromosomes
8
23 unpaired chromosomes Haploid # Gamete
9
Tour of Meiosis I
10
Tour of Meiosis II
12
How Meiosis Introduces Variation in Traits
13
Crossing Over in Prophase I Crossing over The process by which a chromosome and its homologous partner exchange DNA
14
Fig. 10-6b, p. 160 Crossing Over in Prophase I
15
Fig. 10-6c, p. 160 Crossing Over in Prophase I
16
Fig. 10-6d, p. 160 Crossing Over in Prophase I
17
Random Assortment Random assortment produces 10 23 (8,388,608) possible combinations of homologous chromosomes!!!
18
Sperm Formation in Animals
19
Egg Formation in Animals
20
Mitosis Fig. 10-11b, p. 165 one diploid nucleus two diploid nuclei ProphaseMetaphaseAnaphaseTelophase Chromosomes condense. Chromosomes align midway between spindle poles. Sister chromatids separate as they are pulled toward spindle poles. Chromosome clusters arrive at spindle poles. Bipolar spindle forms; it attaches chromosomes to spindle poles. New nuclear envelopes form. Nuclear envelope breaks up. Chromosomes decondense.
21
Meiosis I Fig. 10-11c, p. 164 one diploid nucleus two haploid nuclei Prophase I Chromosomes condense. Homologous chromosomes pair. Metaphase I Anaphase I Telophase I Crossovers occur. Chromosomes align midway between spindle poles. Homologous chromosomes separate as they are pulled toward spindle poles. Chromosome clusters arrive at spindle poles. Bipolar spindle forms; it attaches chromosomes to spindle poles. New nuclear envelopes form. Nuclear envelope breaks up. Chromosomes decondense.
22
Fig. 10-11d, p. 165 two haploid nucleifour haploid nuclei Prophase II Metaphase IIAnaphase IITelophase II Chromosomes condense. Chromosomes align midway between spindle poles. Sister chromatids separate as they are pulled toward spindle poles. Chromosome clusters arrive at spindle poles. Bipolar spindle forms; it attaches chromosomes to spindle poles. New nuclear envelopes form. Nuclear envelope breaks up. Chromosomes decondense. Meiosis II
23
Table of Differences Kind of cellKind of Reproduction ProphaseMetaphaseAnaphaseTelophase Mitosis Meiosis
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.