Chapter thirteen: Meiosis and Sexual life cycle

Main questions:
1.What is the two type of reproduction ways?

Asexual and sexual reproduction

2.What are the disadvantages of asexual reproduction?

No new DNA combinations for evolution to work on. Clones may become extinct if attacked by a disease or pest

3.What is the disadvantage of sexual reproduction?

Need two parents. Good gene combinations can be lost. Offspring may not be an improvement over the parents.
Main Facts:

1. The steps of Meiotic division of an animal cell:

Prophase I, Metaphase I, Anaphase I, Telophase I and Cytokinesis, Prophases II, Metaphase II, Anaphase II and Telophase II and cytokinese.

2. Mitosis occurs during interphase before mitosis begins. Meiosis occurs during interphase before meiosis I begins.

3. In Meiosis II sister chromatids separate and form four chromosomes.

4. Meiosis reduces the number of chromosome sets from diploid to haploid

5.Genetic variation produced in sexual life cycles contributes to evolution.

Summary:

Key terms:
1. Heredity: The transmission of traits from one generation to the next.

2. Gametes: a haploid reproductive cell, such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote.

3. Sexual reproduction: a type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from the gametes of the parents.

4. Asexual reproduction: The generation of offspring from a single parent that occurs without the fusion of gametes.

5. Somatic cell: any cell in a multi-cellular organism except a sperm or egg.

6. Karyotype: a display of the chromosome pairs of a cell arranged by size and shape.

7. Homologous chromosomes: a pair of chromosomes of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci.

8. Sex chromosomes: a chromosome responsible for determining the sex of an individual.

9. Autosomes: a chromosome that is not directly involved in determining sex; not a sex chromosome.

10. Fertilization: the union of haploid gametes to produce a diploid zygote.

Video: http://www.youtube.com/watch?v=D1_-mQS_FZ0