Sexual Reproduction and Genetics Chapter 10 Sexual Reproduction and Genetics

Chapter 10.1 Meiosis

Chromosomes Structures that contain the genetic material that is passed from generation to generation of cells. Homologous Chromosomes – make up a pair. Human body cells have 46 chromosomes, each parent contributes 23 chromosomes. 23 pairs of chromosomes per cell. Carry genes that control the same inherited traits. Genes – segments on the DNA that determine the characteristics and functions of the cell.

Haploid vs. Diploid Cells Gametes – sex cells that have half the number of chromosomes This is done to maintain the same number of chromosomes from generation to generation. Haploid (n) Cells – cells with only one set of chromosomes In humans this would be 23 Diploid (2n) Cells – cells with 2n number of chromosomes In humans this would be 46 Fertilization – process in which a a haploid gamete combines with another haploid gamete.

Sexual v. Asexual Reproduction Read the section Sexual Reproduction v. Asexual Reproduction on p. 276. Compare and contrast these types of reproduction by recreating the table in your notebook. Sexual Reproduction Asexual Reproduction

Sexual v. Asexual Reproduction Read the section Sexual Reproduction v. Asexual Reproduction on p. 276. Compare and contrast these types of reproduction by recreating the table in your notebook. Sexual Reproduction Asexual Reproduction Two parents Offspring are genetically different from parents Genetic variation each generation Most Plants & Animals One parent Offspring are genetically identical to parent Bacteria (and most protists)

Important Vocabulary Read through Chapter 10.1 and define the following terms in the table below: Vocabulary Definition Gene Homologous chromosomes Gamete Haploid Fertilization Diploid Meiosis Crossing over

Important Vocabulary Read through Chapter 10.1 and define the following terms in the table below: Vocabulary Definition Gene DNA segments that control the production of proteins (and traits) Homologous chromosomes Paired chromosomes; one chromosome from each parent Gamete Sex cell (sperm or egg); contain HALF the number of chromosomes Haploid (n) A cell with one set of chromosomes (n) Fertilization Process where one haploid gamete joins another haploid gamete Diploid (2n) A cell with two sets of chromosomes (one set from each parent) Meiosis Cell division that reduces the number of chromosomes Crossing over Process where chromosome segments are exchanged between homologous pairs

Meiosis Process in which gametes are formed. Type of cell division that reduces the number of chromosomes; called a reduction division. Reduces chromosome number by the separation of homologous chromosomes. 2n n Occurs in the reproductive structures of organisms that reproduce sexually. Involves two consecutive cell divisions called meiosis I and meiosis II

Animations http://www.biostudio.com/d_%20Meiosis.htm   http://www.stolaf.edu/people/giannini/flashanimat/celldivision/meiosis .swf http://www.sumanasinc.com/webcontent/animations/content/meiosis .html http://www.cellsalive.com/meiosis.htm http://www.johnkyrk.com/meiosis.html http://highered.mcgraw- hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072 437316/120074/bio16.swf::Unique Features of Meiosis

Meiosis I

Interphase and Meiosis I

Meiosis II

Crossing over During prophase, the homologous chromosomes exchange segments of DNA

Mitosis and Meiosis Mitosis Meiosis One division Two divisions (meiosis I and II) DNA replication during interphase Homologous chromosomes do NOT pair up Homologous chromosomes pair up Daughter cells are genetically identical Daughter cells are not genetically identical (crossing over occurs) Mitosis occurs in body cells only Meiosis occurs in reproductive cells Mitosis involved in growth and repair Meiosis involved in producing gametes and increasing genetic variation