Chromosomes & Genes Packet #32 Chapter #13 Thursday, November 15, 2018

Types of Reproduction 11/15/2018

Types of Reproduction Reproduction occurs at two levels Organism Reproduction Sexual Reproduction Humans Asexual Bacteria 11/15/2018

Types of Reproduction II Cellular Reproduction Sexual Reproduction Meiosis Involves the combining of genes from two different individuals into new arrangements Genes are arranged (sorted) into new arrangements. Asexual Reproduction Mitosis (Cell Cycle) Involves the production of a new organism of species from a cell or cells of a single parent. Reproduction without the sorting of genes. 11/15/2018

The Cell Theory—Revisited Scheleiden and Schwann stated that cells are the fundamental unit of life. Virchow stated that cells arise from preexisting cells. Weismann described that cells have a “common ancestor.” What is the relationship between the cell theory and cellular reproduction? 11/15/2018

Chromosomes & Genes 11/15/2018

Chromosomes Chromosome Genes Chromosome set A linear end to end arrangement of genes, other DNA and associated proteins. Genes Segments of DNA, that code for an observable or biochemical characteristic (phenotype). Chromosome set Represented by the letter n, contains a specified number of chromosomes. 2n represents two chromosome sets. Focus will be on eukaryotic cells. Thursday, November 15, 2018

Ploidy 11/15/2018

Haploid vs. Diploid Cells Ploidy Number of sets of chromosomes in the nucleus of a cell. Haploid A cell having one chromosome set Human Sperm 1 set of 23 chromosomes Female Egg 1 set of 23 chromosomes In human sex cells n, we represent the chromosome set by n Diploid A cell having 2 chromosome sets As an individual, human somatic cells contain 46 chromosomes (23 + 23) In human somatic cells, we represent the sets by 2n (2 * 23 chromosomes) Sex cells still have 1 set of 23 chromosomes More on ploidy to come later Aneuploidy Euploidy Thursday, November 15, 2018

Other Important Information 11/15/2018

Chromatids Chromatid Crossing over One of the two side-by-side replicas produced by chromosome division Centromere Place where chromatids are held together Crossing over Genetic material can be exchanged during mitosis (rarely) and meiosis during crossing over. Occurs at a location called the chiasma/chiasmata. More to come on the vocabulary found on this slide later… 11/15/2018

Meiosis & Mitosis Connection What is the relationship between meiosis and mitosis (cell cycle)? Thursday, November 15, 2018