Cellular Reproduction

• * Bacterial Cells• 1. Binary Fission• * Eukaryotic Cells• 1. Mitosis• produces 2 daughter cells, genetically identical to

parent.• 2. Meiosis

• produces 4 daughter cells, each with half the genetic material of the parent. Produces gametes (i.e. eggs

and sperm)

Binary Fission

Mitotic Cell DivisionFunctions

• Development

• Differential expression of genes in daughter cells

• Allows for specialization of groups of cells in multi-cellular organisms

•Growth•Organisms can grow to adult size

•Maintenance and Repair•Organisms can replace old or damaged cells

Sexual Versus Asexual Reproduction

• Asexual reproduction uses mitosis

• Produces daughter cells that are genetically identical to the parents

• The daughter cells are diploid

• Allows for formation of clones

•Sexual reproduction uses meiosis•Produces gametes (i.e. eggs and sperm) with half the genetic material of the parent.•The daughter cells are haploid

Sexual Versus Asexual Reproduction

• Why did sexual reproduction evolve?

• Increase in genetic variation

• At least some of the offspring will be able to deal with changing environment

• At least some of the offspring may be able to find new niches for existence

• Some organisms have both sexual and asexual reproduction. When would they use one versus the other?

• Sexual during stress or times of environmental change

• Asexual during stable conditions

• Why?

The Cell Cycle

Division and cytokinesis in animals

Division and cytokinesis in plants

Note that in mitosis, all chromosomes line upin the center of the cells. The division will separate the sister chromatids.

Note that in meiosis I, homologous pairs ofchromosomes line up together. This first division will NOT separate the sister chromatids, just the homologous chromosomes.

In meiosis, the lining up of homologous chromosomes allows for crossing over (i.e.exchange of genetic information betweenthe homologous chromosomes).

Crossing over* and Random alignment of homologous pairs of chromosomes* combine with random mutations (which is also foundin mitosis) to create the higher geneticvariability associated with sexual reproduction.

Random alignment of chromosomes in meisis

Review Mitosis and Meiosis