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 Division
Functions
• 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 up
in the center of the cells. The division will
separate the sister chromatids.
Note that in meiosis I, homologous pairs of
chromosomes 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 between
the homologous chromosomes).
Crossing over* and Random alignment of
homologous pairs of chromosomes* combine
with random mutations (which is also found
in mitosis) to create the higher genetic
variability associated with sexual
reproduction.
Random alignment of chromosomes in meisis
Review Mitosis and Meiosis