Date post: | 30-Jun-2015 |
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Technology |
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Meiosis
• Homologous chromosomes: a pair of chromosomes, one from each parent.
• Haploid (n): one set of chromosomes
• Diploid (2n): two sets of chromosomes
• n = number of chromosomes
What do we need to know?(background information)
Two major types of cells
• Somatic or body cells-(most of our cells)
examples: skin, stomach, brain, liver, blood cells, etc.
• Sex cells or germcells (also called gametes) ex. Egg and sperm
Within each somatic (body) cell are chromosomes
• Sex Chromosomes:the X and Y that determine the gender of an organism.
males- XYfemales- XX
• Autosomes: all of the other chromosomeschromosomes 1-22
What is Meiosis?• Meiosis makes
germ cells, eggs and sperm
• Meiosis is a cell division process that reduces the number of chromosomes byhalf
• There are two main stages of Meiosis.
Meiosis I
Crossing Over
• During prophase of Meiosis I, the homologous chromosomes form tetrads, which may exchange genetic information. This increases genetic variability and is called crossing over.
Independent Assortment of chromosomes
• The chromosomes line up during metaphase I at random which leads to genetic variability.
Inherited from mother (red)
Inherited from father (blue)
Meiosis II