Generating Diversity III Flashcards
What are the main characteristics of meiosis in animals? (4 things)
- diploid phase dominates
- haploid phase shortened
- meiosis is followed by gamete formation
- fertilization creates diploid cells
What are the main characteristics of meiosis in most plants and some fungi? (4 things)
- similar to animals but they produce diploids called sporophytes
- spores are not gametes
- in plants, female gametophyte is in flower, males is in pollen
- sperm+egg- diploid zygote- mitosis- diploid sporophyte
What are the main characteristics of meiosis in most fungi? (2 things)
- diploid phase is limited
- +/- haploids fuse- diploid nucleus- mitosis- haploid spores
What are the characteristics of meiosis and chromosome numbers? (3 things)
- functions to create difference
- occurs only in specialized tissues
- one chromosome pair from the male parent, other from the female parent
What are the 3 steps in genetic recombination?
- Homologous DNA regions paired up, enzymes break bonds in backbone
- Free ends of backbone are exchanged
- Bonds reform
What is genetic recombination?
cutting and pasting of DNA backbones into new combinations
What is non-disjunction?
chromosome pairs are not separated and end up at the same pole, results in one gamete having 2 copies of a chromosome
How random segregation contribute to genetic diversity?
in pro metaphase I spindles attach randomly to pairs which randomizes the DNA sent to daughter cells
How does genetic recombinations contribute to genetic diversity?
synaptomal complex holds pairs together allowing them to exchange sections of DNA via enzymes end result is 2 cells with recombined alleles, 2 with parental alleles
Where are the 4 places that genetic diversity happens?
- Recombination
- Anaphase I
- Anaphase II
- Fertilization
What are the 9 stages of meiosis?
- Prophase I
- Prometaphase I
- Metaphase I and Anaphase
- Telophase I and Interkinesis
- Prophase II
- Prometaphase II
- Metaphase II
- Anaphase II
- Telophase II
What happens in Prophase I?
- sister chromatids condense and put in pairs through synapsis to form a tetrad
- pairs physically exchange DNA
- spindle forms
What happens in Prometaphase I?
- nuclear envelope breaks down
- chromosomes attach to kinetochore, both sister chromatids attached to same spindle pole
What happens in Metaphase I and Anaphase?
- tetrads aligned on metaphase plate
- homologous pairs separate and move to opposite spindle poles
- chromosomes at poles still sister chromatids
What happens in Telophase I and Interkinesis?
- new nuclear envelope reforms
- spindle from first division dissemble and microtubules reassemble into new spindles for second division
- no DNA replication
