Chapter 8 (PART 2) Flashcards
***Diploid =
2n = 2 sets of CHROMOSOMES
***Germ cells are ____ goin in, end of mitosis they’re half way _______
diploid / gametes
***Haploid =
1n = 1 copy of chromosomes
Meiosis
-cell division that reduces a diploid cell’s chromosome # by HALF, producing haploid GAMETES
Homologous Chromosomes***
-PAIRS of similar chromosomes, one from each parent
-each species has a characteristic…
of chromosomes
W/O meiosis, chromosome #’s
grow dramatically
Meiosis includes one round of chromosome replication flowed by _____ divisions
TWO cell divisions
In Meiosis l…
diploid parent cell divides to produce TWO HAPLOID daughter cells containing REPLICATED chromosomes
- ONLY time you have homologous pairing
- 2 members of each homo pair are SEPARATED
Meiosis ll
-sister chromatids are SEPARATED
Down Syndrome is the result of having…
- 3 copies of chromosome 21
- 2 copies come from egg, ONE copy from sperm
Nondisjunction
- too many or too few chromosomes
- place in Meiosis l
Mitosis leads to ____ genetically identical daughter cells
TWO
Genetic variation arises through ______ ________ during Meiosis 1
genetic recombination
Crossing Over (c/o)
- trade parts btwn. homo chromosomes
- gives chance of more combinations
Independent Assortment
- chromosomes are given randomly along the equator of cell
- more combinations of MAternal & PAternal traits
Number of possible combinations of chromosomes is 2n, where “n” is the ______ #
haploid #
Resulting variations in offspring produce differences in…
fitness, raw material which natural selection acts
_______ reproduction may be advantage in constant environments
Asexual
Genetic variability made by _____ _______ may be helpful in CHANGEABLE environments
sexual reproduction
Mitosis accomplishes 2 things…
1) reproduction of cells
2) equal issuing of DNA to each daughter cell
Meiosis accomplishes 3 things:
1) reduces # of chromosomes by HALF so won’t be doubled during fertilization
2) c/o allows new combinations of maternal & paternal traits
3) provides more combinations of MAternal & PAternal traits
