Mitosis and Meiosis 2 Flashcards
1
Q
Describe Human Chromosomes
A
- Humans have 22 autosomal chromosomes, 1 pair of sex determining (23 total)
2
Q
Homologous chromatids
A
- result of obtaining one set of chromosomes from the male and one from the female parent
- contain the same set of genes that may differ slightly in sequence
3
Q
Prophase I
A
- pairing of homologous chromosomes, key difference between meiosis and mitosis
- structure called a tetrad
- has crossover
4
Q
Metaphase I
A
- tetrads within middle of cell
5
Q
Anaphase I
A
- each set of chromosomes migrate to opposite poles
- NOT sister chromatids, they are not identical anymore from crossing over
- each pair has 1 chromatid untouched, and that crossed over (both sides must receive a set of small, medium, and large)
6
Q
Telophase I
A
- cells with the same DNA content but not identical genomes
7
Q
Prophase II
A
- crossover DOES NOT OCCUR
- not true sister chromatids
8
Q
Metaphase II
A
- chromatids line up at metaphase plate
9
Q
Anaphase II
A
- chromatids are separated with each chromatid pulled to opposite poles
- both receive equal amounts of DNA
10
Q
Telophase II
A
- results in 4 cells each with half the chromosomes as the original cell
- notice each cell has a unique genome!!
11
Q
Nondisjunction
A
- chromatids fail to separate (in anaphase I or II, errors in meiosis)
- results in gametes and zygot with abnormal chromosome number
- Aneuploidy: variations in chromosome number that involve one or more chromosomes
12
Q
Nondisjunction in Anaphase 1 vs 2
A
- this mechanism will create bigger defects in anaphase I over anphase II, because chromosomes will not be spread evenly over two cells instead of one
13
Q
Normal Sex Chromosomes
A
- X Y, normal male
- XX, normal female
14
Q
Klinefelter syndrome
A
- female nondisjunction, XX–Y
- meiosis I, X–XY
- 47 chromosomes
15
Q
Turner syndrome
A
- female nondisjunction, –X
- male nondisjunction, X–
-meiosis II, X– - 45 chromosomes
