Meiosis Flashcards
1
Q
What are homologous chromosomes made up of?
A
One maternal copy (inherited from mom), one paternal copy (inherited from dad)
2
Q
What are cells other than gametes (sex cells) called?
A
Somatic cells
3
Q
How many pairs of chromosomes are there in the body?
A
23
4
Q
What are 4 haploid daughter cells produced by?
A
Reduction division
5
Q
What are the basics of meiosis 1? (first division)
A
- Homologous chromsome pairs separated (reduction division)
- Each intermediate cell produced is haploid (1 full set of genes instead of 2)
6
Q
What are the basics of meiosis 2? (second division)
A
- Chromatid separation
- 4 haploid daughter cells are produced
7
Q
What happens in prophase 1?
A
- Homologous chromosomes pair alongside eachother length ways (synapsis) to form a bivalent
- Parts of chromatid arms cross over each other + reform (chiasma)
- Reshuffles genes, new combos = makes new chromosomes that didnt exist before
- Nuclear envelope breaks down
8
Q
What happens in metaphase 1?
A
- Homologous chromosomes assemble along metaphase plate
- Independent assortment = arrangement of pairs on plate is random
- Random segregation = chromosomes pulled to opposite end of pole, randomly split
- Results in genetic variation
9
Q
How many combinations are possible?
A
2 to the power of num of chromosomes paired with
10
Q
What happens in anaphase 1?
A
- Homologous chromosomes pulled to opposite poles, chromatids stay joined
- DNA sections on chromatids break off + rejoin
- Chiasmata = point that chromatids break + rejoin
- Recombinant chromatids formed from exchange
- Genetic variation
11
Q
What happens in telophase 1?
A
- Chromosomes assemble at each pole + nuclear envelope reforms
- Chromosomes uncoil + cell undergoes cytokinesis + divides into 2 cells
- Reduction of chromosomes from diploid to haploid
12
Q
What happens in prophase 2?
A
- 2 daughter cells that each have 3 chromosomes are present
- Chromosomes, still consisting of 2 chromatids, condense + become visible again
- Nuclear envelope breaks down + spindle formation begins
13
Q
What happens during metaphase 2? (differs from metaphase 1)
A
- Individual chromosomes assemble on metaphase plate
- Due to crossing over, chromatids no longer identical so theres more independent assortment
- More genetic variation
14
Q
What happens in anaphase 2?
A
- Unlike anaphase 1, chromatids of individual chromosomes are pulled to opposite poles after division of centromeres
15
Q
What happens in telophase 2?
A
- Chromatids assemble at pole, chromosomes uncoil _ form chromatin again
- Nuclear envelope reforms + nucleolus becomes visible again
- Cytokinesis results in division of cells, forming 4 haploid genetically different daughter cells
