Meiosis

Question 1

what is meiosis

Answer 1

Sexual reproduction which leads to gametes, in which the number of chromosomes is reduced to half

Question 2

fertilization

Answer 2

two haploid gametes fuse and restore the number of chromosomes to its diploid value

Question 3

What is the difference between mitosis and meiosis

Answer 3

• mitosis has single cell division and meiosis has two divisions
• mitosis has the same number of chromosomes and meiosis has the chromosome number reduced to half
• mitosis has genetically identical cells and meiosis has genetically variable cells
• original cell is diploid and after meiosis ,it is haploid with 2 chromosomes

Question 4

What occurs in meiosis I?

Answer 4

Reduction division, homologous chromosomes separate and number of chromosomes is reduced in half
-produces nonidentical daughter cells

Question 5

what happens in meiosis 2

Answer 5

sister chromatids separate, making haploid cells with non-duplicated DNA

Question 6

Five stages of Meiosis I

Answer 6

1. Leptotene
2. Zygotene
3. Pachytene
4. Diplotene
5. Diakinesis

Question 7

Leptotene

Answer 7

chromosomes condense and are visible;

Question 8

Zygotene

Answer 8

chromosomes continue to condense and homologous chromosomes pair up and begin synapsis

Question 9

Pachytene

Answer 9

chromosomes are short and thick, 3 part synaptonemal complex develops between homologous chromosomes

Question 10

Diplotene

Answer 10

centromeres of paired chromosomes move apart, but the homologous chromosomes remain attached at the chiasma

Question 11

Diakinesis

Answer 11

chromosome condensation continues and the nuclear membrane breaks down and the spindle forms

Question 12

bivalent/tetrad

Answer 12

consists of four chromosomes and is homologous pair of synapse chromosomes

Question 13

Prophase I

Answer 13

chromosomes condense, homologous chromosomes synapse, crossing over takes place, nuclear membrane breaks down and the mitotic spindle forms

Question 14

Metaphase I

Answer 14

homologous chromosomes line up against the metaphase plate

Question 15

Anaphase I

Answer 15

the two chromosomes (each with 2 chromatids) of a homologous pair separate and move toward opposite poles

Question 16

Telophase I

Answer 16

chromosomes arrive at the spindle poles

Question 17

Interkinesis

Answer 17

period between meiosis I and meiosis II, the nuclear membrane reforms and spindle breaks down

Question 18

crossing over

Answer 18

homologous chromosomes exchange information with one another, take place in prophase I
- sister chromatids are no longer identical

Question 19

chiasma

Answer 19

each location where two chromosomes cross is called a chiasm

Question 20

What are products on meiosis?

Answer 20

• four cells
• chromosome number reduced to half (haploid)
• cells produced are genetically different from parent cell b/c of crossing over and random separation of homologous chromosomes

Question 21

what is the number of possible combinations of homologous pairs

Answer 21

2^n
and n = the number of homologous pairs

Question 22

random separation of chromosomes

Answer 22

different migration patterns during anaphase produce different combinations of chromosomes in resulting cells