Meiosis

Question 1

What is the purpose of Meiosis? when and where does it occur? how many cell divisions are there

Answer 1

Goal is reproduction, making gametes and in specialized cells within testes and ovaries occurs after interphase

Question 2

Can you quickly differentiate mitosis and meiosis

Answer 2

Mitosis: growth repair, development and 1 cell division, Meiosis is reproduction and 2 cell division

Question 3

Heredity def

Answer 3

offspring acquires genes from parents

Question 4

Homologous chromosome def

Answer 4

A pair of chromosomes that are similar in size shape and gene content(control the same characters)
- centromere in same position, 1 maternal and 1 paternal

Question 5

Does the biological father or mother determine sex?

Answer 5

Father, because he has X and Y chromosome

Question 6

What is the composition in human somatic cells(skin,liver,kidney..)

Answer 6

44 autosomes 22 pair and 2 sex chromosomes(1 pair xx or xy)

Question 7

What is the composition in human gametes

Answer 7

22 autosomes and 1 sex chromosome => Sperm x y, egg x

Question 8

Haploid and diploid def

Answer 8

having 1 or 2 sets of chromosome

Question 9

Are human somatic cells diploid or haploid

Answer 9

diploid

Question 10

Are human gametes haploid or diploid

Answer 10

haploid

Question 11

Where are gametes produced by meiosis?

Answer 11

Gonads

Question 12

Fertilization def

Answer 12

2 haploid gametes fuse to form a diploid cell called a zygote

Question 13

How many chromosomes do human gametes have

Answer 13

23

Question 14

What are the steps of meiosis 1

Answer 14

Prophase 1, metaphase 1, anaphase 1, telophase 1, cytokinesis 1

Question 15

What happens during prophase 1 of meiosis 1

Answer 15

Chromosomes condense, mitotic spindle forms, centromeres move apart, nuclear envelope fragments
THEN Homologous chromosomes pair up => forming a tetrad through synapsis
Crossing over: homologous chromosomes exchange segments

Question 16

What happens during metaphase 1 of meiosis 1

Answer 16

Tetrads(homologous pairs) line up at the metaphase plate

Question 17

What happens during anaphase 1 of meiosis 1?

Answer 17

Homologous chromosomes are separated and pulled to opposite sides of the cell

Question 18

What happens during telophase 1 of meiosis 1?

Answer 18

Spindle fibers disassemble, nuclear envelope reforms, chromosomes decondense
THEN Haploid set of chromosomes are at each pole, sister chromatids still linked

Question 19

What happens during cytokinesis 1 of meiosis 1?

Answer 19

Separation into 2 haploid cells, with duplicated sister chromatids still attached

Question 20

What happens during Meiosis 2?

Answer 20

Prophase 2, metaphase 2, anaphase 2 , telophase 2

Question 21

What happens during cytokinesis 2 of meiosis 2?

Answer 21

separated into 4 haploid cells

Question 22

What does Meiosis 1 do?

Answer 22

Separate the homologous chromosomes from 2n to n

Question 23

What are tetrads? what is a synapsis

Answer 23

structure formed during prophase 1 consisting of 4 chromatids, synapsis is when they pair up and align closely

Question 24

At the end of cytokinesis 1, if we started with 4 chromosomes and 2n and 8 chromatids, what do we get now

Answer 24

2 chromosomes each, 4 chromatids and n

Question 25

After anaphase 2, if we started meiosis 1 with 4 chromosomes and 2n and 8 chromatids, what do we get now

Answer 25

4 chromosomes and n

Question 26

At the end of cytokinesis 2, if we started meiosis 1 with 4 chromosomes and 2n and 8 chromatids, what do we get now

Answer 26

2 chromosomes and n

Question 27

True or False? The genetic composition of daughter cells due to crossing over and independent assortment due to meiosis is unique

Answer 27

True

Question 28

What are the three processes that cause gene shuffling?

Answer 28

Independent assortmnt,crossing over, random fertilization

Question 29

What is independent assortment in terms of meiosis?

Answer 29

Maternal and paternal chromosomes are sorted independently, there is random orientation of tetrads at metaphase plate

Question 30

What is crossing over in terms of meiosis?

Answer 30

Segments of homologous chromosomes are exchanged

Question 31

how many possible combinations for humans?

Answer 31

2^n = 2^23

Question 32

What are recombinant chromosomes?

Answer 32

Chromosomes having a mix of maternal and paternal genes

Question 33

How does crossing over work?

Answer 33

special proteins cut the homologous sister chromatids at same location, then joined together and the cuts on nonsister chromatids joined together

Question 34

Explain random fertilization and the chances

Answer 34

Any sperm can fuse with any egg, so there are 2^n * 2^n chances , for humans is 70 trillion