Meiosis

Question 1

what is a haploid?

Answer 1

only 1 set of chromosomes, symbol showed as an “N”

Question 2

What is the definition of meiosis

Answer 2

type of nuclear division that results in the formation of cells containing half the number of chromosomes in the parent cell

Question 3

what is a homologous pair

Answer 3

set of one maternal and paternal chromosome, which pair during fertilisation

Question 4

what is crossing over

Answer 4

is the process by which non-sister chromatids exchange alleles by swapping sections of chromatids.

Question 5

Explain the process of crossing over

Answer 5

Homologous pairs can cross and become entangled

The entanglement places stress on the DNA molecules

this causes chromatids in the chromosome to break and re-join to the other chromosome

Question 6

what does the crossing over allow to happen

Answer 6

create a new combination of alleles on the two chromosomes

Question 7

What is a bivalent?

Answer 7

a pair of a homologous chromosomes which come together in meiosis to create a homologous pair and are lying alongside eachother

They are crossed over, but there alleles are not yet shuffled

Question 8

what is a diploid zygote?

Answer 8

a cell that forms when two haploid gametes fuse during fertilisation.

Question 9

how many chromosomes are in the human body

Answer 9

46

Question 10

What happens in prophase 1 of meiosis 1

Answer 10

chromatin condenses each chromsome becomes supercoiled- visible under microscope with stain.
nuclear envelope breaks down
Spindle threads form from the centriole
Homologous pairs form
Crossing over occurs- non sister chromatids entangle and swaps sections of chromatid to shuffle alleles

Question 11

In what phase of meiosis are bivalents formed

Answer 11

Prophase 1

Question 12

how many chromatids is in a bivalent

Answer 12

4 chromatids in a bivalent

Question 13

what is the name given to the area where homologous pairs cross over

Answer 13

Chiasmata

Question 14

What happens in metaphase 1

Answer 14

Bivalents attach to the spindle at the equator, each attached by centromere

The maternal and paternal chromosomes assort themselves independently on the equator,

Question 15

anaphase 1

Answer 15

motor proteins separate the homologous pairs, dragging them across the spindle fibres
NO CENTROMERE DIVISION.
Crossed over areas separate resulting in swapped areas of chromosome and allele shuffling

Question 16

telophase 1-

Answer 16

two new nuclear envelopes form around each set of chromosomes, cell divides by cytokinesis

Each new nucleus contains half the original number of chromosomes, 23 OR “n”

Question 17

what is meiosis 2

Answer 17

Just mitosis

Question 18

how is independent assortment achieved