Everything You Need To Know Bout Meiosis

Question 1

What is Meiosis?

Answer 1

A type of cell division that produces four haploid daughter cells

💁🏻‍♀️Recall: Haploid cells contain half the number of chromosomes of the parent cell.

Question 2

Where does Meiosis occur?

Answer 2

Reproductive cells only

In humans & animals: testes (males) ovaries (females)
In plants: pollen(anther) ovule(ovary)

Question 3

Importance of Meiosis #1

Answer 3

It results in formation of cells that are not identical
This ensures that each daughter cell has a different combination of genes
This leads to variation
Variation is a survival advantage as it allows species to adapt to changing environments.

Question 4

Importance of Meiosis #2

Answer 4

Ensures that the chromosome number for the species is restored after fertilization and formation of zygote

Question 5

Importance of Meiosis #3

Answer 5

Some genetic traits are transferred from parent to offspring. This means a parent of inferior quality can produce offspring of superior quality.

Question 6

Homologous

Answer 6

2 pieces of DNA within a diploid organism that carries the same genes, one from each parent.

Question 7

Homozygous

Answer 7

Homozygous describes a gene with identical alleles

Question 8

Heterozygous

Answer 8

Describes genotype with different or varying alleles

Question 9

Allele

Answer 9

One or more forms of a gene

Question 10

Genotype

Answer 10

Composition of genes within cell

Question 11

Phenotype

Answer 11

Observable characteristics of organism as a result of its genotype and environment.

Question 12

Meiosis Phases

Answer 12

2Cycles: Meiosis 1 and Meiosis 2

Interphase
[Meiosis 1]
Prophase 1
Metaphase 1
Anaphase 1
Telophase 1

[Meiosis 2]
Prophase 2
Metaphase 2
Anaphase 2
Telophase 2-> Cytokinesis

Question 13

Interphase

Answer 13

G1 phase- cell grows
S phase- copies all chromosomes
G2 phase- prepares for division

Question 14

Prophase 1

Answer 14

Chromosomes begin to condense
Each chromosome lines up with homologous partner so that meet up at corresponding positions along their full length.
A chiasma forms between adjacent chromatids of different homologs
Breakage and rejoining at the chiasma results in recombinant chromatids
The DNA is broken at the same spot on each homologous and reconnected in criss-cross pattern so they exchange part of their DNA.(crossing over- process where homologous chromosomes exchange parts)

Question 15

Metaphase 1

Answer 15

These homologous pairs line up along the equator

Orientation for each pair is random

Question 16

Anaphase 1

Answer 16

Homologues are pulled apart
Move towards opposite sides of cell
Sister chromatids remained attached and don’t come apart

Question 17

Telophase 1

Answer 17

Two cells each with the haploid number are formed

Question 18

Review of Meiosis 1

Answer 18

Start with ONE parent cell
Homologous chromosomes pair up
Crossing over occurs to exchange gene segments on chromosomes(recombination)
Homologous chromosomes separate and move to ends of cell
Cell divides
End with TWO daughter cells

Question 19

Meiosis 2

Answer 19

Cells move from meiosis 1 to 2 without copying their DNA.
They are haploid cells with one chromosome from each homologous pair
The chromosomes still consist of 2 sister chromatids
Period between meiosis 1 and 2 known as interkinesis

Question 20

Prophase 2

Answer 20

Chromosomes in each cell condense
Nuclear envelope breaks down
Centrosomes move apart
Spindle forms between them and begin to capture chromosomes from opposite poles of cell

Question 21

Metaphase 2

Answer 21

Chromosomes line up along equator

Question 22

Anaphase 2

Answer 22

Sister chromatids separate

They are pulled away from each other at different ends of the cell

Question 23

Telophase 2

Answer 23

Nuclear membranes form around each set of chromosomes.

Chromosomes unravel

Question 24

Cytokinesis

Answer 24

Cytokinesis splits the chromosome sets into new cells

Question 25

Products of Meiosis

Answer 25

FOUR haploid cells

Each chromosome has one chromatid