Chapter 13 - Meiosis

Question 1

What is genetics?

Answer 1

A mixture of heriditery gene expressions and individual variation

Question 2

What are genes?

Answer 2

hereditary units passed from parents to offsprings

Question 3

What is the main difference between sexual and asexual reproduction genetics wise?

Answer 3

In sexual reproductions, genes undergo through a lot of variations naturally whereas in asexual reproduction, genes are copied exactly from parent to offsprings.

Question 4

What is a karyotype?

Answer 4

The systematically organized set of condensed chromosomes displayed to show genes that all organisms have.

Question 5

How many sets of chromosomes are typically defined to be in a karyotype?

Answer 5

23 pairs of homologous (identical) chromosomes

46 chromsomes in total

Question 6

Why is one pair of chrosome in karyotype different from the rest?

Answer 6

The 23rd pair of chromosome is called the sexual chromosome. They define the organisms gender.

Question 7

How are homologous chromosomes paired up?

Answer 7

They have the same genes on them, their physical characteristics match such as height and looks.

Question 8

Where does each chromosome pair come from in sister chromatid?

Answer 8

Each chromosome comes from each parent.

Question 9

What’s considered a haploid cell and what’s considered to be a diploid cell?

Answer 9

A haploid cell has only one set of parental chromosomes

A diploid cell has two sets of parental chromosomes (aka when dividing)

Question 10

where can we see diploid chromosomes in animal cells?

Answer 10

We can see diploid cells occuring when the egg is fertilized by the sperm and creates a zygote and throughout adult stage.

Question 11

Where does meiosis occur?

Answer 11

In testes in males and in ovaries in females

Question 12

When do we see haploid cells in animal cells?

Answer 12

We can see haploid cells in gametes and the haploid cells remain haploid from start of meiosis to fertilization

Question 13

Is the diploid/halpoid cycle different for plant cells?

Answer 13

Yes, it’s different because both diploid and haploid cells can reproduce adult plants

Question 14

What are haploid and diploid cells called in plant cells?

Answer 14

Haploid cells are called gametophyte
Diploid cells are called sporophyte

Question 15

How do halpoid cells in plants reproduce another adult plant?

Answer 15

They join another haploid cell/gametophyte and create a diploid cell that then turns into a full adult plant.

Question 16

How do diploid cells in plants reproduce another adult plant?

Answer 16

They undergo through meiosis to turn into a haploid cell and converts into an adult plant.

Question 17

How is the haploid/diploid phase different in animals vs. fungi and protists?

Answer 17

It’s different in fungis and protists because they are in diploid phase after being fertilized and during meiosis. But after meiosis, during their adult stage, they are haploids.

Question 18

Are there different phases of cell division in sex cells in animals?

Answer 18

Yes, interphase and meiosis

Question 19

What occurs during Interphase?

Answer 19

DNA is replicated - homologous chromosomes duplicate themselves and turn into sister chromatids

Question 20

What basically occurs in Mitosis?

Answer 20

The homologous pair of chromosomes get sorted from being diploid to haploid.

Question 21

How many daughter cells with meiosis produce?

Answer 21

4 daughter cells

Question 22

Are there subphases of meiosis?

Answer 22

Yes, meiosis 1 and meiosis 2

Question 23

What basically occurs in meiosis 1?

Answer 23

The two pairs of sister chromatids from each parents seperate and turn into haploid cells.
One parent’s sister chromatid into one. Second parent’s sister chromatid into another.

Question 24

What occurs in meiosis 2?

Answer 24

The sister chromatids are seperated into two further daughter cells on both parent’s side.

Question 25

So in a homologous chromosome pair, are there 4 chromosomes?

Answer 25

Yes, each side comes from either parent. And the chromosome from either parent are duplicated into TWO chromosomes. So there are total of 4 chromosome

Question 26

Explain meiosis I more in depth along with its subphases

Answer 26

Meiosis I is seperated into four different phases.
1. Prophase : DNA condensation, nuclear envelope dissolves, mitotic spindle starts forming

2. Metaphase : mitotic spindle is in place, Chromosome are lined up on metaphase plate.
3. Anaphase : Homologous chromosomes are pulled apart but sister chromatids remain attached
4. Telophase/Cytokinesis : mitotic spindle dissappears, cleveage furrow pinches off two cells,

Question 27

Explain meiosis II in more depth

Answer 27

1. Prophase : DNA DOES NOT REPLICATE, mitotic spindle forms
2. Metaphase : mitotic spindle is in place, Chromosome are lined up on metaphase plate.
3. Anaphase : Sister chromatids are pulled apart but sister chromatids remain attached
4. Telophase/Cytokinesis : mitotic spindle dissappears, cleveage furrow pinches off two cells,

Question 28

What’s the difference between meiosis 1 and meiosis 2

Answer 28

In meiosis 1, homologous chromosomes are being pulled apart but in meiosis 2, sister chromatids are being pulled apart.

In meiosis 1, synapsis occurs

Question 29

What’s the difference between meiosis and mitosis?

Answer 29

In mitosis, we are seperating sister chromatids of duplicated chromosomes ONLY whereas in meiosis, we are seperating homologous pairs of chromosomes FIRST.

During mitosis, the homologous pairs do not associate themselves with one another chemically but they get together in meiosis to perform a process called synapsis.

During mitosis, the cell remains diploid the whole process.

Introduces variation

Question 30

What occurs in synapsis?

Answer 30

During meiosis, one pair of duplicated chromosome from one parent associates itself with the other parent’s duplicated chromosome pair.

When they pair up, crossing over occurs which increases variation

Question 31

How does genetic variation increase in meiosis?

Answer 31

It increases through several techniques such as independent assortmert, crossing over and random fertilization

Question 32

What is random mutation? Does random mutation occur in mitosis as well?

Answer 32

Random mutations are changes in genes that occur due to errors or damage. This can also occur in mitosis.

Question 33

What is independent assortment and when does it occur?

Answer 33

Independent assortment during metaphase 1. When homologous pairs line up against the metaphase plate, the mother and father’s pairs do not pair orderly all the time.

This causes the first two daughter cells to have varying patterns of mother and fathers homologous pairs.

Question 34

How does crossing over create variation? In which part of meiosis does this occur?

Answer 34

This occurs during prophase 1. When two homologous pairs stick together at certain region called chiasma. During this bonding, a small region on the same side of the mother’s and father’s chromosomes is exchanged.

Question 35

How does random fertilization cause genetic variation?

Answer 35

Random fertilization means that any sperm can fuse with any eggs and this dramatically increases the possibilities of genetic combinations of an offspring (64 trillion diploid combination)