Mitosis And Meiosis

Question 1

What are the functions of cell division in mitosis?

Answer 1

Growth, injury repair (scarring), replacement of worn out cells.

Question 2

What are the functions of cell division in meiosis?

Answer 2

Creating genetic diversity, reproduction.

Question 3

All long is the cell life cycle?

Answer 3

Approximately 20 hours.

Question 4

What are the four phases of interphase for mitosis?

Answer 4

G1,G0,S,G2.

Question 5

What is the G1 phase?

Answer 5

Takes place before DNA replication. RNA and proteins grow and organelles are synthesized. (2n)

Question 6

What is the G0 phase?

Answer 6

It is the cell cycle arrest (some cells such as neurones and muscles stop dividing).

Question 7

What is the S phase?

Answer 7

It is the synthesis phase where DNA is replicated. (2n —> 2N)

Question 8

What is the G2 phase?

Answer 8

It is the cell checkpoint where proteins check for copy errors and fix mistakes. (2N)

Question 9

What is prophase in mitosis?

Answer 9

The chromosomes condense into threads. The two pairs of centrosomes separate-and generate the spindle fibers. The nuclear membrane starts to disappear.

Question 10

What is the prometaphase in mitosis?

Answer 10

The nuclear envelope is no more. The spindles enter the former nuclear area. Microtubles from opposite spindle poles attach to the two kinetechores of one chromosome.

Question 11

What is metaphase in mitosis?

Answer 11

The chromosomes become aligned at the spindle midpoint.

Question 12

What is anaphase in mitosis?

Answer 12

Separate cleaves the part holding the two sister chromatids together. The spindle separates the sister chromatids and bring them to opposite spindle poles.

Question 13

What is the telophase phase in mitosis?

Answer 13

The chromosomes unfold and return to the interphase state. A new nuclear envelope forms around both daughter nuclei. There is cleavage furrow that represent the cytoplasm that is about to divide.

Question 14

What do chromatin contain?

Answer 14

They contain DNA and histones.

Question 15

What are alleles?

Answer 15

They are different version of the same gene/trait (2 +)

Question 16

What is the G1 phase of interphase in meiosis (how are chromosomes arranged)?

Answer 16

A diploid cell shows two homologous chromosomes (in the form of chromatin at that point). (2n)

Question 17

What is the S phase of interphase during meiosis?

Answer 17

Both homologous chromatin fibers are replicated to form identical sister “ chromatids”.

Question 18

What is the first step in prophase I and what does it imply?

Answer 18

The chromatin begin to condense into chromosomes. Each consists of 2 sister chromatids. There are two homologous pairs. (2N)

Question 19

What is the second step of prophase I and what does it imply?

Answer 19

Synapsis. Homologous chromosomes come together and pair. There are now 4 sister chromatids within 2 homologous chromosomes (tetrad). (2N)

Question 20

What is the third phase of prophase I and what does it imply?

Answer 20

Recombinaison. Chromatids of homologous chromosomes undergo recombination , they exchange segments. (2N)

Question 21

What does prometaphase I consist of?

Answer 21

The nuclear envelope breaks down and the spindle moves into the former nuclear are. Kinetechore microtubles connect to chromosomes (2 sister chromatids on each side). (2N)

Question 22

What does metaphase I consist of?

Answer 22

Tetrads align on the metaphase plate with the help of spindle microtubules. (2N)

Question 23

What does anaphase I consist of?

Answer 23

The spindle microtubles separate both homologous pairs so that 2 different chromosomes are at each pole. The sisters chromatids are still bonded together by the centromere. (2N)

Question 24

What does telophase I consist of?

Answer 24

The spindle of the first meiosis dissemble and two new spindles are created for the next division. The chromosomes don’t change a lot. There is no nuclear envelope at this point. (2N —> 1N)

Question 25

What is interkinesis and what happens during this transition phase?

Answer 25

It is the transition of cells after their first meiosis and before their second meiosis. There is no DNA replication that happens.

Question 26

What happens during prophase l l?

Answer 26

The chromosomes of both cells re-condense and a spindle forms. (1N)

Question 27

Why is there no prometaphase 2 in meiosis?

Answer 27

Because there is no nuclear envelope that has to disappear.

Question 28

What happens during metaphase 2?

Answer 28

The movement of the spindle microtubles align each set of chromosomes on the metaphase plate. (1N)

Question 29

What happens during anaphase 2?

Answer 29

The spindle microtubles separate the sister chromatids of each chromosome and bring them to opposite poles. (1N —> 2n)

Question 30

What are the steps of meiosis most similar to mitosis?

Answer 30

Metaphase 2 and anaphase 2.

Question 31

What happens during telophase 2?

Answer 31

The chromosomes start decondensing because of the creation of a new nuclear membrane. The spindle also disassemble and 4 daughter cells that are unique are created.