Interphase + Meiosis 1

Question 1

Define Meiosis

Answer 1

Meiosis is the cell division during which diploid germ cells give rise to haploid gametes.

Question 2

Where does meiosis occur?

Answer 2

It takes place in the testes and the ovaries through a cycle of growth, development and division called the cell cycle.

Question 3

What’s the phases of the cell cycle?

Answer 3

There are 2 main phases, interphase and meiosis

Question 4

What is Interphase and what are their phases?

Answer 4

Before meiosis starts, there’s a preparatory phase called interphase.
- It consists of 3 stages:
G1: growth 1 stage, cell increases by mass.
S stage: DNA is if synthesized. (2 chromatids)
G2 stage: growth 2 staye, cell continues to increase by sizeand produces proteins.

During this phase, each cell contains 46 decondensed
chromosones of 2 chromatids due to the replication
in the S phase

Question 5

Schematize the cell during interphase

Answer 5

.

Question 6

What happens in Prophase 1?

Answer 6

• nuclear membrane disappears
• chromatins condense into chrs.
• Synapsis occur: pairing of homologous chrs to form Tetrads ( 4 chromatids).
• Crossing over happens where the non sister chromatids exchange DNA segments. (the site of crossing over is called chiasmata)
• Centrioles transform to asters that are connected by spindle fibers.
• 2n=4

Question 7

schematize the cell at prophase 1:

Answer 7

.

Question 8

Metaphase 1:

Answer 8

homologous chrs line up randomly at the middle of the cell forming the equatorial plate.
2n=4

Question 9

schematize M1

Question 10

anaphase 1?

Answer 10

homologous chrs separate and migrate towards the opposite poles of the cell /polar ascension.
2n=4

Question 11

schematize anaphase 1

Question 12

telophase 1

Answer 12

-nuclear membrane starts to reappear.
-asters transform back to centrosomes.
-spindle fibers disappear.
-the mother cell undergoes cleavage leading to 2 daughter cells.
-The cleavage of the cell membrane is called cytokinesis.
- n=2

Question 13

schemes T1