Meiosis, Mitosis, and the Cell Cycle

Question 1

What is G0-G1? what happens to chromosomes?

Answer 1

Normal cell activity (Interphase)
Chromosomes are decondensed so that gene expression can take place
-homologous pair
-2n
-diploid

Question 2

What is S-phase? What is the state of the chromosomes?

Answer 2

Duplication of the chromosomes. * still not condensed yet*
-dyads are formed
-4n
-diploid

Question 3

What is G2? What is the state of the chromosomes?

Answer 3

Growth and protein synthesis
-mitotic spindle forms
-breakdown of nuclear envelope
condensation of chromosomes
-4n
-diploid
-dyads

Question 4

Where are the different opportunities to interrupt the cell cycle?

Answer 4

-Check for completion of S-phase (duplication)
- DNA damage check points
-Spindle check points
-alignment
- attachment to kinetochores

Question 5

What does p53 do?

Answer 5

It senses DNA damage and acts as a check point
-stops cycle at G1
-tumor suppression gene
-forces defective cells to undergo apoptosis

Question 6

What are the 5 stages of Mitosis?

Answer 6

1. Early prophase
2. Late prophase
3. Metaphase
4. Anaphase
5. Telophase

Question 7

In terms of chromosomes, what is the starting status and what is the ending status in MITOSIS

Answer 7

Start: 4n, diploid
End: 2n, diploid

Question 8

What occurs in Mitosis early prophase?

Answer 8

-M-phase promoting factor
-chromatin condensation
-formation of mitotic spindle

Question 9

What occurs in Mitosis/Meiosis late prophase?

Answer 9

-M-phase promoting factor
-nuclear membrane dissolves
-interaction of microtubules and kinetochores @ centromere

Question 10

What occurs in Mitosis metaphase?

Answer 10

Dyads line up at the equator

Question 11

What occurs in Mitosis/Meiosis anaphase?

Answer 11

-Anaphase promoting complex
-Separation of chromosome from its replicate

Question 12

What occurs in Mitosis telophase?

Answer 12

-nuclear membrane formation
-chromatids decondense
-cytokenesis

Question 13

In terms of chromosomes, what is the starting status and what is the ending status in MEIOSIS 1

Answer 13

Start: 4n, tetrads, diploid
End: “2n”, dyads, haploid

Question 14

In terms of chromosomes, what is the starting status and what is the ending status in MEIOSIS 2

Answer 14

Start: “2n”, dyads, haploid
End: 1n, haploid

Question 15

What occurs in meiosis early prophase 1?

Answer 15

As chromatin condenses, dyads align in pairs forming tetrads
- the dyads are joined at the kinetochores forming synaptonemal complexes
-non sister chromatids can cross over and attach forming chiasmata (genetic recombination)

Question 16

What occurs during meiosis 1 metaphase?

Answer 16

-Tetrads line up randomly
-start of synaptonemal complex seperation
-chiasmata are still attached

Question 17

What occurs during meiosis 1 telophase?

Answer 17

Same as mitosis except the daughter cells enter prophase 2 without going through an S phase