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One cell into two

One cell into two

1.[1p]

Put the phases of the cell cycle in order, starting from the end of one division.

  1. M

  2. S

  3. G1

  4. G2

Show the answer

a, b, c, d

2.[3p]

Hartwell's temperature-sensitive mutants each arrested at their own defined point in the cycle. Why did that matter?

Correct
The answer is: It showed the cycle is a series of discrete steps, each needing a particular gene product
The answer is: It showed the cycle is a series of discrete steps, each needing a particular gene product
The answer is: It showed the cycle is a series of discrete steps, each needing a particular gene product

3.[3p]

Why is cyclin destroyed rather than merely inhibited at the end of mitosis?

Correct
The answer is: Destruction is irreversible, so the cell cannot slip back into mitosis
The answer is: Destruction is irreversible, so the cell cannot slip back into mitosis
The answer is: Destruction is irreversible, so the cell cannot slip back into mitosis

4.[2p]

Checkpoint mutants in yeast grow normally under good conditions and fail only when conditions are made difficult, which is why checkpoints are called surveillance rather than machinery.

Correct
The answer is: True

5.[3p]

How sensitive is the spindle assembly checkpoint in a human cell?

Correct
The answer is: One unattached kinetochore out of ninety-two is enough to hold the whole division
The answer is: One unattached kinetochore out of ninety-two is enough to hold the whole division
The answer is: One unattached kinetochore out of ninety-two is enough to hold the whole division

6.[3p]

Match each protein to its role in division.

  • Cohesin

  • Separase

  • Condensin

  • Aurora B

  • The anaphase promoting complex

  • cuts cohesin once securin is destroyed

  • compacts chromosomes in prophase

  • holds sister chromatids together until anaphase

  • releases attachments that are not under tension

  • ubiquitinates securin and cyclin B

Show the answer

Cohesin: holds sister chromatids together until anaphase Separase: cuts cohesin once securin is destroyed Condensin: compacts chromosomes in prophase Aurora B: releases attachments that are not under tension The anaphase promoting complex: ubiquitinates securin and cyclin B

7.[2p]

With 23 chromosome pairs, how many combinations can independent assortment alone produce in one gamete?

CorrectNot quite: 8388608

8.[3p]

Knudson inferred the two-hit model from the statistics of retinoblastoma alone. What was the reasoning?

Correct
The answer is: Hereditary cases inherit one hit and need only one more, so they appear early and in both eyes, while sporadic cases need two independent hits in one cell
The answer is: Hereditary cases inherit one hit and need only one more, so they appear early and in both eyes, while sporadic cases need two independent hits in one cell
The answer is: Hereditary cases inherit one hit and need only one more, so they appear early and in both eyes, while sporadic cases need two independent hits in one cell

9.[3p]

Which statements about cancer genetics follow from the lesson?

Select all that apply

Correct
Correct
Correct
The answer is: Proto-oncogene mutations are gain-of-function and act with one altered copy, Tumour suppressor mutations are loss-of-function and require both copies, Incidence rising as a high power of age is consistent with several rate-limiting events