Assessment 1: Class 6

Question 1

What are the phases of mitosis? (5)

Answer 1

1. Prophase
2. Prometaphase
3. Metaphase
4. Anaphase
5. Telophase/Cytokinesis

Question 2

How long does Prophase and Prometaphase last and what takes place?

Answer 2

• About 36 minutes
• Nuclear membrane breaks down
• Centrioles duplicate
• DNA condenses
• Spindles begin to form

Question 3

How long does Metaphase last and what takes place?

Answer 3

• About 3 minutes
• All the chromosomes line up at the ‘metaphase plate’ (not a physical structure, just the term for where they line up)
• Microtubules from the spindle connect to the chromosomes

Question 4

How long does Anaphase last and what takes place?

Answer 4

• About 3 minutes
• The glue that holds the sister chromatids together is broken down allowing them to separate
• The chromosomes are pulled apart
• Microtubules push the poles apart

Question 5

How long does Telophase last and what takes place?

Answer 5

• About 18 minutes
• Since the cell is nearly done dividing, it begins to re-establish its normal structures as cytokinesis takes place
• Mitotic spindle is broken down into its building blocks
• Two nuclei form, one for each set of chromosomes
• Chromosomes decondense and return to their stringy form

Question 6

What is Cytokinesis?

Answer 6

The cytoplasmic division of a cell at the end of mitosis or meiosis, bringing about the separation into two daughter cells

Question 7

What can go wrong? (2)

Answer 7

1. Misregulation: Chromosome only gets 1 spindle fiber

2. Aneuploidy: The presence of an abnormal number of chromosomes e.g. 45 or 47 instead of the usual 46

Question 8

What happens if a mutation occurs during G2?

Answer 8

There can only be 1 mutation because the DNA has already been duplicated