Mitosis & Meiosis

Question 1

What is a telomere?

Answer 1

Repeated sequences (TTAGGG) at each end of the chromosome

Question 2

What is the centromere?

Answer 2

Connects sister chromatids, is a repetitive sequence of DNA

Question 3

What 3 centromere positions are found in humans? Where is the centromere positioned in each type of chromosome?

Answer 3

Metacentric (middle)
Submetacentric (between middle and end)
Acrocentric (between submetacentric position and telomere)

Question 4

What are the stages of mitosis after G2 of the cell cycle?

Answer 4

Prophase
Prometaphase 
Metaphase 
Anaphase
Telophase 
(Cytokinesis)

Question 5

What occurs in prophase of mitosis?

Answer 5

The nuclear membrane disappears

Chromosomes condense and become visible

Question 6

What occur in prometaphase of mitosis?

Answer 6

Microtubule spindles form and connect to centromeres of chromosomes

Question 7

What occurs in metaphase of mitosis?

Answer 7

Chromosomes line up along the metaphase plate

Question 8

What occurs in anaphase of mitosis?

Answer 8

Microtubule spindles pull each replicated chromosome apart
Centromere splits
Sister chromatids separate to opposite poles of the cell

Question 9

What occurs in telophase of mitosis?

Answer 9

Spindle fibres break down and disappear
Nuclear envelope reforms around chromosomes
Cleavage furrow appears —> cytokinesis

Question 10

What is produced from one cycle of mitosis?

Answer 10

1 diploid cell —-> 2 identical diploid daughter cells

Question 11

What cells are produced as a result of meiosis?

Answer 11

1 diploid cell —> 4 non identical haploid cells

Question 12

What is the difference between the genetic material on sister chromatids and non-sister chromatids?

Answer 12

Sister chromatids = same genes, same alleles

Non-sister chromatids = same genes, different alleles

Question 13

Prometaphase only exists in mitosis or meiosis?

Answer 13

Prometaphase is only in mitosis

Question 14

What happens in prophase I of meiosis?

Answer 14

Nuclear membrane disappears
Spindles form
Maternal/paternal chromosomes ‘find’ each other
Recombination and crossing over occurs between two of the non-sister chromatids

Question 15

What occurs in metaphase I of meiosis?

Answer 15

Random assortment

Homologous pairs line up along the metaphase plate as a tetrad

Question 16

What occurs in anaphase I of meiosis?

Answer 16

Homologous chromosomes are separated

Question 17

What occurs in telophase I of meiosis?

Answer 17

Nuclear membrane reforms

Spindles disappear

Question 18

What is the resulting cellular product of meiosis I? What happens next?

Answer 18

2 daughter cells each with 23 replicated chromosomes

Meiosis II without any dna replication stage

Question 19

Which part of meiosis is nearly exactly the same as classical mitosis?

Answer 19

Meiosis II

Question 20

What occurs in prophase II of meiosis?

Answer 20

Nuclear membrane disappears

Spindles form

Question 21

What occurs in metaphase II of meiosis?

Answer 21

Chromosomes line up along the metaphase plate

Question 22

What happens in anaphase II of meiosis?

Answer 22

Chromatids separate into separate daughter cells

Question 23

What happens in telophase II of meiosis?

Answer 23

Nuclear membrane reforms

Spindles disappear

Question 24

In what two ways is genetic variation provided by meiosis? At what stages of meiosis do these occur?

Answer 24

Random assortment of chromosomes (metaphase I)

Crossing over/recombination (prophase I)