Cell division - Meiosis

Question 1

Define Meiosis:

Answer 1

Meiosis is a form of cell division that only occurs in the formation of gametes. (reproductive cells)

Question 2

What is the key function of Meiosis? Why is it important?

Answer 2

To create daughter cells which are genetically different to their parent cells.
It is important because it allows genetic variation between parents and offspring.

Question 3

How many chromosomes are there within gametes compared to somatic cells?

Answer 3

Contains half the number of chromosomes of somatic cells.

Question 4

What is a haploid cell?

Answer 4

Cells containing only one copy of each chromosome are referred to as haploid (n) cells. (cells containing 23 chromosomes)

Question 5

What is a diploid cell?

Answer 5

Cells containing two copies of each chromosome are referred to as diploid (2n) cells. (cells containing 46 chromosomes)

Question 6

Does meiosis produce diploid or haploid cells?

Answer 6

It produces haploid (n) cells.

Question 7

How many daughter cells does meiosis produce?

Answer 7

4 Daughter cells

Question 8

What are the two divisions of the nucleus called in Meiosis?

Answer 8

Meiosis I, and Meiosis II

Question 9

What is the aim of Meiosis I?

Answer 9

To reduce the number of chromosomes in the cell from diploid to haploid.

Question 10

What is the aim of Meiosis II

Answer 10

To increase the number of daughter cells produced from two to four.

Question 11

Interphase in meiosis one - define key things that happen:

Answer 11

• cell prepares to divide by replicating its DNA
• DNA compresses into chromatin
  (same as in mitosis)

Question 12

Prophase one (meiosis one) - define key things that occur:

Answer 12

• Nuclear membrane disappears
• Spindle fiber forms
• Chromatin condenses to form double-stranded chromosomes

Question 13

Metaphase one (meiosis one) - define key things that occur:

Answer 13

• Spindle fiber attaches to the centromere of a double-stranded chromosome
• Fibers maneuver the chromosomes to the equator of the cell and line them up with their homologous pairs
• NOTE* Spindle fibers from each end attached to one member of each homologous pair

Question 14

Anaphase one (meiosis one) - define key things that occur:

Answer 14

• Spindle fibers contract
• One chromosome from each homologous pair is pulled to opposite poles of the cell

Question 15

Telophase one (meiosis one) - define key things that occur:

Answer 15

• Spindle fiber disappears
• Nuclear membranes form around two bundles of chromosomes
• Cytokinesis occurs, creating two haploid daughter cells
• meiosis I is complete