16.2 The reproduction of somatic cells

Question 1

Each cell that undergoes mitosis will divide to produce:

Answer 1

2 new cells

Question 2

Mitosis and cytokinesis are important as they: (3)

Answer 2

• Growth: enable organisms to grow from a single celled zygote into a mature organism that may contain hundreds of trillions of cells
• Maintenance: produce new cells to replace worn out or dead cells
• repair: regenerate damaged tissues

Question 3

Prophase (5)

Answer 3

• first of four phases of mitosis
• the chromatin condenses into tightly packed chromosomes
• nuclear membrane breaks down releasing the chromosomes into the cytoplasm.
• the nucleolus disappears
• centrioles moves apart to opposite poles of the cells. As centrioles move, a network of spindle apparatus fibres form between them

Question 4

Mitosis has___ phases

Answer 4

4

Question 5

Spindle apparatus: (3)

Answer 5

• a network of fibres
• each spindle fibre is made of microtubules (hollow tubes of protein that facilitate movements of chromosomes within a cell)
• lengthens with the additional microtubule subunits. The removal of these subunits causes spindle fibre to shorten

Question 6

Metaphase (4)

Answer 6

• second phase of mitosis
• the spindle fibres guide the chromosomes to the equator or centre line of the cell
• the spindle fibre from opposite poles attach to the centromere of each chromosome
• the spindle fibres attach in a way where one sister chromatid faces one pole while the other faces the opposite.

Question 7

Anaphase (4)

Answer 7

• Third phase of mitosis
• each centromere splits apart and the sister chromatids separate from one another
• spindle fibre that link the controls to the poles shorten pulling sister chromatids to opposite poles. At the same time other microtubules lengthen and force the poles of the cell away from one another
• one complete diploid set of chromosomes has been gathered at each pole of the elongated cell

Question 8

Telophase (6)

Answer 8

• The fourth and final phase pf mitosis
• Begins when the chromatids have reached the opposite poles of the cell.
• chromatin begin to unwind into the longer and less visible strands of chromatin
• spindle fibre breaks down
• nuclear membrane forms around each new set of chromosomes
• nucleolus forms within each new nucleus

Question 9

Cytokinesis (4)

Answer 9

• division of the cytoplasm to complete the creation of two new daughter cells
• during cytokinesis, an indentation forms in the cell membrane along the equator
• the indentation deepens until cell is pinched in two
• cytoplasm and organelles divide equally between the two halves