Continuity of cells

Question 1

Describe interphase

Answer 1

G1 (organelles form), S (Chromatids form), G2 ( ATP synthesis)

Question 2

Meiosis I

Answer 2

Different from mitosis as it only occurs in reproductive organs, and involves 2 different cell cycles

Question 3

Meiosis 2

Answer 3

Chromosomes sorted into 2 sets, and pair up into bivalents (two homologous chromosomes). Metaphase, anaphase, telophase and cytokinesis are the same. Meiosis 2 is just mitotic cell division.

Question 4

Independent assortment

Answer 4

When the chromatids are formed they may break and exchange sections with each other during Prophase I This occurs at the chiasmata.

Question 5

Cell cycle in mitosis

Answer 5

Interphase- G1 (organelles form), S (Chromatids form), G2 ( ATP synthesis)
Prophase- Chromatin becomes condensed into chromatids, joined by centromere
Metaphase-Chromatids line up middle of cell
Anaphase-Spindle fibres contract and pull chromatids apart to different poles.
Telophase-chromosomes decondense

Cytokinesis-cell divides (cleavage in animal cells, middle lamella in plant)

Question 6

What is cytokinesis?

Answer 6

The stage where two daughter cells, each containing the haploid number of chromosomes

Question 7

What is crossing over?

Answer 7

When sections of chromatids break and exchange sections with one another,. The two chromatids are called recombinants.

Question 8

Why is crossing over important?

Answer 8

The two chromatids of the same chromosome are no longer genetically identical.

Question 9

What is diploid in humans?

Answer 9

46, the full number of chromosomes

Question 10

What is haploid in humans?

Answer 10

23, the half number of chromosomes