FR Chap 9

Question 1

Why do cells divide? (3 reasons)

Answer 1

Repair, Growth, Reproduction.

Question 2

What are two main types of reproduction?

Answer 2

asexual reproduction - produces offspring from just one parent.
sexual reproduction “ “ two parents

Question 3

Describe the structure of a chromosome.

Answer 3

Each chromosome consists of 2 identical joined copies called sister chromatids. The region where the 2 chromatids are joined tightly together is called the centromere.

Question 4

What are the stages of one complete cell cycle?

Answer 4

Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokenises

Question 5

Summarize the major events that occur during each phases of mitosis.

Answer 5

1) Prophase - chromosomes are visible, spindle forming, nuclear envelope breaks up, chromosomes consisting of 2 sister chromatids joined at the centromere.
2) Metaphase - chromosomes gather in a plane across the middle, spindle fully formed, chromosomes attached to spindle microtubules.
3) Anaphase - chromatids separate becoming daughter chromosomes. Microtubules shorten bringing chromosomes closer to poles. Spindle microtubules that are not attached to centromeres do just the opposite–they grow longer, pushing the poles farther apart.
4) The final stage of mitosis, telophase, begins when the chromosomes reach the poles of the spindle. During this stage, the processes that occurred in prophase are reversed. The spindle disappears, two nuclear envelopes reform (one around each set of daughter chromosomes), the chromosomes uncoil & lengthen, & the nucleoli reappear. Mitosis, the division of one nucleus into two genetically identical daughter nuclei, is now finished.

Question 6

How is cytokinesis different b/w animal & plant cells

Answer 6

animal - a ring of microfilaments in the cytoplasm contracts like the pulling of a drawstring, pinching the parenr cell in two
plant - cell plate forms inside cell & grows outward
cell plate –> cell wall which divides the cell in two

Question 7

What is the purpose for cells undergoing Meiosis?

Answer 7

Producing haploid gametes by meiosis keeps the chromosome number from doubling in every generation.

Question 8

What are homologous pairs?

Answer 8

The two chromosomes of each matching pair are called homologous chromosomes.

Question 9

What is crossing over?

Answer 9

exchange of genetic material between homologous chromosomes during prophase I of meiosis.

Question 10

What important event occurs in anaphase of Meiosis I?

Answer 10

Homologous chromosomes separate as they migrate to opposite poles of the spindle.

Question 11

What is the end result of Mieosis?

Answer 11

Producing four haploid daughter cells as a final result.