The Cell Cycle

Question 1

what is the cell cycle?

Answer 1

Is an ordered sequence of events that take place in a cell from the time a cell is formed until the duplication of its DNA and division of cytoplasm and organelles to produce two daughter cells

Question 2

what are the 2 broad stages of the cell cycle? what generally happens during these stages?

Answer 2

1. Interphase = growing stage

2. M phase = cell division stage (mitosis or meiosis)

Question 3

what are the 3 sub-phases of the interphase stage?

Answer 3

• G1 and G2 = cell grows by producing all of the organelles, proteins, etc. found within the cell
• S phase = genetic information duplicated

Question 4

what are the 2 parts of the m phase?

Answer 4

the cell divides

1. division of genetic material by Mitosis or Meiosis
2. division of cell = Cytokinesis

Question 5

in which stage does a cell spend most of its time?

Answer 5

interphase stage

Question 6

what are the 2 types of cell division in eukaryotic cells?

Answer 6

1. Mitosis

2. Meiosis

Question 7

what is mitosis? what kind of cells does mitosis occur in? what are the 3 functions of mitosis?

Answer 7

it is when a cell divides to produce two cells that are
genetically identical to the original cell (parent cell)
-mitosis occurs in haploid and diploid cells
1. Asexual reproduction
2. Growth in multicellular organisms
3. Cell replacement in multicellular organisms

Question 8

what is meiosis? what kinds of organisms does this occur in? what is the function of meiosis?

Answer 8

it is when a diploid cell divides to produce genetically unique haploid cells
-occurs in sexually reproducing organisms only
-the function is to reduce the chromosome number by
half so when gamete fuse during fertilization a diploid zygote is formed

Question 9

what is a diploid cell? what is a haploid cell? what kinds of organism are humans? what kinds of cells are their gametes?

Answer 9

Diploid (2n) = any cell with two sets of chromosomes
Haploid (n) = any cell with one set of chromosomes
-humans are diploids, gametes (eggs/sperms) are haploids

Question 10

what are microtulules?

Answer 10

long proteins that attach to chromosomes and allow them to be moved inside the cell

Question 11

what are centrosomes?

Answer 11

structures that organize the microtubules into a ‘spindle’ shape, enabling separation of the chromosomes during M phase

Question 12

what are kinetochores?

Answer 12

protein complexes that attach a microtubule to the centromere of a chromosome

Question 13

what are the 4 stages of mitosis? what always precedes mitosis?

Answer 13

1. Prophase
2. Metaphase
3. Anaphase
4. Telophase

-interphase always precedes mitosis

Question 14

what is the function of interphase?

Answer 14

• Cell growth during G1 and G2

- DNA synthesis during S phase

Question 15

what happens in early prophase stage?

Answer 15

1. Chromatin condenses into visible chromosomes
2. Mitotic spindle begins to form
3. Centrosomes separate
4. Nucleoli disappear

Question 16

what happens during late prophase? what else is this called?

Answer 16

1. Nuclear envelope breaks down
2. Microtubules attach to chromosomes at kinetochore
3. Mitotic spindle is formed

-also called prometaphase

Question 17

what happens during metaphase?

Answer 17

1. Chromosomes line up along metaphase plate

2. Sister chromatids attached to microtubules from opposite poles of spindle

Question 18

what happens during anaphase?

Answer 18

1. Sister chromatids separate

2. Chromosomes move towards opposite poles of the spindle

Question 19

what happens during telephase?

Answer 19

1. Two daughter nuclei form
2. Chromosomes decondense
3. Nuclear envelopes reform
4. Nucleoli reappear

Question 20

what is the mitotic spindle composed of? how is it organized, where is this found? how are chromosomes attached?

Answer 20

• Composed of microtubules
• Organized by the centrosome
• Centrosome is found at each pole of the spindle
• Microtubules attach to each chromosome at the kinetochore

Question 21

how are chromatids pulled apart during anaphase?

Answer 21

pulled apart by microtubles from opposite poles that are attached to kinetochores on chromosomes

Question 22

what is cytokinesis? what does it divide? when does it occur?

Answer 22

the division of a cell into two
-Divides the cytoplasm and everything within it
-occurs after division of the nucleus (separation of
the chromosomes); late anaphase or telophase

Question 23

what is cytokinesis in animal cells called? what happens during this?

Answer 23

is called cleavage
-During cleavage a ring of protein filaments contracts
until the cell divides into two new cells

Question 24

what happens during cytokinesis in plants cells?

Answer 24

• a cell wall is formed between the two new nuclei

- vesicles form cell plate, which fuses to cell wall of parent cell and divides the two daughter cells