Lecture 4a: Cell Cycle- Mitosis and Meiosis

Question 1

Cell Cycle (Cell-divison cycle)

Answer 1

The series of events that take place in a cell that causes it to divide into 2 daughter cells (4 processes)

Question 2

The 4 Coordinated Processes of the cell-divison cycle:

Answer 2

Cell growth, DNA replication, distribution of the duplicated chromosomes to daughter cells, and cell divison

Question 3

Binary Fission

Answer 3

A means of asexual reproduction in prokaryotes in which a cell divides to form 2 identical organisms

Question 4

The bacterial cell cycle is divided into 3 stages:

Answer 4

B period: The period extends from the end of cell divison to the beginning of DNA replication
C Period: The period rquired for chromosome replication
D Period: The time between the completion of chromosome replication and the completion of cell cycle

Question 5

Mitosis

Answer 5

The process in which a eukaryotic cell nucleus splits in 2 (evolved from an early form of binary fission)

Question 6

The Origin of Replication

Answer 6

The place where DNA replication begins, enabling a plasmid to reproduce itself as it must to survive within cells (once the ori is duplicated, the 2 origins actively migrate to the 2 ends of the cell

Question 7

The Eukaryotic cell cycle consists of 4 distinct phases:

Answer 7

G1 phase, S phase (synthesis), G2 phase (interphase) and M phase (mitosis and cytokinesis)
- interphase extends from the end of one mitosis to the beginning of the next mitosis. After interphase, mitosis proceeds in 5 stages

Question 8

Chromosomes

Answer 8

Nuclear units of genetic information that are divided and distributed by mitotic cell divison

Question 9

Chromatids:

Answer 9

Replication of DNA of each individual chromosome creates 2 identical molecules called sister chromatids

Question 10

Chromatin

Answer 10

A complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells

Question 11

Ploidy:

Answer 11

The # of chromosome sets in a cell or species
Diploid (2n)
Haploid (n)

Question 12

3 phases of the interphase:

Answer 12

1. G1 phase (Gap 1 phase, or Growth 1 phase): The cell carries out its function, and in some cases grows
2. S phase (Synthesis phase): DNA replication and chromosome duplication occur
3. G2 phase (Gap 2 phase, or Growth 2 phase): Brief gap in the cell cycle when cell growth continues and the cell prepares for mitosis and cytokinesis

G0 phase (quiescence) G0 is a resting phase where the cell has left the cycle and has stopped diividing

Question 13

5 Stages of Mitosis:

Answer 13

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

Question 14

Mitotic Cell Cycle- Chromosome segregation:

Answer 14

The equal distribution of daughter chromomsomes into each of the 2 daughter cells that results from cell divison

Question 15

Mitotic Cell Cycle- Spindle:

Answer 15

The spindle apparatus is the cytoskeletal strutcure that forms durin cell division to separate sister chromatids between daughter cells. it is composed of hundreds of proteins and microtubules that comprise the most abundant components of the machinery

Question 16

Mitotic Cell Cycle-Centromere:

Answer 16

The region pf a chromosome to which the microtubules of the spindle attach, via the kinetochore, during cell divison

Question 17

Mitotic Cell Cycle-Centrosome:

Answer 17

The main microtubule organising center of the cell, which organises the microtubule cytoskeleton during interphase and positions many of the cytoplasmic organelles

Question 18

Mitotic Cell Cycle-Kinetochore

Answer 18

Are large protein assemblies that connect chromosomes to microtubules of the mitotic and meiotic spindles in order to distribute the replicated gneome from a mother cell to its daughters

Question 19

Mitotic Cell Cycle- Cleavage furrow

Answer 19

In cytokinesis, a groove that girdles the cell and gradually deepens unitl it cuts the cytoplasm into 2 parts

Question 20

Mitotic Cell Cycle-Cell plate

Answer 20

New cell walls forms during cytokinesis in terrestial plants. this process entails the delivery of golgi-derived and endosomal vesicles carrying cell wall and cell membrane components to the plane of cell divison and the subsequent fusion of these vesibles within this plate

Question 21

Prophase:

Answer 21

1. Chromosomes condense into compact, rodlike structures
2. Each chromosome is doubled as a result of replication
3. The centrosome has divided into 2 parts, which are generating the spindle as they separate
4. spindle forms in the cytoplasm

Question 22

Prometaphase:

Answer 22

1. Nuclear envelope breaks down
2. Spindle enters former nuclear area
3. Microtubules from opposite spindle poles attach to 2 kinetochores of each chromosome

Question 23

Metaphase:

Answer 23

spindle connection and chromosome movement at prometaphase
1. spindle is fully formed and chromosomes align at spindle midpoint
2. Each sister chromatid pair is held in position by opposing forces: the kinetochore microtubules pulling to the poles and the cohesins binding the sister chromatids together

Question 24

Anaphase:

Answer 24

1. separase cleaves the cohesion ring holding sister chromatids together
2. spindle separates sister chromatids and moves them to opposite spindle poles
3. chromosome segregation is complete

Question 25

Telophase:

Answer 25

1. chromosomes decondense
2. return to extended state typical of interphase
3. new nuclear envelope forms around chromosomes
4. the cytoplasm is beginning to divide by furrowing

Question 26

Cytokenesis-

Answer 26

the physical process of cell divison, which divides the cytoplasm of a parental cell into 2 daughter cells