Chapter 8: Mitosis

Question 1

For every 200 chromosomes . . .

Answer 1

DNA duplex is cooked around a core of 8 histone proteins called a nucleosome.
—> Further coiled into solenoid

Question 2

G1 Phase

Answer 2

• Primary growth phase
• major portion of cell life

Question 3

S phase

Answer 3

• DNA Synthesis
• DNA replication (creates 2 copies of each chromosome)

Question 4

G2 Phase

Answer 4

• Final preparations for cell division
• Replicates mitochondria
• Chromosomes condense
• Synthesis of Microtubules

Question 5

Prophase

Answer 5

• Replicated chromosomes condense further
• nucleolus disappears & the cell dismantles the nuclear envelope
• Assembles apparatus to pull sister chromatids to opposite side of the cell
• Spindle fibers—network of protein cables—are formed

Question 6

Metaphase

Answer 6

• Sister chromatids align in the middle of the cell
• Spindle fibers attack to the kinetochores of centromeres

Question 7

Anaphase

Answer 7

• Sister chromatids are split and pulled to opposite ends of cell
• Each pole has 1 set of chromosomes

Question 8

Telophase

Answer 8

• Disassembles Mitotic Spindle
• Nucleolus reappears

Question 9

Cytokinesis

Answer 9

• Initial pinching of nucleus for division
• Signals end of division

Question 10

Mitosis

Answer 10

Mechanism of cell division that occurs in an organism’s non-reproductive cells, or somatic cells

Question 11

Homologous Chromosomes (Mitosis)

Answer 11

Two chromosomes in a pair

Question 12

Haploid Cells

Answer 12

Two of each type of chromosome

Question 13

Sister Chromatids

Answer 13

Two identical copies of a chromosome formed by DNA replication

Question 14

Centromere

Answer 14

Linkage site in the center of homologous chromosomes

Question 15

Human chromosomes . . .

Answer 15

Can be paired as homologous chromosomes by size, shape, location of centromere, and so on.

Question 16

What are chromosomes composed of?

Answer 16

Chromatin (DNA & Protein)

Question 17

Histones

Answer 17

Positively charged brackets that the DNA helix wraps around.

Question 18

Kinetochore

Answer 18

Site on centromere that spindle fiber connects to in order to pull sister chromatids to opposite sides of the cell.

Question 19

G1 Checkpoint (Assessing Cell Growth)

Answer 19

• Location: End of G1 is phase
• Key decision of whether cell should divide, delay division, or be committed to G0 phase (resting phase)

Question 20

G2 Checkpoint (Assessing DNA Replication)

Answer 20

• Location: After G2 phase before prophase
• Prevents DNA-damaged cells from entering mitosis and allows for the repair of DNA replicated in late S and early G2 phase.
• Triggers the start of Metaphase (M phase)

Question 21

M checkpoint (Assessing Mitosis)

Answer 21

• Location: After metaphase, before anaphase
• Examines whether or not sister chromatids are correctly attached to spindle fibers
• Triggers the exit from from mitosis and cytokinesis, the beginning of G1 phase (beginning of cell cycle)

Question 22

Growth Factors

Answer 22

Small proteins that bind to the plasmas membrane and trigger intracellular signaling systems.

Question 23

Platelet-Derived Growth Factor (PDGF)

Answer 23

• Found in connective tissue known as Fibroblasts
• By binding to membrane receptor, PDGF initiates a chain of internal cell signals that stimulates cell division
• PDGF, and similar GFs, override cellular controls that inhibit cell division. In the case of an injury, a blood clot forms, PDGF is released, neighboring cells are signaled to divide, and the wound is healed.

Question 24

G0 Phase

Answer 24

• If cells are deprived of appropriate growth factories, they stop at G1 checkpoint and remain in the resting phase.

Question 25

Cytokinesis in Plants

Answer 25

• Due to the toughness of the cell wall in plants, plant cells create a cell plate that will divide the cell, where as, in animals, the cell is pinched.

Question 26

Prokaryotic cells divide by

Answer 26

Binary fission

Question 27

The G1, S, and G2 phases of the cell cycle are collectively known as

Answer 27

Interphase

Question 28

The proper sequence, beginning to end, for the stages of mitosis

Answer 28

Prophase-anaphase-metaphase-telophase

Question 29

During which phase of the cell cycle is DNA Synthesized?

Answer 29

S

Question 30

During which stage of mitosis do replicated chromosomes condense and the nuclear envelope disappears?

Answer 30

Prophase

Question 31

The spindle is

Answer 31

The network of protein cables that will pull the chromatids to opposite ends of the cell

Question 32

You look in the microscope and see sister chromatids moving to opposite sides of cell. You conclude that the cell is in

Answer 32

Anaphase

Question 33

In which cell type would a cell plate form after telophase is complete

Answer 33

Plants

Question 34

When the chromosomes line up at the equatorial plane, you can conclude that the cell is in

Answer 34

Metaphase

Question 35

During which mitotic stage is the spindle disassembled, the nuclear membrane formed, and the chromosomes uncoiled?

Answer 35

Telophase

Question 36

TRUE or FALSE: Interphase is not a stage in mitosis

Answer 36

TRUE

Question 37

During metaphase

Answer 37

Chromosomes line up on the equatorial plane

Question 38

TRUE or FALSE: The nuclear membrane disappears during telophase

Answer 38

FALSE

Question 39

After duplication, sister chromatids remain joined together

Answer 39

By the centromere

Question 40

During which stage of the cell cycle does the mitotic spindle begin to form

Answer 40

Prophase