Lecture 7

Question 1

prophase

Answer 1

• Chromosomes condense
• Nuclear membrane breaks down
• 2 spindle poles migrate to opposite ends of cell
• Microtubules grow out from spindle poles

Question 2

Metaphase

Answer 2

• Kinetochore microtubules attach to the kinetochore proteins on the centromeres of the chromosomes
• Kinetochore microtubules move the chromosomes back and form until they reach metaphase plate (middle of cell, not an actual structure)

Question 3

Microtubule Dynamics

Answer 3

• Are hollow tubes made up of a protein called tubulin
• Each tubulin made out of an 𝛼 and 𝛽 subunit
• Microtubules lengthen and shorten from + end
  *

Question 4

Polymerization

Answer 4

(addition) of tubulin proteins to the + end which allows it to grow in length

Question 5

Depolymerization

Answer 5

(loss) of tubulin proteins from + end

Question 6

How do chromosomes stay attached to end of MTs

Answer 6

Motor proteins** CENP-E** and Dynein walk chromosome up or down microtubue when it grows or shrinks

Question 7

Anaphase

Answer 7

• Anaphase promoting complex (APC) activated after chromosomes aligned in center of cell
• APC destroys cohesin proteins holding sister chromatids together
• Chromosome number in cell doubles
• Chromosomes are then segregated to opposite ends of cell by depolymerization of kinetochor microtubules

Question 8

Kinetochore microtubules:

Answer 8

connect chromosomes to spindle poles and segregate DNA

Question 9

Polar microtubules

Answer 9

extend from pole to spindle pole

Question 10

Aster microtubules

Answer 10

connext spindle poles to cell membrane

Question 11

Anaphase A

Answer 11

• chromosomes move away from each other, toward spindle poles
• Depolymerization of kinetochore microtubules

Question 12

Anaphase B

Answer 12

• spindle poles move away from each other
• Polymerization fo polar microtubules
• Kinesin motor proteins push overlapping polar microtubules apart

Question 13

Telophase

Answer 13

• Spindle apparatus disassembles
• Nuclear membranes form around each set of chromosomes
• Chromosomes decondense