Unit 5

Question 1

List all types of motor proteins in slides (4), and the filament they associate with

Answer 1

Myosin (actin), Kinesin (microtubules), axonemal and cytoplasmic dynein (microtubules)

Question 2

Compare and contrast myosin and kinesin

Answer 2

Very similar in structure and function, except that myosin walks along actin while kinesin walks along microtubules. Both toward + end.

Question 3

Describe phases of mitosis

Answer 3

Prophase: Formation of chromosomes, mitotic spindle
Prometaphase: nuclear envelope breaks down, chromosomes attach to kinetochores
Metaphase: chromosomes aligned along metaphase plate
Anaphase: Chromatids separate, pulled toward spindle poles (by MT shortening, spindle poles moving apart)
Telophase: Chromatids arrive at spindle poles, decondense, nuclear envelopes form
Cytokinesis: Contraction of actin/myosin contractile ring pinches the cell in two (different in plants)

Question 4

What must happen before mitosis begins?

Answer 4

Centrosomes divide to create two spindle poles

Question 5

Role of kinesin and dynein in mitosis

Answer 5

Kinesin: walks along interpolar microtubules to push spindle poles to cell cortex
Dynein: walks along astral microtubules to pull spindle poles to cell cortex

Question 6

What causes chromatid movement?

Answer 6

MT instability, motor proteins

Question 7

3 groups of MTs in mitotic spindle

Answer 7

Astral, interpolar, kinetochore

Question 8

Ciliary motor proteins and their functions

Answer 8

Kinesin: Anterograde transport (to tip) in IFT, helps build cilium
Cytoplasmic dynein: retrograde transport (to base) in IFT, helps disassemble cilium
Axonemal dynein: microtubule sliding= ciliary beating

Question 9

Name the MTOC of cilia, mitotic spindle, cytosolic MTs

Answer 9

Cilia: Basal body (mother centriole)
Mitotic spindle: Spindle poles (centrosomes - 2 centrioles)
Cytosolic: Centrosomes (2 centrioles

Question 10

Describe structure of cilia

Answer 10

9 doublet MTs on outside, 2 singlet inside. Also dynein arms and radial spokes.

Question 11

Kinesin and dynein direction of movement

Question 12

List types of MAPs (MT-associated proteins)

Answer 12

Stabilizing, disassembling, severing, bundling, +tips, gamma-tubulin ring complex, motors

Question 13

Where to find singlet, doublet, triplet MTs

Answer 13

Singlet: cytoplasmic MTs, mitotic spindle, inner MTs in cilia
Doublet: Outer MTs in cilia
Triplet: Centrioles/Basal bodies

Question 14

Sliding filament model and switchpoint hypothesis

Answer 14

Alternating dynein activity on either side of cilia results in bending motion