Biology Exam #2

Question 1

What is the order of IF filament building blocks?

Answer 1

Monomer to parallel dimer to anti-parallel staggered tetramer to Filament (8 tetramers) to Immature Filament to mature filament

Question 2

What is the function of intermediate filaments?

Answer 2

mechanical strength and shape

Question 3

What is the function of Actin?

Answer 3

large scale movement, motion and shape

Question 4

What is the function of microtubules?

Answer 4

Trafficking and mitosis

Question 5

Where do you find IF in a cell?

Answer 5

cell-cell junctions and nuclear envelope

Question 6

Where do you find actin in a cell?

Answer 6

the actin cortex just under the plasma membrane

Question 7

Where do you find microtubules in a cell?

Answer 7

The MTOC next to the nuclear membrane

Question 8

How do IF’s assemble?

Answer 8

IF’s assemble through spontaneous assembly, then the polymers are held together by hydrophobic forces.

Question 9

What is the role of dynamic instability?

Answer 9

Dynamic instability is the growth and shrinkage of a cytoskeleton filaments. The role of dynamic instability is to allow microtubules to rapidly grow and shrink in cells, which allows cellular traffic to re-route.

Question 10

What is the role of treadmilling?

Answer 10

Allows actin too quickly rearrange itself in one direction which helps with cell migration and is important for cell motility.

Question 11

What is the role of kinesin?

Answer 11

motor protein that walks toward the (+) end of the microtubule.

Question 12

What is the role of dyenein?

Answer 12

motor protein that walks toward the (-) end of the microtubule.

Question 13

Describe the structure of myosin?

Answer 13

motor domain regulatory domain (lever arm) a tail domain

Question 14

Describe the structure of kinesin?

Answer 14

head, as stalk (coiled coil), and a tail (light chains)

Question 15

Describe the structure of Dynein

Answer 15

stalk, head, stem, and tail (intermediate chain/ light chain complex)

Question 16

What role does ATP play?

Answer 16

ATP is required for motor proteins movement. The cycle of ATP -> ADP hydrolysis is required to let head groups swing past each other and attach to the microtubule in front.

Question 17

How do motor proteins control sperm flagella movement?

Answer 17

As dynein walks down the - end of the microtubules in the sperm flagella it causes the microtubules to slide pass each other causing the swimming motion.

Question 18

How do motor proteins control cell migration?

Answer 18

Myosin exerts force to move the actin filaments by using a “Rope pulling” grab-release motion which makes cells roll at the front and squeeze at the back.

Question 19

a network of filamentous proteins that links organelle and the plasma membrane

Answer 19

cytoskeleton

Question 20

What causes the disassembly of intermediate filaments?

Answer 20

Phosphorylation: phosphate charge disrupts hydrophobic interaction

Question 21

What is an example of specialized intermediate filaments?

Answer 21

nuclear lamins which are located by nuclear envelope and bind DNA and chromatin and provide structural support to nucleus/DNA

Question 22

What is the building block of microtubules?

Answer 22

Alpha (-)Beta(+) dimer

Question 23

What energy molecules do alpha-beta bind?

Answer 23

GTP

Question 24

What starts microtubule assembly?

Answer 24

gamma-tubulin

Question 25

What is the polymer of microtubules called?

Answer 25

protofilaments

Question 26

What is this reaction called? GTP ---> GDP +P

Answer 26

GTP hydrolysis

Question 27

How do ATP/GTP control protein function?

Answer 27

Shape change

Question 28

How do MTs assemble?

Answer 28

alpha beta dimers polymerize to form microtubules which are composed of 13 protofilaments assembled around a hollow core.

Question 29

How do MT's disassemble?

Answer 29

- When the (+) end hydrolyzes GTP to GDP mt will fall apart

Question 30

What is it called when MT's lose their GTP cap and fall apart?

Answer 30

Catastrophe

Question 31

What is it called when mt regain their GTP cap and begin growing again?

Answer 31

Rescue

Question 32

What proteins are involved with MTs

Answer 32

dynein and kinesin

Question 33

What is required to let head groups "swing" past each other

Answer 33

cycle of ATP to ADP hydrolysis

Question 34

What is the initiation formation of microtubules

Answer 34

nucleation

Question 35

What drug target microtubule function

Answer 35

taxol

Question 36

What is the polymer of actin?

Answer 36

actin filaments

Question 37

What are the three stages of actin assembly?

Answer 37

1) Nucleation: monomers start to bind 2) Elongation: monomers added 3) Steady state: rate of adding monomers = rate of losing monomers

Question 38

What is the function of capping proteins?

Answer 38

binding to either end of filament and hold length at steady state

Question 39

What is the function of cross linking proteins?

Answer 39

organize actin filaments into bundles and networks

Question 40

What is the function of myosins?

Answer 40

motor protein to create movement and force.

Question 41

What are the four steps of cell migration?

Answer 41

Step 1: Cell pushes out a portion of the plasma membrane and actin filament polymerize. Step 2: Plasma membrane is secured in new location- interns of ECM connect to actin filaments Step 3: Stress fibers form and actin filaments attached to interns grow back towards the center of the cell Step 4: Mysoins pull actin filaments forward at the rear of the cell and intern complexes at the rear of cell disassemble

Question 42

narrow threadlike protrusions

Answer 42

filopodia

Question 43

Broad shallow distortions

Answer 43

lamellipodia

Question 44

What type of energy molecule does actin use?

Answer 44

ATP

Question 45

What are the 9 steps of vesicle formation

Answer 45

1) Cargo Selection 2) Budding 3) Scission 4) Uncoating 5) Transport 6) Tethering 7) Docking 8) Fusion 9 )Disassembly

Question 46

What happens in cargo selection

Answer 46

cargo binds to partner receptor

Question 47

What happens in budding?

Answer 47

coat proteins bind adaptor proteins, deforms membrane

Question 48

What happens in Scission?

Answer 48

Dynamin and GTP bind vesicle, GTP hydrolysis causes shape change and dynamic pinches vesicle off donor membrane.

Question 49

What happens in uncoating?

Answer 49

coat proteins fall off

Question 50

What happens in transport

Answer 50

kinesin moves vesicle down microtubule

Question 51

What happens in tethering

Answer 51

Rab and tethering protein partner for first contact between the vesicle and acceptor protein

Question 52

What happens in Docking?

Answer 52

v-snare and t-snare partner for close proximity of vesicle and membrane

Question 53

What happens in fusion

Answer 53

vesicle and acceptor membrane fuse

Question 54

What happens in disassembly?

Answer 54

Receptors and c-snare sent back to the donor membrane

Question 55

What is the structure of the Golgi?

Answer 55

5-8 cistern held together by grasp proteins; made of cis, medial and trans

Question 56

What are the function of the Golgi?

Answer 56

Cis (CGN)-receive vesicle from ER Medial - protein modification Trans (TGN) - protein sorting, cargo selection, and vesicle fate

Question 57

Outline the process of exocytosis

Answer 57

Starts in ER > COPII vesicle > cis Golgi> trans Golgi> PM COPI vesicle goes from Golgi to ER

Question 58

Outline the process of endocytosis

Answer 58

Starts at PM > ends at lysosome

Question 59

What is the role of Clathrin?

Answer 59

endocytosis vesicles from PM to endosome/ lysosome

Question 60

Coat protein from ER to Golgi

Answer 60

COPII

Question 61

Vesicle coat protein from Golgi back to Er

Answer 61

COPI

Question 62

What are the characteristics of a lysosome?

Answer 62

- has degrative enzymes - acidic pH - can fuse w/ and degrade old organelle and viruses

Question 63

What is the function of an Endosome?

Answer 63

sort and deliver of internalized material from cell surface