Exam III Review Questions

Question 1

What is the diameter of actin?

Answer 1

7-8 nm

Question 2

What end do actin filaments grow from most rapidly?

Answer 2

(+) end or barbed end

Question 3

Which side is expected to always have actin bound to ADP?

Answer 3

(-) end or pointed end

Question 4

What is the protein complex that allows for branching patterns?

Answer 4

Arp2/3

Question 5

What protein increases the concentration of actin bound to ATP?

Answer 5

profilin

Question 6

What causes a long unbranched strand?

Answer 6

formin

Question 7

What is the monomer of a microtubule?

Answer 7

protofilin (13)

Question 8

What makes up the protofilaments?

Answer 8

a dimer of alpha and beta tubulin

Question 9

What is the state of the alpha and beta tubulin (what else is attached to it and where)?

Answer 9

• GTP is on the beta tubulin
• GTP is between the alpha and the beta tubulin (never gets hydrolysized)

Question 10

What is a centriole composed of?

Answer 10

9 microtubule triplets (13 in the “a” microtubule, 10 in “b” and 10 in “c”)

Question 11

Dynein typically moves towards the _____ end and kinesin typically moves towards the ___ end of microtubules.

Answer 11

minus; plus

Question 12

Why do microtubules disassemble?

Answer 12

a microtubule loses its GTP cap + a depolymerase removes tubulin-GTP

Question 13

what is similar between microtubules + actin filaments?

Answer 13

polarity

Question 14

what is the diameter of a microtubial?

Answer 14

24-25 nm

Question 15

what is the diameter of an intermediate filament?

Answer 15

10-12 nm

Question 16

what type of cells are keratins in?

Answer 16

epithelial cells

Question 17

how are intermediate filaments different from actin and microtubules?

Answer 17

they lack polarity

Question 18

what happens if there is a mutation in my keratin?

Answer 18

skin could fall off

Question 19

what glycerol phospholipids have a negative charge?

Answer 19

phosphatidylinositol + phosphatidylserine

Question 20

What is the difference between a sphingolipid and a glycerol lipid?

Answer 20

sphingolipids do not have a glycerol backbone

Question 21

What is an amyloplast?

Answer 21

a leucoplast that stores starch

Question 22

What is the difference in structure between a chromoplast and a chloroplast?

Answer 22

pigments

Question 23

What do chromoplasts have that chloroplasts don’t?

Answer 23

thylakoid membrane

Question 24

What phospholipids will you expect to find in high amounts on the outer membrane?

Answer 24

sphingomyelin, glycolipids & phosphatidylcholine

Question 25

What phospholipids will you expect to find in high amounts on the inner membrane?

Answer 25

phosphatidylinositol, phosphatidylserine & phosphatidylethanolamine

Question 26

Where is cholesterol found?

Answer 26

a lot on the outside of the phospholipid bilayer (but also some on the inside)

Question 27

What are the names of the proteins that are involved in the fusion of a vesicle to a target membrane?

Answer 27

V-SNARE --> vesicle T-SNARE --> target

Question 28

How many polypeptide chains are in a V-SNARE?

Answer 28

1

Question 29

How many polypeptide chains are in a T-SNARE?

Answer 29

3

Question 30

What protein will be found on the target + the vesicle?

Answer 30

Rab proteins

Question 31

What's a multiple vesicular body + where is it coming from?

Answer 31

It's a vesicle made up of vesicles. Comes from an early endosome.

Question 32

Where are Tim22 located + what do they do?

Answer 32

Located: inner membrane Function:

Question 33

Where are Tim23 located + what do they do?

Answer 33

Location: inner membrane Function:

Question 34

Where are Tom complexes located + what do they do?

Answer 34

Located: outer membrane Function:

Question 35

Where are Oxa1 translocases located + what do they do?

Answer 35

Located: inner membrane Function: puts transmembrane proteins in the inner membrane; can do single + mulitpass; does it with info from the mitochondria

Question 36

What components are needed to make lipid rafts?

Answer 36

cholesterol & sphingolipids

Question 37

What would the equilibrium potential be when there is 150mM of sodium ions outside the cell and 15mM of sodium ions inside the cell. This will be at body temperature (310K) R = 8.314 J/mol*K F = 96,485 coulombs/mol z = charge of the ion

Answer 37

61.5 mV

Question 38

What would the equilibrium potential be when there is 150mM of chloride ions outside the cell and 13mM of chloride ions inside the cell. This will be at body temperature (310K) R = 8.314 J/mol*K F = 96,485 coulombs/mol z = charge of the ion

Answer 38

-65.3 mV

Question 39

What would the equilibrium potential be when there is 2mM of calcium ions outside the cell and 0.0002mM of calcium ions inside the cell. This will be at body temperature (310K) R = 8.314 J/mol*K F = 96,485 coulombs/mol z = charge of the ion

Answer 39

123.08 mV

Question 40

What would the equilibrium potential be when there is 5mM of potassium ions outside the cell and 100mM of potassium ions inside the cell. This will be at body temperature (310K) R = 8.314 J/mol*K F = 96,485 coulombs/mol z = charge of the ion

Answer 40

-80 mV

Question 41

How many sodium ions are pumped into the cell to restore normal ion concentrations?

Answer 41

0