Block 1 Lecture 6

Question 1

how many hydrophobic transmembrane spans does a G protein coupled receptor have

Answer 1

7

Question 2

how many hydrophobic transmembrane spans does a CTFR have

Answer 2

12

Question 3

what is the function of the Golgi and rough ER

Answer 3

making and moving proteins

Question 4

what happens to proteins in the golgi

Answer 4

the enter at the cis face, the Golgi modifies sorts and packages raw proteins, they exit the trans face

Question 5

what is a trimer ion channel

Answer 5

epithelial Na+ channel

Question 6

what is a tetramer ion channel

Answer 6

voltage gated Na+, K+, Ca2+ channels

Question 7

what is a pentameter ion channel

Answer 7

nicotinic Ach receptor

Question 8

what is a hexameter ion channel

Answer 8

hemi junction or connexon

Question 9

what happens in O linked glycosylation

Answer 9

adding sugar units on serine

Question 10

what happens in N linked glycosylation

Answer 10

adding ogliosaccharide to an asparagine

Question 11

what happens in GPI linkage

Answer 11

an enzyme cuts and attaches to an asparagine

Question 12

what is a glycocalyx

Answer 12

formed from proteoglycans on endothelial cells on lining of blood vessels

Question 13

what does a glycocalyx do

Answer 13

protects and detects strain to cytoskeleton

Question 14

what happens in cotranslation targeting of secretory proteins to the ER

Answer 14

1. signal sequence emerges from the ribosome, recognized and bound by SRP
2. the SRP escorts the complex to the ER membrane where it binds to SRP receptor
3. the SRP is released, the ribosome binds to a membrane translocation complex of sec61 proteins and the signal sequence is inserted into a membrane channel
4. translation resumes and the growing polypeptide chain is translocated across the membrane
5. cleavage of the signal sequence by signal peptidase releases the polypeptide into the lumen of the ER

Question 15

how are proteins deposited straight from the ribosome into the ER

Answer 15

translocon mechanism

Question 16

where does synthesis of phospholipids and cholesterol occur

Answer 16

smooth ER

Question 17

where are glycerol phospholipids synthesized

Answer 17

in the ER fro cytosolic precursors

Question 18

what yields phosphatidic acid

Answer 18

2 fatty acids linked to coenzyme A carriers linked to glycerol-3-phosphate

Question 19

what yields diacylglycerol

Answer 19

phosphatidic acid

Question 20

what yields phosphatidylinositol

Answer 20

phosphatidic acid

Question 21

where are phospholipids synthesized

Answer 21

the cytosolic side of the membrane

Question 22

what do phospholipid flippases do

Answer 22

they translocated across the membrane so both sides of the membrane grow together evenly

Question 23

where are secreted proteins synthesized

Answer 23

rough ER

Question 24

what are coated vesicles “coated” with

Answer 24

triskelions and adaptins

Question 25

what are secretory granules

Answer 25

organelle that hormones are packaged and stored for secretion

Question 26

what are the 2 secretory pathways

Answer 26

constitutive pathway and regulated pathway

Question 27

what happens in the constitutive pathway

Answer 27

secretion is continuous and unregulated

Question 28

what happens in the regulated pathway

Answer 28

secretion is directed by hormonal or neural signal

Question 29

where are lysosomal enzymes made

Answer 29

rough ER

Question 30

what do lysosomes do

Answer 30

digest cells

Question 31

what are the steps to lysosome enzyme sorting

Answer 31

1. lysosome hydrolase precursor enters Golgi from ER
2. phosphate is added forming mannose 6 phosphate (M6P)
3. M6P binds to M6P receptor in the Golgi and enters a budding vesicle
4. receptor dependent transport of vesicle from Golgi to prelysosomal endoscope occurs
5. an H pump acidifies the endosome
6. M6P dissociates
7. M6P receptors organize within a budding vesicle
8. receptors recycle back into the trans Golgi