CH5-E.R

Question 1

This network is contineous with E.R membrane

Answer 1

Cisternae

Question 2

This is the internal compartment of the ER

Answer 2

ER lumen

Question 3

Contain ribosome

Answer 3

R.ER

Question 4

What synthesizes protein

Answer 4

Ribosomes (many ribosomes make a polysome)

Question 5

Two population of ribosomes in cytosol

Answer 5

Membrane bound ( cytosolic side of the RER - synth of prot co-translational
Free ribosome- synth prot from nucl.genome

Question 6

What protein insures folding

Answer 6

chaperones

Question 7

Post-translational process is done for protein import in the:

Answer 7

mitochondria, chloroplast, peroxisomes

those need chaperones

Question 8

Co-translational

Answer 8

Not released into cytosol so doesn’t need chaperones

Question 9

Ribosome sub-units

Answer 9

Large and Small, 18nm

Question 10

Smooth ER fxn

Answer 10

Lipid synthesis
& 
Detox 
&
Take away Ca2+ from cytosol

Question 11

Muscle Smooth ER

Answer 11

sarcoplasmic reticulum

Question 12

How does muscle contract

Answer 12

Uses the Sacro-pl.retic

release and re-uptake of Ca, trigger contraction and relaxation

Question 13

What are two types of protein imported into the ER + what do they all need

Answer 13

Transmembrane proteins = partly transolcated / partly embedded
Water soluble - fully translocated +released into ER lumen

ALL need an ER Signal sequence

Question 14

what is the ER signal sequence made of

Answer 14

Hydrophobic a.a resideus , a +’ve residue at Amino end and a polar sequence at carobyxl end.

Question 15

What is needed to direct the ER signal sequence

Answer 15

a signal recognition particle (SRP) to bind

Question 16

what are the SRP bound to

Answer 16

SRP-R (integral membr protein complex in the RER)

Question 17

What ways does protein modification happen in the ER

Answer 17

Glyocosylation
or
GPi anchor

Question 18

How is glyosylation done

Answer 18

Oligosacc transfer to amino-NH3 grp on ASN-chain

Which give rise to a N-link oligosacch.

Question 19

What does the O-link oligosacch differ from the N-link

Answer 19

O-link uses a Hydroxy-OH-grp on side chain of ser/threo/OH-Lysine,

Where as N-link uses NH3 on ASN-chain

Question 20

What is the name of the precursor to oligosaccharide

Answer 20

Dolichol

Question 21

What enzyme is needed for Dolichol

Answer 21

oligosaccheride-transferase

Question 22

What are the chaperones of the ER for Glyocosylation

Answer 22

Calnexi and calreticulin

Question 23

What is the function of proteosomes

Answer 23

they degrade misfolded proteins using retrotranslocation

Question 24

How is retro-transolocation done to misfolded proteins?

Answer 24

Need a transolcator complex to recognize misfolded proteins , and exported , and then the proteosomes de-glycosylate them

Question 25

what type of membrane protein is the GPi-anchor

Answer 25

peripheral membran protein

Question 26

What is ceramide converted to

Answer 26

sphingomyelin

Question 27

where does the active site face

Answer 27

cytosol

Question 28

where does lipid synthesis occur

Answer 28

cytosol

Question 29

What lipid are derived from di-acylglerol

Answer 29

phosphotadyl- ser / choline / ethanolamine

Question 30

What lipids are derived from sphingosine base

Answer 30

sphingo-myelin and sine

Question 31

How is di-acylglycerol made

Answer 31

phosphatidic acid –> diacylglycerol using phosphatadase

Question 32

What enzyme transfer lipid molecules from cytosol side to lumen to keep it equal

Answer 32

scramblase

Question 33

what enzyme flips phospholipids for asymetry

Answer 33

flipase

Question 34

Where are new lipid molecules only added to

Answer 34

Cytosol of the ER bilayer