Cells And Tissues Biology Lec 4

Front 1

List 4 compartments through which newly synthetized secretory proteins travel on their way out of the cell

Back 1

1.Rough ER
2.Smooth ER
3.Golgi apparatus
4.Secretory vesicles

Front 2

All proteins synthesized at the Rough ER will pass through the Golgi on their way to the Cell surface or Compartments in the cell such as lysosomes
T/F?

Back 2

T.

Front 3

The Rough ER and smooth ER are discontinuous with each oter while vesicles move molecules between the ER and the Golgi, within the Golgi cisternae, and from the Golgi to the Cell surface.
T/F?

Back 3

F.
They are continuous

Front 4

What are the main types of material that constantly flow through the ER and Golgi apparatus?

Back 4

1.Membrane material
2.Secretory vesicle
3.Lysosome

Front 5

1.found in all cells
2.particularly abundant in professional secretory cells
3.proliferate in pancreatic acinar cell, packing together in the basolateral portion of the cell
1. Smooth ER
2. Rough ER

Back 5

1. Rough ER
Rough ER is found in all cells, but is particularly abundant in professional secretory cells such as the pancreatic acinar cell. The high demand for secretory products from these cells causes proliferation of the rough ER and the packing together of these membranes in the basolateral portion of the cell

Front 6

The following choices are characteristics of the rough ER except:
1. proliferates in cells that are devoted to the production of steroids or detoxification of drugs
2. proliferates particularly in professional secretory cells
3. forms stacks of flattened cisternae
4.Its cisternae have a lumen space 20-30 nm wide.
4.

Back 6

1.
Smooth ER, not Rough ER is amplified in cells devoted to the production of steroids or detoxification of drugs

Front 7

The smooth ER is connected to the Rough ER cisternae and forms a fine network of tubules 30-60 nm in diameter
T/F?

Back 7

T

Front 8

Each of the following choices are characteristic of the Golgi apparatus except:
1.consist of 3-5 disk-shaped flattened membranes or cisternae
2.Freeze fracture EM shows sheets of membrane that appear to be maintained as separate compartments
3.Small holes in these sheets, also called fenestrae, are commonly seen
4.morphologically and functionally polarized
5.stains intensely with H&E

Back 8

5.
The Golgi apparatus does not stain with H&E

Front 9

Explain the mophological and functional polarity of the golgi apparatus

Back 9

The Cis Golgi network (CGN) is the entrance site for vescicles coming from ER. The Trans Golgi network (TGN) is the exit site for the vesicles traveling to the cell surface or the lysosomes
2.CGN = forming face
TGN = maturing face
3.Each cisterna harbors a different set of ezymes that modify sugar groups on cargo proteins that pass through the Golgi

Front 10

Secretory vesicles come in a large varitey of shapes and sizes but all originate from the TGN
T/F?

Back 10

T.
TGN: trans Golgi Network

Front 11

What is the difference between constitutive and regulated secretory proteins?

Back 11

1.constitutive secretory proteins transit to other compartments as soon as they are made while regulated secretory proteins are stored for release in response to a stimulus

Front 12

Constitutive secretory vesicles can be easily identified on EM but not on LM
T/F

Back 12

F.
They are too difficult to id by EM as they do not accumulate in the cell

Front 13

Both regulated and constitutive secretion can occur in the same cell
T/F

Back 13

T.
That's a fact

Front 14

Synthesis of the phospholipid bilayer are never synthesized de novo.
T/F

Back 14

T.
use existing pieces of membrane as template for addition for the addition of the new bilayer

Front 15

Insertion of new phospholipids on the cytoplasmic side requires integral protein
T/F

Back 15

F.
New phospholipids can be inserted into the cytoplasmic side of existing bilayers

Front 16

Insertion of new phospholipids or modification of the lipids for the EC side of the membrane requires "FLIPPASES"
T/F

Back 16

T.
FLIPPASES flip lipids from the EC of the membrane to cytoplamic side for modification.

Front 17

Name two cytoplamic enzymes that play an important role in phospholipids, as well as the covalent modification of lipids

Back 17

Flippases and Scramblases

Front 18

List 6 steps in the synthesis of an integral protein

Back 18

1. Translation in cytoplasmic free ribosome
2. Recognition of the growing chain by a ribonucleoprotein complex called signal recognition particle (SRP)
3. SRP arrests translation, targets the ribosome to the ER and docks the complex by binding a affinity receptor in rER membrane
4.Peptide elongation restarts and the nascent peptide is pushed through the membrane of the ER utilizing a a Hydrophilic channel specialized for this purpose
5.ATP-dependent translocation of the protein into the ER by a translocator protein
6.Protein folding by Chaperones

Front 19

The following are characteristics of the translocator protein present in ER membrane except:
1.has a hydrophobic START-transfer peptide binding site
2.has a hydrophobic STOP-transfer peptide binding site
3.changes its conformation and discharges the protein laterally into the lipid bilayer upon binding to the N-terminal ER signal sequence
4.The translocator protein is located in the ER membrane

Back 19

3.
It changes its conformation and discharges the protein laterally into the lipid bilayer upon binding to the STOP-transfer sequence signal sequence.
The N-terminal ER signal sequence functions as a START-transfer signal

Front 20

A copy of the enzyme SIGNAL PEPTIDASE is associated with each protein translocator in the ER membrane.
T/F?

Back 20

T
Also, the same is true for oligosaccharyl transferase (N-Glycosylation).

Front 21

Name the 2 types of linkages involved in glycolysation occuring during translocation of the membrane proteins

Back 21

1.O-linked oligosaccharide (linked to serine or threonine)
2.N-linked oligosaccharides (linked to aspargine)

Front 22

What are Chaperones?

Back 22

1.Chaperones
Set of proteins in the lumen of the ER that bind to incorrectly folded proteins and either assist proper refolding or target them to a degradation pathway

Front 23

Describe 2 consequences of protein misfolding

Back 23

1.Refolding
2.Degradation

Front 24

Describe the process of PROTEIN REFOLDING

Back 24

1.The ER membrane-bound CALNEXIN binds to incompletely folded proteins containing 1 terminal glucose on N-linked oligosacc,trapping the protien in the ER.
2.Removal of the terminal glucose by a glucosidase releases the protein from calnexin
3.A glucosyl transferase determines wether protein is folded properly or not.
4.If properly folded, the protein exits from ER
5.If not properly folded, glucosyl transferase transfers a new glucose to the N-linked oligos, renewing the proteins affinity for canelxin and retaining it in the ER.
6.The cycle repeats until the protein has folded completely

Front 25

Describe the process of PROTEIN DEGRADATION

Back 25

1.Protein retranslocation into the cytoplasm
2.Protein deglycosylation
3.Protein Ubiquitylation
4.Protein degradation by proteasome :ERAD
(ER associated degradation)

Front 26

Synthesis of secretory proteins involves all the following except:
1.it utilizes the same machinery as the membrane synthesis
2.Multiple start and stop sites for translocation along the peptide chain generate multiple transmembrane domains
3.The peptide chain is translocated completely accross the ER membrane
4.All secretory proteins are made with a leader peptide that is cleaved once the protein reaches the lumen of the ER
5.The folding of protiens and covalent modifications occur using the same enzymatic machinery as described for membrane proteins

Back 26

2.
There are NO multiple start and stop sites for translocation along the peptide chain of secretory protein. Only one of each.

Front 27

Name a few additional covalent modifications that secretory and membrane proteins undergo as they pass through the Golgi apparatus

Back 27

1.Addition and trimming of carbohydrate chains
2.fatty acylation
3.phosphorylation

Front 28

In addition to covalent modification, proteins undergo what other change as they pass through the golgi?

Back 28

1.Domain formation
It is controlled by the phase transition of cholesterol, glycosphingolipid-rich regions of the bilayer as they encounter a low ph.

Front 29

List 2 steps that are necessary for protein sorting from the Golgi apparatus

Back 29

1.Incorporation of the molecules into the correct vesicle
2.Tageting the vescicle to the proper location

Front 30

Explain the process of retention that occur during protein sorting from the Golgi apparatus

Back 30

ER resident chaperones contain a KDEL retrieval sequence
2.KDEL receptor in the Golgi captures the ER resident chaperones
3.The ER resident chap are carried back to the ER in COPI-coated vesicles
4.In the neutral-pH environment of the ER, the ER proteins dissociate from the KDEL receptor
5.The KDEL receptor is then retruned to the Golgi in COPII vesicle for reuse

Front 31

Describe the function of small GTPase proteins in protein sorting. Give an example of a GTPase protein.

Back 31

1.Small GTPase proteins play a role in the specificity of vesicle targeting to compartment.
2.Rab protein targets the vesicle to compartments like lysosome

Front 32

What is the function of SNARE proteins in vesicle transportation through the Golgi

Back 32

SNARE proteins play a role in membrane fusion. Once a vesicle arrives at its target the membranes of the 2 compartments must fuse
1. The v-SNAREs on the transport ves bind to matching t-SNAREs in the target membrane
2.The complexes dissociate
3.A new cycle can now restart, or a the v-snare can be recycle

Front 33

What is the effect of botulism and tetanus toxins on SNARE proteins?

Back 33

They cleave SNARE proteins in nerve terminals, thereby block the release of neurotransmitter

Front 34

Describe the function of small GTPase proteins in protein sorting. Give an example of a GTPase protein.

Back 34

1.Small GTPase proteins play a role in the specificity of vesicle targeting to compartment.
2.Rab protein targets the vesicle to compartments like lysosome

Front 35

What is the function of SNARE proteins in vesicle transportation through the Golgi

Back 35

SNARE proteins play a role in membrane fusion. Once a vesicle arrives at its target the membranes of the 2 compartments must fuse
1. The v-SNAREs on the transport ves bind to matching t-SNAREs in the target membrane
2.The complexes dissociate
3.A new cycle can now restart, or a the v-snare can be recycle

Front 36

What is the effect of botulism and tetanus toxins on SNARE proteins?

Back 36

They cleave SNARE proteins in nerve terminals, thereby block the release of neurotransmitter

Front 37

The mutation results in the deleition a single AA, which causes the protein to misfold. The protein is then RETRANSLOCATED and DEGRADED and never reaches the plasma membrane:
1.Tetanus
2.Botulism
3.Cystic Fibrosis

Back 37

3.cystic fibrosis