Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Cell Biology > Endoplasmic Reticulum > Flashcards

Endoplasmic Reticulum Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What percentage of the cells volume does the ER take up?

A

10%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What percentage of the cells membranes does the ER take up?

A

60%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the function of the ER?

A

The site of phospholipid synthesis = by membrane bound enzymes of the outside of the ER

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is scramblase responsible for?

A

The translocation of phospholipids between the two monolayers of a lipid bilayer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How is the rough ER different from the smooth ER?

A

It has attached ribosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the function of the ribosomes attached to the rough ER?

A

Protein sythesis

  • secretory proteins
  • transmembrane proteins
  • ER and golgi proteins
  • lysosomal proteins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How is the location of protein synthesis linked to where the protein will go once its been synthesised?

A

If proteins are destined to end up in the cytosol they will be synthesised in the cytosol
If proteins are destined to end up being excreted they will be synthesised on the rough ER

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the process by which proteins are targeted to the rough ER to be synthesised.

A
  1. mRNA binds to a ribosome
  2. Translation begins
  3. When the signal peptide is translated a SRP (signal recognition particle) will bind to it, temporarily pausing translation
  4. The ribosome travels to the rough ER where the SPR binds to a SPR recpetor on the membrane of the ER
  5. The ribosome interacts with the ER membrane
  6. The SRP and SRP receptor are displaced and recycled
  7. Translation resumes with the elongating chain being ‘pushed’ into the ER lumen through a translocator protein
  8. The signal peptide detaches from the polypeptide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does SRP stand for?

A

Signal recognition particle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the translocator protein called that ‘pushes’ the polypeptide into the ER lumen?

A

Sec61 translocon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is glycosylation?

A

The modification of proteins by the addition of a 14 sugar sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Which proteins are glycosylated?

A

Almost all proteins synthesised on the rough ER

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the 14 sugar sequence?

A

Oligosaccharide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where on the protein do sugars attach?

A

To a specific amino acid sequence starting with asparginine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How many glucose molecules are there within the oligosaccharide?

A

3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the molecule that the precursor oligosaccharide is produced on and where is it found?

A

Phosphodolichol

On the ER membrane

17
Q

What is the enzyme that transfers the oligosaccharide onto the elongating polypeptide?

A

Membrane bound oligosaccharyltransferase enzyme

Found in the ER lumen

18
Q

What does glycolysation also act as?

A

A folding tag

19
Q

Describe the process by which glycolysation acts as a folding tag.

A
  1. During the initial phase of protein folding 2 of the 3 glucose molecules are removed
  2. Calnexin recognises the single glucose molecule on the incompletely folded protein and prevents it leaving the golgi
  3. The final glucose is removed
20
Q

What happens if the final glucose is removed before the protein has completed folding?

A

Glucosyl transferase added another glucose to prevent it from leaving the golgi

21
Q

What happens if the final glucose is removed from misfolded proteins?

A

Misfolded protein is transported back to the dislocation complex and is sent to the cytoplasm to be degraded

22
Q

What happens if the glucose is removed from a correctly folded protein?

A

The protein is exported to the golgi

23
Q

What is the smooth ER a site for?

A

Lipid synthesis

Steroid hormone synthesis

24
Q

How does the smooth ER change in order for it to be able to synthesis cholesterol?

A

It expands in order to accomodate the enzymes which synthesise and modify cholesterol

25
Q

Where does the detoxification of drugs occur?

A

In hepatocytes in the liver

26
Q

Describe the process of drug detoxification.

A
  1. Lipophilic drugs are found on the ER membrane
  2. Drugs are oxidised which increases their water solubility
  3. The drug leaves the ER membrane where it further modified in the cytoplasm
  4. The drug is excreted in the bile and urine

Cell Biology (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions