Brainscape's Knowledge GenomeTM

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


See full index

Phase 1 Medicine > Week 1 - Intracellular Processes > Flashcards

Week 1 - Intracellular Processes Flashcards

1
Q

What are ribosomes composed of

A

Protein and rRNA

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

In what 2 ways does the cell act to segregate molecules

A

Through multicomponent complexes (such as the two subunits of the ribosome)
Through compartmentalisation into membrane-bound organelles

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

What do the membranes around organelles provide

A

A closed compartment in which sets of enzymes can operate without interference

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

Proteins in the membrane of organelles need to be what?

A

Replenished and maintained
Through production in cytosol where they are made and then to the organelle where they are used

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

Name the process by which synthesised proteins target their eventual location

A

Protein sorting

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

Where are proteins initially synthesised

A

Ribosomes in the cytosol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where is the information that tells a protein where to end up

A

Specific signal peptides ‘address labels’ contained in the amino acid sequence

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

The ribosome is made up of how many subunits

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Clinically used antibiotics target which sites on the ribosome?

A

Decoding site (small subunit)

Peptidyl-transferase centre (large subunit)

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

Name 3 ways in which proteins can get into organelles and give an example of when this happens

A

Nuclear pores
(proteins going into nucleus)
Protein translocators
(proteins moving from cytosol into ER)
Transport vesicles
(proteins moving from the ER onwards)

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

Why do some ribosomes know to go to the ER

A

The presence of a signal peptide on the protein being made (called the N-terminal amino acids at the start of the protein)

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

What is the C-terminal of the protein

A

The end of the protein

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

The signal peptide is guided to the ER by what?

A

The signal-recognition particle ( which detects the presence of signal peptide) and the SRP receptor (which is on the ER membrane

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

What is the name of the protein channel in the ER membrane

A

The translocon

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

Which enzyme cleaves the signal peptide once the protein is within the ER

A

Peptidase

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

What happens after the signal peptide has been cleaved by peptidase

A

The protein in the ER lumen is encapsulated into a transport vesicle that buds off and is secreted from the ER

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Analogy of signalling to the ER FIX THIS WHEN SOBER

A

New protein = letter
Signal peptide = address label
Signal recognition particle = postman
SRP receptor in ER membrane = Postman
SRP receptor in ER membrane = Name-plate on door
Translocon (pore/channel in ER) = Letterbox

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Once proteins are transported by vesicles to the Golgi apparatus, what is this called?

A

The cis cisterna

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens as the proteins move through the Golgi stack

A

The proteins undergo enzymatic modification which labels them for a specific cell destination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What allows the transport from ER to Golgi apparatus and Golgi apparatus to other compartments

A

The continual budding and fusion of transport vesicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Which side of the golgi apparatus is closest to the ER

A

Cis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Which side of the Golgi apparatus is furthest away from the ER

A

Trans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What happens at the trans end of the Golgi apparatus

A

Proteins are sorted into groups with the same target sequence as these are destined for the same location

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What happens once proteins have been sorted into groups at the trans side of the golgi apparatus

A

The proteins migrate via vesicles to their eventual location

25
Q

What directs proteins to the lysosome instead of the plasma membrane

A
26
Q

What are the two processes that can occur after the golgi apparatus

A

Exocytosis
Endocytosis

27
Q

Which signal ensures that the protein takes the exocytosis pathway

A

The stop translocation signal

28
Q

What causes a protein to take the alternative pathway towards the lysosome

A

An ‘address label’ added in the Golgi apparatus such as the side chain ‘mannose-6-phosphate’ (M6P)

29
Q

What happens to a protein that is labelled with M6P

A

It binds to a specific receptor in the golgi membrane
Protein will then bind with an endosome via vesicle transport which matures to become a lysosome

30
Q

What do endosomes often contain

A

A pathogen which has been endocytosed by the cell previously for it to be destroyed by the protein has been targeted in the first place (example hydrolase)

31
Q

Names of different sides of golgi apparatus

A

Cis cisterna (first side reached
Trans Golgi Cisternae

32
Q

What is glycosylation

A

Addition of sugar (such as M6P) to protein (happens in Golgi apparatus(

33
Q

What are proteins called that are extensively glycosylated

A

Proteoglycans

34
Q

What are proteins that are composed of little sugar content

A

Glycoproteins

35
Q

What is a hallmark of several neurodegenerative disorders

A

Hyperphosphorylation of the protein Tau

36
Q

Describe phosphorylation

A

Addition of a phosphate group which alters the activity of a protein

37
Q

Describe acetylation

A

Addition of an acetyl group which in histones regulates gene expression

38
Q

Describe Farnesylation

A

Addition of a farnesyl group which targets proteins to the cytoplasmic face of the plasma membrane

39
Q

Describe Ubiquitination

A

Addition of a ubiquitin chain which targets proteins for degradation

40
Q

What causes a protein to move to the ER and subsequently the Golgi

A

The presence of a signal peptide

41
Q

By default what will happen to the protein if there exists nothing other than a signal peptide

A

It will be secreted out of the cell

42
Q

What happens to protein that has the ‘stop translocation’ peptide

A

It will end up in the plasma membrane

43
Q

What will happen to a protein that has had a M6P sugar side chain added in the golgi apparatus

A

It will end up in the lysosomes

44
Q

What happens to a protein that lacks a signal protein

A

It will remain in the cytosol

45
Q

What happens to a protein that has a nuclear localisation signal in the protein sequence

A

It will end up in the nucleus

46
Q

What will happen to a protein that has a mitochondrial import sequence

A

It will end up in the mitochondira

47
Q

What will happen to proteins that have a c-terminal tripeptide?

A

They will end up in the peroxisomes

48
Q

What is protein degradation required for (3)

A

Proteins that have passed their ‘sell by’ date
Proteins that are faulty
Proteins that are foreign to the cell i.e pathogens

49
Q

What are the two mechanisms that can cause degradation

A

Lysosomal degradation
Proteasomal degradation

50
Q

Name 3 lysosomal enzymes

A

Lipases, nucleases and proteases/proteolytic enzymes

51
Q

How are lysosomal enzymes activated

A

By the acidic environment (pH 4.8) inside the lysosome

52
Q

Which types of proteins is lysosomal degradation used for (4)

A

Proteins with a long half life (>20 hours) (autophagy)

Membrane proteins brought into the cell via endocytosis

Extracellular proteins brought into the cell via receptor-mediated endocytosis

Pathogenic proteins brought into the cell via phagocytosis

53
Q

Where does proteasomal degradation occur

A

At the proteasomes

54
Q

Describe the structure of proteasomes

A

Cylindrical protein complexes which consist of protease enzymes (the active site is inside the cylinder)

55
Q

What controls the entry of proteins about to be degraded into the proteasome

A

Protein ‘stoppers’

56
Q

What are proteosomes dependant on for their function

A

ATP

57
Q

What is proteasomal degradation used for

A

Proteins that have a short half life and hence need to be removed quickly (seconds or minutes)

58
Q

Proteins with a short half life generally are rich in which specific sequence

Key metabolic enzymes and proteins that need to gotten rid of

Proteins that have been covalently tagged with ubiquitin

A

PEST (P) proline, (E) glutamic acid (S) Serine and (T) threonine

59
Q

Describe the 4 steps relating to proteasomal degradation of proteins that have been covalently tagged with ubiquitin

A

Shuttling proteins take ubiquitinated protein to proteasome
Tagged proteins are recognised, unfolded and translocated
Ubiquitinated proteins are degraded inside proteasome to give peptides
Peptides are extruded and digested by cytosolic peptidases

Phase 1 Medicine (37 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions