Brainscape's Knowledge GenomeTM

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


See full index

SFM Quiz 2 > Functions & Dysfunctions of Protein Processing > Flashcards

Functions & Dysfunctions of Protein Processing Flashcards

1
Q

How does streptomycin inhibit prokaryotic translation?

A

Streptomycin binds to the 30S subunit to disrupt INITIATION of translation. Interferes with the 30S subunit and 50S subunit interacting.

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

How does clindamycin inhibit prokaryotic translation?

A

Clindamycin (and erythromycin!) bind to the 50S subunit to disrupt TRANSLOCATION of the ribosome.

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

How does erythromycin inhibit prokaryotic translation?

A

Erythromycin binds to the 50S subunit to disrupt TRANSLOCATION of the ribosome.

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

How does tetracycline inhibit prokaryotic translation?

A

Tetracyclines bind to the 30S subunit to disrupt ELONGATION. It blocks entry of the aminoacyl-tRNA to ribosomal complex and impairs elongation. (the aminoacyl t-RNA would come in during the first step of elongation normally. This occurs higher up in the pathway before clindamycin and erythromycin bind.

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

How does chloramphenicol block translation?

A

Inhibits peptidyl transferase activity and impairs peptide fond formation. The peptide bond-forming with help of peptidyl transferase is the 2nd step of elongation.

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

why should we look at the differences in protein synthesis between prokaryotes and eukaryotes?

A
  1. To selectively inhibit prokaryotic protein synthesis (this is the molecular basis of abx)
  2. To understand the mechanism of human disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What 2 subunits make up a prokaryotic ribosome

A

30S and 50S

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

what 2 subunits make up a eukaryotic ribosome

A

40S and 60S

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

Where is peptidyl transferase activity housed

A

In the large (bigger number!) subunits

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

How does GTP-bound EF-2 relate to ribosomal translocation?

A

The GTP bound EF will get hydrolyzed and help to translocate the ribosome. This is the 3rd step of elongation.

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

What does Diptheria toxin inactivate?

A

EF2-GTP. This will INHIBIT elongation.

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

How does puromycin cause premature chain termination?

A

Puromycin forms a puromycylated chain causing premature chain release. This premature chain is more resistant to hydrolysis. Stops ribosome from functioning.

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

Where does puromycin enter to inhibit elongation?

A

It enters the A site and adds to the growing chain.

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

What is a silent mutation?

A

A mutation that does not change the amino acid

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

What is a missense mutation?

A

Changes the amino acid in the protein with:
A. No effect OR
B. Vastly different function

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

What is a nonsense mutation?

A

Changes a codon into a STOP codon.

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

In a nonsense mutation, what does the stop codon cause?

A

Premature termination of the chain. The protein will either be degraded or formed as a truncated version.

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

What is a frameshift mutation?

A

One or more nucleotides are deleted or inserted into the open reading frame.

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

What does out of frame (frameshift mutation) cause?

A

OOF causes a change in the codon sequence and thus alters the amino acid sequence of the protein. (DMD)

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

How does the hydrophobic nature of Val relate to sickle cell anemia?

A

The hydrophobicity of Val from Glutamate (hydrophilic) changes the HbA conformation and causes it to aggregate and form rigid rod structures

This deforms the RBC into “sickle” shape. They have poor O2 capacity and clog capillaries.

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

What mutation causes sickle cell anemia?

A

A missense mutation of the 6th codon in the allele of the gene for human beta globin (HBB)

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

In relation to DMD, where do OOF and in-frame deletions come in?

A

OOF (out of frame): results in little to no expression of dystrophin = severe DMD

In-Frame: Expression of truncated forms of dystrophin - a milder form of DMD called “Becker muscular dystrophy”

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

How does DMD affect different body systems?

A

Leads to muscle wasting (musculoskeletal system, respiratory problems, cardiac myopathies)

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

Why do only males get DMD

A

It is a sex-linked gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What’s the benefit of having a truncated protein in disease?

A

While it’s still bad, it will be a milder version of the disease because you do have SOME expression instead of NO expression. I.e. DMD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are the 2 protein sorting pathways

A
  1. Cytoplasmic

2. Secretory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what kinds of proteins use the cytosolic sorting pathway

A

Proteins destined for the cytosol, mitochondria, nucleus, and peroxisomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what kinds of proteins use the secretory sorting pathway

A

Proteins destined for the ER, lysosomes, plasma membranes, or for secretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What happens if there is no sorting signal?

A

In the cytoplasmic pathway, if there is no translocation signal it will go to the cytoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Translocation signal for the mitochondria

A

N-terminal hydrophobic alpha-helix signal peptide

MitochondriA has ALPHA-helix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Translocation signal for the nucleus

A

A KKKRK signal sequence. This is Lys and Arg rich.

32
Q

Translocation signal for peroxisomes

A

C-terminal SKL signal sequence

33
Q

Translocation signal for the ER lumen

A

C-terminal KDEL retention signal (Lys, Asp, Glu, Leu)

34
Q

Translocation signal for lysosomes

A

Mannose 6-phosphate signal group (I-Cell disease)

35
Q

Translocation signal for secretion

A

Trp-rich domain signal region. Absence of retention motifs.

“Sec-rich-on”

36
Q

Translocation signal for membranes

A

N-terminal apolar region (stop transfer sequence)

*like the mitochondria signal (Alpha helix b/c of the A) but membranes aren’t as cool so they don’t have the alpha helix, they only have the APOLAR

37
Q

what is special about proteins with a Rough ER sequence

A

They each of an ER-targeting signal peptide composed of 15-60 amino acids at N terminus of the protein

38
Q

What does KDEL mean

A 
It is the translocation signal for proteins destined for the ER lumen. 
K=Lysine
D=Aspartate
E=Glutamate
L=Leucine
39
Q

What organelle/(s) are involved in I-cell disease?

A

Lysosomes. Tagging of lysosomal proteins with mannose 6P is defective. There are high numbers of lysosomal enzymes in the blood.

40
Q

Sx of I-Cell disease

A
  • Failure to thrive
  • Developmental delay
  • Abnormal skeletal development
  • Coarse facial features
  • Claw hands
  • Cornea clouding
  • Hepatomegaly
  • Splenomegaly
  • CHF
  • Defective heart valves
41
Q

What does HSP70 do?

A

HSP70 (heat shock proteins 70) are chaperones that unfolded proteins bind to for protection. Nuclear-coded mitochondrial proteins bind to this and then go through TOM and TIM into the mitochondria.

42
Q

To cross the nuclear membrane, some proteins need ____

A

a nuclear ionization signal if they are large (>40 kDa). If they are small, they can pass through specific pores.

43
Q

What kinds of residues do proteins need for nuclear import?

A

4 continuous basic residues (Lys and Arg)

44
Q

What pathway is SRP (signal recognition particle) needed?

A

Secretory pathway.

45
Q

What does an SRP do?

A
  1. Bind to ER-targeting signal and ribosome during translation
  2. Wraps itself around the ribosome-mRNA-peptide complex, causes tethering, and halts translation (for now)
  3. Once directed to the ER lumen, translation begins again
  4. Luminal enzymes cleave the signal to release the protein
  5. Protein undergoes post-translational modifications in ER/Golgi
  6. Addition signal sequences guide protein to final destination
46
Q

Explain trypsinogen and chymotrypsinogen to trypsin and chymotrypsin in relation to proteolytic cleavage

A

Proteolytic cleavage, a type of post-translational processing, converts inactive forms to active enzymes by unmasking the enzyme site. Trypsinogen and chymotrypsinogen have a “masking” sequence that is removed to reveal the active enzyme (trypsin and chymotrypsin) by proteolytic cleavage.

47
Q

Is protein folding part of post-translational processing?

A

Yes. Small proteins can fold into native conformations spontaneously. Large proteins cannot and are at risk for aggregations and proteolysis.

48
Q

What do large proteins require in post-translational processing?

A

Chaperones to protect the protein and help it fold into its proper tertiary form (ex. HSP70)

49
Q

What do chaperonins do?

A

Admit unfolded proteins and catalyze folding in ATP dependent manner (ex. HSP60)

50
Q

What are the 4 covalent post-translational modifications

A
  1. Glycosylation
  2. Phosphorylation
  3. Disulfide bond formation
  4. Acetylation
51
Q

Acetylation modification

A

Definition: covalent linkage to amine
Functional group: AMine (-NH3)
Residue affected: Lys
The acetyl group donor is acetyl coA

52
Q

Glycosylation modification

A

There is O and N glycosylation.
O: Hydroxyl (-OH), Ser&Thr
N: Acid amide (-CONH2), Asn&Gln

“O (oh sir) N that glyc sauce”

53
Q

Phosphorylation modification

A

Phosphate linked via esterification
HYdroxyl (-OH)
Ser, Tyr, Thr, Asp, His

54
Q

Disulfide bond modification

A

Oxidation to achieve covalent linkage of cysteine residues
Sulfhydryl (-SH)
Cysteine

55
Q

What kinds of residues and kinases are present in phosphorylation?

A

Phosphorylation uses the activity of serine and threonine and tyrosine kinase (transfers a phosphate onto a protein from ATP). To inactivate the enzyme, use a protein phosphatase to remove the phosphate from the active enzyme.

56
Q

What enzyme catalyzes disulfide bond formation

A

Protein disulfide isomerase

57
Q

Where does the formation and reorganization of disulfide bonds occur

A

In the ER lumen

58
Q

What is acetylation catalyzed by?

A

Histone acetyltransferase (HAT)

59
Q

What is deacetylation catalyzed by?

A

Histone deacetylase (HDAC)

60
Q

where are proteins typically acetylated?

A

Lysine residues

61
Q

which vitamin is essential for the activity of lysyl and prolyl hydroxylases

A

Ascorbic Acid (Vit. C)

62
Q

What are some post-translational modifications of collagen?

A
  • Lysines modified to form 5-hydroxylysine
  • Lysines deaminated to aldehydes
  • Prolines hydroxylated to hydroxyprolines
63
Q

what are some results of lysyl hydroxylase defects

A

skin, bone, and joint disorders (Ehlers-Danlos, Nevo, Bruck, Epidermolysis Bullosa Simplex)

64
Q

Alzheimers Disease sx

A

Loss of memory, cognitive function, and language

65
Q

Parkinsons disease sx

A

Fine motor control issues

66
Q

Huntingtons disease sx

A

Loss of movement, cognitive issues, psych issues

67
Q

Crutzfeldt-Jacob sx

A

Memory failure, behavior changes, lack of coordination, extremity weakness, coma

68
Q

What happens to proteins in Alzheimers

A

Amyloid precursor protein (APP) breaks down to form Amyloid beta peptide –> forms extracellular plaques

69
Q

What happens to Tau protein in Alzheimers

A

Tau (neurofibrillary tangles, intracellular) gets hyperphosphorylated

70
Q

Mutations in APP and Tau cause what form of AD?

A

The familial form of Alzheimer’s (early onset)

71
Q

What is the common denominator in sporadic form of AD?

A

Brain aging aka not genetic

72
Q

What aggregates are in PD?

A

An aggregation os alpha-synuclein (AS) protein form insoluble fibers which lead to Lewy bodies

73
Q

Where are Lewy Bodies located and what does this lead to

A

Located in the dopaminergic neurons in the substantia nigra. Leads to reduced availability of dopamine.

74
Q

What does a mutation in the Huntington gene cause

A

CAG triplet repeats. Leads to polyglutamine repeats which form intramolecular H-bonds which misfold and aggregate. Selective death of cells in the basal ganglia cause sx.

75
Q

what’s unique about Creutzfeldt-Jacob disease?

A

It is transmissible. Infection by misfolded proteins converts normal proteins to misfolded form. Key word=prion.

SFM Quiz 2 (10 decks)

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