Processing Flashcards
1
Q
Is eukaryotic mRNA monocistronic or polycistronic?
A
monocistronic
2
Q
What type of RNA contains inosine? What can inosine bind to?
A
tRNA
A, C and U
3
Q
What is the function of aminoacyl-tRNA synthetases?
A
to link tRNAs for their amino acid
4
Q
80S?
A
human, cytosolic
5
Q
55S?
A
human, mitochondrial
6
Q
70S?
A
bacteria
7
Q
What is the first tRNA beginning protein translation?
A
tRNA-met
8
Q
What is eIF2a activated by?
A
GTP
9
Q
What binds tRNA-met? What is this complex called?
A
eIF2a-GTP
ternary complex
10
Q
What does the ternary complex bind?
A
small ribosomal subunit
11
Q
What binds to the small ribosomal subunit?
A
mRNA
12
Q
What marks the transition between the pre-initiation complex to the initiation complex?
A
binding of a large ribosomal subunit and GTP hydrolysis
13
Q
When does elongation begin?
A
once tRNA-met binds to the P site
14
Q
Where does the second amino acid go? WHat places it there? What provides the energy for this process?
A
E-site
EF-1
GTP
15
Q
What protein aids the ribosome in moving one codon of the mRNA?
A
EF-2
16
Q
The uncharged tRNA leaves the ribosome at what site?
A
E-site
17
Q
What is the one amino acid a stop codon can code for?
A
selenocysteine
18
Q
What protein pairs with a stop codon in the A site?
A
eukaryotic release factor
19
Q
What is hydrolyzed on eRF to terminate translation?
A
GTP
20
Q
How does streptomycin inhibit bacterial growth?
A
inhibits bacterial ribosome small unit and inhibits initiation
21
Q
How do both neomycin and gentomycin function?
A
by causing mistranslation of codons
22
Q
How does tetracycline function?
A
binds in A site.
inhibits tRNA binding
23
Q
What is the MOA of chloramphenicol?
A
prevents peptidyl bond formation
24
Q
How does ricin work?
A
removes adenine bases from rRNA large subunit
25
How does diptheria toxin function?
inactivates EF-2 by ADP-ribosylation
26
What two mechanisms are used to regulate translation?
preventing recognition of start codon
regulating activity of initiation factors
27
Chaperones bind to what region of nascent polypeptides?
hydrophobic
28
Where are chaperones concentrated in regards to their location?
cytosol and ER
29
Heat Shock Proteins are implicated in what disease?
Charcot Marie Tooth Disease
30
Where are exported proteins synthesized?
ER
31
Is the signal sequence hydrophilic or hydrophobic?
hydrophobic
32
What binds the signal sequence?
signal recognition particle (SRP)
33
Where does the SRP take the nascent polypeptide? What protein does it transger the polypeptide to?
ER membrane
translocon
34
What happens to the SRP after the nascent polypeptide has been transferred to the translocon?
dissociates
35
Where does the translocon transfer the nascent polypeptide?
from the cytosol to the ER
36
What cleaves the signal peptide?
a signal peptidase
37
What can trigger the unfolded protein response?
environmental responses
38
What is the unfolded protein response?
accumulation of unfolded proteins in the ER
39
What two types of proteins are often glycosylated?
excreted proteins and cell surface proteins
40
What donates the sugar for a glycosylated protein?
activated sugar nucleotide
41
What three tenets are glycosyltransferases specific for?
sugar donar, aceptor molecule, type of bond formed
42
Where are N-linked sugars attached?
asparagine
43
Where does N-linked glycosylation begin?
as protein emerges into the ER
44
What is the function of dolichol phosphate?
serves as a substrate for the genesis or a universal oligosaccharide
45
What is the first sugar to be transferred to asparagine during N-linked glycosylation?
universal oligosaccharide
46
Where does modification of the universal oligosaccharide occur?
golgi
47
What two types of protein are yielded following oligosaccharide trimming?
high mannose content and complex
48
Does N-linked glycosylation occur as the protein is being folded or after?
while the protein is being folded
49
When does O-linked glycosylation occur?
only after the protein has been folded
50
Where does O-linked glycosylation occur?
Golgi
51
What residues can be O-linked glycosylated?
serine of threonine
52
What is the first sugar to be transferred during O-linked glycosylation?
N-acetyl-galactosamine
53
What are common examples of O-linked glycosylation?
blood group antigens
54
The A allele possesses what sugar?
N-acetyl-galactosamine
55
The B allele possesses what sugar?
galactose
56
What is the disease process in multiple sulfatae deficiency?
failure to convert cysteine to formylglycine
57
Patients with MSD present with what type of symptoms?
mucopolysaccharidoses
58
What is always the first amino acid to be incorporated into a protein?
methionine
59
What three hydrophobic molecules can be added to proteins?
palmitic acid, myristic acid isoprenoids
60
What residue is myristic acid attached to?
glycine at N-terminus
61
What residue to palmitic acid attached to?
cysteine residues throughout protein
62
What residue are isoprenoids attached?
cysteine residues at c-terminus of protein
63
Where are proteins phosphorylated to be destined for the lysosome?
mannose residues
64
What donates the phosphate for phosphorylation of mannose?
N-acetyl-glucosamine
65
What targets proteins to the lysosome?
Mannose-6-phosphate
66
What targets proteins to the mitochondria?
presequence
67
Where is this presequence located?
N-terminally
68
What proteins mediate a protein containing a presequence into the mitochondria?
TOM and TIMs
69
What are two energy intensive muscles?
nerves and mitochondria
70
What causes Deafness-dystonia syndrome?
defective TIM protein
71
Where is defective CFTR protein moved?
cytosol and degraded
72
In I-cell disease, what two conditions can be detected?
dense inclusion bodies in fibroblasts
lysosomal proteins in the serum
73
What kind of degradation process takes place in the lysosome?
non-specific degradation
74
What other cellular process is the lysosome implicated in?
autophagy
75
What type of degradation occurs in the proteasome?
specific degradation
76
Addition of what protein targets a protein for proteasomal degradation?
ubiquitin
77
How many units of ubiquitin are transferred?
multiple
78
What is the function of E1?
activate ubiquitin
79
What protein is ubiquitin conjugated to before being added to proteins?
E2
80
What protein conjugates ubiquitin to proteins?
E3
81
What else does E3 do?
identifies proteins for ubiquitination
82
What specifically targets a protein for proteasomal degradation?
poly-ubiquitination
83
What two amino acids at the N-terminal signal for a short life span?
Arg or Lys
84
What two amino acids at the N-terminal signal for a longer life span?
Met or Ser
85
What tetramer sequence signals for a short life-span of a protein?
PEST sequence
86
What base is contained in tRNA that is not contained in other RNAs?
inosine
87
What protein attaches an amino acid to a tRNA?
aminoacyl-tRNA synthetases
88
How does streptomycin function?
inhibits initiation
89
How do neomycin and streptomycin function?
cause mistranslation of codons
90
What does ricin do to rRNA?
removes adenine bases
91
What does diptheria toxin inhibit? How does it do this?
inhibits EF-2
ADP ribosylation
92
What binds the signal sequence of a protein?
signal recognition particle (SRP)
93
What is the function of the translocon?
to transfer a nascent protein from cytosol to the ER
94
What signals the unfolded protein response?
accumulation of unfolded proteins in the ER
95
What two types of proteins are glycosylated?
proteins to be excreted and cell surface proteins
96
Where does glycosylation begin? Where does it continue?
ER
Golgi
97
During N-linked glycosylation, where does modification of the univeral oligosaccharide occur?
golgi
98
Where does O-linked only occur? What type of proteins is O-linked occuring?
only golgi
only fully formed proteins
99
What is transferred to proteins during O-linked glycosylation?
N-acetyl-galactosamine
100
What type of cells commonly express O-liknked proteins?
blood cell antigens
101
What is added to the antigen of the A allele?
N-acetyl-galactosamine
102
What is added to the antigen of the B allele?
galactose
103
What residue is myristic acid added to?
glycine
104
What residue is palmitic acid added to?
cysteines throughout
105
What residue are isoprenoids added to?
cysteines as C-terminus
106
What is the function of a GPI anchor?
anchor proteins to external surface of plasma membrane
107
What serves as the phosphate donor for mannose?
N-acetyl-glucossamine
108
Deafness-Dystonia disorder is caused by a mutation in what protein?
TIM protein
109
What two cellular happenings can one see with I-cell disease?
lysosomal proteins in the serum
inclusion bodies on fibroblasts
110
Other than non-specific degradation of proteins, what else can the lysosomes be involved in?
autophagy
111
What is the function of the E1 proteins?
activate ubiquitin
112
What is the function of the E3 proteins?
ligate uiquitin to proteins
113
Proteins with what two N-terminal residues are unstable?
arginine or lysine
114
What particular tetramer shortens the life-span of proteins?
PEST
115
What is a congenital disease involving protei chaperones?
Charcot Marie Tooth Disease
116
What is CDG-1?
defective production of lipid linked oligosaccharide
117
What is CDG-2?
defective trimming of oligosaccharide tree
118
What is the first sugar added in O-linked glycosylation?
N-acetylgalactosamine
119
What are two examples of O-linked glycosylated proteins?
proteoglycans and blood group antigens
120
What sugar does the A antigen possess?
N-acetylgalactosamine
121
What sugar does the B antigen possess?
galactose
122
Where is the GPI anchor added? What is its purpose?
GPI anchor added at C-terminus
to tether proteins to external side of C-terminus
123
What two residues is the ubiquitin bond formed between?
glycine and lysine
