Metabolism 2 (part 2) Flashcards Preview

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1
Q

If the carbon skeleton of an amino acid, after losing its amino group is degraded into acetyl CoA, oxaloacetate, and/or ketone bodies, what is it called?

A

Ketogenic

ketone bodies for ketogenesis

2
Q

What are the 2 ketogenic amino acids?

A

LL

Lysine and Leucine

3
Q

How many essential amino acids are there?

What does it mean to be essential?

A

10 out of 20

we can’t synthesize essentials

4
Q

How many non-essential AA’s are there?

Is arginine essential?

A

10

Arginine sometimes considered essential, because we don’t synthesize enough

5
Q

Is tyrosine an essential AA?

A

No, it’s considered non-essential because we make it from phenylalanine.

However, phenylalanine IS essential

6
Q

What is tyrosine for an individual incapable of metabolizing phenylalanine?

A

Conditionally essential

7
Q

Name the non-essential AA’s

A

PVT TIM HLL

8
Q

What is the term to define an amino acid losing its amino group, and the leftover carbon skeleton entering GNG pathway?

A

Glutogenic

9
Q

What is gastric acid and from where is it secreted?

What is its function?

A

HCl
secreted from parietal cells in the stomach

denatures proteins (begins process) and releases intrinsic factor so B12 can be absorbed

10
Q

What type of hormone is Cholecystokinin?

What is its function?

A

Peptide hormone

digests Fat AND Protein, stimulates gall bladder, slows gastric emptying, satiety signal

11
Q

What zymogen stimulates the release of a basic solution from the pancreas?
How long is the zymogen and active form?

A

Secretin

121AA cut to 27 AA hormonal active form

12
Q

What enzyme cleaves trypsinogen to become trypsin?

A

Enteropeptidase

13
Q

How is trypsin activated?

What does it do?

A

Trypsinogen > (Enteropeptidase) > Trypsin

Trypsin cleaves chymotrypsinogen > chymotrypsin

14
Q

What are the 3 main zymogens in protein digestion?

A

Pepsinogen
Chymotrypsinogen
Trypsinogen

15
Q

What zymogen is released by chief cells in the stomach in response to HCl?

A

Pepsinogen

HCl activates Pepsin

16
Q

Where is chymotrypsinogen made and what does its active form break down?

A

Pancreas

Chymotrypsin breaks down aromatic AA residues

17
Q

What activates trypsinogen (trypsin)?

What does trypsin activate?

A

Enteropeptidase

Chymotrypsin (from chymotrypsinogen)
Elastase (from proelastase)
Carboxypeptidase (from procarboxypeptidase)
Lipase (from prolipase)

18
Q

What do trypsin, chymotrypsin, and elastase preferentially cleave?

A

trypsin - arg/lys residues
chymotrypsin - aromatic AA residues
elastase - hydrophobic AA’s

19
Q

After proteins are sufficiently broken down in the lumen how do they get into the enterocyte?

A

Secondary Active Transport (specific carrier-mediated)

20
Q

What size are the AA chains that enter the enterocyte from the lumen?

A

Free AA, di, and tri-peptides

1-3

21
Q

What catalyzes the cleavage of AA’s from the N-terminus of oligopeptides entering the enterocyte?

A

Aminopeptidase

22
Q

Once 1-3 AA chains are in the enterocyte, what occurs before they are released into the blood?
How are they released into the blood?

A

Peptidases continue to break into single AA’s

Facilitated transport

23
Q

What determines the lifespan of a protein?

A

The AA at the N-terminus

24
Q

What determines the shelf life of a protein?

A

PEST sequences (Proline, Glutamate, Serine, Threonine)

AA sequences that serve as marker for death - more protein has shorter its life

25
Q

What death marker attaches to Lysine?

A

Ubiquitin?

26
Q

What structure does the ubiquitin-attached protein enter for degradation?
What survives?

A

26S Proteasome

Ubiquitin survives the shredder

27
Q

What catalyzes the transfer of amino groups from AA’s to Alpha-ketoglutarate?
What is the major co-enzyme in this rxn?

A

Aminotransferases

Pyridoxal Phosphate

28
Q

What catalyzes the transfer of an amino group of Alanine to Alpha-ketoglutarate to form pyruvate and glutamate?
Alanine > Pyruvate
A-ketoglutarate > Glutamate

A

Alanine Aminotransferase (ALT)

THE RULE

remember: co-enzyme is pyridoxal phosphate

29
Q

Glutamate > Alpha-Ketoglutarate
Oxaloacetate > Aspartate

amino goes from glutamate to aspartate. What is this called?
What is the co-enzyme?

A

Aspartate aminotransferase

Pyridoxal phosphate

30
Q

What are 3 important reactants and products of aminotransferase (deamination)?

A

Glutamate > Alpha-Ketoglutarate
Alanine > Pyruvate
Aspartate > oxaloacetate

31
Q

What AA spontaneously goes through oxidative deamination?
Where does this occur?
What enzyme is involved?
What does this produce?
Why are ATP and GTP allosteric inhibitors of this rxn?

A
Glutamate
Liver (mitochondria) 
Glutamate dehydrogenase 
free ammonia (and alpha-keto acid)
NADH is produced (AMP activates)
32
Q

What is the key controlling regulatory step in the urea cycle?
What allosterically regulates?
What is the product?
Where does the amino group come from?

A

CPSI (Carbamoyl Phosphate Synthetase I)

N-acetylglutamate (high concentrations after eating)

Carbamoyl Phosphate

ammonia comes from Glutamate

33
Q

Where in the body does the urea cycle occur?

Where in the cell?

A

Liver (principally)

2 rxns in mitochondria (including key CPSI/Carbamoyl-P/N-acetylglutamate rxn)
rest in cytosol

34
Q

Where does the Nitrogen in urea come from?

How many ATP are required to form urea?

A

Glutamate and Aspartate

4

35
Q

What is the benign way we transport ammonia in blood?

A

via Alanine and Glutamine

36
Q

What is a product of the urea cycle, an intermediate in the CAC, and can make aspartate in an aminotranferase (transamination) reaction with oxaloacetate?

also a link to GNG

A

Fumarate

37
Q

What does glutaminase do?

A

Glutamine > Glutamate

in the liver

38
Q

What happens if the glutamate dehydrogenase reaction is pushed too far toward the formation of glutamate?

A

It depletes Alpha-Ketoglutarate, which is essential for the CAC to run

(remember Alpha-ketoglutarate + NH3 = glutamate)

this is ammonia toxicity

39
Q

What are the 2 kinds of hyperammonemia?

A

Acquired (liver cirrhosis)

Hereditary (mental retardation usually occurs)

40
Q

What transfers the most reduced (methyl) groups?

A

S-adenosyl methionine

41
Q

What transfers intermediately reduced carbon groups?

A

Tetrahydrofolate

42
Q

Is CO2 considered part of the one carbon pool?

How is it transferred?

A

NO

Biotin (vitamin B7)

43
Q

Where does folic acid come from?

What is its structure?

A

Vitamin B9

pteridine ring, p-aminobenzoic acid (PABA), glutamate
only bacteria make the link between pteridine and PABA

44
Q

What is ingested folic acid metabolized to?

What steps and enzyme involved?

A

Tetrahydrofolate (THF)

dihydrofoltate reductase

two reducing steps (using two NADPH)

45
Q

Folic acid rxn:

A

Folic acid > dihydrofolate (NADPH>NADP+) > tetrahydrofolate (NADPH>NADP+)

46
Q

What drug is an analog of dihydrofolate and important in cancer treatment?
What does it inhibit?

A

Methotrexate

enzyme of rxn: dihydrofolate reductase

47
Q

What is the most common vitamin deficiency in the world?

A

Folate

48
Q

What 3 molecules is tetrahydrofolate a requirement to metabolize?

A

Purine, Thymine, and AA metabolism

49
Q

Where does THF usually get its carbon from?

this is the major source of carried carbon

A

Serine

serine is converted to glycine in the process

50
Q

What rxn forms S adenosyl methionine (SAM)?

What catalyzes?

A

methionine + ATP

methionine adenosyl transferase

51
Q

What does SAM carry?

A

ONE thing.

A methyl group

52
Q

How is methionine formed?

enzyme?

A

Homocysteine + CH3 (from THF) > Methionine

methyltransferase

53
Q

What is the rate limiting step of the active methyl cycle?

A

MTHFR

Methylene tetrahydrofolate reductase

54
Q

Summarize the activated methyl cycle:

A

Methionine+ATP=SAM (methionine adenyl transferase) >
SAM donates methyl group (methyl transferase) >
SAHC (- adenosine by hydrolysis) >
Homocysteine methylated by methyl-THF (methionine synthase) >
Methionine

55
Q

What provides the methyl-THF for the Homocysteine>methionine step in the methyl cycle?

What’s the motherfuckin enzyme for this rxn?

A

Methyl THF

MTHFR

56
Q

What creates the methyl trap?

What accumulates?

A

methyl-THF, once made, is irreversible

methyl FH4 (if not accepted by homocysteine)

57
Q

What are 2 conditionally essential amino acids?

A

Tyrosine (from phenylalanine)

Cysteine (from homocesteine + serine)

58
Q

Pyruvate + amine =

Oxaloacetate + amine =

A

Alanine

Aspartate

59
Q

Alpha-ketoglutarate + amine =

What is the enzyme converting product to glutamine?

A

Glutamate

Glutamine synthetase

60
Q

What is the pathway that produces cysteine and glycine?

A

3-Phosphoglycerate > Serine, then

  1. with 1C transfer to THF via MTHFR > glycine
    • homocysteine > cysteine

(remember, homocysteine comes from methionine, an essential AA)

61
Q

What important molecule is made from cysteine?

A

Glutathione

rids ROS in H2O2 pathway

62
Q
How is tyrosine made?
What enzyme (a deficiency in which causes PKU) is involved?
A

Phenylalanine >

phenylalanine hydroxylase

Tyrosine

63
Q

What causes PKU?

A

autosomal recessive

phenylalanine hydroxylase dysfunctional

(phenylalanine cannot metabolize to tyrosine)

64
Q

Where is Heme made and what is the limiting step?

A

Liver and bone marrow

DALA synthase is rate limiting step

65
Q

What is the must-know step in Heme synthesis?
enzyme?
Where does it occur?

A

Succinyl CoA + Glycine > Delta aminolevulinate (DALA)

DALA synthase

mitochondria of liver and bone marrow

66
Q

What is the coenzyme used for Heme synthesis and how is Heme production regulated?

A

pyridoxal phosphate (vitamin B6)

allosterically regulated by Heme

67
Q

Myoglobin consists of a single _____, while hemoglobin consists of two ____.

A

polypeptide chain with 8 alpha helices

alpha/beta dimers

68
Q

What is special about the Hba1c type of hemoglobin?

A

binds glucose non-enzymatically

69
Q

How many heme groups are found on hemoglobin?

myoglobin?

A

4

1

70
Q

Hemoglobin is most likely to accept oxygen in what conformation?
give oxygen?

A

Relaxed

T (taut)

71
Q

What stabilizes the T-conformation of hemoglobin?

What does this do?

A

2,3 bisphosphoglycerate (a byproduct of glycolysis)

this makes it more likely hemoglobin will give up oxygen and deliver it to the tissues that need it the most. (airplane looking at smokestacks)

72
Q

T/F

Over the physiological range of blood, myoglobin is usually saturated with oxygen.

A

True

73
Q

What are the 3 main markers of metabolic industry that allosterically affect hemoglobin?

A

H+
CO2
2,3- bisphosphoglycerate

74
Q

T/F

2,3 bisphosphoglycerate is released at the lungs

A

False

it is released before the lungs (only in smokers is the statement true)

75
Q

What is the Bohr effect?

A

additive allosteric effects of H+ and CO2

76
Q

CO2 reacts with terminal amine group on hemoglobin that forms _______ and stabilizes the T conformation.

A

Carbamate

carbamate is also a CO2 carrier to the lungs

77
Q

What are 4 allosteric effectors of hemoglobin?

A

O2
H+
CO2
2,3 bisphosphoglycerate

78
Q

How does carbon monoxide out compete oxygen?

A

Hemoglobin has a 200x affinity for CO

79
Q

How does fetal hemoglobin differ from adult?

A

Fetal Hb has higher O2 affinity

does not bing 2,3 BPG

80
Q

What accounts for about 14% of CO2 transport to the lungs?

A

carbamate

RBC transport - rest goes as bicarbonate

81
Q

What is the major form of CO2 transport to the lungs?

What enzyme is involved?

A

CO2 to bicarbonate (HCO3-)

carbonic anhydrase (Zn)

82
Q

What AA substitution creates sickle cell trait?

A

Valine for a glutamate in beta globin at 6th position

glutamate kicks out valine - this is a polar for a nonpolar AA

83
Q

Does sickle cell train affect oxyhemoglobin state?

A

no

affects deoxy solubility

84
Q

Nucleoside refers to:

A

Sugar and Base

85
Q

What is the difference between deoxyribonucleotide and ribonucleotide?

A

Both are nitrogenous base (AGCTU), ribose sugar, phosphate

Deoxy is dehydroxylated at the C2 position in ribose

86
Q

What is the difference between the salvage and De Novo pathways?

A

salvage - recycles

de novo - PPP > PRPP (activated ribose)

*de novo is expensive

87
Q

What are the purines?

Pyrimidines?

A

A and G (two rings)

T, U, C

88
Q

What does a nucleoside lack to be a nucleotide?

A

phosphate

89
Q

Name 4 precursors for purine

he would hate to ask this question

A

CO2, glutamine, aspartate, glycine

need PRPP

90
Q

What are the precursors for Pyrimidine?

A

Aspartate, glutamine, CO2

need PRPP

91
Q

What is PRPP and how is it made?

A

phosphorylated x2 Ribose 5-P (from PPP)

PRPP synthetase

92
Q

What is the first committed step in de novo purine biosynthesis?

What allosterically inhibits/activates?

A

PRPP > 5-Phosphorylribosyl-1-amine

via PRPP amidotransferase

allosterics:
ATP, ADP, AMPTP, GDP, GMP (different sites) inhibit (because purines)
PRPP activates

93
Q

What is the function of PRPP?

A

Provides the activated sugar for synth

94
Q

How do purine and pyrimidine synth from PRPP differ?

A

Purine builds onto sugar

Pyrimidine builds base and adds to sugar

95
Q

What are the precursors and the committed step in de novo pyrimidine synthesis?

A

Aspartate, Glutamine, CO2

CPS II (carbamoyl phosphate synthetase II)

96
Q

What are the 2 steps of de novo pyrimidine synth?

A

Carbamoyl formation

OMP

97
Q

How is carbamoyl formed

remember: this is step 1 of de novo pyrimidine synth

A

2 ATP + bicarbonate + glutamine (for nitrogen) > Carbamoyl phosphate

via CPSII enzyme

98
Q

What does carbamoyl phosphate combine with to form a pyrimidine ring?

A

Aspartate

99
Q

What is the enzyme carbamoyl phophatase II inhibited/activated by?

A

inhibited - UTP

activated - ATP and PRPP

100
Q

What are the parent molecules in purine and pyrimidine synth?

A

purine = IMP (inosine monophosphate)

pyrimidine = OMP (orotidine-5-monophosphate)

101
Q

What are the rate limiting steps for purine and pyrimidine synth?

A

purine:
PRPP > 5-phophoribosylamine (PRPP amidotransferase)

pyrimidine:
HCO3- + NH3 (from glutamine) +2 ATP > carbamoyl phosphate (CPSII)

102
Q

How are ribonucleotides converted to deoxyribonucleotides?

A

Step 1: RNR - ribonucleotide reductase (dehydroxylate my C2)
Step 2: thioredoxin (reduces OH)

then, NADPH regenerates thioredoxin via thioredoxin reductase

103
Q

Urate causes gout. What is its soluble form?

A

Hypoxanthine

104
Q

How does the Purine salvage pathway work?

A

Combine a base with PRPP

105
Q

What are the two purine salvage pathways?

A

APRT: Adenine phosphorybosyl transferase (adenine + PRPP)

HGPRT: Hypoxanthine-Guanine phosphorybosyl transferase

106
Q

Why is Pyrimidine salvage rare?

What enzyme is used if they are salvaged?

A

They usually degrade and excrete

Pyrimidine phosphoribosyltransferase

107
Q

After pyrimidine phosphoribosyltransferase catalyzes PRPP onto a base, what is the next step?

A

U, T, and C are phosphorylated by their respective kinases

108
Q

What is defective in Lesch Nyhan syndrome?

A

HGPRT enzyme (can’t recycle purines)

this causes gout from too much uric acid

109
Q

5 stages of cell cycle:

A
G0 - resting
G1 - growing (11 hrs)
S - DNA replication (8 hrs)
G2 - continued growth (4 hrs) 
M - division
110
Q

What’s in a nucleosome?

A

8 Histone proteins

around each protein is wrapped 146 bp (1.75 turns)

111
Q

T/F

In every instance, DNA replication requires an RNA primer.

A

True

112
Q

How does the lagging strand replicate?

A

Still 5’ to 3’, but in Okazaki fragments

113
Q

What is the function of DNA polymerase?

A

Catalyzes the formation of the sugar phosphate (backbone) connection in DNA

114
Q

What are the 3 requirements for DNA polymerase to synthesize DNA?

A
  1. ATCG (nucleotide triphosphates present)
  2. Template strand
  3. Primer
115
Q

How big is the RNA primer and why is it needed?

A

10-20 nucleotides long

DNA polymerase can’t initiate (but can continue)

116
Q

What is the RNA primer made from?

Does it incorporate itself into DNA?

A

DNA polymerase alpha

No. It’s removed and replaced after the strand has fully replicated

117
Q

How many RNA primers does the leading strand have?

Lagging strand?

A

1

multiple (each okazaki fragment)

118
Q

Why might it be better to be the lagging strand in replication?

A

Lagging strand doesn’t get shortened (Okazaki’s repair themselves at each fragmentation)

Leading strand doesn’t replace primer with DNA. SHORTENS (only 50-80 mitotic divisions possible)

119
Q

The primase/DNA polymerase use _____, but incorporate ______.

A

Triphosphates
Monophosphates

(attached to the pentose sugar)

120
Q

What splices together Okazaki fragments?

A

DNA ligase

121
Q

What are the terms Processivity and Fidelity mean pertaining DNA synthesis?

A

Processivity - enzyme ability to catalyze consecutive rxns (50k nucleotides)

Fidelity - very low error rate

122
Q

How is high processivity attained in DNA synth?

A

Through RFC and PCNA (clamping mechanism)

123
Q

What creates the replication fork? (two enzymes)

A

DNA helicase opens strand

Topoisomerase uncoils

124
Q

Summarize leading strand synthesis:

A
RNA primer
RFC, PCNA, DNA Polymerase bind
nucleotides added, sliding down from 5' to 3'
RNA primer leaves hole
Telomerase (in some cases) repairs gap
125
Q

Summarize lagging strand synth:

A

Multiple RNA primers
RFC, PCNA, DNA Polymerase
RNA primers leave and replaced by DNA polymerase
DNA ligase joins fragments

126
Q

What is the only enzyme able to work with nucleoside monophosphates?

A

DNA ligase

127
Q

What clinical technique uses palindromic sequences?

A

Restriction endonuclease

128
Q
Blots:
Southern
Northern
Western
Eastern
A

DNA
RNA
Proteins
trick exam question

129
Q

What are the 3 layers that ensure DNA replication accuracy?

A

Intrinsic fidelity (1/1000)
Proofreading (1/10 mil)
scanning enzymes/repair enzymes(1/1 billion)

130
Q

What are the enzymes responsible for the immediate “proof reading” of DNA?

A

DNA polymerase makes error, stops
Exonuclease repairs

note: exonucleases go in both directions

131
Q
What errors result in the following:
single replacement
stop codon
protein missing all or part of exon sequence 
shifting sequence
A

missense
nonsense
RNA-splicing mutation
frameshift mutation

132
Q

What is a trinucleotide expansion?

A

Mutation 3 bp’s repeat

133
Q

What are the 5 forms of DNA damage discussed in lecture?

A

Mispairing (wrong bases line up)
Depurination (A/G fall out)
Deamination (creates confusion in replication)
Chemical damage
UV damage (dimers, covalent bonds, nicks)

134
Q

The addition of a methyl group to guanine (via chemical damage) causes it to pair with what (instead of cytosine)?

A

Thymine

135
Q

UV light, in particular, causes damage in the form of covalent bonding in what dimer?

A

TT

(thymines) 90% of UV damage

136
Q

What is the enzyme used in the Direct Reversal of methylated Guanine?

A

O6-methyguanine methyltransferase

137
Q

What is the main enzyme used in the very specific type (single base) excision repair?

A

Gycosylase

138
Q

What 3 steps (4 enzymes) are used in the excision repair of longer strips of DNA?

A

Nuclease
DNA Helicase
DNA Polymerase + DNA Ligase

139
Q

When can double-stranded DNA breaks be repaired and what process utilizes this?

A

During replication

Homologous/non-homologous recombination

140
Q

A defect in the nucleotide excision repair system leads to what pathology?

A

Xeroderma Pigmentosum

141
Q

What is the major watchman of the cell (defect of which is found in 50% of cancer patients)?
What does this watchman normally do?

A

p53 pathway

programs cell apoptosis

142
Q

What is the class of eicosanoid derived from Omega 6 linoleic acid?

A

Arachidonic Acid

143
Q

What is the class of eicosonoid derived from Omega 3 linolenic acid?

A

Eicosapentanoic acid (EPA)

144
Q

What end is the modified G nucleotide attached to in RNA?

What end are the A nucleotides attached to in RNA?

A

5’ (G)

3’ (AAAA’s)

145
Q

What is the process of exon shuffling to make RNA strands (and therefore different proteins)?

A

Alternative splicing

146
Q

What is a promoter?

What are two gene sequence features?

A

A region of DNA that initiates transcription of a certain gene.

TATA box and CAAT box (sometimes GC)

147
Q

What does hnRNA signify?

A

The cap site (PyAPy)

148
Q

What does the protein start and stop signal look like on DNA/RNA?

A

ATG - TGA (DNA)

AUG - UGA (RNA)

149
Q

Describe mRNA from 5’ to 3’ (anatomy).

A

5’ cap - AUG - (coding sequence) - UGA - poly A tail - 3’

150
Q

What sequence denotes the cap site (where transcription begins)?

A

ACATTTG

151
Q

The promoter region, consisting of the TATA (or CAAT) box, is responsible for binding what?

A

RNA polymerase

152
Q

What are the two areas found within promoter sites in eukaryotes?
How big is the promoter site?

A

CAAT and GC are the upstream activating sequences
TATA box

100 bp long

153
Q

If RNA polymerase is the helicopter, the promoter is the…

A

helipad

154
Q

What determines the specificity of transcription of a certain gene?

A

the Promoter

155
Q

How many types of RNA polymerase are there in eukaryotes?

A

3

156
Q

What is the name of a family of transcription factors?

A

C/EBP’s (CCAAT-enhancer)

157
Q

What do enhancers do?

A

open up chromatin, recruit other enhancers

And physically contacts promoter

158
Q

What does the Leader Sequence refer to?

A

the 50 bp’s preceding the ATG start codon

159
Q

What is the translation termination codon?

What follows it?

A

TAA

poly A tail

160
Q

Are promoters transcribed?

A

No. they designate where transcription begins and are just upstream

161
Q

What binds the promoter sequence before RNA polymerase can bind?

A

Transcription factors

162
Q

What is the basal transcription apparatus?

A

The promoter, transcription factors, and RNA pol II acting together

163
Q

What proteins interact with the basal transcription apparatus to regulate the transcription rate?

A

Activator proteins

164
Q

What type of RNA stays in the nucleus and regulates other RNA?

A

snRNA

165
Q

What is the mediating factor between RNA pol II and promoter sites?

A

Transcription factors

166
Q

What direction does RNA polymerase travel?

A

5’ to 3’

167
Q

Does RNA polymerase require a primer?

A

no

168
Q

T/F

RNA polymerase unwinds, transcribes, and rewinds DNA

A

True

169
Q

When does the elongation phase of transcription end?

A

When termination signal reached

170
Q

What does the 5’ cap and the 3’ tail consist of?

A

methylated guanosine

200 A tail

171
Q

Where is RNA pol I found?

A

nucleolus

172
Q

Which RNA is the major one in mammals?

A

rRNA (85%)

173
Q

What 3 sites must be in place for proper splicing and removal of introns?

A

5’ splice site (GUA)
Branch site (A)
3’ splice site (AG)

174
Q

What is the function of snRNP’s?

A

bind introns (at 3 sites)

175
Q

What is the structure of tRNA

A

coverleaf (secondary H-bond structure)
covalent ester bond to AA
anti-codon

176
Q

What do all tRNA have at their 3’ terminus?

A

CCA - then ester bond to AA

5’ doesn’t connect to anything

177
Q

How many nucleotides long is tRNA

A

70-80

178
Q

What binds tRNA to Amino Acids?

the matchmaker

A

Aminoacyl tRNA synthetase

179
Q

How many aminoacyl tRNA synthetases are there?

A

20

180
Q

What are the two components of the ribosome?

What do they make when combined?

A

40S and 60S

80S

181
Q

What ribosome binds the mRNA codon

A

40S

182
Q

What does the tRNA capable of initiating translation carry?

A

methionine

183
Q

What recognizes met-tRNA and binds it to the 40S ribosomal unit?

note: at least 10 of these are required to initiate translation

A

Eukaryotic initiation factor 2

184
Q

During initiation of translation, what attaches to the methyl-guanosine cap at the 5’ end?

A

Cap binding proteins

eukaryotic factors 4A and 4B

185
Q

What needs to occur before the 60S ribosomal subunit binds in translation?

A

The 40S needs to travel down to the AUG start codon

186
Q

AUG is start codon. What is start anticodon?

A

CAU

187
Q

What are the 3 binding sites in a ribosome?

A

A (aminoacyl)
P (peptidyl)
E (Exit)

188
Q

What brings the tRNA to the A-site?

like an usher

A

EF-Tu

with GTP

189
Q

What regenerates the spend EF-Tu GDP after ushering a tRNA?

A

EF-Ts

190
Q

What are the 3 stop codons and what recognizes these?

A

UAA UAG UGA

Release factors

191
Q

What do release factors bind to?

A

The termination codon

UAA UAG UGA

192
Q

Where does the unusual base pairing occur according to the wobble hypothesis?

A

3rd base codon (1st base anticodon)

variability occurs in 3rd base codon

193
Q

What is the function of Ferritin?

A

binds iron

194
Q

What happens to Ferritin if iron is scarce?

A

IRE-BP binds IRE (Iron Response Element), blocking translation of Ferritin

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