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Tim's Cards > Metabolism 2 (part 2) > Flashcards

Metabolism 2 (part 2) Flashcards

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

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2
Q

What are the 2 ketogenic amino acids?

A

LL

Lysine and Leucine

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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

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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

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5
Q

Is tyrosine an essential AA?

A

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

However, phenylalanine IS essential

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6
Q

What is tyrosine for an individual incapable of metabolizing phenylalanine?

A

Conditionally essential

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7
Q

Name the non-essential AA’s

A

PVT TIM HLL

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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

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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

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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

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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

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12
Q

What enzyme cleaves trypsinogen to become trypsin?

A

Enteropeptidase

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13
Q

How is trypsin activated?

What does it do?

A

Trypsinogen > (Enteropeptidase) > Trypsin

Trypsin cleaves chymotrypsinogen > chymotrypsin

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14
Q

What are the 3 main zymogens in protein digestion?

A

Pepsinogen
Chymotrypsinogen
Trypsinogen

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15
Q

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

A

Pepsinogen

HCl activates Pepsin

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16
Q

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

A

Pancreas

Chymotrypsin breaks down aromatic AA residues

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17
Q

What activates trypsinogen (trypsin)?

What does trypsin activate?

A

Enteropeptidase

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

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18
Q

What do trypsin, chymotrypsin, and elastase preferentially cleave?

A

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

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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)

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20
Q

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

A

Free AA, di, and tri-peptides

1-3

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21
Q

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

A

Aminopeptidase

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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

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23
Q

What determines the lifespan of a protein?

A

The AA at the N-terminus

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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

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25
Q

What death marker attaches to Lysine?

A

Ubiquitin?

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26
Q

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

A

26S Proteasome

Ubiquitin survives the shredder

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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

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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

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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

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30
Q

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

A

Glutamate > Alpha-Ketoglutarate
Alanine > Pyruvate
Aspartate > oxaloacetate

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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)
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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

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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

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34
Q

Where does the Nitrogen in urea come from?

How many ATP are required to form urea?

A

Glutamate and Aspartate

4

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35
Q

What is the benign way we transport ammonia in blood?

A

via Alanine and Glutamine

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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

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37
Q

What does glutaminase do?

A

Glutamine > Glutamate

in the liver

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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

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39
Q

What are the 2 kinds of hyperammonemia?

A

Acquired (liver cirrhosis)

Hereditary (mental retardation usually occurs)

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40
Q

What transfers the most reduced (methyl) groups?

A

S-adenosyl methionine

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41
Q

What transfers intermediately reduced carbon groups?

A

Tetrahydrofolate

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42
Q

Is CO2 considered part of the one carbon pool?

How is it transferred?

A

NO

Biotin (vitamin B7)

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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

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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)

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45
Q

Folic acid rxn:

A

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

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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

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47
Q

What is the most common vitamin deficiency in the world?

A

Folate

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48
Q

What 3 molecules is tetrahydrofolate a requirement to metabolize?

A

Purine, Thymine, and AA metabolism

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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

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50
Q

What rxn forms S adenosyl methionine (SAM)?

What catalyzes?

A

methionine + ATP

methionine adenosyl transferase

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51
Q

What does SAM carry?

A

ONE thing.

A methyl group

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52
Q

How is methionine formed?

enzyme?

A

Homocysteine + CH3 (from THF) > Methionine

methyltransferase

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53
Q

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

A

MTHFR

Methylene tetrahydrofolate reductase

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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

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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

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56
Q

What creates the methyl trap?

What accumulates?

A

methyl-THF, once made, is irreversible

methyl FH4 (if not accepted by homocysteine)

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57
Q

What are 2 conditionally essential amino acids?

A

Tyrosine (from phenylalanine)

Cysteine (from homocesteine + serine)

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58
Q

Pyruvate + amine =

Oxaloacetate + amine =

A

Alanine

Aspartate

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59
Q

Alpha-ketoglutarate + amine =

What is the enzyme converting product to glutamine?

A

Glutamate

Glutamine synthetase

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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)

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61
Q

What important molecule is made from cysteine?

A

Glutathione

rids ROS in H2O2 pathway

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

Phenylalanine >

phenylalanine hydroxylase

Tyrosine

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63
Q

What causes PKU?

A

autosomal recessive

phenylalanine hydroxylase dysfunctional

(phenylalanine cannot metabolize to tyrosine)

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64
Q

Where is Heme made and what is the limiting step?

A

Liver and bone marrow

DALA synthase is rate limiting step

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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

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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

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67
Q

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

A

polypeptide chain with 8 alpha helices

alpha/beta dimers

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68
Q

What is special about the Hba1c type of hemoglobin?

A

binds glucose non-enzymatically

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69
Q

How many heme groups are found on hemoglobin?

myoglobin?

A

4

1

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70
Q

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

A

Relaxed

T (taut)

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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)

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72
Q

T/F

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

A

True

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73
Q

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

A

H+
CO2
2,3- bisphosphoglycerate

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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)

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75
Q

What is the Bohr effect?

A

additive allosteric effects of H+ and CO2

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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

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77
Q

What are 4 allosteric effectors of hemoglobin?

A

O2
H+
CO2
2,3 bisphosphoglycerate

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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

Tim's Cards (140 decks)

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