Flashcards in crambiochem Deck (399)
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1
What does it mean for genetic code to be commaless?
Read from a fixed starting point as a continuous sequence of bases
2
What does it mean for genetic code to be non-overlapping?
Read from a fixed starting point
3
What does it mean for genetic code to be universal?
Genetic code is conserved throughout evolution
4
What are the properties of the genetic code?
1. Unambiguous.
2. Degenerate/redundant.
3. Commaless/nonoverlapping
4. Universal
5
When is genetic code not commaless/nonoverlapping?
In some viruses
6
What are exceptions to universality of genetic code?
1. Mitochondria
2. Archaebacteria
3. Mycoplasma
4. Some yeasts
7
Name that mutation: Same amino acid, often with a base change in 3rd position of codon
Silent mutation
8
What kind of mutation is called: silent
Same amino acid, often with a base change in 3rd position of codon
9
What mutation is masked by tRNA wobble?
Silent mutations
10
Name that mutation: Changed amino acid whose structure is dissimilar to proper amino acid
Missense mutation (not conservative)
11
Name that mutation: Changed amino acid whose structure is similar to proper amino acid
Conservative missense mutation
12
What kind of mutation is called: missense
Amino acid is changed. If the structure of the new amino acid is similar to the original, it is called conservative.
13
Name that mutation: Change resulting in early stop codon
Nonsense mutation
(Mnemonic: Stop the nonsense!)
14
What kind of mutation is called: nonsense
Change resulting in early stop codon
(Mnemonic: Stop the nonsense!)
15
Name that mutation: change resulting in misreading of all nucleotides downstream, usually resulting in a truncated protein
Frame shift mutation
16
What kind of mutation is called: frameshift
change resulting in misreading of all nucleotides downstream, usually resulting in a truncated protein
17
Mutations ordered by decreasing severity of damage
1. Nonsense
2. Missense
3. Silent
18
Eukaryotic genome: single/multiple origins of replication
multiple
19
Prokaryotic genome: single/multiple origins of replication
single
20
Eukaryotic genome: Trigger for replication
Consensus sequence of AT-rich base pairs
21
Prokaryotic genome: Describe DNA replication
Continuous bidirectional DNA synthesis on leading strand and discontinuous (Okazaki fragments) on lagging strand
22
Enzyme function: DNA topoisomerases
Create a nick in the helix to relieve supercoils
23
DNA Topoisomerase I: Mechanism
cuts one strand, passes the other through it then reanneals the cut strand
24
DNA Topoisomerase II: Mechanism
cuts both strands, and passes an unbroken double strand through it then reanneals the cut strand
25
Enzyme function: Primase
Makes an RNA primer on which DNA polymerase III can initiate replication
26
DNA polymerase III: Mechanism
1. Adds deoxynucleotides to the 3' end until it reaches primer of preceding fragment
2. 3' to 5' exonuclease activity proofreads" each added nucleotide"
27
DNA polymerase III: Which direction does it read?
3' to 5'
28
DNA polymerase III: Which direction does it write?
5' to 3'
29
DNA polymerase III: Which direction does it proofread?
3' to 5'
30
Enzyme function: DNA polymerase III
Elongates the chain
31
Enzyme function: DNA polymerase I
Degrades RNA primer and fills in the gap with DNA
32
DNA polymerase I: Which direction does it read?
3' to 5'
33
DNA polymerase I: Which direction does it write?
5' to 3'
34
DNA polymerase I: Which direction does it proofread?
5' to 3'
35
Enzyme function: DNA helicase
Separates the two strands of DNA into single strands allowing for replication to occur. The position of these separated strands is called the replication fork.
36
Types of DNA repair
Single stranded:
1. Nucleotide excision repair
2. Base excision repair
3. Mismatch repair
Double stranded:
1. Nonhomologous end joining
37
Nucleotide excision repair: Mechanism
1. Specific endonucleases release the oligonucleotide containing damaged bases
2. DNA polymerase and ligase fill and reseal the gap, respectively
38
In what condition is nucleotide excision repair mutated?
Xeroderma pigmentosa (dry skin with melanoma and other cancers)
39
Base excision repair: Mechanism
1. Specific glycosylases recognize and remove damaged bases
2. AP endonuclease cuts DNA at apyrimidinic site
3. Empty sugar is removed
4. Gap is refilled and resealed
40
Mismatch repair: Mechanism
1. Unmethylated, newly synthesized string is recognized
2. Mismatched nucleotides are removed
3. Gap is refilled and resealed
41
In what condition is mismatch excision repair mutated?
Hereditary Nonpolyposis Colon Cancer
42
Nonhomologous end joining: Mechanism
Brings together two ends of DNA fragments (no requirement for homology)
43
What is on the 5' end of a nucleotide
Triphosphate
44
What is on the 3' end of a nucleotide
Hydroxyl group
45
True/False: DNA is synthesized 5' to 3'
TRUE
46
True/False: DNA is synthesized 3' to 5'
FALSE
47
True/False: RNA is synthesized 5' to 3'
TRUE
48
True/False: RNA is synthesized 3' to 5'
FALSE
49
True/False: Protein synthesis proceeds 5' to 3'
TRUE
50
True/False: Protein synthesis proceeds 3' to 5'
FALSE
51
Types of RNA and their important qualities
Massive, Rampant, Tiny
mRNA is the largest type
rRNA is the most abundant type
tRNA is the smallest type
52
What does eukaryotic RNA polymerase I make?
rRNA
53
What does eukaryotic RNA polymerase II make?
mRNA
54
What does eukaryotic RNA polymerase III make?
tRNA
55
Which RNA polymerase makes rRNA?
eukaryotic RNA polymerase I and prokaryotic RNA polymerase
56
Which RNA polymerase makes mRNA?
eukaryotic RNA polymerase II and prokaryotic RNA polymerase
57
Which RNA polymerase makes tRNA?
eukaryotic RNA polymerase III and prokaryotic RNA polymerase
58
True/False: RNA polymerase proofreads.
FALSE
59
True/False: RNA polymerase does not proofread.
TRUE
60
Special points about RNA polymerase II
1. Opens DNA at promoter site
2. Inhibited by alpha-amanitin
61
What does alpha-amanitin do?
Inhibits RNA polymerase II leading to hepatic necrosis
62
mRNA initiation codons
1. AUG (inAUGurates protein synthesis)
2. GUG (rarely)
63
What does the mRNA initiation codon code for?
Methionine in eukaryotes. formyl-methionine in prokaryotes.
64
mRNA stop codons
1. UGA (U Go Away)
2. UAA (U Are Away)
3. UAG (U Are Gone)
65
Define promoter of gene expression.
Site where RNA polymerase and multiple other transcription factors bind to DNA upstream from gene locus
66
What characterizes a promoter of gene expression?
AT-rich upstream sequence with TATA and CAAT boxes
67
What is the result of promoter mutation?
Dramatic decrease in amount of gene transcribed
68
Define enhancer of gene expression.
Stretch of DNA that alters gene expression by binding transcription factors. May be located close to, far from, or even within the gene whose expression it regulates.
69
Define operator of gene expression
Site where repressors bind
70
What is alternative splicing?
Rearrangement of exons to make unique proteins
71
What is the sequence of mRNA splicing?
1. Primary transcript combines with snRNP (snerp") to form spliceosome 2. Lariat-shaped intermediate is generated 3. Lariat is released to remove intron precisely and join two exons"
72
Where and when does eukaryotic RNA processing happen?
In the nucleus after transcription
73
What is the initial RNA transcript called?
heterogeneous nuclear RNA (hnRNA)
74
What are the steps in processing hnRNA to make mRNA? (Note: This is more than splicing.)
1. Capping on 5' end with 7-methyl-G
2. Polyadenylation on 3' end (approximately 200 As)
3. Splicing out of introns
75
How many nucleotides does tRNA contain?
75 to 90 nucleotides
76
What sequence does every tRNA share at the 3' end?
CCA along with a high percentage of chemically modified bases
77
Amino acid binding to tRNA: Where (on the tRNA) and how?
Where: 3' end
How: Covalently
78
What is the enzyme involved in processing tRNA
Aminoacyl tRNA synthetase (uses 1 ATP)
79
Aminoacyl tRNA synthetase: Mechanism
1. Scrutinizes amino acid before it binds to tRNA
2. Binds AMP-amino group to 3' end of tRNA
3. Scrutinizes amino acid again. If incorrect, bond is hydrolyzed.
80
What is wrong with a mischarged tRNA
Reads the regular bond but inserts wrong amino acid.
81
Which position on the codon is the wobble position?
3rd position
82
Names of the steps in protein synthesis
1. Initiation
2. Elongation
3. Termination
83
Sequence of events in the initiation step of protein synthesis.
1. Initiation factors assemble the 40S ribosomal subunit with the initiator tRNA
2. mRNA and (60S?) ribosomal subunit combine with the 40S subunit.
3. Initiation factors are released.
84
Sequence of events in the elongation step of protein synthesis.
1. Aminoacyl tRNA binds to the A site
2. Peptidyltransferase catalyzes peptide bond formation.
3. Peptidyltransferase transfers growing polypeptide to amino acid in A site.
4. Ribosome advances three nucleotides toward 3' end of RNA moving peptidyl RNA to P site.
85
Sequence of events in the termination step of protein synthesis.
1. Completed protein is released from ribosome.
2. Ribosome dissociates.
86
Role of ATP in protein synthesis
ATP does tRNA Activation (charging)
87
Role of GTP in protein synthesis
GTP does tRNA Going places (aka translocation) and Gripping
88
Role of A site in protein synthesis
A site holds incoming Aminoacyl tRNA.
89
Role of P site in protein synthesis
P site accomodates growing Peptide.
90
Role of E site in protein synthesis
E site holds Empty tRNA as it Exits
91
Which post-translational modification involves removal of N or C terminal pro-peptides from zymogens to generate mature proteins?
Trimming
92
What happens in post-translational trimming?
removal of N or C terminal pro-peptides from zymogens to generate mature proteins
93
Which post-translational modification involves phosphorylation?
post-translational covalent alteration
94
What happens during post-translational covalent alterations?
Either:
1. Phosphorylation
2. Glycosylation
3. Hydroxylation
95
Which post-translational modification involves glycosylation?
post-translational covalent alteration
96
Which post-translational modification involves hydroxylation?
post-translational covalent alteration
97
What happens during proteasomal degradation?
Attachment of ubiquitin to defective proteins to tag them for breakdown.
98
Ubiquitin or Ubiquinone: Proteosomal degradation
Ubiquitin
99
Ubiquitin or Ubiquinone: Coenzyme Q in oxidative phosphorylation
Ubiquinone
100
Where in the cell does the following occur: Fatty acid oxidation (beta-oxidation)
Mitochondria
101
Where in the cell does the following occur: acetyl-CoA production
Mitochondria
102
Where in the cell does the following occur: Krebs cycle
Mitochondria
103
Where in the cell does the following occur: Glycolysis
Cytoplasm
104
Where in the cell does the following occur: Fatty acid synthesis
Cytoplasm
105
Where in the cell does the following occur: Hexose Monophosphate Shunt
Cytoplasm
106
Where in the cell does the following occur: Protein Synthesis
Rough endoplasmic reticulum in the cytoplasm
107
Where in the cell does the following occur: Steroid synthesis
Smooth endoplasmic reticulum in the cytoplasm
108
Where in the cell does the following occur: Gluconeogenesis
Pathway has steps in the mitochondria and in the cytoplasm
109
Where in the cell does the following occur: Urea cycle
Pathway has steps in the mitochondria and in the cytoplasm
110
Where in the cell does the following occur: Heme synthesis
Pathway has steps in the mitochondria and in the cytoplasm
111
What type of bonds hold the phosphoryls together in ATP, and how much energy are the bonds worth?
Phosphoanhydride bonds are worth 7 kilocalories per mole (but only between the alpha and beta and the beta and the gamma, thus AMP's phosphoryl is not cleaved off for energy)
112
How many ATP molecules are produced by aerobic metabolism of glucose?
38 via the Malate shuttle, and 36 via the G3P shuttle.
113
In aerobic metabolism of glucose, which pathway produces 38 ATP?
Malate shuttle
114
In aerobic metabolism of glucose, which pathway produces 36 ATP?
G3P shuttle
115
How much ATP is produced by anaerobic glycolysis?
2 ATP per glucose
116
What is this molecule an activated carrier of?: ATP
Phosphoryls
117
What is this molecule an activated carrier of?: NADH
Electrons
118
What is this molecule an activated carrier of?: NADPH
Electrons
119
What is this molecule an activated carrier of?: FADH2
Electrons
120
What is this molecule an activated carrier of?: Coenzyme A
Acyl
121
What is this molecule an activated carrier of?: Lipoamide
Acyl
122
What is this molecule an activated carrier of?: Biotin
CO2
123
What is this molecule an activated carrier of?: Tetrahydrofolate
1-carbon units
124
What is this molecule an activated carrier of?: S-adenosyl-methionine
Methyl groups
125
What is this molecule an activated carrier of?: Thiamine Pyrophosphate
Aldehydes
126
What activated carriers carry: Phosphoryl
ATP and GTP
127
What activated carriers carry: Electrons
1. NADH
2. NADPH
3. FADH2
128
What activated carriers carry: Acyl
1. Coenzyme A
2. Lipoamide
129
What activated carriers carry: CO2
Biotin
130
What activated carriers carry: 1-carbon units
1. Tetrahydrofolates (originally as formyl then methyl)
2. Biotin (as CO2)
3. S-adenosyl-methionine (as CH3)
131
What activated carriers carry: CH3 groups
1. S-adenosyl-methionine
2. N5-methyl-THF
132
What activated carriers carry: Formyl groups
N10-formyl-THF
133
What activated carriers carry: Aldehydes
Thiamine Pyrophosphate
134
ATP and methionine react to form what?
S-adenosyl-methionine
135
What reacts to yield S-adenosyl-methionine?
ATP and methionine
136
What vitamin is necessary for regeneration of S-adenosyl-methionine?
Vitamin B12
137
When is NAD used?
Catabolic processes to carry reducing equivalents away as NADH
138
When is NADPH used?
1. Anabolic process (steroid and fatty acid synthesis)
2. Respiratory burst
3. P-450
139
Where does NADPH come from?
HMP shunt
140
What disease results from NADPH oxidase deficiency?
Chronic Granulomatous Disease
141
This enzyme phosphorylates glucose with high affinity.
Hexokinase (as opposed to glucokinase)
142
This enzyme phosphorylates glucose with low affinity.
Glucokinase (as opposed to hexokinase)
143
This enzyme phosphorylates glucose with a low capacity.
Hexokinase (as opposed to glucokinase)
144
This enzyme phosphorylates glucose and is feedback inhibited by Glucose-6-Phosphate.
Hexokinase (as opposed to glucokinase)
145
This enzyme phosphorylates glucose with a high capacity.
Glucokinase (as opposed to hexokinase)
146
This enzyme phosphorylates glucose and is not feedback inhibited.
Glucokinase (as opposed to hexokinase)
147
Glucokinase: Where is it found and why does it do what it does?
Found in the liver and pancreatic beta cells. Phosphorylates glucose to sequester it after a big meal.
148
Hexokinase: Where is it found and why does it do what it does?
Found in every cell's cytoplasm. Phosphorylates glucose to proceed with glycolysis.
149
What are the net reactants and products in glycolysis.
Reactants
1. Glucose
2. 2 Phosphates
3. 2 ADP
4. 2 NAD
Products
1. 2 Pyruvate
2. 2 ATP
3. 2 NADH
4. 2 H+
5. 2 H20
150
What are the rate limiting steps of glycolysis?
1. Hexokinase (Glucose to Glucose-6-P)
2. *Phosphofructokinase-1 (Fructose-6-P to Fructose-1,6-BP)
3. Pyruvate kinase (Phosphoenolpyruvate to Pyruvate)
151
Phosphofructokinase-1: What does it do, and what stimulates and inhibits it?
PFK-1 1-phosphorylates fructose-6-phosphate to produce Fructose-1,6-Bisphosphate.
Inhibited by:
1. ATP (don't need more of me)
2. Citrate (my cycle is going well)
Stimulated by:
1. AMP (Hey, we need more ATP)
2. Fructose-2,6-BP (The fact that I'm being made means there's tons of glucose.)
152
Pyruvate kinase: What does it do, and what stimulates and inhibits it?
Pyruvate kinase converts phosphoenolpyruvate to pyruvate, thereby producing two ATP.
Inhibited by:
1. ATP (don't need more of me)
2. Alanine (I came from pyruvate, so we don't need any more.)
Stimulated by:
1. Fructose-1,6-BP (I was told we needed more ATP, so here I am, so you better move the line along.)
153
Pyruvate dehydrogenase: What does it do, and what stimulates and inhibits it?
Pyruvate dehydrogenase converts pyruvate to acetyl-coA, and produces NADH and CO2.
Stimulated by: excess pyruvate?
Inhibited by:
1. NADH (Listen, seriously, we don't need anymore of me.)
2. NADH (You produce NADH, soon there'll be more of me.)
3. Acetyl-CoA (Enough of me, save your pyrvuate.)
154
What disease state is glycolytic enzyme deficiency generally associated with?
Hemolytic anemia
155
What is the mechanism of hemolytic anemia in someone with glycolytic enzyme deficiency?
1. Lack of glycolysis leads to lack of ATP in RBCs
2. Lack of ATP leads to inactivity of Na, K-ATPase pump.
3. Lack of the pump leads to sodium influx.
4. Water follows sodium into the cell.
5. The cell swells and bursts.
156
What are the two most common glycolytic enzyme deficiencies?
Pyruvate kinase (95% of cases) followed by glucose phosphate isomerase (4% of cases)
157
What are the 5 cofactors necessary for pyrvuate dehydrogenase?
Lipoic acid plus the first four B vitamins in their active forms:
1. B1: TPP
2. B2: FAD
3. B3: NAD
4. B5: CoA
158
What are the 5 cofactors necessary for alpha-ketoglutarate dehydrogenase?
Lipoic acid plus the first four B vitamins in their active forms:
1. B1: TPP
2. B2: FAD
3. B3: NAD
4. B5: CoA
159
What are the net reactants and products in the reaction that Pyruvate Dehydrogenase catalyzes?
Reactants:
1. Pyruvate
2. CoA
3. NAD
Products
1. Acetyl CoA
2. CO2
3. NADH
160
What activates and what inhibits pyruvate dehydrogenase?
Activated by exercise, which stimulates:
1. Increased NAD/NADH ratio (We need more NADH.)
2. Increased ADP (We need more ATP.)
3. Ca2+ (More of me leads muscles to contract, and I'm taken up by mitochondria where I tell PDH that we need more ATP.)
Inhibited by:
1. NADH (No more of me please)
2. ATP (likewise)
3. Acetyl CoA (ditto)
161
Lipoamide or lipoate: Which carries aldehydes?
Lipoamide
162
Lipoamide or lipoate: Which is a cofactor for pyruvate dehydrogenase?
Lipoate (Lipoic acid)
163
What toxin inhibits lipoic acid?
Arsenic
164
What is the presentation of arsenic toxicity?
1. Vomiting
2. Rice water stools
3. Garlic breath
165
Pyruvate dehydrogenase deficiency: Mechanism
Backup of pyruvate and alanine leads to lactic acidosis.
166
Pyruvate dehydrogenase deficiency: Congenital or Acquired
Both. Acquired cases happen in cases of B1 deficiency (such as in alcoholics.)
167
Pyruvate dehydrogenase deficiency: Presentation
Lactic acidosis and neurologic defects
168
Pyruvate dehydrogenase deficiency: Treatment
Increased intake of ketogenic nutrients (such as high fat content or increased lysine and leucine)
169
What are the miscellaneous fates of pyruvate, and what are the end products used for?
1. Alanine: Carries amino groups to the liver from muscle
2. Oxaloacetate: Replenishes TCA cycle or is used gluconeogenesis
3. Acetyl-CoA: Used in TCA cycle
4. Lactate: No good use
170
Which tissues and organs primarily convert pyruvate into lactate?
1. RBCs and WBCs
2. Lens and cornea
3. Renal medulla
4. Testes
171
What enzymes and cofactors are used in conversion of pyruvate to alanine?
Enzyme: Alanine Transaminase (ALT)
Cofactors: None
172
What enzymes and cofactors are used in conversion of pyruvate to oxaloacetate?
Enzyme: Pyruvate Carboxylase (contains biotin and magnesium)
Cofactors: CO2 and ATP
173
What are the reactants and products in the reaction catalyzed by pyruvate carboxylase?
Reactant:
Pyruvate (with CO2 and ATP)
Product:
Oxaloacetate
174
What are the reactants and products in the reaction catalyzed by lactate dehydrogenase?
This reaction is reversible, so the products can switch with the reactants.
Reactants:
1. Pyruvate
2. NADH (rehydrogenates in this direction)
3. H+
Products:
1. Lactate
2. NAD
175
Where do the various pyruvate transformation reactions happen?
Cytosol:
1. ALT (Alanine to/from pyruvate)
2. LDH (Lactate to/from pyruvate)
Mitochondria
1. Pyruvate carboxylase (pyruvate to oxaloacetate)
2. Pyruvate dehydrogenase (pyruvate to acetyl-coa)
176
Where does the Cori Cycle happen?
In the liver and muscle/RBCs
Liver: Pyruvate converts to glucose
Muscle/RBCs: Glucose converts to Pyruvate
177
What is the purpose of the Cori cycle?
Transfers excess reducing equivalents from RBCs and the muscle to liver so they can function anaerobically
178
What reaction does citrate synthase catalyze?
Oxaloacetate and acetyl coA combine to yield citrate.
179
What is the order of the citric acid cycle beginning at citrate?
CAn I Keep Selling Sex For Money, Officer?
1. Citrate
2. cis-Aconitate
3. Isocitrate
4. alpha-Ketoglutarate
5. Succinyl CoA
6. Succinate
7. Fumarate
8. Malate
9. Oxaloacetate
180
What is the order of the citric acid cycle beginning at cis-aconitate?
1. cis-Aconitate
2. Isocitrate
3. alpha-ketoglutarate
4. succinyl coA
5. succinate
6. fumarate
7. money
8. oxaloacetate
9. citrate
181
What is the order of the citric acid cycle beginning at isocitrate?
1. isocitrate
2. alpha-ketoglutarate
3. succinyl coa
4. succinate
5. fumarate
6. malate
7. oxaloacetate
8. citrate
9. cis-aconitate
182
What is the order of the citric acid cycle beginning at alpha-ketoglutarate?
1. alpha-ketoglutarate
2. succinyl coA
3. succinate
4. fumarate
5. malate
6. oxaloacetate
7. citrate
8. cis-aconitate
9. isocitrate
183
What is the order of the citric acid cycle beginning at succinyl coA?
1. succinyl coA
2. succinate
3. fumarate
4. malate
5. oxaloacetate
6. citrate
7. cis-aconitate
8. isocitrate
9. alpha-ketoglutarate
184
What is the order of the citric acid cycle beginning at succinate?
Sex Feels Marvelous Over Cordelia And If Kruti Sucks-a-Neil.
1. Succinate
2. Fumarate
3. Malate
4. Oxaloacetate
5. Citrate
6. cis-aconitate
7. Isocitrate
8. alpha-ketoglutarate
9. succinyl coA
185
What is the order of the citric acid cycle beginning at fumarate?
1. fumarate
2. malate
3. oxaloacetate
4. citrate
5. cis-aconitate
6. isocitrate
7. alpha-ketoglutarate
8. succinyl coA
9. succinate
186
What is the order of the citric acid cycle beginning at malate?
1. malate
2. oxaloacetate
3. citrate
4. cis-aconitate
5. isocitrate
6. alpha-ketoglutarate
7. succinyl coA
8. succinate
9. fumarate
187
What is the order of the citric acid cycle beginning at oxaloacetate?
1. oxaloacetate
2. citrate
3. cis-aconitate
4. isocitrate
5. alpha-ketoglutarate
6. succinyl coA
7. succinate
8. fumarate
9. malate
188
What stimulates and inhibits citrate synthase?
Stimulate: Nothing
Inhibit: ATP
189
What stimulates and inhibits isocitrate dehydrogenase?
Stimulate: ADP
Inhibit:
1. ATP
2. NADH
190
What stimulates and inhibits alpha-ketoglutarate dehydrogenase?
Stimulate: Nothing
Inhibit:
1. ATP
2. NADH
3. Succinyl CoA
191
Which steps in the citric acid cycle produce CO2?
The steps where carbons are lost, the two structures after isocitrate each have one less carbon than the last.
1. Isocitrate to alpha-ketoglutarate
2. alpha-ketoglutarate to succinyl coA
192
Which steps in the citric acid cycle produce reducing equivalents?
The only step that produces FADH2 is the only one that also yields an F product.
1. Isocitrate to alpha ketoglutarate (1 NADH)
2. alpha-ketoglutarate to succinyl coA (1 NADH)
3. Succinate to Fumarate (1 FADH2)
4. Malate to Oxaloacetate (1 NADH)
193
Which steps in the citric acid cycle produce ATP?
None, however 1 GTP is produced from the conversion of Succinyl CoA to Succinate.
194
How much ATP is produced by the citric acid cycle per molecule of acetyl coA?
12 ATP.
3 NADH x 3 ATP/NADH= 9 ATP
1 FADH2 x 2 ATP/FADH2 = 2 ATP
1 GTP x 1 ATP/GTP = 1 ATP
The total is 12 ATP
195
How much ATP is produced by the citric acid cycle per molecule of glucose?
24
1 cycle:
3 ATP/NADH= 9 ATP
1 FADH2 x 2 ATP/FADH2 = 2 ATP
1 GTP x 1 ATP/GTP = 1 ATP
The total is 12 ATP per acetyl coA. However, there are 2 acetyl coA molecules produced per glucose molecule. Thus the total is 24.
196
Name the complexes and important coenzymes and cytochromes in the electron transport chain.
1. Complex I
2. Coenzyme Q
3. Complex III
4. Cytochrome C
5. Complex IV
6. Complex V
197
Where in the electron transport chain do NADH and FADH2 release their electrons?
Complex I
198
Where in the electron transport chain is O2 reduced to 2H2O?
Complex IV
199
Where in the electron transport chain is ADP converted to ATP?
Complex V aka ATP synthase aka mitochondrial ATPase
200
Name three classes of oxidative phosphorylation poisons.
1. Electron transport inhibitors
2. ATPase inhibitors
3. Uncoupling agents
201
What is the mechanism of electron transport inhibitors?
1. Directly inhibit electron transport causing:
2. Decreased protein gradient and decrease in O2 consumption, thereby:
3. Blocking ATP synthesis
202
What is the mechanism of ATPase inhibitors?
1. Directly inhibit mitochondrial ATPase causing:
2. Increased protein gradient and increased oxygen consumption, but no ATP is produced because electron transport stops.
203
What is the mechanism of uncoupling agents?
Uncouples" ATP synthesis from gradient production
204
What is rotenone?
An electron transport inhibitor.
205
What is the mechanism of CN?
Electron transport inhibition
206
What is the mechanism of CO?
Electron transport inhibition
207
What is antimycin A?
An electron transport inhibitor.
208
What is the mechanism of oligomycin?
ATPase inhibition
209
What is the mechanism of thermogenin?
Uncoupling protein OR UCP which is an uncoupling agent
210
Where is thermogenin found?
Brown adipose tissue
211
What is the mechanism of 2,4-dinitrophenol?
Uncoupling agent
212
Name three uncoupling agents
1. UCPs (such as Thermogenin)
2. 2,4-dinitrophenol
3. aspirin
213
Name the irreversible enzymes in gluconeogenesis, and where they are found.
Pathway Produces Fresh Glucose
All the enzymes are found only in the liver, kidney, and intestinal epithelium
1. Pyruvate carboxylase in the mitochondria
2. PEP carboxykinase in the cytosol
3. Fructose-1,6-bisphosphatase in the cytosol
4. Glucose-6-Phosphatase in the endoplasmic reticulum
214
Name the irreversible enzymes in glycolysis.
1. Hexokinase
2. Phosphofructokinase-1
3. Pyruvate kinase
4. Pyruvate dehydrogenase
215
What are the requirements of PEP carboxykinase?
GTP
216
Where does the pentose phosphate pathway happen?
Cytoplasm of Red Blood Cells, and in lactating mammary glands, liver, and adrenal cortex (all sites of fatty acid or steroid synthesis except RBCs)
217
How much ATP is used in the pentose phosphate shunt?
None
218
What are the main products of the pentose phosphate shunt and their uses?
1. NADPH (for fatty acid and steroid synthesis, glutathione reduction, and cytochrome P-450)
2. Ribose-5-phosphate (for nucleotide synthesis)
3. G3P and F6P (glycolytic intermediates)
219
What are the key enzymes of the pentose phosphate shunt and are the reactions reversible or irreversible?
1. Glucose-6-phosphate dehydrogenase (irreversible)
2. Transketolase (reversible)
220
What does transketolase require?
Thiamine (Vitamin B1)
221
What is the rate-limiting enzyme in the Pentose phosphate pathway?
Glucose-6-Phosphate Dehydrogenase
222
What is glutathione used for?
Detoxification of free radicals and peroxides.
223
What does NADPH deficiency in RBCs result in?
Hemolytic anemia
224
Name some oxidizing agents that someone with a G6PD deficiency is vulnerable to.
1. Fava beans
2. Sulfonamides
3. Primaquine
4. Antituberculosis drugs
225
What protection does G6PD deficiency provide?
Protection against malaria
226
Which group is more likely to have G6PD deficiency?
Blacks
227
What are Heinz bodies?
altered Hemoglobin precipitates within RBCs, found in G6PD deficiency
228
What histologic change is seen in G6PD deficiency
Heinz bodies within red blood cells
229
What is the etiology of fructose intolerance?
1. Lack of aldolase B
2. Build up of Fructose-1-Phosphate
3. Decrease in available phosphate
4. Inhibition of glycogenolysis and gluconeogenesis
230
What is the clinical presentation of fructose intolerance?
hypoglycemia, jaundice, cirrhosis, and vomiting
231
What is the difference in presentation between von Gierke's disease and fructose intolerance?
Both have hypoglycemia, jaundice, cirrhosis and vomiting.
von Gierke's disease also has lactic acidosis whereas fructose intolerance does not.
232
What is the treatment for fructose intolerance?
Decreased intake of both fructose and sucrose.
233
What is the etiology of essential fructosuria?
Defect in fructokinase leading to lack of metabolism of fructose. Benign and asymptomatic
234
What is the clinical presentation of essential fructosuria?
Fructose appears in the blood and urine
235
Which is more serious, essential fructosuria or fructose intolerance?
Fructose intolerance, because it depletes the cells of phosphate.
236
What is the etiology of classic galactosemia?
1. Absence of galactose-1-phosphate uridyl transferase
2. Build up of toxic substances including galactitol
237
What is the presentation of classic galactosemia?
Early:
1. Galactosemia
2. Galactosuria
3. Vomiting
4. Diarrhea
5. Jaundice
Late:
1. Cataracts
2. Hepatosplenomegaly
3. Mental retardation
238
How does galactokinase deficiency present?
1. Galactosemia
2. Galactosuria
More severe symptoms such as cataracts, hepatosplenomegaly and mental retardation can follow.
239
What is the treatment for classic galactosemia?
Exclude galactose and lactose from the diet.
240
What enzyme converts galactose to galactitol?
Aldose reductase
241
What does aldose reductase do?
Converts galactose to galactitol
242
What enzyme converts Galactose to galactose-1-phosphate?
Galactokinase
243
What enzyme converts Galactose-1-Phosphate to Glucose-1-Phosphate?
Uridyl transferase
244
What enzyme converts UDP-galactose to UDP-glucose?
4-epimerase
245
What does galactokinase do?
converts Galactose to galactose-1-phosphate
246
What does 4-epimerase do?
converts between UDP-galactose and UDP-glucose
247
What does Uridyl transferase do?
1. converts UDP-glucose to UDP-galactose
2. converts Galactose-1-Phosphate to Glucose-1-Phosphate
248
What enzyme converts UDP-glucose to UDP-galactose?
Uridyl transferase
249
Which groups are more likely to be lactose intolerant?
1. Blacks
2. Asians
250
What is the etiology of lactose intolerance?
Loss of brush-border lactase
251
How does lactose intolerance present?
1. Bloating
2. Cramps
3. Osmotic diarrhea
252
What is the treatment for lactose intolerance?
Avoid milk or add lactase pills to the diet
253
What are the essential amino acids?
PVT TIM HALL
1. Phenylalanine
2. Valine
3. Threonine
4. Tryptophan
5. Isoleucine
6. Methionine
7. Histidine
8. Alanine
9. Leucine
10. Lysine
254
What are the conditionally essential amino acids, and why are they conditionally essential?
The condition is age. They are necessary early in life during growth.
Mnemonic: Babies CRY for Help
1. Cysteine
2. aRginine
3. tYrosine
4. Histidine
255
Cysteine or Cystine: The amino acid
Cysteine
256
Cysteine or Cystine: Two copies of the amino acid joined by a disulfide bond
Cystine
257
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Phenylalanine
Essential
Both glucogenic and ketogenic
258
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Valine
Essential
Glucogenic
259
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Tryptophan
Essential
Both glucogenic and ketogenic
260
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Threonine
Essential
Both glucogenic and ketogenic
261
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Isoleucine
Essential
Both glucogenic and ketogenic
262
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Methionine
Essential
Glucogenic
263
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Histidine
Essential
Glucogenic
264
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Arginine
Essential
Glucogenic
265
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Leucine
Essential
Ketogenic
266
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Lysine
Essential
Ketogenic
267
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Tyrosine
Conditionally essential (during life and early growth)
(Phenylalanine and Tetrahydrobiopterin produce tyrosine and dihydrobiopterin)
Both glucogenic and ketogenic
268
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Glutamate
Inessential (made from alpha-ketoglutarate)
Glucogenic
269
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Aspartate
Inessential (made from asparagine or oxaloacetate by aspartate aminotransferase)
Glucogenic
270
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Proline
Inessential (Glutamate makes proline and ornithine)
Glucogenic
271
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Glycine
Inessential (synthesized during reactions involving tetrahydrofolate)
Glucogenic
272
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Cysteine
Conditionally essential (during life and early growth)
(Methionine begets S-adenosyl methionine which begets intermediates which beget cysteine)
Glucogenic
273
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Alanine
Inessential (made from pyruvate by alanine aminotransferase in the Cori cycle)
Glucogenic
274
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Serine
Inessential (made from a descendant of 3PG and with an amine group from glutamate)
Glucogenic
275
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Glutamine
Inessential (made from glutamate)
Glucogenic
276
Is the following amino acid essential or inessential, and is it glucogenic, ketogenic, or both?: Asparagine
Inessential (made from aspartate)
Glucogenic
277
Which amino acids are acidic?
Aspartate and glutamate are negatively charged at body pH
278
Which amino acids are basic?
Arginine, Lysine and Histidine
Arginine and Lysine are increased in histones which bind negatively charged DNA.
Histidine has no charge at body pH.
279
Zinc deficiency: Presentation
Delayed wound healing, hypogonadism, and decreased adult hair (axillary, facial, pubic)""
280
Zinc deficiency: Predisposes to what?
Alcoholic cirrhosis
281
Ethanol metabolism: All steps with enzymes and cofactors
Step 1: Ethanol is oxidized by NAD (forming NADH) to acetaldehyde using alcohol dehydrogenase. Step 2: Acetaldehyde is oxidized by NAD (forming NADH) to acetate using acetaldehyde dehydrogenase.""
282
Ethanol metabolism: Limiting reagent
NAD+
283
Ethanol metabolism: Order of kinetics of alcohol dehydrogenase
Zero-order kinetics
284
Disulfiram: Mechanism
Disulfiram inhibits acetaldehyde dehydrogenase, leading to an accumulation of acetaldehyde, leading to increased hangover symptoms.""
285
Which drug inhibits acetaldehyde dehydrogenase?
Disulfiram
286
Ethanol hypoglycemia: mechanism
1. Ethanol metabolism increases NADH/NAD ratio in the liver. 2. Pyruvate and oxaloacetate are reduced by NADH respectively to lactate and malate. 3. Decreased pyruvate and oxaloacetate leads to decreased gluconeogenesis. 4. Decreased gluconeogenesis leads to hypoglycemia.""
287
What are the consequences of the altered NADH/NAD ratio seen in alcoholics?
Short-term: Hypoglycemia, Long-term: Hepatic fatty change""
288
What is the mechanism behind chronic fatty change in alcoholics?
1. Ethanol metabolism leads to an increased NADH/NAD ratio in the liver. 2. This ratio prefers fatty acid synthesis over glycolysis.""
289
Kwashiorkor: Clinical picture
Small child with a swollen belly and depigmented hair.
290
Kwashiorkor: Clinical presentation
Kwashiorkor results from protein-deficient MEALS. Malabsorbtion, Edema, Anemia, Liver (fatty change), Skin lesions""
291
Protein malnutrition leads to what disease?
Kwashiorkor (as opposed to Marasmus from energy malnutrition)
292
Energy malnutrition leads to what disease?
Marasmus (as opposed to Kwashiorkor from protein malnutrition)
293
Marasmus: Clinical presentation
Tissue and muscle wasting, loss of subcutaneous fat, and variable edema""
294
Chromatin structure: In the beads on a string analogy, what are the beads?""
Start with a nucleosome core made up of an 8 histone cube (two each of positively-charged histones H2A, H2B, H3, and H4). Negatively charged DNA loops twice around nucleosome core.""
295
Chromatin structure: In the beads on a string analogy, what is the string and how long is it?""
Histone H1 ties the nucleosomes together in a 30-nm fiber string
296
Chromatin structure: What histones are included and which of these are not in the nucleosome core?
H1 (only one not in the core), H2A, H2B, H3, and H4""
297
Heterochromatin or Euchromatin: Which is more condensed?
Heterochromatin. Euchromatin is less condensed.
298
Heterochromatin or Euchromatin: Which is less condensed?
Euchromatin. Heterochromatin is more condensed.
299
Heterochromatin or Euchromatin: Which is transcriptionally active?
Euchromatin (""eu"" means true, so think ""truly transcribed"")""
300
Heterochromatin or Euchromatin: Which is transcriptionally inactive?
Heterochromatin
301
Name the purines.
Adenine and Guanine
302
Name the pyrimidines.
Cytosine, Uracil, Thymine""
303
Which base pair bond has 3 Hydrogen bonds?
Guanine to Cytosine
304
Which base pair bond has 2 Hydrogen bonds?
Adenine to Thymine
305
How many Hydrogen bonds does the Guanine to Cytosine pairing have?
3
306
How many Hydrogen bonds does the Adenine to Thymine pairing have?
2
307
Which amino acids are necessary for purine synthesis?
Glycine, Aspartate, Glutamine""
308
In nucleic acids, what kind of substitution is a transition?""
TransItion = Identical type (Purine for purine or pyrimidine for pyrimidine")"
309
In nucleic acids, what kind of substitution is a transversion?""
TransVersion = conVersion between types (Purine for pyrimidine or vice versa")"
310
What does it mean for genetic code to be unambiguous?
Each codon specifies only one amino acid.
311
What does it mean for genetic code to be degenerate?
More than one codon may code for the same amino acid.
312
What does it mean for genetic code to be redundant?
More than one codon may code for the same amino acid.
313
Which amino acid is coded by only one codon?
Methionine
314
~ average pKa of carboxyl group on AA""
2.3
315
~ pKa of side chain of Glutamic Acid""
>4""
316
~ pKa of side chain of Histidine""
6
317
~ pKa of side chain of Cysteine""
8
318
~ average pKa of amino group on AA""
9.6
319
~ pKa of side chain of Tyrosine""
10
320
~ pKa of side chain of Lysine""
10.5
321
~ pKa of side chain of Arginine""
12.5
322
An acid with a pKa of x serves as a buffer best at x + what?""
positive or negative 1 (equal amounts of charged and uncharged acid)""
323
Trypsin cleaves peptides at which side of what residues?""
C-terminal of lysine or arginine (the most basic amino acids)""
324
Cyanogen bromide cleaves peptides at which side of what residues?""
C-terminal of methionine""
325
Pepsin cleaves peptides at which side of what residues?""
C-terminal side of tyrosine, phenylalanine, and tryptophan (all have phenyl groups, these are the same bonds as chymotrypsin. Pepsin's action ceases when the NaHCO3 raises the pH of the intestinal contents)""
326
Chymotrypsin cleaves peptides at which side of what residues?""
C-terminal side of tyrosine, phenylalanine, and tryptophan residues (all have phenyl groups, these are the same bonds as pepsin, whose action ceases when the NaHCO3 raises the pH of the intestinal contents).""
327
# of aas in one turn of alpha-helix""
3.6
328
Amino acids that disrupt alpha-helix""
proline, many charged aas, bulky side chains""
329
Which reagent sequentially removes N-terminal residues from a polypeptide?""
Phenylisothiocyanate (Edman degradation)""
330
Which reagent sequentially removes C-terminal residues from a polypeptide?""
Carboxypeptidase""
331
What kind of inheritance and mutation is the alpha-1-antitrypsin deficiency?""
Autosomal recessive, single purine substitution (GAG to AAG)""
332
Anode: What does it attract?""
Anions""
333
Anode: What does it contain?""
Cations""
334
Cathode: What does it attract?""
Cations""
335
Cathode: What does it contain?""
Anions""
336
Inhibitors of electron transport from FMNH2 to Coenzyme Q""
Amytal and Rotenone""
337
Inhibitors of electron transport from Cytochrome b to Cytochrome c""
Antimycin A""
338
Inhibitors of electron transport from Cytochrome a+a3 to Oxygen""
Cyanide, CO, and Sodium azide""
339
Where do GLUT1 receptors predominate over other GLUT receptors?""
RBCs""
340
Where do GLUT4 receptors predominate over other GLUT receptors?""
Adipose tissue and skeletal muscle""
341
Which tissues have cotransport of glucose?""
Epithelial cells of the intestine, renal tubular cells, and choroid plexus""
342
Which tissues (7) need glucose as fuel?""
Brain, RBCs, Renal medulla, lens, cornea, testes, exercising muscle""
343
Where is pyruvate carboxylase found and not found?""
Found in mitochondria of liver and kidney cells, not foudn in mitochondria of muscle""
344
Where is Fructose 1-6 bisphosphatase found?""
Liver and kidney""
345
What is the Cori cycle?""
Lactate in muscle is shuttled to liver where it is turned into glucose.""
346
How does glucagon stimulate gluconeogenesis?""
Regulation of F2,6-BP and inactivation of Pyruvate Kinase via elevation of cAMP-dependent protein kinase A.""
347
This oxidation accounts for about two thirds of the total oxygen consumption and ATP production in most animals, including humans.""
Oxidation of acetyl coA to CO2 and H2O.""
348
What inhibits pyruvate dehydrogenase?""
Acetyl CoA and NADH (no need for more of either). These activate PD kinase (Phosphorylates enzyme with ATP, which must be in abundance, so no more is needed)""
349
What stimulates pyruvate dehydrogenase?""
ADP (need more ATP. Inhibits PD kinase and stimulates PD phosphatase.)""
350
Which is active?: Phosphorylated or dephosphorylated pyruvate dehydrogenase""
Dephosphorylated.""
351
What inhibits citrate synthase?""
ATP and NADH (no need for more of either), Succinyl CoA (""Slow down partner, the guys ahead of you are trying to do their job!""), Acyl CoA fatty acid derivatives (Citrate provides acetyl CoA to synthesize fatty acids and activates acetyl CoA carboxylase, rate limiting enzyme of fatty acid synthesis).""
352
Where in glycolysis and TCA does CO2 come off?""
3 places: Pyruvate to Acetyl CoA, Isocitrate to alpha-ketoglutarate, and alpha-ketoglutarate to Succinyl CoA""
353
What is the rate-limiting step of the TCA?""
Isocitrate to alpha-ketoglutarate by isocitrate dehydrogenase""
354
What activates isocitrate dehydrogenase?""
ADP""
355
What inhibits isocitrate dehydrogenase?""
ATP and NADH""
356
Sources of Succinyl CoA""
TCA intermediate, and from odd chained fatty acids, and from propionyl coA from metabolism of branched-chain amino acids.""
357
Uses of Succinyl CoA""
TCA intermediate, and biosynthesis of heme""
358
Where in the TCA does NADH come from?""
Pyruvate to Acetyl CoA, Isocitrate to alpha-ketoglutarate, alpha-ketoglutarate to succinyl coA, Malate to Oxaloacetate""
359
Where in the TCA does FADH2 come from my dear?""
Succinate to fumarate my sweet.""
360
Why is FAD used to oxidize succinate?""
Succinate is not powerful enough to reduce NAD.""
361
What are the important products of the HMP pathway?""
2 NADPH, Ribose, and glyceraldehyde-3-Phosphate and Fructose-6-phosphate""
362
Which major metabolic reactions require Thiamine as a cofactor?""
TCA: Pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase, HMP shunt: Transketolase""
363
What is NADPH used for?""
1. Reductive biosynthesis (eg fatty acids and steroids) 2. Reduction of oxygen directly (myeloperoxidase system's famed respiratory burst) and hydrogen peroxide indirectly (through reduction of glutathione) 3. Cytochrome P-450 mono-oxygenase system""
364
What is the famed respiratory burst?""
The rapid conversion of O2 to superoxide using NADPH.""
365
What disease process is due to a missing respiratory burst?""
Chronic granulomatous disease""
366
Where is the mutation for G6PD?""
Point mutation in coding region of the G6PD gene (X-linked)""
367
What is the relation of polyols to sugars?""
Polyols are monosaccharides where the carbonyl group is reduced to an alcohol.""
368
What is a glycoside?""
Carbohydrate attached to non-carbohydrate structures.""
369
What is a reducing sugar?""
A monosaccharide where the anomeric carbon (Carbon 1) is free.""
370
What is the result of lack of disaccharidase activity of intestinal mucosa?""
Osmotically active disaccharides suck water out of mucosa causing osmotic diarrhea.""
371
Where is fructokinase found?""
Liver (processes most dietary fructose), kidney, small intestine""
372
Why is fructose metabolism faster than glucose metabolism?""
Bypasses PFK, major regulatory step of glycolysis.""
373
What enzyme is missing in hereditary fructose intolerance?""
Aldolase B""
374
What does aldose reductase do?""
Reduces glucose to sorbitol""
375
Where is aldose reductase found?""
Lens, retina, Schwann cells, kidney, placenta, RBCs, and gonads""
376
What does sorbitol dehydrogenase do?""
Oxidizes sorbitol to fructose.""
377
Where is sorbitol dehydrogenase found?""
Liver and gonads (ovaries, seminal vesicles, sperm)""
378
Mechanism of sorbitol toxicity""
Extra glucose freely enters cells containing aldose reductase which converts it to sorbitol. Sorbitol may not pass through, and low or absent sorbitol dehydrogenase prevents it from being changed to fructose. Strong osmotic effects lead to swelling and damage.""
379
Chondroitin Sulfate: Where found?/Distinguishing characteristic from other GAGs""
Cartilage, tendons, ligaments, aorta. Most abundant GAG in body.""
380
Chondroitin Sulfate: Use/Mechanism""
Form proteoglycan aggregates. Cartilage: Bind collagen and hold fibers in a tight, strong network""
381
Dermatan Sulfate: Where found?/Distinguishing characteristic from other GAGs""
Found in skin, blood vessels, and heart valves""
382
Keratan Sulfate: Where found?/Distinguishing characteristic from other GAGs""
Found in cartilage proteoglycan aggregates with chondroitin sulfate, and in cornea. Most heterogeneous GAG.""
383
Heparin: Where found?/Distinguishing characteristic from other GAGs""
Intracellular compound (unlike other GAGs). Found in mast cells of artery walls, especially in lungs, liver, and skin""
384
Heparin: Use/Mechanism""
Anticoagulant""
385
Heparan Sulfate: Where found?/Distinguishing characteristic from other GAGs""
Extracellular, unlike heparin. Found in basement membrane and as a ubiquitous component of cell surfaces.""
386
Hyaluronic Acid: Where found?/Distinguishing characteristic from other GAGs""
Found in synovial fluid of joints, vitreous humor f eye, umbilical cord, and loose connective tissue. Unlike other GAGs: Unsulfated, not covalently attached to protein, and only GAG not limited to animal tissue, but also found in bacteria.""
387
Hyaluronic Acid: Use/Mechanism""
Lubricant and shock absorber""
388
Hunter's Syndrome vs Hurler's Syndrome: Enzyme deficiency""
Hunter's: Iduronate sulfatase, Hurler's: alpha-L-iduronidase""
389
Hunter's Syndrome vs Hurler's Syndrome: Corneal clouding?""
Hunter's: No, Hurler's: Yes""
390
Hunter's Syndrome vs Hurler's Syndrome: Mental retardation?""
Both (Hunter's ranges from mild to severe)""
391
Hunter's Syndrome vs Hurler's Syndrome: Physical deformity?""
Hunter's: Mild to severe, Hurler's: Dwarfing, coarse facial features, (gargoylism)""
392
Hunter's Syndrome vs Hurler's Syndrome: Which GAGs' degradation is affected?""
Both: Dermatan sulfate and Heparan sulfate""
393
Hunter's Syndrome vs Hurler's Syndrome: Severity?""
Hunter's: Less Hurler's: More""
394
Hunter's Syndrome vs Hurler's Syndrome: Inheritance?""
Hunter's: X-linked Recessive, Hurler's (and all other mucopolysaccharidoses): Autosomal recessive""
395
Hunter's Syndrome vs Hurler's Syndrome: Aggressive behavior?""
Hunter's: Yes, Hurler's: No""
396
Mnemonic for Hurler's syndrome: HURLERS. What does it stand for?""
H: Hepatosplenomegaly/Heparan and Dermatan sulfate, U:Ugly facies, R: aRteries filled with GAGs, L: L-iduronidase, E: Eyes clouded, early death, R: Retardation/Respiratory obstruction, S: Short/stubby fingers""
397
I-Cell disease: Pathophysiology""
Inability of cell to phosphorylate mannose residues on glycoproteins indicating that they are lysosome bound.""
398
I-Cell disease: Presentation""
Skeletal abnormalities, restricted joint movement, coarse facial features, severe psychomotor impairment, death by 8 years""
399
