studystack 2 Flashcards
(221 cards)
1
Q
Amino acid catabolism produces what toxic product?
A
Ammonia
2
Q
When does negative nitrogen balance occur?
A
Dietary Deficiency (starvation) Catabolic stress (ex. infection)
3
Q
What 3 cofactors are required for amino acid synthesis?
A
Pyridoxal phosphate Tetrahydrofolate Tetrahydrobiopterin (BH4)
4
Q
When pyruvate is transaminated, what does it synthesize?
A
Alanine
5
Q
When oxaloacetate is transaminated, what does it synthesize?
A
Aspartate
6
Q
When alpha-ketoglutarate is transaminated, what does it synthesize?
A
Glutamate
7
Q
What forms alanine by transamination?
A
Pyruvate
8
Q
What forms aspartate by transamination?
A
Oxaloacetate
9
Q
What forms glutamate by transamination?
A
alpha-ketoglutarate
10
Q
Where is arginine generated?
A
Urea cycle
11
Q
Where does Cysteine get its S?
A
Methionine
12
Q
What is pyridoxal phosphate (PLP) synthesized from?
A
Vitamin B6
13
Q
What are two mechanisms through which nitrogen is removed from amino acids?
A
Transamination
Deamination
14
Q
What enzyme is involved in the oxaloacetate –> aspartate reaction?
A
AST
15
Q
What is the function of glutamate dehydrogenase?
A
It deaminates glutamate, resulting in alpha-ketoglutarate and ammonia.
16
Q
Where does the deamination of glutamate by glutamate dehydrogenase take place?
A
Liver
17
Q
What enzyme is involved in the deamination of glutamate into alpha-ketoglutarate and ammonia?
A
Glutamate dehydrogenase
18
Q
What enzyme is involved in the conversion of glutamate + ammonium (NH4+) –> glutamine
A
Glutamine synthase
19
Q
What conversion does glutamine synthase catalyze?
A
glutamate and ammonium –> glutamine
20
Q
What enzyme is involved in the conversion:glutamine –> glutamate + NH4+?
A
Glutaminase
21
Q
In the FASTED state, what do the liver and muscles contribute to amino acid metabolism?
A
Muscles = provide amino acids for metabolismLiver = uses lots of amino acids in fasted state.
22
Q
Where does the urea cycle occur?
A
Liver
23
Q
What is the enzyme that converts HCO3- + NH4+ –> Carbamoyl phosphate?
A
CPS1 (carbamoyl phosphate synthase 1)
24
Q
What is the rate limiting step in the urea cycle?
A
CPS1 (carbamoyl phosphate synthase 1)
25
What is the enzyme that converts Ornithine to Citrulline?
OTC (ornithine transcarbomylase)
26
What is the common source of both of the N's in urea?
Glutamate
27
Where do the first two steps of the urea cycle occur?
Mitochondria
28
In the urea cycle, after the first two steps, where do the following steps occur?
Cytoplasm
29
What are two products from the urea cycle?
Arginine fumarate
30
What is the role of NAG in the urea cycle?
It is synthesized by acetyl CoA and glutamate and it STIMULATES CPS1
31
Ornithine transcarbamoylase deficiency (OTC), the most common cause of urea cycle disorder, is what type of genetic trait?
x-linked
32
Beginning Product of FA synthesis
Citrate
33
Shuttle used in FA synthesis
Citrate shuttle
34
What cofactor is needed in all carboxylases?
Biotin
35
Location of FA synthesis
Hepatic cytosol
36
Where do we get NADPH?
Pentose Phosphate Pathway
37
Large complex of enzymes that binds growing acyl chain and malony CoA in first round.
Fatty Acid Synthase
38
What are the three types of macromolecular synthesis?
DNA replication (DNA synthesis)
Transcription (RNA synthesis)
Translation (protein synthesis)
39
What is the basic dogma of biology?
DNA - RNA - protein
40
Where does prokaryotic replication take place?
In the cytoplasm
41
Where does eukaryotic replication take place?
In the nucleus during S phase of the cell cycle.
42
Duplicate chromosomes, so that after mitosis each daughter cell will inherit a complete genome.
DNA Replication
43
Requirements for DNA replication
DNA polymerase, Mg2+, template, primer, and dNTPs
44
In what direction does DNA replication occur?
5` to 3` direction
45
Stage: Ribosomes assembled with mRNA between large and small subunits along with 1st aminoacyl tRNA (Met); tRNa bound to P site of ribosome.
Initiation
46
Where does B oxidation occur?
Mitochondria
47
What enzyme combines succinyl-CoA and glycine to start the Heme pathway?
ALA (aminolevulinic acid) synthetase
48
Rare enzyme deficiency in the heme pathway.
Porphyria
49
Genetic defect in UDP-glucuronyl Transferase.
Crigler-Najar syndrome
50
Maximum possible number of hydrogen atoms, single bonds only between carbon atoms, solid at room temperature.
Saturated fats
51
Has at least one double bond between carbon atoms because hydrogen atoms are missing. Double bond is point of unsaturation, they are unstable. Liquid at room temperature.
Unsaturated fats
52
An omega-6 fatty acid, precursor of Arachidonic acid.
Linoleic Fatty Acids
53
Enzyme responsible for catalyzing chain elongation in prokaryotes for both the leading and lagging strands.
DNA Polymerase III
54
Seals the gap that remains after Pol I removes the RNA primer and replaces it with DNA
DNA ligase
55
Some polymerases can copy an RNA template into DNA in the process known as ________
Reverse transcription
56
Hereditary nonpolyposis colorectal cancer (HNPCC), one of the most common inhereted cancers has been shown a defect in this DNA system.
Mismatch
57
This type of enzyme recognize a misincorporated nucleotide, nicks the strand, and remove sthe misincorporated nucleotide.
Endonucleases
58
Dihydrofolate reductase inhibitor
Methotrexate
59
Drug that induces Vitamin B6 deficiency
Isoniazid
60
Dietary insufficiency of thiamine/impaired intestinal absorption of B1; apathy, memory loss, nystagmus (eyeball motion)
Wernicke-Korsakoff syndrome
61
In infants, present as tachycardia, vomiting, convulsions, death; adults: dry skin, irritability, disorderly thinking progressive paralysis
Beriberi
62
Niacin defiency causes
Pellagra: dermatitis, diarrhea, dementia, death
63
Coenzyme in carboxylation reactions, carrier of activated CO2
Biotin
64
Selectively stimulates gene expression or specifically repress gene transcription, regulates plasma levels of calcium and phosphorous
Vitamin D
65
Post translational modification of various blood clotting factors.
Vitamin K
66
Active form of Vitamin E
a-tocopherol
67
DNA double helix that have additional twists applied to them that have coiled up upon themselves.
Supercoiling
68
– heterocyclic compound consisting of pyrimidine fused to a 5 member imidazole ring (adenine and guanine)
Purine
69
Heterocyclic compounds with nitrogen atoms at positions 1 and 3 of a 6 member ring (thymine, cytosine, uracil).
Pyrimidine
70
nitrogenous base (attached to 1’ C by B-N-glycosidic bond), a ribose sugar (OH at 2’ C), and a phosphate group (backbone of DNA, attached to 5’ C) – present in RNA molecules
Ribonucleotide
71
bond is between the 3’ OH group of the deoxyribose/ribose on the last nucleotide and the 5’-phosphate of the dNTP/NTP precurson – basically it is a bond that connects nucleotides in DNA
phosphodiester bond
72
Linear and single stranded, carries codon information for translation (2%)
mRNA
73
folded loop structures formed by intra-molecular H-bonding, carries amino acids to ribosomes (16%)
tRNA
74
Method: Take a single stranded DNA with gene sequence of interest with a fluorescent probe let it anneal to DNA in cell and look for fluorescence.
FISH
75
complex of DNA and chromosomal proteins (histones)
Chromatin
76
Rich in lysine and arginine, and as a result carry a positive charge. This makes it easier for negatively charged chromatin to associate.
Histones
77
Antibiotic drugs that interfere with DNA gyrase
Quinolone
78
Decondensed and transcriptionally active DNA
Euchromatin
79
Condensed and transcriptionally inactive DNA
Heterochromatin
80
Nucleotide that is an analogue of Acyclovir.
Guanine
81
prevent re-annealing of DNA and prevent hairpin loops from forming
SSB proteins
82
Drug inhibits bacterial DNA gyrase
Ciprofloxacin
83
Combines with certain proteins and is involved in RNA processing and gene regulation in eukaryotes
snRNA
84
3 stop codons
UGA, UAG, UAA
85
predicts the base pairing of the 5' anticodon and 3' codon
Wobble hypothesis
86
Enzyme that cleave trypsinogen to trypsin.
Enteropeptidase
87
Where does Urea synthesis begin and end within the cell?
Mitochondria to start, cytoplasm to finish
88
How much energy is required to run the urea cycle?
4 ATP
89
Rate limiting first enzyme for urea synthesis
carbamoyl phosphate
90
It can enter the TCA for energy or gluconeogenesis following urea cycle.
Fumarate
91
Molecular technique used to identify DNA.
Southern Blot
92
Molecular technique used to identify RNA.
Northern Blot
93
Molecular technique used to identify protein.
Western Blot
94
technique used to amplify DNA.
PCR
95
Sequence change with no phenotypic affect (i.e. 3rd base of wobbly codon, intron spliced out of message, spacer region o/s of expresed gene, similar AA w/ same effect on protein function, region of protein not critical for function - linker)
Silent mutation
96
Alteration of one codon, usually due to single base pair subsitution
Point mutation
97
Single base pair substitution altering one AA.
Missense mutation
98
Base pair substitution producing premature stop codon, resulting in truncated polypeptide.
Nonsense mutation
99
Insertion or deletion of sequence that is not a multiple of 3, so that codon reading frame is altered & random AA sequence is produced beyond the change.
Frame shift mutation
100
Misplacement of DNA fragment to different location of genome (different spot on same chromosome or on different chromosome)
Translocation
101
Deletion of part of the short arm of chromosome 5
Cri-du-chat syndrome
102
Removal of amino group from base by oxidation of keto group; A / C = will result in transition mutation during next round of replication; deamination of G not mutagenic, T does not have amino group to remove.
Deamination
103
DNA polymerase proofreading, ligation of strand breaks, direct base repair, excision repair.
DNA repair mechanisms
104
Product of defective UV specific endonuclease; results in extensive skin tumors after exposure to sunlight
Xeroderma pigmentosum
105
Most common conformation of DNA
B form
106
2nd most abundant class of chromatin proteins.
Scaffold proteins
107
Vitamin A derived from animals provide retinyl esters at are readily digested & absorbed as
Retinol
108
First detectable sign of a vitamin A deficiency
Nyctalopia
109
How many carbons does palmitic fatty acid have?
16
110
How many carbons does stearic fatty acid have?
18
111
How many carbons does oleic fatty acid have?
18
112
What makes up a triaclglycerol?
A glycerol and 3 fatty acids
113
genetically defective LDL receptors occur and LDL levels become extremely high
Familial Hypercholestemia
114
There is a mutation in the nucleotide excision repair enzymes. Individuals with this genetic defect are unable to repair thymine dimers.
Xeroderma pigmentosum
115
Excess NADH in the fed state will inhibit _______ in the Kreb cycle
isocitrate dehydrogenase
116
Inhibition of isocitrate dehydrogenase causes a build up of ____________.
Citrate
117
FA synthesis is induced by _____________.
Insulin
118
Inhibits carnitine trasport of fatty acyl groups into the mitochondrion.
Malonyl CoA
119
Lipoprotein lipase synthesis and secretion is induced by ____________.
Insulin
120
2 types of sphingolipid
Sphingomyelin & Glycosphingolipids
121
sphingosine (18C palmitate) connected by amide (serine) linkage to long chain fatty acid
Sphingolipids
122
Where does the 5th step of sphingolipid synthesis occur?
Golgi
123
Where do steps 1-4 of sphingolipid synthesis occur?
ER
124
What are the most abundant gangliosides in myelin?
Cerebrosides
125
What lipid disease involves the lipid gal-gal-glucosylceramide (ganglioside) due to deficient enzyme alpha-galactosidase?
Fabry's
126
What lipid disease involves the lipid glucosylceramide (cerebroside) due to deficient enzyme beta-glucosidase?
Gaucher's
127
What lipid disease involves the lipid sphingomyelin (sphingolipid) due to deficient enzyme sphingomyelinase?
Niemann-Pick
128
What lipid disease involves the lipid GM2 ganglioside (ganglioside) due to deficient enzyme hexosaminidase A?
Tay-Sachs
129
Where are sphingolipids destroyed?
Lysosomes
130
What kind of linkage joins the amino acid to the tRNA molecule?
Ester
131
upstream sequence to a start codon that can base pair to 3' end of 16S RNA
Shine-Dalgarno sequence
132
Patient with Hepititis A has what type of elevated bilirubin levels?
Indirect Bilirubin
133
Defect in a transporter for cysteine and basic AA that results in kidney stones
Cystinurea
134
Catalyzes transamination
aminotransferases
135
ApoB 100 is attached to which lipoproteins?
LDL, IDL and VLDL
136
ApoB48 is attached to which lipoprotein
Chylomicrons
137
Major component of membrane lipids. Analogue of plasmalogen in heart.
Phospatidylcholine
138
Major component of membrane lipids. Analogue of plasmalogen in nerve tissue.
Phospatidylethanolamine
139
Used to form PIP2 which is cleave by phospholipase C to DAG and IP3 in Ca2+ second messenger system.
Phospatidylinositol
140
Glycerol from fatty acids (after fatty acid metabolism) is converted into DHAP in the liver to go back into glycolysis or gluconeogenesis
DHAP
141
Lipase that releases fatty acids from fat (activated by PKA via adenyl cyclase).
Hormone Sensitive Lipase
142
Soluble mixed balls of fat that are created in order to bring fat to the intestinal lining of the small intestine (enterocytes) in order for fat to be re-absorbed, and then they are reabsorbed
Micelles
143
Pyrimidines
Cytosine, Thymine (DNA) and Uracil (RNA)
144
Percentage of A=T and G=C
Chargaff's Rules
145
Where are very long chain fatty acids degraded?
peroxisomes
146
directs circulating lipoproteins to their destinations
apolipoproteins
147
most circulating cholesterol found
LDL
148
acts on chylomicrons in the capillaries
lipoprotein lipase
149
Most common familial dyslipidemia
Type 2a hypercholesterolemia
150
Increased IDL, VLDL, chylomicrons; increased risk of atherosclerosis
Type 3 hyperlipoproteinemia
151
Lipoprotein lipase deficiency
Type 1 hyperchylomicronemia
152
Altered apolipoprotein C-II
Type 1 hyperchylomicronemia
153
Pancreatitis, HSM, eruptive xanthomas, abdominal pain after fatty meals; may lead to retinal vein occlusion
Type 1 hyperchylomicronemia
154
Increased LDL & cholesterol; increased risk of atherosclerosis
Type 2a hypercholesterolemia
155
LDL receptor deficiency
Type 2a hypercholesterolemia
156
Autosomal dominant; corneal arcus, tendon xanthoma, xanthelasma
Type 2a hypercholesterolemia
157
Increased triglycerides, cholesterol, chylomicrons; no increased risk of atherosclerosis
Type 1 hyperchylomicronemia
158
Increased VLDL & triglycerides
Type 4 hypertriglyceridemia
159
Hepatic overproduction of VLDL; pancreatitis
Type 4 hypertriglyceridemia
160
ApoE3/ApoE4 defect
Type 3 hyperlipoproteinemia
161
Autosomal dominance (late onset), CAG repeats in the coding section (encoded bc of strand slippage during replication)
Huntington
162
deficiency --> Lesch Nyan, X-linked recessive
HGPRT
163
used in purine salvage pathway, causes SCID, ATP and dATP accumulate --> imbalnce of nucleotide pool, prevents DNA synthesis
Adenosine deaminase deficiency
164
suicide inhibitor of xanthine OXIDASE, enzyme can't degrade purines to urate
Allopurinol
165
hemoglobin's oxygen binding affinity is inversely related both to acidity and to the concentration of carbon dioxide.
Bohr effect
166
It is an inducer, inducer presented to the cell is 1, 6 Allolactose. It has a regulator gene and structural gene
Lactose Operon
167
elaborates mRNA referred to as imRNA which is responsible for the synthesis of a transcription factor that acts as a repressor
i gene
168
Name 3 diseases related to CAG expansion
Huntington, Kennedy and SC Ataxia
169
Inherited mental retardation, CGG repeat at 5' UTR, FMR1 gene that encodes a RNA binding gene. Over 200 repeats no transcription of FMR1
Fragile X syndrome
170
explains why the third base in a codon may differ and be recognised by the same tRNA and therefore code for the same amino acid. The wobble hypothesis states that the first and second bases must pair in the watson-crick manner but 3rd less constrained
wobble hypothesis
171
Promoter site in prokaryotes
pribnow box (tataat)
172
major phospholipid and surfaceactivecomponent of surfactant
Dipalmitoylphosphatidylcholine (DPPC)is the major phospholipid and surfaceactivecomponent of surfactant.
173
glycerophospholipid serves as a substrate for LCAT
Phosphatidylcholine
174
What is the precursor of all glycerophospholipids?
Phosphatidic acid
175
Severely impaired or absent glucronyltransferase activity -Uncommon -Severity depends on how much activity remains -Type I, severe defect leads to kernicterus & death if untreated -Type II, less severe defect
Crigler-Najjar syndrome
176
Mildly reduced expression of glucuronyltransferase -Very Common (estimated 3-7% of US Pop.) -Results in slightly elevated bilirubin levels but no detrimental health effects -May have increased sensitivity to certain drugs
Gilbert's syndrome
177
Very complex synthetic pathway where N-linked (usually to Asp) or O-linked (usually Ser or Thr) glycosidic bonds
Glycoproteins
178
Their synthesis is very complex -Turn over by shedding from the cell surface and by endocytosis (broken down in lysozomes) -Can be extracellular or attached to the membrane
Proteoglycans
179
a disease that results when there is a deficiency in the enzyme that phosporylates mannose residues
I-cell disease
-Lysosomal enzymes get secreted -lysosomes don't have the full complement of required enzymes so proteins build up in them (inclusions) -Extremely rare
180
Ceramide + UDP-Glucose
Glucocerebroside
181
Ceramide + UDP-Galactose
Galactocerebrosides
182
Ceramide + 2 or more UDP-sugars and N-acetylneuraminic acid (NANA)
Ganglioside
183
deficiency of enzymes that breakdown GAG fragments, thus they accumulate in the lysosomes -can cause a variety of problems such as skeletal deformities and mental retardation
mucopolysaccharidoses
184
a deficiency in an enzyme that results in an accumulation of sphingolipids in the lysosomes -Fabry disease is x-linked, others are autosomal recessive
sphingolipidosis
185
What happens to acetoacetate when it remains in the blood stream?
converted non-enzymatically to acetone
186
Alternative route for metabolism of glucose
Pentose Phosphate Pathway
187
PPP leads to the synthesis of ----- for nucleotide and nucleic acid formation
Ribose
188
Main hexoses that are absorbed from GI tract
Glucose, fructose and galactose
189
First enzyme of PPP
Glucose 6 Phosphate Dehydrogenase
190
Deficiency to glucose 6 phosphate dehydrogenase will yield to acute hemolysis of RBC leading to
Hemolytic anemia
191
The oxidative phase of PPP generates
NADPH
192
ransketolase requires what coenzyme
Thiamine
193
Reduced glutathione removes H2O2 in a reaction catalyzed by
Glutathione peroxidase
194
An enzyme found in the liver which also functions in glycolysis in the liver by cleaving fructose 1,6 bisphosphate
Aldolase B
195
CCA at 3'. Adaptor molecule, 2 ends are anchoring the AA at the 3' end & at other end there is anticodon loop which interacts with mRNA. 5' loop=di-hydrouridine. 3' loop=T-psuedouridine C loop
tRNA
196
Requires EF-G & GTP. 1st aminoacyl tRNA gets ejected from P site to E site.
Translocation
197
Sequence of AA residues that is highly enriched in hydrophobic amino acid residues.
Signal peptide
198
Site of production of chylomicron
Small intestines
199
Transport of cholesterol from liver to tissues
VLDL and LDL
200
Transport of cholesterol from tissues to liver (reverse transport)
HDL
201
Transport of cholesterol from intestine to liver
Chylomicrons
202
Toxicity: cleft palate, diarrhea, bone resorption, headache, nausea, aplopecia, hepatomegalia
Vit A
203
Deficiency: hemorrhaging, stomach pain, bone malformation, deposits of Ca2+ in arteries
Vit K
204
Function: Antioxidant, Radical Scavenger
Vit E
205
What are the tissue sites for production of adrenal steroids?
zona glomerulosa (aldosterone)
zona fasciculata (cortisol)
zona reticularis (DHEA & androstenedione)
206
What type of steroid is aldosterone?
mineralocorticoid
207
What type of steroid is cortisol?
glucocorticoid
208
14 subunits, nucleolus, produces rRNA precursors, resistant to inhibition by alpha-amanitin.
RNA polymerase I
209
12 subunits, nucleus, precursor to mRNA, sensitive to alpha-amanitin
RNA polymerase II
210
17 subunits, nucleus, synthesizes 5SrRNA, tRNA & small RNAs, moderated sensitivity to alpha-amanitin
RNA polymerase III
211
What effect does fasting have on HMG-CoA reductase?
decreases activity
212
What effects do insulin and thyroxin have on HMG-CoA reductase?
increase activity
213
What is the committed step in cholesterol synthesis?
HMG-CoA reductase
214
What receptor in the liver endocytoses chylomicrons?
Hepatic Apo-E receptor
215
What disease boasts defective Apo-B100/E receptors?
familial hypercholesterolemia
216
What 2 enzymes does HDL donate to maturing chylomicrons and VLDLs?
ApoCII and ApoE
217
activates lipoprotein lipase
Apo CII
218
What is the committed step in the synthesis of bile salts?
7-alpha-hydroxylase
219
a rare disorder caused by defective Cys2 carrier across lysosomal membranes
cystinosis
220
Impaired transport of neutral AAs across intestinal and renal epithelial cells
Hartnup disease
221
lack of homogentisate oxidase involved in the catabolism of Tyr
Alkaptonuria
