MCM midterm Flashcards
1
Q
normal fasting blood glucose levels are
A
70-100mg/dL
2
Q
what levels of blood glucose are characteristic of hypoglycemia?
what are the symptoms of hypoglycemia
A
below 60 mg/dL
hunger, sweating, trembling
3
Q
what levels of blood glucose are characteristic of diabetes?
A
above 126 mg/dL fasting OR
199 mg/dL 2 hours after receiving dose of 75mg glucose
4
Q
red blood cells generate ATP from what biochemical process
A
glycolysis only
5
Q
describe the pasteur effect and how it relates to cellular energy
A
aerobic conditions tend to suppress glycolysis via allosteric regulation of glycolytic enzymes by CITRATE and ATP
6
Q
describe the Warburg effect and how it relates to cellular energy
A
cancer exhibits high rates of glycolysis despite adequate oxygen. evidence comes from PET scan with fluorodeoxyglucose (FdG)
7
Q
this 4 carbon sugar alcohol is used as artificial sweetener. low glycemic index, doesn’t fuck up teeth, absorbed and excreted so less flatulence than other sugar alcohols
A
eryrthritol
8
Q
this 5 carbon sugar alcohol is used as natural sweetener. low glycemic index, doesn’t promote tooth decay, lower energy content than sucrose at same level of sweetness. no bad aftertaste. very gassy though
A
xylitol
9
Q
this sugar alcohol is used by plants and microorganisms to store energy. in medicine it is used to make BBB permeable and to treat head trauma and kidney failure. inhaled solid useful for cystic fibrosis treatment as well.
low glycemic index, tooth friendly sweetener. half as sweet as sucrose, causes flatulence in high doses
A
mannitol
10
Q
sugar alcohol is used as a sweetener in chewing gum, toothpaste and mouthwash and as a laxative
A
sorbitol
11
Q
explain the formation and treatment of gallstones
A
bile contains too much cholesterol and too little bile salts.
treated with chenodeoxycholic acid (bile salt) to help restore bile salt pool and in some cases dissolve gallstones
12
Q
list a few symptoms of gallstones
A
malabsorption syndromes such as steatorrhea and deficiency in fat soluble vitamins (A,D,E,K)
13
Q
what kind of environment is necessary for disulfide bond formation?
what effect does glutathione have on disulfide bond formation
A
oxidizing environment. present in rough ER, but not cytoplasm (due to high glutathione formation). therefore, disulfide bonds are usually present in secreted proteins
14
Q
describe the daily intake of protein in the average person and how it relates to nitrogen balance
A
100g of protein consumed daily
400g of protein broken down per day
400g of protein synthesized each day
positive nitrogen balance = nitrogen intake exceeds nitrogen excretion (protein synthesis)
negative nitrogen balance = nitrogen loss exceeds nitrogen intake (protein degradation)
15
Q
deficiency of this vitamin is marked by night blindness, visual impairment, xerophthalmia and/or keratin in the conjunctiva (Bitot’s)
A
vitamin A
16
Q
excess levels of this vitamin result in liver toxicity and joint pain
A
vitamin A
17
Q
exposure of infants to this substance leads to cleft palate and heart abnormalities
A
isotretinoin
18
Q
list sources of synthetic vitamin A
A
tretinoin
isotretinoin
19
Q
the bioactive form of vitamin D is called
A
calcitriol
20
Q
this disease is an autoimmune condition resulting in damaged gut mucosa and inflammation as well as malabsorption of nutrients and GI discomfort
A
Crohn Disease
treated by surgical resection of damaged areas and further prevention via drugs
21
Q
how does cystic fibrosis can affect the exocrine function of the pancreas?
A
cystic fibrosis causes mucus plug in pancreatic ducts; check serum amylase and lipase levels to diagnose
22
Q
describe what can happen in a patient when the endocrine function of their pancreas becomes abberant
A
diabetes mellitus (insulin/glucagon dysfunction)
23
Q
excess fat in the stool due to poor digestion or malabsorption is called what? what is a concern of this condition?
A
steatorrhea
malabsorption of fat soluble vitamins
24
Q
what are the results of vitamin D deficiency
A
brittle bones (rickets/osteomalacia) hypocalcemic tetany
25
what are the results of excess vitamin D
hypercalcemia (dazed, loss of appetite, sarcoidosis)
| hypercalicuria
26
vitamin C is necessary for collagen formation and carnitine function. what results from vitamin C deficiency?
scurvy - purple spots on skin, bruising, spongy/bleeding gums, poor wound healing
27
the energy released in the removal of the terminal phosphate group of ATP is about equivalent to the energy stored in what other high energy bond?
thioester bond between the thiol group of CoA and carboxylic acids
28
describe how the kidney regulates blood pH
in acidic conditions, kidney will secrete NH4+ and reabsorb bicarbonate
in basic conditions, kidney will reabsorb less bicarbonate and secrete fewer protons via NH4+
29
1) what is the function of the gastric proton pump?
2) what is the function of omeprazole
3) what are the sideffects of this drug
1) H+/K+ ATPase (pumps proton into gastric lumen and K+ into the cell)
2) inhibit this proton pump, increasing pH in gut lumen
3) reduced absorption of nutrients, hypochlorhydria, increased sensitivity to food poisoning, reduced efficacy of gastric enzymes
30
explain why troponin can be useful in diagnosis of MI
troponin is trimer - 3 different subunits (Tn-T, Tn-I, Tn-C)
Tn-I subunit exists in 3 isoforms based on tissue
cTn-I found in cardiac tissue, elevated in blood after MI
31
certain enzymes, while everpresent in low levels in blood, exist in elevated levels in certain disease states. Elevated levels of alkaline phosphatase indicates what disease?
bone disease
32
certain enzymes, while everpresent in low levels in blood, exist in elevated levels in certain disease states. Elevated levels of sorbitol dehydrogenase or lactate dehydrogenase (LDH-5) indicate what disease?
obstructive liver disease
33
certain enzymes, while everpresent in low levels in blood, exist in elevated levels in certain disease states. Elevated levels of acid phosphatase is indicative of what disease?
prostatic cancer
34
certain enzymes, while everpresent in low levels in blood, exist in elevated levels in certain disease states. Elevated levels of amylase is indicative of what disease?
acute pancreatitis
35
certain enzymes, while everpresent in low levels in blood, exist in elevated levels in certain disease states. Elevated levels of aldolase and AST are indicative of what disease?
muscular dystrophy
36
certain enzymes, while everpresent in low levels in blood, exist in elevated levels in certain disease states. Elevated levels of ALT and/or CK-MM isoform of creatine kinase are indicative of what disease?
liver disorder
37
```
metalloenzymes are inhibited by what class of substances
give an example of one such substance
```
chelators
| EDTA
38
patient with lead poisoning can be treated using what class of substances?
chelators, specifically Ca-EDTA or Succimer in children
39
1) GLUT2 exhibits high ______ but low _______
2) GLUT2 operates in which direction
3) GLUT2 operates by what kind of transport
4) explain how GLUT2 can function as glucose sensor in pancreas
1) capacity; affinity
2) bi-directional based on concentration
3) facilitated diffusion
4) rapid influx into pancreatic beta cell; converted to ATP; closure of ATP-dependent K+ channels; membrane depolarization; Ca++ entry into cell; release of insulin (fast); activation of calmodulin and initiation of insulin synthesis
40
1) describe Fanconi-Bickel syndrome and how it relates to glucose transport
2) what are signs and symptoms as well
3) treatment?
1) autosomal recessive; mutation in GLUT2 of hepatocytes and pancreatic Beta cells; leads to impaired transport of glucose, galactose and fructose
2) failure to thrive, hepatomegaly, tubular nephropathy, and resistant rickets, fasting ketotic hypoglycemia and postprandial hyperglycemia
3) administration of vitamin D and phosphate to treat rickets and uncooked corn starch for the glycemic issues
41
1) what is the function of mannose-6-phosphate group on hydrolytic glycolipids?
2) what enzyme is responsible for the addition of the mannose-6-phosphate group to the hydrolytic enzyme
3) where does this tagging process take place)
4) deficiency in the enzyme mentioned in 2) results in what disease
1) sorting to the lysosome
2) GlcNac-PT
3) golgi
4) inclusion cell disease
42
1) phosphatidylserine is normally found in which leaflet of the PM?
2) translocation to the other leaflet is indicative of what?
1) internal
| 2) apoptosis
43
list 3 membrane lipids that are usually found in the outer leaflet of PM
phosphatidylcholine
sphingomyelin
glycolipids
44
list 3 membrane lipids that are usually found in the inner leaflet of PM
phosphatidylinositol
phosphatidylserine
phosphatidylethanolamine
45
explain Rh factor and hemolytic disease of the newborn
also called D antigen
1st newborn in Rh positive, mother is Rh negative, 2nd fetus, if Rh negative will be attacked by mother's antibodies that were generated from first pregnancy
treated at 28 weeks pregant with anti-RhD immunoglobulin
46
what are the class of enzymes called that are capable of translocating lipids from one leaflet of PM to the other
flippases
47
1) special type of hemolytic anemia characterized by elevated levels of cholesterol in the RBC membrane, resulting in lysis as they pass capillaries of spleen
2) With what other pathology is this special hemolytic anemia associated?
1) spur cell anemia
| 2) associated with alcoholic cirrhosis
48
describe the mechanism behind spur cell anemia
build up of cholesterol in the membranes of RBCs, causes lysis of the RBCs as they pass through spleen capillaries
49
describe how a cell would alter the composition of its PM in response to changes in temperature
cold - add cholesterol or unsaturated fatty acids
text doesn't specifically say cholesterol just FYI but i think we've always heard up until now that cholesterol is the main player in membrane fluidity changes
50
hartnup disease is the result of what
defect in transporter (kidney and intestines) for nonpolar or neutral amino acids eg TRYPTOPHAN
presents as failure to thrive, nystagmus, intermittent ataxia, tremor, photosensitivity
51
defect in the transportation of tryptophan, resulting in failure to thrive, nystagmus, intermittent ataxia, tremor, photosensitivity is called
hartnup disease
52
1) cystinuria is caused by
| 2) what are the symptoms of cystinuria
1) defect in the transport system responsible for the uptake of dimeric amino acid cystine and dibasic amino acids ARG, LYS and ornithine. (RoCK)
2) formation of cystine crystals or stones in the kidneys which can be identified via positive positive nitroprusside test
53
inability to properly transport dimeric cystine and dibasic amino acids, arg, lys and ornithine is the result of what disease
cystinuria
54
oubain and digoxin operate how?
inhinbition of Na+/K+ ATPase on cardiace myocyte PM
| leads to increase of cellular NA+ and Ca++; increased Ca++ in sarcoplasm leads to stronger contractions
55
defects in the CFTR gene results in what?
bulildup of Cl- inside the airway of epithelial cells and in the sweat. Na+ flows into airway cells and water follows. results in thicker mucus, leaves airway prone to bacterial infection (cystic fibrosis)
56
explain how cystic fibrosis can occur due to an abberant transporter protein
Chloride channel is messed up leading to accumulation of chloride inside the cells of airways and in the sweat. leads to thick mucus and a propensity to develop bacterial infections
57
the coat protein that is responsible for getting vesicles to move between stacks of golgi apparatus
COP I
58
coat protein that is responsible for getting vesicles to move from rough ER to the golgi
COP II
59
1) vesicles are coated by the protein clathrin
clathrin is seen in what pathways?
2) no matter what process is happening clathrin is always located in the same cellular compartment. which compartment is clathrin found in?
1) exocytosis/secretory as well as endocytosis
| 2) cytoplasm
60
what is the name of the protein that is responsible for pinching off clathrin coated vesicles
dynamin-1
61
what is the name of the protein that mediates interaction between receptor protein and clathrin coating protein
adaptin
62
true or false, all proteins in the lysosome are due to be degraded?
false, some proteins in the lysosome are actually hydrolytic enzymes that are RESPONSIBLE for carrying out the degradation
63
lysosomes maintain their acidic environment via what structure?
H+ ATPase
64
what distinguishes a secondary lysosome from a primary lysosome
digestive enzymes are present in a secondary
secondary are heterogeneous
secondary lysosome has active enzymes
65
what distinguishes a secondary lysosome from a primary lysosome
digestive enzymes are present in a secondary
secondary are heterogeneous
secondary lysosome has active enzymes
66
what is the underlying pathology present in familial hypercholesteremia?
mechanism of cholesterol uptake is disrupted. elevation of LDL due to abberant LDL receptor
leads to atherosclerotic plaques
67
what is the function of peroxisomes
synthesis and degradation of hydrogen peroxide
Beta oxidation of long chain fatty acids
bile acid/cholesterol synthesis
detoxify alcohol
68
zellweger spectrum disorders are characterized by what
defects in the assembly of the peroxisome
| no treatment, usually die by one year of age
69
mitochondria are more or less dynamic in high energy cells?
less dynamic, much more fixed
70
identify the amino acids that are strictly ketogenic
lysine
| leucine
71
glucogenic amino acids are defined this way because they break down into what?
pyruvate or TCA cycle intermediates
72
ketogenic amino acids are named this way because they break down into what?
acetyl CoA or acetoacetate
73
identify the amino acids that break down into pyruvate
tryptophan --> alanine--> pyruvate
threonine-->glycine-->serine --> pyruvate
cystine --> pyruvate
74
identify the amino acids that break down into oxaloacetate
asparagine
| aspartate
75
identify the amino acids that break down into fumarate
phenylalanine
| tyrosine
76
identify the amino acids that break down into succinyl CoA
Isoleucine
valine
methionine
threonine
77
identify the amino acids that break down into alpha-ketoglutarate
Glutamine
histidine
arginine
proline
78
1) all transamination reactions occur via a specific ________ enzyme
2) these enzymes all require ______ as a coenzyme
1) transaminase
| 2) PLP
79
1) aminotransferases are normally located in what cellular areas? in what organs?
increase in levels of these enzymes is indicative of diesease. 2) increase in levels of what enzyme is indicative liver disease?
3) increase in levels of what enzyme is indicative of MI?
1) mitochondria/cytoplasm of liver, kidney, intestine and muscle
2) ALT
3) AST
80
1) what is the function of glutaminase?
| 2) where would you not expect to find high glutaminase activity?
1) glutamine to glutamate via the loss of ammonium ion
| 2) brain
81
what is the function of glutamine synthetase?
conversion of glutamate to glutamine by addition of an ammonium ion
82
1) homocystinuria can occur as a result of dysfunction or lack of 2 different enzymes or their cofactors. name those two enzymes and their cofactors
1) homocysteine methytransferase/cobalamin(B12)
| cystathionine Beta-synthase/PLP(B6)
83
a patient shows elevated homocysteine levels
| what enzyme must be affected or what cofactor must be absent?
cystathionine Beta synthase/PLP (B6)
AND/OR
homocysteine methyltransferase/cobalamin/B12
84
a patient comes to clinic with piss that smells like burnt maple syrup. he must have a jacked up enzyme. what can you expect to find in his urine?
branched chain amino acids and their derivatives
85
phenylketonuria is due to a deficiency in what enzyme
phenylalanine hydroxylase
86
PKU is a disease that involves the inability to convert what amino acid to what product
phenylalanine to tyrosine
87
name the common derivatives of tryptophan
serotonin-->melatonin
| niacin-->NADP
88
name the common derivatives of serine
acetylcholine
89
name the common derivatives of tyrosine
dopamine --> norepinephrine --> epinephrine
thyroid hormones
melanin
90
name the common derivatives of glutamate
GABA
91
1) describe tyrosine and it relates to the thyroid and Graves disease
2) how can we treat Graves patients
1) thyroglobulin is a protein that is produced by the thyroid that has many tyrosine residues. these tyrosine residues can be iodinated to form monoiodotyrosine or diidotyrosine. these can be combined to form T3 (more potent but less persistant) or T4
2) patients with GRAVES are treated with drugs such as carbimazole and propythiouracil which block the iodination of thryoglobulin
92
identify the enzyme responsible for iodinating thyrglobulin
thyroperoxidase
93
ammonia is removed from the muscle in the form of what amino acid?
alanine
94
the enzyme involved in the rate limiting step of the urea cycle is called what
cabamoyl phosphate synthetase
95
high protein diets increase urea production
| about 20-30% of this urea has a fate other than excretion. what is that fate?
gut bacteria absorb, hydrolyze by bacterial UREASE, salvage and resuse is possible
96
name the 3 amino acids used in the generation of purine and pyrimidine biosynthesis
aspartate
glutamine
glycine
97
the primary function of the pentose phosphate pathway is to produce what
NADPH
98
list the functions of nucleotides
components of cofactors (CoA, FAD, FMN, UDP-Glc, NADPH, NADH)
regulatory roles (cAMP, cGMP)
stabilizing roles
part of important biomolecules (B12)
99
list the purines in order of least oxidized to most oxidized
adenine
guanine and hypoxanthine
xanthine
uric acid
100
what is the function of ribonucleotide rieductase
conversion of a ribonucleic acid to a deoxyribonucleic acid
101
describe the function of mycophenolic acid
immunosuppressant
oxidation of IMP to XMP by IMP DEHYDROGENASE gets blocked, causing a shortage of dGTP in B and T cells. useful in graft vs. host
102
describe Lesch-Nyhan syndrome
defect in HGPRT enzyme in the purine salvage pathway
Guanine undergoes degradation into urea, furthermore, the PRPP that could've been used to salvage that nucleotide is instead used for de novo synthesis, leading to more guanine that can be degraded. leads to hyperuricosuria and hyperuricemia.
the activation of glutamine:PRPP amidotransferase by excess PRPP is the underlying cause of elevated purines
103
what is acyclovir and how does it carry out its intended medical function
looks like guanine but isn't guanine. viral THYMIDINE KINASE has higher affinity for the acyclovir than does the human thymidine kinase. because of this viral thymidine kinase will incorporate the acyclovir into the viral DNA and the lack of 3' hydroxyl group leads to termination of replication
104
what is the enzyme of interest in the acyclovir situation
thymidine kinase
105
the pyrimidine ring is synthesized from what two substrates
carbamoyl phosphate
| aspartate
106
what enzyme is affected in orotic aciduria
ump synthase
107
mycophenolic acid works by inhibiting what enzyme
IMP dehydrogenase
108
explain the
1) intended function of methotrexate and
2) how it carries out that intended function
anti-neoplastic drug
inhibitor of DNA synthesis
binds DIHYDROFOLATE REDUCTASE (DHR) 100 times more tightly
DHR normally converts dietary folate to bioactive form THF in the liver. by blocking this action the THF supply is limited, limiting DNA replication in rapidly dividing cancer cells
109
explain sulfa drugs and
1) their intended function as well as
2) how they achieve that intended function
competitive inhibitors of the bacterial enzyme that incorporates PABA into folate
because humans acquire folate from their diet, the drug affects bacteria preferentially
110
describe the result of excess adenosine deaminase (ADA)
hemolytic anemia due to the insufficient levels of Adenine in RBCs
111
describe the result of insufficient adenosine deaminase (ADA) production
SCID (severe combined immunodeficiency)
due to the the inability of B and T cells to properly degrade Adenine, there is a build up. this build up negatively regulates (inhibits) Purine production and therefore inhibits DNA synthesis in the affected B and T cells. BUBBLE BOYS
112
describe the mechanism of action of Allopurinol
allopurinol inhibits xanthine oxidase
xanthine oxidase is involved in 2 consecutive steps in the creation of uric acid. by blocking xanthine oxidase we can treat gout
113
uric acid is normally soluble at a plasma concentration of how many mg/dL
7 mg/dL
114
gout occurs when plasma concentrations of uric acid exceeds what levels
9 mg/dL
115
which pyrimidines degrade into ketogenic products due to the action of uridine phosphorylase?
Uracil and cytosine (malonyl CoA)
116
which pyrimidines degrade into glucogenic products due to the action of uridine phosphorylase?
thymine (methylmalonyl CoA/succinyl CoA)
117
5-fluorouracil inhibits what enzyme
thmidylate synthase
118
jacked up APRT leads to what
renal lithiasis
119
HGPRT at > 8% normal HGPRT levels leads to what syndrome
Kelley Seegmiller syndrome
120
what is the primary enzyme of importance in pyrimidine nucleotide salvage
thmidine kinase
121
explain the role of cortisol in fasting states
cortisol is important in the catabolism of proteins. serves as a priming agent
without cortisol, death from hypoglycemia occurs
122
explain lactic acidosis
lactic acidosis occurs when the body is not producing energy from the TCA cycle. instead we are using pyruvate via the lactic acid cycle and ultimately we are producing too much lactic acid. usually occurs due to hypoxia but can also occur due to a dysfunctional pyruvate dehydrogenase
123
the only fuel that can cross the blood brain barrier is
glucose
124
explain glucokinase and how it functions as a glucose sensor
glucokinase genes regulated by insulin in liver
constitutive in pancreas
p. 121
125
type 1 diabetes results from
loss of pancreatic B cells
126
type 2 diabetes results from
insensitivity to insulin
127
RBCs can undergo hemolytic anemia due to inadequate expression of which glycolytic enzymes
explain the reason for the hemolysis
phosphoglucose isomerase, triosphosphate isomerase, pyruvate kinase,
no energy to supply Na+ pumps, leads to accumulation of water in cells and blowing up
128
the cofactor at the E1 site of pyruvate dehydrogenase is waht
B1 (TPP)
129
mutations in liver glycogen phosphorylase lead to what
GSD VI (hers)
130
mutations in muscle glycogen phosphorylase lead to what
GSD V (McArdle)
131
1) liver glycogen phosphorylase is inhibited by what?
| 2) what metabolite does not activate liver glycogen phosphorylase that does activate muscle glycogen phosphorylase
1) free glucose
| 2) AMP
132
a genetic disorder where the patient does not produce any glycogen synthase
GSD 0
133
a genetic disorder (autosomal recessive) where the patient has a deficiency in 4:6 transferase activity or production
usually exhibit hepatosplenomegally and death by 5 years of age
GSD IV (Andersen's)
134
1) explain the role of calcium in glycogen breakdown
| 2) list drugs that affect this proces
1) muscle glycogen phosphorylase is very sensitive to activation by Ca++. calcium is released due to membrane depolarization as well as epinephrine action and inositol triphosphate signaling.
2) Dantrolene counteracts malignant hyperthermia induced by general anesthesia in genetically susceptible patients. in these patients reabsorption of Ca++ requires a ton of energy and leads to hyperthermia
135
palmitic acid, a 16 carbon, saturated fatty acid, when completely oxidized, can yield a maximum of how many ATP?
129 ATP
136
which amino acids are both ketogenic and glucogenic
```
PITTT or WIFTY if you prefer to use the one letter codes
Phenylalanine
Isoleucine
Threonine
Tyrosine
Tryptophan
```
137
Acetyl CoA sits at the junction of anabolic and catabolic pathways. explain why high levels of Acetyl CoA generated from the breakdown of fatty acid synthesis cannot be utilized in the TCA cycle?
oxaloacetate is committed to gluconeogenesis
138
pyruvate dehydrogenase is active in what state? (phosphorylated or dephosphorylated?)
dephosphorylated
139
explain how calcium can upregulate PDH function/activation in cardiomyocytes
calcium binds to and activates PDP, which dephosphorylates PDH, activating it
140
explain how insulin may activate PDH in adipose tissue
PDP is a Mg dependent enzyme
in adipose tissue, insulin lowers Km of PDP for Mg, activating it at lower Mg conentrations. remember PDP activates pyruvate dehydrogenase
141
1) explain why pyruvate dehydrogenase deficiency leads to neonatal lactic acidosis.
2) how can we treat these kiddos
1) Without effective PDH, infants cannot properly convert pyruvate to acetyl CoA. Without Acetyl CoA, these little tykes must obtain energy strictly from conversion of pyruvate to lactate. what a bummer.
2) supplementation of vitamin B1, Lipoic acid and biotin
and/or a ketogenic diet
142
explain how arsenite affects the TCA cycle
| where is arsenite found?
lipoic acid subunit (E2) of PDH is modified by arsenite. arsenite limits the availability of the lipoic enzyme by binding the S-H groups irreversibly. so PDH cannot function properly, neither can several TCA cycle enzymes, such as alpha ketoglutarate dehydrogenase
143
1) what is beriberi
2) list common symptoms
3) how do we diagnose
4) why do alcoholics tend to show a thymine deficiency?
5) beriberi in chronic alcoholics goes by a special name, what is that special name
6) why would patients with beriberi exhibit heightened levels of pyruvate and alpha-ketoglutarate?
1) nutritional deficiency condition in which the body does not have sufficient thiamine (B1)
2) weight loss, shortness of breath, difficulty walking, confusion, speech difficulties, involuntary eye movements. dry beri beri affects
3) measure blood thiamine levels
4) alcohol inhibits the absorption of thiamine
5) wernicke-korsakoff syndromeimpaired action of PDH and alpha-ketoglutarate dehydrogenase, which require TPP (B1 derivative) as an essential cofactor
144
how does citrate promote the storage of excess energy in the form of fat
citrate is an allosteric activator of acetyl CoA carboxylase
Acetyl CoA carboxylase converts Acetyl CoA to malonyl CoA (rate-limiting first step of fatty acid synthesis)
145
how does rat poison (fluoroacetate) inhibit the TCA cycle?
forms fluoroacetyl CoA, which subsequently binds with oxaloacetate to form fluorocitrate. fluorocitrate inhibits aconitase as well as PFK. therefore, fluorocitrate causes a build up of citrate, which inhibits glycolysis and PDH
146
how does Succinyl CoA relate to heme synthesis
succinyl CoA condenses with glycine and is decarboxylated to generate delata-ALA, the first step in heme biosynthesis
147
pyruvate carboxylase deficiency occurs in a higher prevalence in the Algonkian Indian tribes. what symptoms will these natives display if afflicted with this deficiency
buildup of pyruvate, more is converted to lactate than oxaloacetate
muscle weakness and uncontrolled muscle movements
148
what classic TCA cycle disorder manifests in infants via
metabolic acidosis
severe microcephaly
mental retardation
2-Oxoglutaric aciduria
149
what classic TCA disorder is characteried by sever neurological impairment and causes death within two years of life. patients present with
encephalomyopathy
dystonia
increased urinary excretion of fumarate, succinate, alpha-ketoglutarate and citrate
fumarase deficiency
150
what recently discovered TCA cycle disorder is associated with mutation in SUCLA2 and SUCLG1
succinyl-CoA synthetase
151
what TCA cycle disorder is associated with profound hypotonia, progressive dystonia, muscular atrophy, severe sensory neural hearing impairment
mitochondrial depletion syndrome
152
1) what are ferredoxins?
| 2) what are some common ferredoxins and what are their functions?
1) small proteins that serve as carriers of electrons in mitochondrial cytochrome P-450 systems. contain sulfur and iron, allow exchange of electrons between ferredoxins.
2) adrenodoxin (FDX1) - biosynthesis of steroids/metabolism of vitamin D and bile acids
(FDX2) - biosynthesis of heme-a
153
1) explain the role of ubiquinone radical in OxPhos
1) ubiquinone radical is an intermediate in teh transffer of electrons from complex I to ubiquinone as well as the transfer from reduced ubiquinone to complex III
154
1) how does cytochrome C relate to apoptosis
1) cytochrome C normally functions as a mobile carrier of electrons between complexes III and IV of mitochondrial electron transport chain. apoptosis can be initiated by causing cytochrome C to be released from the mitochondrial membrane, initiating a cascade of biochemical events and the murder of the cell via Caspases
155
explain what rotenone is and how it affects humans
NADH dehydrogenase inhibitor (complex I)
inhibits the transfer of electrons from complex I to ubiquinone
can be overcome by administration of menadione
chronic poisoning related to Parkinson's disease somehow
156
explain how cyanide affects the electron transport chain
blocks component of complex IV, preventing 02 reduction (TERMINAL STEP). If caught early, nitrites can prevent death by competing with cyanide for binding with complex IV
157
cyanide works by what type of inhibition of complex IV
noncompetitive inhibitor
158
carbon monoxide works by what type of inhibition of complex IV
competitive inhibitor (raises Km)
