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Biochem metabolism Flashcards

1
Q

ATP is carrier molecule for what

A

phosphoryl groups

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2
Q

NADH, NADPH, FADH2 is carrier molecule for what

A

electrons

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3
Q

Coenzyme A, lipoamide is carrier molecule for what

A

Acyl groups

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4
Q

Biotin is carrier molecule for what

A

CO2

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5
Q

THF is carrier molecule for what

A

1 carbon units

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6
Q

SAM is carrier molecule for what

A

CH3 groups

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7
Q

TPP is carrier molecule for what

A

aldehydes

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8
Q

What processes is NADPH used in? why?

A

anabolic processes (steroid & FA synthesis) to reduce equivalents;
Respiratory bursts;
p-450;
Glutathione reductase

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9
Q

What is NADPH a product of?

A

HMP shunt

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10
Q

what are the universal electron acceptors?

A

Nicotinamides (NAD+ from vitB3 & NADP+) & flavin nucleotides (FAD+ from vit B2);
NADPH

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11
Q

What processes is NAD+ used in?

A

Catabolic processes to carry reducing equivalents away as NADH

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12
Q

Describe the 1st step in glycolysis & 1st step of glycogen synthesis in the liver. what is the result?

A

phosphorylation of glucose to G-6-P via hexokinase or glucokinase

traps glucose inside the cell

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13
Q

Describe where, speed and what leads to use of hexokinase

A

ubiquitous w/ high affinity (low Km), low capacity (low Vmax)
UNINDUCED by insulin

inhibited by G-6-P

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14
Q

Describe where, speed and what leads to use of glucokinase

A

Liver & Beta cells of pancreas use GLUT-2 which has low affinity (high Km), high capacity (high Vmax)
INDUCED by insulin
High Vmax bc it cannot be satisfied

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15
Q

Describe how glucose is sequestered dependent on its concentration

A

At low glucose (low insulin) then hexokinase sequesters glucose into the tissue;
At high glucose, excess glucose is stored in the liver

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16
Q

Where does glycolysis occur?

A

cytoplasm

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17
Q

Since RBC’s use glycolysis only, What will occur if the MC enzyme deficiency is present?

A

Pyruvate kinase deficiency will decrease pyruvate along w/ leading to hemolytic anemia due to the cell swelling & increased bilirubin

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18
Q

Gluconeogenesis & Glycolysis are regulated by what?

A

F-2,6-BisP & PFK-2

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19
Q

The pyruvate DH complex contains 3 enzymes that require 5 cofactors - name them

A

1) pyrophosphate (B1, thiamine (TPP))
2) FAD (B2, riboflavin)
3) NAD (B3, niacin)
4) CoA (B5, pantothenate)
5) Lipoic acid

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20
Q

Other than the fed state, what else activates the pyruvate DH complex? what is the result?

A

exercise leads to
increased NAD+/NADH ratio
increased ADP
increased Ca+

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21
Q

What 2 complexes use the same cofactors w/ similar substrate & action?

A

Pyruvate DH complex to make Acetyl-CoA & alpha-KG DH complex in TCA cycle to make succinyl-CoA

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22
Q

What poison will damage the pyruvate DH & alpha-KG DH complexes? what is the result?

A

Arsenic inhibits lipoid acid leading to vomit, rice water stools, garlic breath

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23
Q

If you have a muscle Bx that reveals increased glycogen, increased F-6-P & decreased pyruvate, what is the cause?

A

deficiency in PFK-1

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24
Q

What are the enzymes responsible for increased & decreased levels of F-2,6-BP?

A

PFK-2 increases

FBP-2 decreases

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25
Q

Describe how a SANS response will change F-2,6-BP in the liver & muscle

A

Liver levels will decrease thus decreasing glycolysis

Muscle levels will increase to activate PFK-1 to increase glycolysis

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26
Q

Pyruvate DH complex deficiency will lead to a backup of what? result?

A

pyruvate & alanine resulting in lactic acidosis

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27
Q

What are most cases of Pyruvate DH complex deficiency due to? What are the findings?

A

XL gene for E1-alpha subunit of PDC causing neuro defects that typically start in infancy

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28
Q

Acquired Pyruvate DH complex deficiency can come from what?

A

Arsenic poison;

Decreased in B vitamins especially thiamine

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29
Q

What is the Tx for Pyruvate DH complex deficiency?

A

increase intake of ketogenic nutrients such as HIGH FAT content or increased lysine (dairy, fish) & leucine (eggs, soy)

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30
Q

What are the 4 products & cofactors of pyruvate metabolism?

A

Alanine via Alanine aminotransferase, B6;
Oxaloacetate via pyruvate carboxylase, biotin;
Acetyl-CoA via Pyruvate DH (B1-3,5, Lipoic acid);

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31
Q

During pyruvate metabolism, What processes occur in the cytosol? Mitochondria?

A

Alanine & lactate are produced in cytosol;

Oxaloacetate & Acetyl-CoA are produced in the mitochondria

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32
Q

Where does the TCA cycle reactions occur?

A

Mitochondria

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33
Q

ETC & oxidative phosphorylation has a main function of what?

A

put H+ into inter membrane space to use as a gradient to power ATPase

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34
Q

What drug(s) inhibits complex 1 of ETC?

A

rotenone, barbituates, amytal, MPTP (synthetic demorol) => parkinson cause

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35
Q

What drug(s) inhibits complex 3 of ETC?

A

Antimycin A

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36
Q

What drug(s) inhibits complex 4 of ETC?

A

Cyanide, CO, NH3-, H2S

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37
Q

What drug(s) inhibits complex 5 of ETC?

A

Oligomycin

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38
Q

What drug(s) inhibits CoQ of ETC

A

Doxorubicin

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39
Q

Name ETC inhibitors along w/ action

A

rotenone, CN, antimycin A, CO => Directly inh electron transport leading to decreased proton gradient & ATP synthesis block

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40
Q

Name ATP synthase (complex 5) inhibitors along w/ action

A

Oligomycin=> directly inhibits mitochondrial ATPsynthase leading to increased proton gradient => NO ATP PRODUCED bc electron transport stops

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41
Q

Describe how uncoupling agents affect the ETC

A

increase permeability of inner Mt membrane leading to decreased proton gradient & increased O2 consumption => ATP synthesis stops but electron transport continues so HEAT IS PRODUCED

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42
Q

What are uncoupling agents of ETC?

A

2,4 DNP (wood preserver);
Aspirin (overdose fever);
thermogenin (brown adipose - baby fat)

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43
Q

What are the irreversible enzymes of gluconeogenesis? name location & substrate/product

A

pyruvate CB in Mt (biotin, ATP, acetyl-CoA)= pyruvate to OAA;

PEP CB in cytosol (GTP) = oxaloacetate to phosphoenolpyruvate;

F-1,6-BPase in cytosol = F-1,6-BP to Fructose-6-P;

G-6-Pase in ER = Glucose-6-P to glucose

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44
Q

Where does gluconeogenesis occur primarily? where can it not occur?

A

occurs in liver

cannot in muscle bc it has no G-6-Pase

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45
Q

What type of FA chains can serve as glucose sources? Why?

A

Odd bc yields 1 propionyl-CoA during metabolism to enter TCA (succinyl-CoA) to undergo gluconeogenesis

Even only yield acetyl-CoA so cannot make new glucose

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46
Q

What is the purpose of the HMP shunt?

A

provide NADPH from G-6-P for reductive rxn then produces ribose for nucleotide syn & glycolytic intermediates

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47
Q

Where do the 2 phases of HMP shunt occur? what is the difference in them?

A

Oxidative is irreversible using G-6-P DH (rate limiter) & NADP+to produce CO2, NADPH, Ribulose-5-P for PRPP generation for nucleotide syn

Nonoxidative is reversible & requires Thiamine & transkelotases to produce ribose-5-P, G3P, F6P

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48
Q

What cells can use respiratory burst (oxidative burst)? What is involved?

A

Neutrophils & monocytes activate membrane bound NADPH oxidase for immune response & release of ROI

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49
Q

What are the basic roles of NADPH?

A

create AND neutralize ROIs

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50
Q

Where in the neutrophil or monocyte does respiratory burst occur?

A

Phagolysosome

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51
Q

What is the result if NADPH oxidase is deficient?

A

chronic granulomatous disease

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52
Q

How does a WBC of pt w/ chronic granulomatous disease make ROI?

A

utilize H2O2 that is generated by invading organism (bacterial catalase) & convert it to ROI

53
Q

If a patient is deficient in G6PD or NADPH oxidase, what type of infection risk is present?

A

catalase positive (S. aureus, Aspergillus) bc they neutralize own H2O2 leaving WBCs w/o ROI to fight infection

54
Q

What is the MC human enzyme deficiency? How is it inherited & who shows the most prevalence?

A

XLR of G6PD deficiency that is MC in blacks assoc w/ increased malarial resistance

55
Q

What is the result of G6PD deficiency in RBCs?

A

NADPH is decreased so cannot keep glutathione reduced therefore free rad & peroxides occur leading to damage & hemolytic anemia

56
Q

What will be seen on a blood smear in a pt w/ G6PD deficiency?

A

Heinz bodies => oxidized Hgb precipitated w/in RBCs

Bite cells result from splenic macs taking out heinz bodies thus leading to hemolytic anemia

57
Q

What can induce a person w/ G6PD deficiency leading to hemolytic anemia?

A

fava beans (mediteranean food); sulfonamides, Primaquine, anti-TB; infection

58
Q

Essential fructosuria has a defect in what and how is it inherited? What will diagnose & what Sx?

A

AR benign defect in fructokinase will lead to fructose in blood & urine
rare osmotic diarrhea

59
Q

Fructose intolerance has a defect in what and how is it inherited?

A

AR deficiency in aldolase B leading to accumulation of F1P which binds phosphate resulting in inhibition of glycogenolysis & gluconeogenesis

60
Q

Sx & Tx for fructose intolerance?

A

Sx are hypoglycemia, jaundice, cirrhosis, vomit;

Tx is to decrease intake of both fructose & sucrose (glucose+fructose)

61
Q

How does fructose bypass rate limiting step in glycolysis (PFK)?

A

aldolase B enzyme to yield glyceraldehyde & dihydroxyacetone-P

62
Q

What type of sugar is galactose?

A

monomer sugar

63
Q

Name enzyme & inheritance of galactokinase deficiency. What are the Sx of the deficiency?

A

AR deficient galactokinase leads to accumulation of galactitol if galactose is in the diet but will appear in blood & urine

may present as failure to track objects or develop social smile due to infantile cataracts

64
Q

Name enzyme & inheritance of classic galactosemia. What causes the damage?

A

AR absence of galactose-1-phosphate uridyltransferase that leads to accumulation of toxins such as GALACTITOL that accumulates in lens of eye

65
Q

Sx & Tx of classic galactosemia

A

Sx are failure to thrive, jaundice, hepatomegaly, infantile cataracts, mental retardation
Tx must exclude galactose & lactose (galactose + glucose) from diet

66
Q

What is the most serious defects in classic galactosemia?

A

PO4 depletion

67
Q

What enzyme other than G6P can trap glucose in the cell? how?

A

aldose reductase converts glucose to sorbitol (alcohol relative)

68
Q

Once sorbitol is trapped within the cell, what occurs so it can be used for energy metabolism?

A

sorbitol DH converts it to fructose

69
Q

Tissues that have insufficient amount of sorbitol DH are at risk for what?

A

osmotic damage due to accumulation leading to cataracts, retinopathy, peripheral neuropathy as in chronic hyperglycemia of diabetics

70
Q

A patient w/ galactokinase deficiency will use what enzyme to make its damaging toxic metabolite?

A

High galactose uses aldose reductase to convert to galactitol that will accumulate in the eye

71
Q

What tissues have both aldose reductase & sorbitol DH? What enzyme would have to be deficient to cause osmotic damage?

A

Liver, ovaries, seminal vesicles => sorbitol DH

72
Q

What tissues have ONLY aldose reductase?

A

Schwann cells, retina, lens, kidneys

73
Q

What type of sugar is lactose? what makes it?

A

disacaridase made of glucose & galactose

74
Q

What are the causes of lactase deficiency?

A

Age dependent loss in enzyme;
hereditary lactose intolerance (AA, asians);
gastroenteritis due to temporary loss of microvilli

75
Q

What are the Sx & Tx for lactase deficiency?

A

Sx are bloating, cramps, osmotic diarrhea

Tx is to avoid dairy products or add lactase pills to diet

76
Q

Where is lactate used?

A

energy molecule that goes to liver cytoplasm for glucose to go to skeletal muscle via the Cori cycle

77
Q

Give the essential amino acids and what they produce

A

glucogenic=> Met, Val, His
Gluco/Keto-genic => Ile, Phe, Thr, Trp
Ketogenic => leu, Lysine

78
Q

What amino acid is targeted by oral HSV?

79
Q

What are the acidic amino acids?

A

Aspartate & glutamate => negative at body pH

80
Q

What are the basic amino acids? which has no charge at body pH

A

Arginine, Lysine, Histidine

His has no charge at body pH

81
Q

Which amino acids are required during periods of growth?

A

arginine & histidine

82
Q

Which amino acids are increased in histones? why?

A

Arginine & lysine so the negative charge DNA can bind

83
Q

What is the rate limiting enzyme of urea cycle? where is it located?

A

CPS 1 located in mitochondria

84
Q

Other than CPS 1, what other enzyme is found in the mitochondria?

A

ornithine transcarbamoylase in the conversion of ornithine to citrulline

85
Q

What is the function of the urea cycle? What amino acids are necessary to carry it out?

A

Amino acids break down to pyruvate, acetyl-CoA so nitrogen must be excreted to avoid excess so converted to urea

Aspartate donates NH4 while Arginine is final step before urea is made

86
Q

What molecule is essential for communicating anaerobic metabolism?

87
Q

Amino transferases (ALT, AST) require what?

A

vitamin B6

88
Q

Hyperammonemia occurs how? what are the results?

A

acquired via liver dz or hereditary via urea cycle deficiencies => results in excess NH4 that depletes a-KG leading to inhibition of TCA cycle

89
Q

Sx of ammonia intoxication?

A

Hepatoencephalopathy

tremor (asterixis), slurred speech, somnolence, vomit, cerebral edema, blurring of vision

90
Q

Tx for hyperammonemia

A

limit protein in diet & benzoate or phenylbutyrate can be given to decrease ammonia levels;
lactulose

91
Q

How does benzoate or phenyl butyrate treat hyperammonemia?

A

both bind amino acid & lead to excretion

92
Q

How does lactulose treat hyperammonemia?

A

it is a sugar that is not absorbed so gets to colon & bacteria there have a feast thus making the colon acidic causing binding of the NH4+ for excretion

93
Q

What is the MC urea cycle disorder? How is it inherited? When does it present?

A

ornithine transcarbamoylase deficiency is XLR presenting in first few days of life but can present later

94
Q

What are the labs of OTC deficiency?

A

excess carbamoyl phosphate in mitochondria spills out & is converted to orotic acid (part of pyrimidine synthesis)

increased orotic acid in blood & urine, decreased BUN, Sx of hyperammonemia (tremor, vomit, somnolence, cerebral edema)

95
Q

Differentiate OTC deficiency vs orotic aciduria

A

OTC deficiency is NOT associated w/ megaloblastic anemia

96
Q

What are the derivates of phenylalanine?

A

(via BH4) tyrosine to make Dopa (vit B6) DA, (vit C) NE, (SAM) Epi

97
Q

derivates of tryptophan

A

(vit B6) niacin to NAD+/NADP+

(BH4) serotonin to melatonin

98
Q

derivates of histidine

A

(vit B6) histamine

99
Q

derivates of glycine

A

(via B6) porphyrin to heme

100
Q

derivates of arginine

A

creatine;
urea;
(BH4) nitric oxide

101
Q

derivates of glutamate

A

(via B6) GABA;

glutathione

102
Q

What amino acid derives melanin? How?

A

phenylalanine (BH4) to tyrosine to (BH4) Dopa which is converted to melanin

103
Q

What amino acid derives thyroxine?

A

Phenylalanine via BH4 to tyrosine to thyroxine

104
Q

derivates of methionine

105
Q

What are the respective breakdown products of catecholamines? how are they broken down?

A

MAO & COMT breaks down

DA to HVA
NE to VMA
Epi to metanephrine

106
Q

What is the etiology of PKU? What will be found in urine?

A

AR decrease in phenylalanine hydroxylase (adds OH) or decrease in BH4 (malignant PKU)

phenylketones in urine (phenylacetate, phenyllactate, phenylpyruvate)

107
Q

When does PKU typically present & earliest signs?

A

2-3 days after birth bc uses mother’s enzyme during fetal life

musty odor due to aromatic AA metabolism

108
Q

Findings of child with PKU

A 
mental & growth retardation;
seizures;
fair skin;
eczema;
musty odor
109
Q

Treatment of PKU

A

decrease Phe in diet (NO aspartame ~ nutrasweet)

Increase tyrosine (essential AA now)

Must be done w/in first 3 wks

110
Q

Maternal PKU can occur how? what are the findings in the child?

A

lack of proper diet during pregnancy

microcephaly; growth & mental retardation; congenital heart defects

111
Q

Pt notices urine turns black in the air & presents to ortho w/ debilitating joint pain. What is the disease caused by?

A

Alkaptonuria (ochronosis) =>

AR congenital deficiency of homogentisic acid oxidase in degradation of tyrosine to fumarate

112
Q

What are the findings of alkaptonuria?

A

dark connective tissue;
brown pigmented sclera;
urine turns black w/ air exposure;
May have debilitating arthralgias

113
Q

What are the debilitating arthralgias of alkaptonuria from?

A

homogentisic acid being toxic to cartilage

114
Q

What are the 2 causes of albinism?

A

congenital deficiency of:

tyrosinase (inability to synthesize melanin) => AR

Defective tyrosine transporters (decrease amounts of tyrosine & melanin)

115
Q

During embryology, what also may cause albinism?

A

lack of migration of neural crest cells

116
Q

Describe the inheritance pattern of albinism

A

variable inheritance due to locus heterogeneity

ocular albinism is XLR

117
Q

What are the 3 forms of homocystinuria? How are they inherited & what is result?

A

ALL are AR resulting in excess homocysteine & cysteine is now essential amino acid

Cystathionine synthase deficiency

Decreased affinity of cystathioinine synthase for pyridoxal phosphate

Homocysteine methyltransferase deficiency

118
Q

How is Cystathionine synthase deficiency treated?

A

decreased methionine;

increase cysteine, B12 & folate, B6 in diet

119
Q

How is Decreased affinity of cystathioinine synthase for pyridoxal phosphate treated?

A

increased a lot of vitamin B6 in diet

120
Q

How is Homocysteine methyltransferase deficiency treated?

A

requires B12 so give it

121
Q

What are the findings in homocystinuria?

A 
lots of homocysteine in urine; mental retardation;
osteoporosis & tall stature;
kyphosis;
Lens subluxation (down & in);
atherosclerosis (stroke & MI)
122
Q

What is the cause of cystinuria?

A

AR defect of renal tubular AA transporter for COLA (cysteine, ornithine, lysine, arginine) in the PCT of kidneys

123
Q

How will cystinuria present? What is the Tx?

A

excess cystine in urine leads to precipitation of hexagonal crystals & renal stag horn calculi

Tx is good hydration & urinary alkalinization

124
Q

What makes up cystine? How is a cystine stone treated?

A

2 cysteines connected by disulfide bone

if stone then Acetazolimide (diuretic) & hydrate

125
Q

Maple syrup urine disease is caused by what? what are the labs for it?

A

AR defect causing blocked degradation of branched amino acids (Ile, Leu, Val) due to decrease in alpha-ketoacid DH (B1) leading to increased alpha-ketoacids in blood (esp Leu)

126
Q

What does maple syrup urine disease cause?

A

severe CNS defects;
mental retard;
death

127
Q

I Love Vermont maple syrup from maple trees with Branches

A

maple syrup urine disease

128
Q

What causes Hartnup disease?

A

AR dz w/ defective neutral AA transporter on renal & intestinal epithelial cells

129
Q

What is the result of Hartnup disease?

A

tryptophan excreted in urine & decreased absorption from gut

leads to pellagra ( decreased B3/niacin) => diarrhea, dementia, dermatitis

FA: random (15 decks)

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