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General...stuff that doesn't go elsewhere
Terms in this set (131)
What is the difference between CPS (carbamoyl phosphate synthetase) I and CPS II?
CPS I - mitochondria, part of urea cycle, nitrogen source is ammonia; CPS II - cytosol, part of pyrimidine synthesis, nitrogen source is glutamine
What is the rate-limiting step in purine synthesis?
glutamine PRPP amidotransferase
What is the rate-limiting step in pyrimidine synthesis?
What are the sources of carbons for purine synthesis?
CO2, tetrahydrofolate, glycine
What are the sources of carbons for pyrimidine synthesis?
CO2 (carbamoyl phosphate), aspartate
What accounts for the positive charge of histones?
What accounts for the negative charge of DNA?
What medication inhibits ribonucleotide reductase?
What medication inhibits dihydrofolate reductase?
What medication inhibits thymidylate synthase?
What medication inhibits inositine monophosphate dehydrogenase?
What medication inhibits PRPP synthetase?
What are the characteristic features of orotic aciduria?
Increased orotic acid in the urine, no hyperammonemia, failure to thrive, megaloblastic anemia (does not improve with B12 or folate)
How does UV light damage DNA?
Creates thymine dimers on the same strand of DNA
Which DNA polymerase replicates the lagging strand and synthesizes the RNA primer?
Which DNA polymerase repairs DNA?
Which DNA polymerase replicates mitochondrial DNA?
Which DNA polymerase replicates leading strand DNA?
What are the motifs of transcription factors?
Helix-loop-helix, helix-turn-helix, zing finger, leucine zipper
What are the two requirements for a functional lac operon?
1. no glucose (CAP is only present in the absence of glucose) 2. lactose (lac repressor leaves in the presence of lactose)
What are the 3 different mechanisms cells can employ to break down proteins?
Ubiquitin, lysosomes, Ca dependent enzyme
What enzyme catalyzes peptide bond formation during protein synthesis?
What enzyme matches amino acids to tRNA?
What are the mRNA stop codons?
UGA, UAA, UAG
What are the different RNA polymerases in eukaryotes?
I - rRNA, II - mRNA, III - tRNA
What is the mRNA start codon?
How is hnRNA processed before it leaves the nucleus?
5' CAP, polyA tail, splicing out of introns
What is the characteristic sequence of the promoter region?
TATA and CAAT
What enzyme is deficient in Lesch-Nyhan syndrome?
HGPRT; treat w/ allopurinol
What drugs act on microtubules?
Vincristine/vinblastine, paclitaxel, colchicine, -bendazoles, griseofulvin
What are the two most abundant substances in plasma membranes?
How are molecules transported into the nucleus?
Nuclear transport signals (made up of lysine, arginine, or proline); activates an ATPase that recognizes the signal and allows it into the nucleus
What histologic features are seen in apoptosis?
Cell and nuclear shrinkage, basophilia, membrane blebbing, apoptotic bodies
Relieve supercoils during replication; inhibited by fluoroquinolones, etoposide, and anti-Scl70 (diffuse scleroderma)
DNA polymerase III
Prokaryotic; elongates leading and lagging strands; 3'->5' exonuclease activity
DNA polymerase I
Prokaryotic; degrades RNA primer and fills in the gap with DNA
What tumor suppressors inhibit G1->S progression?
Rb and p53
RER in neurons; synthesize enzymes and peptide neurotransmitters
Smooth endoplasmic reticulum (SER)
Site of steroid synthesis and detoxification of drugs and poisons; abundant in liver hepatocytes and steroid hormone-producing cells
1. distribution center 2. modifies N-oligosaccharides on asparagine 3. adds O-oligosaccharides to serine and threonine 4. addition of mannose-6-phosphate to specific lysosomal proteins -> targets protein to lysosome 5. proteoglycan assembly 6. sulfation of sugars
Type I collagen
Bone, skin, tendon, dentin, fascia, cornea, late wound repair ("strong")
Type II collagen
Cartilage, vitreous body, nucleus pulposus ("slippery")
Type III collagen
Skin, blood vessels, uterus, fetal tissue, granulation tissue ("bloody")
Type IV collagen
Hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome)
AD; inherited disorder of blood vessels
telangiectasia, recurrent epistaxis, skin discolorations, AV malformations
AR; trinucleotide repeat expansion (GAA)
progressive ataxia (degeneration of posterior spinocerebellar tract)
HCM in 50%
kyphosis, pes cavus, hammertoes
Labs in Down syndrome
decreased α-FP, estriol
increased β-hCG, inhibin A
US: increased nuchal translucency
Drinking age (21) - Down's
Election age (18) - Edward's
Puberty age (13) - Patau's
congenital microdeletion of short arm of chromosome 5
microcephaly, mental retardation, high-pitched crying/mewing, epicanthal folds
Think Will Ferrell in Elf
-long arm of chromosome 7
-extreme friendliness with strangers
22q11 deletion syndromes
Metabolism rxns that take place in mitochondria and cytosol
Heme synthesis, urea cycle, gluconeogenesis (HUG)
uses ATP to add high-energy phosphate
adds inorganic phosphate without ATP
removes phosphate group
adds 1 carbon with the help of biotin
How is NADPH generated?
What is NADPH used in?
1. anabolic processes (steroid and fatty acid synthesis)
2. respiratory burst
4. glutathione reductase (protects RBCs from oxidative damage)
Hexokinase and glucokinase
phosphorylation of glucose for glycolysis or glycogen synthesis (liver)
stimulated by insulin
high Km of glucokinase - only active when there is abundance of glucose
Net outcome of glycolysis
What inhibits PFK-1?
ATP and citrate
What is the most common deficiency in glycolysis?
-hemolytic anemia, due to inability to maintain Na/K ATPase -> RBC swelling and lysis
What stimulates PFK-1?
5 cofactors for pyruvate DH and α-KG DH
Tender Loving Care For Noone
1. Thiamin (pyrophosphate)
2. Lipoic acid
3. CoA (B5)
4. FAD (B2, riboflavin)
5. NAD (B3, niacin)
What inhibits lipoic acid?
-vomiting, rice water stools, garlic breath
Pyruvate DH deficiency
back up of substrates
in alcoholics, due to B1 deficiency
tx: leucine and lysine in diet - ketogenic amino acids
1. alanine - carries aa groups to liver from muscle
2. OAA - replenish TCA cycle or gluconeogenesis
3. acetyl-CoA - TCA cycle
4. lactate - end of anaerobic glycolysis
Products of TCA cycle
= 12 ATP/acety-CoA = 24 ATP/glucose
TCA cycle intermediates
"Can I keep selling sex for money, officer?"
How does NADH enter mitochondria for ECT?
How many ATP do NADH and FADH2 produce?
NADH = 3 ATP
FADH2 = 2 ATP
Uncoupling agents of ECT
increase permeability of membrane
ATP synthesis stops, heat production
2,4-DNP, aspirin, thermogenin in brown fat
Key steps in gluconeogenesis
1. Pyruvate -> OAA via pyruvate carboxylase
2. OAA -> PEP via PEP carboxykinase
3. F-1,6-BP -> F-6-P via F-1,6-BPase (rate-limiting*)
4. G-6-P -> glucose via G-6-Pase
Why can't muscles undergo gluconeogenesis?
Purpose of HMP shunt
provide a source of NADPH from abundantly available glucose-6-phosphate
occurs in the cytoplasm, no ATP used
sites: lactating mammary gland, liver, adrenal cortex, RBC
Rxns of HMP shunt
1. glucose-6-P -> CO2, 2 NADPH, ribulose-5-P (via G6PDH*)
2. ribulose-5-P -> ribose-5-P (nucleotides), G3P and F6P (glycolysis) via transketolase (requires B1)
activation of membrane-bound NADPH oxidase (in neutrophils and macs) for immune response
rapid release of reactive oxygen intermediates
chronic granulomatous disease
deficiency in NADPH oxidase
increased risk of infection by catalase+ species (s. aureus, aspergillus)
NADPH necessary to keep glutathione reduced to detoxify free radicals
poor RBC defense against oxidizing agents (fava beans, sulfonamides, primaquine, anti-TB drugs) and infection -> hemolytic anemia
XLR, most common human enzyme deficiency
increased malarial resistance
Heinz bodies - oxidized hemoglobin
Bite cells - phagocytic removal of Heinz bodies by macs
defect in fructokinase
AR, benign and asymptomatic since fructose doesn't enter cells
fructose appears in blood and urine
defect in aldolase B
Fructose-1-P accumulates, causing a decrease in available phosphate and inhibition of gluconeogenesis and glycogenolysis
sx: hypoglycemia, jaundice, cirrhosis, vomiting
tx: decrease intake of fructose and sucrose
deficiency of galactokinase
relatively mild, AR
sx: galactose in blood and urine, infantile cataracts
may present as failure to track objects or develop a social smile
absence of galactose-1-phosphate uridyltransferase
accumulation of toxic substances
sx: failure to thrive, jaundice, hepatomegaly, infantile cataracts, mental retardation
tx: excluse galactose and lactose from diet
alternative method of trapping glucose in cell
1. glucose -> sorbitol via aldose reductase
2. sorbitol -> fructose via sorbitol DH (liver, ovaries, seminal vesicles)
tissues lacking sorbitol DH are at risk for osmotic damage from sorbitol accumulation (cataracts, retinopathy, peripheral neuropathy)
PVT TIM HALL
Arg, Lys, His
-Arg is most basic
-His neutral at body pH
-Arg and His required during periods of growth
-Arg and Lys increased in histones (bind negatively charged DNA)
amino acid catabolism
nitrogen (NH4+) converted to urea
alanine and glutamine are major carriers of nitrogen from tissues
catalyzed by aminotransferases (require pyridoxal phosphate - B6)
-ALT and AST
excess NH4+, which depletes α-ketoglutarate -> inhibits TCA cycle
limit protein in diet
acquired (liver dz) or hereditary (urea cycle enzyme deficiency)
tremor, slurring of speech, somnolence, vomiting, cerebral edema, blurring of vision
excess carbamoyl phosphate converted to orotic acid
orotic acid in blood and urine, decreased BUN, symptoms of hyperammonemia
sugary syrup used to treat liver dz
MOA: bacteria break up sugar, causing acidic pH -> ammonium trapped in gut
Phenylalanine -> ?
tyrosine -> dopa -> dopamine -> NE -> epi
Tryptophan -> ?
niacin (requires B6)
Histidine -> ?
histamine (requires B6)
Glycine -> ?
porphyrin (requires B6) -> heme
Arginine -> ?
glutamate -> ?
GABA (requires B6)
decrease in phenylalanine hydroxylase or THB (cofactor)
tyrosine becomes essential
sx: mental retardation, growth retardation, seizures, fair skin, eczema, musty body odor
deficiency of homogentisic acid oxidase in the degradative pathway of tyrosine -> fumarate
sx: dark connective tissue, brown pigmented sclera, urine turns black on standing, arthralgias
1. tyrosinase (inability to synthesize melanin from tyrosine)
2. defective tyrosine transporters
increased risk of skin cancer
lack of migration of neural crest cells
deficiency of cystathionine synthase or decreased affinity of cystathionine synthase for B6 or homocysteine methyltransferase deficiency
excess homocysteine - cysteine becomes essential
sx: mental retardation, osteoporosis, tall stature, kyphosis, lens subluxation, atherosclerosis
defect of renal tubular amino acid transporter for cysteine, ornithine, lysine, and arginine (COLA) in the PCT
can lead to the precipitation of cystine kidney stones
tx: acetazolamide (alkalinize urine)
maple syrup urine disease
blocked degradation of branched aa (Ile, Leu, Val) due to decreased α-ketoacid dehydrogenase
sx: CNS defects, mental retardation, death
"I Love Vermont maple syrup"
defective aa transporter in renal and intestinal epithelial cells
tryptophan excretion in urine and decreased absorption from gut
leads to pellagra
What types of bonds to glycogen branches have?
What types of bonds to glycogen linkages have?
rate-limiting in the formation of glycogen
makes α(1,6) linkages
rate-limiting in the degradation of glycogen
breaks α(1,6) linkages (α-1,6-glucosidase)
glycogen degradation in lysosomes
small amount degraded in lysosomes by α-1,4-glucosidase
Fatty acid synthesis
via citrate shuttle
transports acetyl-CoA from mito to cytoplasm
Fatty acid degradation
via carnitine shuttle
transports acyl-CoA from cytoplasm to mito
toxic accumulation in cytosol
weakness, hypotonia, hypoketotic hypoglycemia
acyl-CoA dehydrogenase deficiency
increased dicarboxylic acid, decreased glucose and ketones
acetoacetate, β-hydroxybutyrate, acetone
in prolonged starvation and DKA, OAA is depleted for gluconeogenesis
in alcoholism, excess NADH shunts OAA to malate
*both stall TCA cycle and lead to production of ketones
made from HMG-CoA
breath smells like acetone (fruity odor)
urine test for ketones does not detect β-hydroxybutyrate
Metabolic fuel use for days 1-3 of starvation
adipose release of FFA
Metabolic fuel use for after day 3 of starvation
*amount of adipose stores determines survival time
lecithin-cholesterol acyltransferase (LCAT)
degradation of dietary TG in small intestine
lipoprotein lipase (LPL)
degradation of TG circulating in chylomicrons and VLDLs
hepatic TG lipase (HL)
degradation of TG remaining in IDL
degradation of TG stored in adipocytes
choesterol ester transfer protein (CETP)
mediates transfer of cholesterol esters to other lipoprotein particles
Type I - hyperchylomicronemia
increased chylomicrons -> increased TG and cholesterol
LPL deficiency or altered apolipoprotein C-II
sx: pancreatitis, HSM, xanthomas
Type IIa - familial hypercholesterolemia
increased LDL -> increased cholesterol
AD, absent or decreased LDL receptors
sx: atherosclerosis, tendon xanthomas, corneal arcus
Type IV - hypertriglyceridemia
increased VLDL -> increased TG
hepatic overproduction of VLDL
hereditary inability to synthesize lipoproteins due to deficiencies in apoB-100 and apoB-48
accumulation within enterocytes due to inability to export absorbed lipid as chylomicrons
findings: failure to thrive, steatorrhea, acanthocytosis, ataxia, night blindness
treat w/vitamin E
1. CAP is only present in the absence of glucose
2. lac repressor (bound to operator) gone in the presence of lactose
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