Biochem Flashcards
Signal transduction of alpha1 receptors
IP3 –> Ca2
Signal transduction of Beta receptors
cAMP –> Protein kinase A
Signal transduction of M1 and M3 recptors
IP3 –> Ca2 + protein kinase C
Signal transduction of M2 receptors
cAMP
Signal transduction of nicotinic receptors
Voltage gated Na Ca and K channel
Cytokines that induce systemic inflammatory response
IL 1, IL 6, and TNFa
DNA Pol I
Works on the lagging strand, synthesizes 5’ to 3’ and is an exonuclease at 5’ to 3’
Degrades RNA primers
DNA Pol III
Works on both lagging and leading strand. Synthesizes 5’ to 3’ but is an exonuclease at 3’ to 5’
Xeroderma pigmentosum
deficient endonuclease for thiamine dimer repair due to UV radiation
Base excision repair process
Alteration to a single nucleotide usually by carcinogen
Glycolsylase removes altered base
Lyase and endonuclease repair 3’ and 5’ ends
DNA pol adds in new base
Ligase completes the chain
Mismatch repair
MutS and MutL recruit Endonuclease to the mismatch which removes the surrounding DNA
DNA pol replaces the sugars and ligase completes the process
Defective in lynch syndrome
Homologous end joining
Sister chromosome used as template
Associated with Fanconi anemia and gynecological malignancy
Nonhomologous end joining
Many proteins required, no sister chromosome template
increased risk of errors
associated with ataxia telangiectasia
Amatoxins inhibit
RNA pol II
Amino acids bind this portion of tRNA
3’ acceptor stem sequence CCA
D arm of tRNA
binds aminoacyl tRNA synthetase which adds amino acids to tRNA
T arm of tRNA
binds the ribosome
Mutations in introns are commonly associated with
B thal
E2F
Promotes G1 to S phase transition
Rb protein
Binds E2F and prevents transition to S phase. When phosphorylated by Cyclin-CDK complex it will release E2F. Mutation can result in retinoblastoma or osteosarcoma.
Cyclin-CDK complex
Phosphorylates Rb, releasing E2F and allowing progression to S phase. This action is blocked by p21.
Mutations in Cyclin D1 result in Mantle Cell Lymphoma
p21
Prevents Cyclin-CDK from phosphorylating Rb. This action is promoted by p53.
p53
Further activates p21’s inhibition of Cyclin-CDK
mutations in p53 are associated with Li-Fraumeni syndrome. DNA damage UP REGULATES p53 to prevent cancer.
I cell disease
Defect in N-acetylglucoasminyl-1-phosphotranferase
Proteins become secreted instead of transported to lysosomes
Presentation: Failure to thrive Coarse facial features Cognitive impairment Corneal clouding
Clathrin
associated with transport between the cell membrane and golgi
COP1
transport from golgi to RER
COP2
transport from RER to golgi
Zellweger syndrome
Dysfunction in peroxisome activity, increased very long chain fatty acids
X-linked adrenoleukodystrophy
Impaired transport of very long chain fatty acids to peroxisome
Accumulation in brain (cognitive impairment) and adrenal glands (adrenal insufficiency)
Desmin
Intermediate filament associated with rhabdomyosarcoma
Vimentin
intermediate filament associated with sarcomas
GFAP
intermediate filament associated with astrocytomas
Neurofilaments
intermediate filaments associated with neuroblastomas.
Scurvy mechanism
VitC is required for the hydroxylation of pro alpha chains of collagen
Osteogenesis imperfecta mechanism
Faulty assembly of 3 collagen pro alpha chains into procollagen
Osteogenesis imperfecta
Autosomal Dominant
COL1A1/COL1A2 gene mutations
Multiple fx, blue sclera, hearing loss, abnormal teeth
Ehlers-Danlos mechanism
Deficiency of procollagen peptidase or lysyl oxidase
Decreased cross linking of collagen
Menkes Dz
Decreased Cu absorption which is a cofactor of lysyl oxidase resulting in decreased cross linked collagen
- Brittle hair
- Hypotonia
- Growth Restriction
Marfan mechanism
Fibrillin 1 is a scaffold protein for elastin
Hexokinase
Converts glucose to G6P
Present in most tissue, not Beta cells or liver
Not induced by insulin
Low Km, Low Vmax
Glucokinase
Converts glucose to G6P Found in B cells and liver Induced by insulin High Vmax High Km
Phosphofructokinase-2
Converts F6P to F2,6BP
Upregulated by insulin
Phosphofuctokinase-1
Converts F6P to F1,6BP
Upregulated by F26BP
Downregulated by Citrate and ATP
Fructose 2,6 Bisphosphatase
Converts F26BP to F6P
Upregulated by Glucagon
Fructose 1,6 Bisphosphatase
Converts F16BP to F6P
Inhibited by F26BP
BPG mutase
converts 13BPG to 23BPG
takes place in RBCs when O2 levels are low
23BPG decreases Hb affinity for oxygen
2,3 BPG phosphatase
Converts 23BPG to 3 phosphoglycerate
After recovery from low oxygen state, returns 23BPG to glycolysis
Pyruvate Kinase
Converts phosphoenolpyruvate to pyruvate
Produces ATP
Deficiency results in hemolysis
4 Molecules pyruvate can be converted into
Alanine
Oxaloacetate
Acetyl-CoA
Lactate
Lactate dehydrogenase
Converts pyruvate into Lactate
Requires NADH, Niacin
Pyruvate Dehydrogenase
Converts Pyruvate to Acetyl Coa
Inhibited by NADH and AcetylCoa
Requires NAD, Thiamine (B1), Riboflavin (b2), Niacin(B3), and Pantothenic acid (B5)
Pyruvate carboxylase
converts pyruvate to oxaloacetate
Requires Biotin
promoted by AcetylCoA
Citrate synthase
converts Acetyl CoA and Oxaloacetate to Citrate
Inhibited by ATP
Isocitrate dehydrogenase
Converts Isocitrate and NAD to a-Ketogluterate, NADH, and CO2. Requires Niacin (B3)
a-Ketoglutarate dehydrogenase
Converts a-ketoglutarate and NAD to Sucinyl-CoA, NADH, and CO2
Activated by Ca2+ in skeletal muscle
Requires B1, B2, B3, and B5
Cytochrome C oxidase
Complex 4 of the ETC
Fe goes between 2+ and 3+ states making it a target for CN- (3+) and CO (2+) poisoning.
PEPCK
Converts oxaloacetate to Phosphoenolpyruvate
requires GTP
used in Gluconeogenesis
Von Gierke disease
Deficiency of Glucose 6 phosphatase
Hypoglycemia and hepatomegaly and lactic acidosis
Gierke breaks Gluconeogenesis
a-1,4 glucosidase
Converts glycogen into glucose within lysosmes
Deficient in Pompei Dz
Pompe Disease
Deficient a-1,4 glucosidase Build up of glycogen within lysosomes Cardiomegaly, hepatomegaly, and hypotonia Normal blood sugars "PomPe breaks the PumP" 4 Ps = 1.4
Glycogen Phosphorylase
Cleaves alpha-1,4 links in glycogen
Deficient in McArdles Dz
Activated by Ca2+, AMP, and cAMP
McArdle Disease
Deficient glycogen phosphorylase in skeletal muscle
Muscle cramps, weakness, rhabdomyoslysis
Liver unaffected
“McArdle breaks the Muscle”
a-1,6-glucosidase
Breaks the branches of glycogen
deficiency causes Cori Dz
Cori Disease
Deficient a-1,6-glucosidase
Accumulation of glycogen causes hepatomegaly, hypotonia, and hypoglycemia.
Compensation by fat metabolism causes ketoacidosis
Cori breaks the Corner
Fructokinase
Converts fructose to F1P
Deficient in Essential fructosuria
Essential Fructosuria
Deficiency of fructokinase
relatively benign as Fructose can be converted to F6P by hexokinase
Detected by copper reduction test
Aldolase B
Converts F1P to dihydroxyacetone phosphate and glyceraldehyde
Deficient in Fructose intolerance
Fructose intolerance
Deficient Aldolase B
Accumulation of F1P within cells
Hypoglycemia, hepatomegaly, and liver failure
detected with copper reduction test
Polyol Pathway
Conversion of glucose into sorbitol into fructose
Increase in hyperglycemia
soribitol can be damaging to the eyes causing cataracts.
Lactase
Converts lactose to glucose and galactose
deficient in lactose intolerance
Galactokinase
Converts galactose to G1P
Deficiency causes accumulation of galactitol which can cause infantile cataracts
Galactose-1-phosphate uridyltransferase
Convers Galac-1-P to Glucose 1 P
Deficiency causes classic galactosemia.
classic galactosemia
Deficient Gal1P uridyltransferase
Accumulation of Galac1P causes liver damage, cataracts, and hypoglycemia.
These patients are also at an increased risk of e coli sepsis due to preference of galactose
G6P dehydrogenase
Converts G6P to 6 phosphogluconate
Part of the PPP
Creates NADPH
Deficiency causes hemolysis
NADPH
Created in PPP
Used in FA, steroid, and cholesterol synthesis
Used in production in glutathione for oxidative damage reduction
Used in oxidative burst
Transketolase
PPP
Converts Fructose 6 phosphate to ribose 5 phosphate
Preserves PPP in those with G6PD deficiency
Carnitine shuttle
Combination of Carnitine and Acyl CoA during fatty acid metabolism allows the Acyl CoA to enter the mitochondria
Acyl-CoA Dehydrogenase
Converts Acyl CoA eventually into Acetyl-CoA
Creats FADH2 and NADH
Deficient in Medium chanin acyl-CoA dehydrogenase deficiency (MCAD)
Systemic primary carnitine deficiency
Low carnitine, impairing carnitine shuttle
Hypoglycemia (Acetyl CoA not made, cannot promote gluconeogenesis)
Hypokentonia due to lack of B oxidation
Accumulation of long chain fatty acids in liver and brain
Medium chain acyl CoA dehydrogenase Deficiency
Impaired beta oxidation
Hypoketotic, hypoglycemia
Liver damage, encephalopathy
Carnitine levels are normal.
Ethanol metabolism (NADH) effects
Metabolism of etoh causes an accumulation of NADH
This causes an inhibition of the TCA cycle
AcetylCoA from EtOh is shunted to ketone bodies
High NADH also promotes pyruvates conversion to lactate
High NADH also inhibits the breakdown of fatty acids, causing fatty liver.
Vitamin D metabolism step 1
7 dehydrocholesterol is converted to Vitamin D3 (Cholecalciferol) by UV light
Vitamin D metabolism step 2
Cholecalciferol (Light or diet) is converted to 25 Hydroxvyvitamind D by 25 hydroxylase in the liver
VitD metabolism step 3
25 hydroxyvitamind D is converted to 1,25 dihydroxyvitamin D by 1 alpha hydroxylase in the kidney
This process is regulated by PTH
Effects of 1,25 dihydroxyvitamin D
Increases bone mineralization, increases calcium absorption in SI, increases calcium and phosphate reabsorption in kidneys, decreases PTH secretion
ApoB48
Only found on chylomicrons, allows entering of enterocytes
ApoC-II
Transfered to chylomicron by HDL
Cofactor for LPL
ApoE
Transfered to chylomicron by HDL
Facilitates binding to the hepatic remnant receptors
Found on HDL, chylomicros, HDL, VLDL, IDL
Lipoprotein lipase
Frees fatty acids from Chylomicros and VLDL converting them into Chylomicron remnants and IDLs
ApoB100
Allows VLDL to exit the liver and LDL to re enter the liver
Fibrates, Niacin, Fish oil
all block excretion of VLDL by the liver
Hepatic lipase
Converts IDL to LDL, freeing fatty acids and removing ApoE
Abetalipoproteinemia
Lack of ApoB100 and ApoB48
Inability to secrete VLDL and chylomicrons
Steatorrhea, fat soluble vitamin deficiency, acanthocytosis
Acanthocytosis
lack of lipids in RBC membrane, making them appear spiny
Famililial hyperchylomicronemia (type I)
Deficiency ApoC-II
Increased Chylomicrons and VLDL
Labs: TGs
PCSK9 inhibitors
Decrease LDL receptor degradation on the liver, allowing for increased LDL reabsorption
evolocumab
Lecithin choldesterol acyl transferase
Allows HDL to absorb cholesterol
Cholesterol ester transfer protein
Allows transfer of cholesterol from HDL to VLDL and LDL
Familial hypercholesterolemia (Type II)
ApoB 100 Defect or LDL receptor defect
LDL cannot re enter the liver
Labs: LDL
Familial dysbetalipoproteinemia (Type III)
Defect in ApoE3 and ApoE4
Chylomicrons, VLDL, IDL cannot enter the liver
Labs: Tgs, VLDL, IDL
Familial hypertriglyceridemia (Type IV)
Overproduction of VLDL
Labs: TG
Cystathionine synthase
Converts homocysteine to cystathionine
reqiuires B6
Deficient in homocysteinuria
Homocysinuria
Usually due to a deficiency in cystathionine synthase
elevated homocysteine in the urine
Cysteine becomes an essential AA
ID, hypercoag, ectopia lentis, and marfanoid habitus
B6 can improve symptoms
Methionine synthase
Converts homocysteine to methionine.
Requires 5-methyl THF
Requires B12
Indirectly requires folate for turnover of THF
Deficiency can be an alternative cause of homocystinuria
Uses of Methionine
Can be made into SAM for methylation reactions
Can be converted to propionyl Coa –> MMA –> Succinyl CoA (requires folate)
PRPP amidotransferase
Used in purine synthesis to create IMP which can become AMP or GMP
UMP Synthase
Converts PRPP and orotic acid to UMP for pyrimadine synthesis
Deficient in Orotic aciduria
Orotic Aciduria
Deficient UMP synthase
Megaloblastic anemia
No hyperammonemia
Tx: Uridine
Thymidylate Synthase
Converts dUMP to dTMP
Requires 5,10-methylene THF
Indirectly requires folate
Inhibited by 5FU
Dihydrofolate Reductase
Converts DHF to THF
requires folate
Inhibited by methotrexate, Primethamine, and TMP
HGPRT
Converts Hypoxanthine/Guanine and PRPP to IMP or GMP
Deficiency causes lesch-nyhan syndrome
Adenosine daminase
Converts adenosine to Inosine
Deficiency causes SCID (adenosine metabolites are toxic to T cells)
Lesch-Nyhan Syndrome
Deficient HGPRT
Gout, Self mutilation, and ID
Carbamoyl phosphate synthase I
Combines NH3 CO2 and ATP to form Carbamoyl Phosphate
Orinithine transcarbamylase
Converts carbamoyl phosphate and ornithine to citrulline
Ornithine transcarbamylase deficiency
Decreased urea cycle activity
Hyperammonemia
Increased Orotic acid
NH3 effects on the nervous system
Glutamine is converted to glutamate in presynaptic neurons.
Glutamate is used as an excitatory neurotransmitter
Once released, glutamate is eventually reabsorbed by a nearby astrocyte and combined with NH3 from the bllod to be converted back to Glutamine. This is then returned to the presynpatic neuron.
In situations with increased NH3 in the blood, increased amounts of glutamine are created in astrocytes. This acts as an osmotic agent, drawing water into the astrocyte. When the astrocyte is swollen it is no longer able to transfer its glutamine to the presynaptic neuron.
Connexins
Gap junctions
Claudins, occludin
Tight junction
Cadherins
Adherens junction
desmogleins, desmoplakins
Desmosomes
Integrins
Hemidesmosomes
Maple syrup urine disease
Deficiency in branched chain a ketocaid dehydrogenase complex
Defective metabolism of isoleucine leucine and valine
Cannot produce proprionyl CoA
B1 B2 B3 B5
accumulation of alpha keto acids
ID, seizures, irritability
Thiamine can improve symptoms
Phenylalanine hydroxylase
COnverts phenylalanine to tyrosine
Requires BH4
Deficiency of this is one cause of PKU
Dihyrobiopterin reductase
Converts BH2 to BH4
Deficiency of this is one cause of PKU
PKU
Defiency of Phenylalanine hydroxylase or Dihydrobiopterin reductase
Results in deficiency of neurotransmitters (dopamine, epi, NE)
Tyrosine becomes essential
Tyrosinase
Converts DOPA to melanin
Deficiency causes albinism
Homogentisic acid dioxygenase
Converts homogentisate to maleylacetoacetate
Deficient in Alkaptonuria
Alkaptonuria
Homogentisic acid dioxygenase deficiency
Homogentisic acid accumulates in the connective tissue (ears and sclera, joint pain) and in the urine. When urine is exposed to air it will turn black.
Fabry Dz
lack of a-galactosidase A
accumulation of Ceramide Trixhexoside
Palm and sole neuropathy, anhydrosis, renal and CV failure in adulthood, angiokeratomas
X linked recessive
Fa br A
Niemann Pick Dz
Deficient sphingomyelinase
accumulation of sphingomyelin
Weakness, Chery red spot, HSM, foam cells
Autosomal recessive
Tay Sachs Disease
Deficient Hexoasaminidase A Accumulation of GM2 Ganglioside Weakness cherry red spot lysosomes with onion skin autosomal recessive A GANG of six jews
Gaucher Disease
Glucocerebrosidase deficiency Accumulation of glucocerebroside Bone dz, lipid laden macrophages, pancytopenia Autosomal recessive gaUcher
Arginase Deficiency
Normally converts Arginine to ornithine and urea.
Causes spastic diplegia, abnormal movements, and growth delay. No/mild hyperammonemia.
Huntingtin protein
In Huntington dz there is a gain of function which causes increased histone deacetylation, which silences genes necessary for neuron survival
AAT
AAT is the primary inhibitor of neutrophil and macrophage elastin degradation protein
Results in panacinar empysema
Accelerated by smoking and 2nd hand smoke
Gq G protein
IP3 and DAG –> PKC
Used by H1, a1, va,M1, and M3 (HAV 1 M&M)
Gi G protein
Decreases cAMP
Used by M2, a2, D2 (MAD 2)
Gs G protein
Increases cAMP –>PKA
used by everything besides HAV1 M&M and MAD 2
cGMP
ANP BNP NO and EDRF activate guanylate cyclase creating cGMP
cGMP increased Protein Kinase G
Protein Kinase G causes vasodilation
Receptor Tyrosine Kinases
Insulin, IGF-1, EGF, PDGF, FGF
Act on RAS/MAP kinase pathway
Nonreceptor tyrosine kinases
IL-2, IL-6, prolactin, thrombopoietin, erythropoeitin, GH, GCSF
Acts on the JAK/STAT Pathway
alpha 1
Mydriasis, vasocontriction
alpha 2
Decrease NE release, decrease aqueous humor production
Beta 1
Increase heart rate, increase contractility, increase Renin
Beta 2
Vasodilation in Skeletal muscles, bronchodilation, increased aqueous humor production
M3 sympathetic
Sweating, only sympathetic M receptor
M3 parasympathetic
Miosis, lens accomodation, bronchoconstriction, increased gastric acid, increased salivation, increased parastalsis, bladder contraction
M2
Decreased HR, decreased contractility
H1
Increased mucous production, bronchoconstriction, and vasodilation
H2
Increased HCl secretion
V1
Vasoconstriction
V2
Increased aquaporins in collecting tubule –> increased H20 reabsorption
GLUT4
Transporter found in myocytes and adipose tissue
Responsive to insulin
Ornithine shuttle
Transport of proteins into mitochondria for urea cycle