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Biochem Flashcards

1
Q

AAs in histones

A

Lysine and arginine, positively charged to hold DNA

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2
Q

Histone Structure

A

H2A, H2B, H3, H4 (2ea) form the histone - 10nm fiber
Recall the 10nm fiber is vulnerable to endonucleases
H1s condense to 30nm

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3
Q

Name the purines

A

A, G

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4
Q

Name the pyrimidines

A

C,U,T

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5
Q

Lesch-Nyhan Syndrome

A

Defective purine salvage due to absent HGPRT
Build up of uric acid
XLR
Intellectual Disability, self-mutilation, aggression, hyperurecemia, gout, dystonia

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6
Q

HGPRT Function

A

Converts hypoxanthine to IMP, Guanine to GMP

Purine Salvage pathway

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7
Q

Defect of nucleotide excision repair

A

Xeroderma pigmentosum

no repair of pyrimidine dimers due to UV light

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8
Q

Defect of DNA mismatch repair

A

HNPCC - Chr5

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9
Q

Defect in phosphotranferase -> failure of Golgi to phosphorylate mannose residues

A

I-cell disease
Proteins are secreted rather than targeted to the lysosome
Course facial features, clouded corneas, restricted joint movement, high plasma lysosomal enzymes
Fatal in childhood

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10
Q

ADPKD

A

Bilateral, massive enlargement of the kidneys due to multiple large cysts
AD
85% mutation in PKD1 - Chr16
15% mutation in PKD2 - Chr4

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11
Q

Familial Adenomatous Polyposis

A

Colon has 1000’s of polyps -> 100% progression to colon cancer unless resected
AD
Chr5

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12
Q

Familial Hypercholesterolemia

A

Elevated LDL b/c absent LDL receptors -> severe atherosclerosis in early life, tendonous xanthomas
AD

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13
Q

Hereditary spherocytosis

A

Spheroid RBCs due to absent ankyrin or spectrin -> hemolytic anemia
AD
Treatment: splenectomy

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14
Q

Marfan Syndrome

A

Fibrillin-1 mutation -> connective tissue disorder
tall w/ long extremities, hypermobile joints, cystic medial necrosis of the aorta, dissections, floppy valves, lens subluxations
AD

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15
Q

NF1

A

Chr17
cafe-au-lait, cutaneous neurofibromas
AD, variable expression

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16
Q

NF2

A

Chr22
bilateral acoustic schwannomas, juvenile cataracts, meningiomas, ependymomas
AD, variable expression

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17
Q

von Hippel-Lindau

A

Multiple tumors, benign and malignant
VHL gene on Chr3
AD

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18
Q

Fragile X Syndrome

A

Defect in methylation and expression of FMR1 gene due to CGG repeats on X
2nd most common cause of genetic intellectual disability
enlarged testes, long face w/ large jaw, large ears, autism,
mitral valve prolapse

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19
Q

Trisomy 21

A

Down Syndrome
Flat facies, epicanthal folds, single palmar crease, gap between toes, duodenal atresia, Hirschsprung’s, ostium primum ASDs, ALL, Alzhiemer’s
Most cases due to meiotic non-disjunctions

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20
Q

Trisomy 18

A

Edwards Syndrome

severe intellectual disability, rocker bottom feet, low set ears, clenched hands

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21
Q

Trisomy 13

A

Patau Syndrome

severe intellectual disability, rocker bottom feet, cleft lip/palate, polydactyly

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22
Q

Biochemical action of Glucagon

A

Phosphorylate Stuff!!! through PKA on Ser, Thr

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23
Q

Biochemical action of Insulin

A

Dephosphorylate stuff!!! TK receptors

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24
Q

TLCFN

A 
Cofactors required by PDH and alpha-ketoglutarateDH
Thiamine (B1)
Lipoic Acid
CoA (pantothenate/B5)
Flavin (Riboflavin/B2)
NAD (Niacin, B3)
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25
Inputs to TCA Cycle
1 Acetyl CoA 3 NAD+ 1 FAD+ 1 GDP
26
Outputs of TCA Cycle
2 CO2 3 NADH 1 FADH2 1 GTP
27
Citrate Function, outside of TCA
used in FA synthesis, inhibits glycolysis
28
Succinyl-CoA Sources
VOMIT Valine, Oddchain FA, Met, Iso, Thr Requires B12 In excess energy states (high ATP), goes to heme synthesis
29
Required cofactor of transaminases?
B6 / pyridoxine
30
Malate shuttle
Used to get NADH into the mitochondria for ETC | Get 2.5-3 ATP per NADH (3 H+ pumps)
31
G3P shuttle
Used to get NADH into ETC via FADH2 (1.5-2 ATPs, uses 2 H+ pumps)
32
Rotenone
Blocks Complex 1 of ETC Decreases proton gradient and ATP synthesis Barbiturates also block Complex 1
33
Antimycin A
Inhibits Complex III of ETC | blocks ATP synthesis
34
Cyanine, CO
Block Complex IV of ETC Decreased ATP synthesis House fires, 'almond breath' for cyanide
35
Oligomycin
Inhibits ATP synthase, F0 subunit (channel) | No ATP production
36
Name some ETC uncoupling agents and explain the mechanism
2,4 DNP, high dose aspirin, thermogenin (in brown fat) | leaky membrane causes decreased H+ gradient and increased metabolism -> heat, increased O2 usage
37
Sources of pyruvate for gluconeogenesis
Alanine via ALT [B6] all aa's except leucine and lysine can eventually make pyruvate Lactate via LDH (uses NAD+, produces NADH) DHAP can come from FA and make glucose also
38
Name the enzymes unique to gluconeogenesis
Pyruvate carboxylase: in mito, pyr -> OAA PEP carboxylase: in cyto, OAA -> PEP (induced by cortisol, leading to hyperglycemia in Cushing's) F1,6bisphosphatase: cyto, inhibited by F2,6BP, F16BP->F6P G6phosphatase: cyto, G6P -> glucose, only in the liver
39
Aldolase B Deficiency
Fructose intolerance, AR accumulation of F6P, causing a decrease in available phosphate -> inhibition of glycogenolysis and gluconeogenesis hypoglycemia, jaundice, cirrhosis, vomiting after ingestion of juice, fruit, honey... 'reducing sugar in the urine'- non-specific Tx; avoid fructose and sucrose in the diet
40
Galactokinase Deficiency
Relatively mild, AR Build up of Galactitol (via aldose reductase) -> infantile cataracts, failure to track, failure to develop social smile, galactose in blood and urine
41
Galactose-1-phosphate uridyltransferase deficiency
Classic Galactosemia, AR accumulation of back-products (Galactitol) causes damage FtT, jaundine, hepatomegaly, infantile cataracts, intellecetual disability associated with Ecoli sepsis in neonates
42
Glucose-6-Phosphatase deficiency
Von Gierke's, AR severe fasting hypoglycemia, excess glycogen in liver (megaly), lactic acidosis Normal glycogen Tx: frequent oral glucose/cornstarch
43
Lysosomal alpha1,4-glucosidase (acid maltase) deficiency
Pompe Disease, AR cardiomyopathy and systemic findings lead to early death normal glycogen Tx: ERT
44
Debranching enzyme (alpha16glusidase) deficiency
Cori Disease, AR Mild hypoglycemia, nml blood lactate short (1 residue) branches in glycogen
45
Skeletal muscle glycogen phosphorylase deficiency
McArdle Disease, AR increased glycogen in muscle, but can't break it down painful muscle cramps, myoglobinuria
46
What are the essential FAs?
Linoleic (w6) and Linolenic (3) acids | Linoleic is the precursor to arachidonic acid (w6)
47
ApoE
Mediates remnant uptake by the liver | donated to VLDL, chylomicron by HDL
48
ApoA1
Activates LCAT, allows HDL to pick up peripheral cholesterol
49
ApoCII
Activates lipoprotein lipase | donated to VLDL, chylomicron from HDL
50
ApoB48
In chylomicrons from the gut
51
ApoB100
Binds LDL receptors
52
Chylomicrons
ApoB48. Gets E and CII from HDL; E allows uptake by the liver and CII activates LPL for TGs drop-off. Delivers dietary TGs to peripheral tissues, then (as a chylo remnant) delivers cholesterol to the liver
53
VLDL
ApoB100. Gets E and CII from HDL; E allows uptake by the liver and CII activates LPL for TGs drop-off. Delivers hepatic TGs to peripheral tissues.
54
IDL
Formed from degradation of VLDL (by LPL). Can deliver TGs and cholesterol to the liver or progress to LDL.
55
LDL
Delivers hepatic cholesterol to peripheral tissues. Formed from IDL via hepatic lipase (HL). ApoB100.
56
HDL
Picks up peripheral cholesterol (in vessels) and returns to the liver. Donates CII and E to chylo's and VLDL.
57
Effects of increased liver cholesterol
downregulates LDL receptors leading to increased LDL in the blood Statins work by decreasing denovo synthesis of liver cholesterol, thus increasing the number of LDL receptors and clearing LDL from the blood
58
Fatty Streak Formation Basics
LDL + O2 (oxidized) -> cholesterol deposits in the vessels enhanced by O2 and turbulence: arteries > veins also enhanced by gravity: AA at the iliac bifurcation
59
Smith-Lemli-Optiz Syndrome (SLO)
Mutation in DHCR7 (last step in cholesterol synthesis) decreased cholesterol for development -> FtT, int. disability, decreased steroid hormones, problems with myelination, problems with SSH processing Tx: high dietary cholesterol and HMG-CoA reductase inhibitors
60
Type I Familial Dyslipidemia - Hyperchylomicronemia
AR LPL or CII deficiency -> increased chylo's, TGs in the blood; saturated excretion via bile leads to gallstones and recurrent pancreatitis; xanthomas
61
Type II Familial Dyslipidemia - Famial Hypercholesterolemia
AD absent or defective LDL receptors | accelerated atherosclerosis, tendon xanthomas, corneal arcus
62
Abetalipoproteinemia
no ApoB100 or ApoB48 cant absorb dietary fat: DKEA deficiencies (poor night vision, acanthocytes), steatorhea, no lineoleic acid -> no arachodonic acid products markedly decreased TGs and cholesterol
63
Name the amino acids which are strictly ketogenic
leucine and lysine
64
Name the amino acids which can be glucogenic or ketogenic
Tyr, Trp, Phe, Ile, Thr
65
Symptoms of hyperammonemia?
asterixis tremor, CNS/ mental status changes, blurred vision
66
Increased orotic acid in the urine, decreased BUN, hyperammonemia
Ornithine transcarbamylase deficiency ornithine + carbamoyl phosphate -> citrulline in the urea cycle buildup of carbamoyl phasphate leads to increased orotic acid
67
Derivatives of Phenylalanine
Tyrosine --> Thyroxine Tyrosine -> dopa -> melanin and dopamine dopamine -> NE and epi
68
Derivatives of Tryptophan
Niacin -> NAD/NADP | Serotonin -> Melatonin
69
Peripheral burning neuropathy, angiokeratomas, CV/renal disease
Fabry's; XLR | deficient in alpha-galactosidase A, build up of ceramide trihexoside
70
Bone marrow issues causing fractures and pancytopenia, hepatosplenomegaly
Gaucher Disease, AR Deficient in glucocerebrosidase (beta-glucosidase) Build up of Glucocerebroside
71
Neurodegeneration, cherry red spot on the macula, with hepatosplenomegaly
Niemann-Pick Disease, AR Deficient in Sphingomylinase Build up of sphingomyelin
72
Neurodegeneration, developmental delay, cherry red spot on the macula without hepatosplenomegaly
Tay-Sachs, AR in Ashkenazi Jews Deficient in Hexosaminidase A Build up of GM2 ganglioside
73
Peripheral neuropathy with optic atrophy and globoid cells
Krabbe Disease, AR deficiency of galactocerebrosidase build up of galactocerebroside, psychosine
74
central and peripheral demylination with ataxia and dementia
Metachromatic leukodystrophy, AR Deficiency of arylsulfatase A build up of cerebroside sulfate
75
developmental delay, gargoylism, airway obstruction, corneal clouding and hepatosplenomegaly
Hurler syndrome deficiency of alpha-L-iduronidase build up of heparan sulfate and dermatan sulfate
76
mild Hurler symptoms with aggressive behavior, no clouding
Hunter syndrome 'hunters need to see' deficiency of iduronate sulfatase build up of heparan sulfate and dermatan sulfate
77
alpha-galactosidase A deficiency
Fabry's; ceramide trihexoside
78
glucocerebrosidase (beta-glucosidase) deficiency
Gaucher's Disease; glucerebroside
79
sphingomyelinase deficiency
Niemann-Pick; sphingomyelin
80
hexosaminidase A deficiency
Tay-Sachs; GM2 ganglioside
81
galactocerebrosidase deficiency
Krabbe; galactocerebroside, psychosine
82
arylsulfatase A deficiency
Metachromatic leukodystrophy; cerebroside sulfate
83
alpha-L-iduronidase deficiency
Hurler; heparan sulfate, dermatan sulfate
84
iduronate sulfatase deficiency
Hunter; heparan sulfate, dermatan sulfate

Step Nuggets (23 decks)

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