Biochemistry Flashcards
1
Q
Histones are rich in which amino acids?
A
Lysine and arginine
2
Q
How does MMR enzyme distinguish between old and new strands?
A
DNA methylates cystosine and adenine
3
Q
Cytosine becomes uracil via?
A
deamination
4
Q
Guanine has a ?
A
ketone
5
Q
Thymine has a?
A
Methyl
6
Q
AA necessary for purine synthesis?
A
GAG; glycine; aspartate; and glutamine
7
Q
Blocks de novo purine synthesis?
A
6MP (blocks conversion of PRPP to IMP)
8
Q
IMP comes from?
A
PRPP
9
Q
Involved in pyrimidine synthesis and urea cycle?
A
Carbamoyl phophate
10
Q
Deficiency in key enzyme in urea cycle leads to?
A
Ornithine transcarbamoylase def. leads to accumulation of carbamoyl phophate–>orotic acid–>UMP
11
Q
Blocks ribonucleotide reductase
A
Hydroxyurea (blocks conversion of UDP to dUDP) i.e. blocks doexygenation step
12
Q
Inhibits Thymidylate synthase
A
5-F,U (Thymydilate synthase usually converts dUMP to dTMP)
13
Q
5- F, U MOA?
A
blocks thymidylate synthase which converts dUTP to dTMP
14
Q
Megaloblastic anemia that does not improve with B12 vitamin or folic acid, failure to thrive.
A
Orotic aciduria– inability to convert orotic acid to UMP dt defect in UMP synthase
15
Q
Defect in UMP synthase leads to?
A
Orotic aciduria– megaloblastic anemia that cannot be fixed with B12 or folic acid, failure to thrive, inc orotic acid in urine
16
Q
Hyperammonemia; orotic acid in urine– treatment?
A
OTC deficiency– treat with uridine
17
Q
Adenosine goes to blank via ADA?
A
Inosine–>hypoxanthine
18
Q
Catalyzes Hypoxanthine to IMP (Inosinic acid)
A
HGPRT +PRPP
19
Q
Patient presents with self mutiliation, aggression, hyperuricemia, gout– what else might we see on exam?
A
Choreoathetosis– patient has Lesch Nyhan Syndrome–>excess uric acid production
20
Q
Lesch Nyhan genetics?
A
Xlinked recessive
21
Q
Two amino acids encoded by only 1 codon?
A
Methionine and tryptophan
22
Q
Primase?
A
Makes RNA primer on which DNA pol III can initiate replication
23
Q
Makes RNA primer for DNA pol III to initiate replication?
A
Primase
24
Q
Proofreads with 3’ to 5’ exonuclease?
A
DNA Pol III
25
Degrades RNA primer and replaces it with DNA?
DNA Pol I-- also has 5' to 3' exonuclease activity
26
DNA Pol I
degrades RNA primer and replaces it with DNA
27
DNA ligase functio?
Catalyzes the formation of phosphodiesterase bond within a strand of double stranded DNA
28
Telomerase functin"?
Add DNA to 3' end of chromosomes to avoid loss of genetic material with every duplication
29
Defect in nucleotide excision repair leads to
Xeroderma Pigmentosum-- prevents repair of pyrimidine dimers-->squamous cell carcinoma
30
NER repairs?
bulky helix distorting lesions
31
Glycosylase that recognizes and removes damaged bases?
Base excision repair
32
HNPCC?
Mutated mismatch repair gene
33
Patient presents with dilated blood vessels and history of recurrent falls as he waks?
Ataxia telangiectasia-- defect in ATM gene; nonhomologous end joining
34
Zidovudine MOA?
AZT; blocks 3' OH group
35
Patient develops hepatic necoris after eating a mushroom-- what does toxin in mushroom block?
Alpha amanitin, found in Amanita phalloides inhibits RNA Pol II
36
Processing of RNA occurs where?
Nucleus (5 prime cap with addition of 7 methylguanosine; polyadenylation on 3' end; splicing out introns)
37
Capped, tailed, and spliced mRNA transcript is called?
mRNA
38
Where is 5' capping of RNA not seen?
Mitochondrial genes
39
Introns?
Stay in nuclues; while exons obviously exit nucleus
40
Common disease caused by alternative splicing?
Beta thalaseemia
41
Job of aminoacyl trna?
Scurtinize amino acid before and after it binds to trna-- bond is hydrolyzed if pairing is incorrect
42
Where does tetracycline bind?
30S subunit-- preventing attachment of aminoacyl-tRNA
43
Activation of protein synthesis requires?
GTP hydrolysis
44
ATP and tRNA?
needed for Activation (ATP for Activation)
45
GTP and tRNA?
Needed for initiation-- hydrolyzed
46
rRNA job?
Ribozyme-- catalyzes peptide bond formation, trasnfers growing polypeptide to amino acid in A site
47
Termination of tRNA?
Stop codon is recognized by release facotr and protein is released
48
APE sites on ribosome?
A=Incoming aminoacyl trna
P= accomadates growing peptide
E= holds empty rna as it exits
49
Job of aminoglycosides?
Bind 30S and inhibit formation of initiation complex and cuase misreading of mrna
50
Chloramphenicol?
Binds 50S and inhibits peptidyl transferase
51
Macrolides?
Prevent release of uncharged trna after it has donated its amino acid i.e. blocks translocation
52
Secretory proteins are synthesized?
RER
53
These cells are rich in RER?
Mucus secreting goblet cells of small intestine and antibody secreting plasma cells
54
RER in neurons?
Nissle bodies
55
What do free ribosomes synthesize?
cystosolic and organellar proteins
56
These cells are rich in SER?
Adrenal cortex-- duh! synthesize hormones
57
Patient presents with clouded corneas, restricted joint movements, and hight plasma lysosomal enyzymes?
I cell disease-- failure to add Mannose 6 phosphate
58
Job of peroxisome?
catabolism of very long fatty acids and amino acids
59
Pt. presents with recurrent pyogenic infections; partial albinism and peripheral neuropathy?
Chediak higashi--cannot fuse phagosome to lysosome
60
5 drugs that act on microtubules?
```
Griseofulvin (antifungal)
Paclitaxel (anti breast cancer)
Vincristine
Colchicine
Mebendazole/thiabendazole
```
61
Links peripheral 9 doublets of cilia?
dynein
62
Pt. presents with bronchiectasis; his PMI is located at the right intercostal space-- diagnosis?
Kartageners-- situs inversus; immotile sperm and recurrent sinusitis
63
First mechanism of Ouabain?
Inhibits K+-- acts like cardiac glycoside
64
Type 1 collagen makes?
Bone, skin, tendon, dentin, fascia, cornea, late wound repair
65
Type 2 collagen?
CarTWOlage; vitreous body, nucleus pulposus
66
Type 3 collagen?
Reticulin-- skin, blood vessels, uterus, fetal tissue, granulation tissue
67
Blood vessel-- type of collagen?
3
68
uterus type of collagen?
3
69
vitreous body type of collagen?
2
70
nucleus pulposus type of collagen?
2
71
Fascia-- type of collagen?
1
72
cornea type of collagen?
1
73
Synthesis, hydroxylation and glycosylation of collagen takes place in?
ER
74
Hydroxylation of collagen requires?
Vitamin C
75
Problem forming triple helix of collagen chain?
osteogenesis imperfecta
76
What happens when collagen leaves fibroblast?
Disulfide rich termiahl regions of procollagen are cleaved-->insoluble tropocollagen
77
Enzyme responsible for cross linking collagen?
Cu2+ containing lysl oxidase
78
Pt presents with multiple fractures, hearing loss, and problems with his teeth?
Type 1 collagen defect-- problems with glycosylation-- also causes blue sclera due to translucency of connective tissue over choroidal v3eins
79
Elastine is rich in?
Proline and GLYcine
80
Wrinkles of aging are due to?
Reduced collagen and elastin production
81
What is southwestern blot?
Identifies DNA binding proteins
82
Not all individuals with mutatnt genotype show the mutant phenotype?
Incomplete pentrance
83
One gene contributes to multiple phenotypic effects?
Pleiotropy
84
Tendancy of certain alleles at 2 linked loci to occur together more often than expected to occur
Linkage disequilibrium
85
Mutations in different loci can produce the same phenotype?
Locus heterogeneity (marfans, homocysteinuria, MEN2B)
86
Prsence of both normal and mutated mtDNA?
Heteroplasmy-- results in variable expression in mitochondrial inherited disease
87
Boy presents with mental retardation, hyperphagia, obesity, and hypogonadism?
Prader willi
88
Boy presents laughter, seizures, and ataxia?
Angelmans
89
Genetics of hypophophatemic rickets?
X linked dominant-- increased phosphate wasting at proximal tubule
90
These diseases often present with myopathy and CNS disease?
Mitochondreal myopathies-- RAGGED red fibers
91
Pt presents with dwafism-- this disease is associated with?
Advanced paternal age- Achondroplasia-- autosomal dominant
92
Pt presents with flank pain, hematuria, and progressive kidney failure. What chromosome is disease on? Complications?
16--- APKD-- complications include mitral valve prolapse and berry aneurysms
93
Colon becomes covered with adematous polyps after puberty? Chom?
5-- FAP -- five letters in polyp
94
Red dots on lips; recurrent epistaxis, skin discolorations and AVM?
Hereditary hermorrhagic telangiectasia
95
sphere shaped blood vessels-- defect? Histology?
In spectrin or ankrin-- cells LACK CENTRAL PALLOR
Splenectomy is curative
96
Caudate atrophy? Decreased levels of? Chrom?
Huntingtons-- decreased levels of GABA and ACh
Located on chrom 4
97
Pectus excavatum, hypermobile joints, long fingers? Defect?
Marfans-- defect in fibrillin--> cystic medial necrosis of aorta-->dissecting aneurysm; floppy mitral valve; lens subluxation
98
Lens subluxation +tall?
Marfans-- pectus excavatumj
99
Blotchy spots on skin; pigmented iris hamartomas? Chrom?
Neurofibramotosis type 1-- chromosome 17
100
Bilateral acoustic schannomas? Chrom? What else do children have?
Neurofib 2 on chrom 22; children also have juvenile cataracts
101
Hypopigmented skin, seizures, renal cysts, and rhabdomyomas?
Tuberous sclerosis-- see retinal hamartomas and increased incidence of astrocytomas-- incomplete penetrance
102
AD disease that leads to increased risk for astrocytoma?
Tuberous sclerosis
103
Bilateral renal cell carcinoma and other tumors? Chrom?
Von hippel Lindau is on chromosome 3-- results in constitutive expression of HIF and activation of angiogenic growth factor
104
X- linked recessive diseases
Be Wise, Fool's GOLD Heeds Silly HOpe:
Brutons, Wiskott, Fabrys, G6PD, Ocular albinism, Lesch, Duchenees ( and bekers), Hunters Syndrome, Hemphilia, Orthinine transcarbamoylase
105
Duchennes is a blank mutation?
Frameshift-->deletion of dystrophin; may have cardiac myopathy
106
Trinucleotide repeat inMyotonic dystrophy and Friedreichs?
Myotonic=CTG
| Friedreichs=GAA
107
Predisposition to mitral valve prolapse? 3
PCKD; Fragile X; Marfans
108
Predisposition to Berry aneurysms? 3
PCKD; Ehlers Danlos; marfans
109
Prominent epicanthal folds, simian crease, duodenal atresia, gap between 1st two toes-- associated with waht type of heart defect?
Down syndrome-- ostium primum type ASD
110
Quad screen tests that are increased in Down syndrome?
Inhibin a and Beta hcg
111
Micrognathia, mental retardation, low set ears clenched hands-- chromosome?
Edwards
112
Microphthalmia, cleft lip, holo prosencephaly (failure to develop into two hemispheres)
Pataus syndrome on chromosome 13-- Puberty at 13
113
What is robertson translocation?
When long arms of 2 acrocentric chromosomes (chrom with centromeres near their ends) fuse at the centromere and the 2 short arms are lost
114
Cri du chat syndrome-- chromosome?
VSD-- short arm of chromosome 5
115
Extreme friendliness with strangers? chromosome?
Williams syndrome-- long arm of chromosome 7
116
polyneuritis, symmetrical muscle wasting; vitamin defi
b1-- dry berberi
117
Baby born with cleft palate; mom says she used acne cream
Vit Aexcess
118
Vitamin deficiency causing adrenal insuffiency
B5
119
HbC
glutamate to lysine
120
accumulated ceramide trihexoside
Fabry-- peripheral neuropathy, angiokeratoma
121
idruonate sulfatase
hunters -- no alpha no corneal clouding
122
RLS of urea cycle
carbamoyl phosphate synthetase I
123
increases insulin does what to camp
Decreases camp-->dec protein kinase A-->dec FBP, Inc PFK2, more glycolysis
124
Neurologic defects in infancy; lactic acidosis
pyruvate dehydrogenase-- can't make acetyl coa
125
Blocks complex 1, 3,4,5 in etc
Rotenone 1
antimycin 3
CO,cyanide=4
Oligomycin=5-- atp synthase inhibitor
126
Infantile cataracts; galactose in urine; cannot develop social smile
galactokinase deficiency
127
jaundice, hepatomegaly, infantile cataracts--
Classic galactosemia-- excluse galactose and LACTOSE
128
Hyperammonemia depletes?
excess NH4+ which depletes alpha ketoglutarate leading to inhibition of TCA cycle
129
Glycine
porphyrin
130
arginine-->
creatinie, urea, NO
131
tryptophan-->
niacin via B6 and
Serotonin via BH4
132
lens subluxation; retarded, osteoporosis; tall stature kyphosis; atheroscleorisis
homocystinuria-- cystathionine syntahse defiency
133
AA in urine
cystinuria- COLA-- alkanalize urine
134
tryptophan in urine?
hartnup-->pellagra because tryptophan makes niacin
135
cardiomegaly, pompes disease
lysosomal alpha 1,4, glucosidase
136
deficiency of..... in maple syrup urine disease
alpha ketoacid (b1)
137
Pt. presents with diarrhea, dermatitis, dementia; urine shows aminoa acids
Hartnups disease-- tryptophan excretion in urine and dec absorption from the gut
138
central and peripheral demyelination with ataxia, dementia
Metachromatic leukodystrophy--- arylsulfatase A deficiency and cerebroside sulftate accumulation
139
Arylsulfatase deficiency?
metachromatic leukodystrophy-- see accumulation of cerebroside sulfate
140
peripheral neuropathy, optic atrophy, globoid cell
Krabbe's disease-- galactocerebrosidase
141
apo b48
mediates chylomicron secretion
142
b100
binds ldl receptor
143
CII
lipoprotein lipase
144
glucose 6 phosphatase is found in the
ER
