Flashcards in Biochem. Deck (116):
histones are rich in
arginine and lysine
histones are what charge
positive because DNA is negative
what makes up histone core
H2A, H2B, HC AND H4 X2
histones are created in what cell cycle phase
what nucleotides are methylated in DNA methylation
cytosine and adenine
how do mismatch repair enzymes distinguish between old and new strands in prokaryotes?
deamination of cytosine makes?
what nucleotide has a methyl
3 amino acids required for purine synthesis
glycine, aspartate, glutamine
most important difference between purine and pyrimadine synthesis?
pyrimadine synthesis requires ATP
What enzyme is deficient in orotic aciduria?
UMP synthase - decreases conversion of orotic acid to UMP (thus orotic acid builds up --> orotic aciduria)
Lefluonamide inhibits what enzyme
carbamoyl phosphate ---> orotic acid
hydroxyurea inhibits what enzyme
UDP --> dUDP
5 FU inhibits what enzyme
dUMP to dTMP
what three drugs inhibit dihydrofolate reductase and in what organisms?
MTX --> humans
TMP --> bacteria
pyrimethamine --> protozoa
rate limiting step for pyrimadine synthesis
carbamoyl phosphate synthetase 2
what drugs inhibit IMP dehydrogenase?
ribavirin and mycophenolate
IMP --> GMP
what drug (s) inhibit PRPP amidotransferase
6 MP (azathioprine)
adenosine deaminase deficiency
buildup of ATP and dATP causes feedback inhibition of ribonucleotide reductase - slows DNA synthesis - decreased synthesis of lymphocytes - SCID
lesch nyhan syndrome inheritance
x linked recessive
lesch nyhan syndrome pathogenesis
HGPRT deficiency - no recycling of purines - everything is converted into uric acid and increased de novo purine synthesis
telomerase adds genetic material to what end of the chromosome?
3' (always start at 5')
sickle cell mutation
glutamic acid to valine
type of missense mutation that results in an amino acid that is similar in chemical structure as the original amino acid
duchenne muscular dystrophy is what type of mutation?
defective in XP?
nucleotide excision repair
important in repair of spontaneous / toxic deamination?
base excision repair
defective in HNPCC?
mutated in ataxia telangiectasia?
nonhomologous end joining
mutated in fanconi anemia
nonhomologous end joining
Where does energy for DNA/RNA synth (phosphodiesterase bonds) come from?
5' end of incoming nucleotide = triphosphate
describe how a phosphodiesterase bond is made
3'OH attacks the incoming 5' triphosphate!!!!
3 stop codons
UGA, UAG, UAA
What does alpha amantin do and where is it found?
inhibits RNA polymerase II (mRNA synth), found in amanita phalloides - death cap mushrooms
causes severe hepatotoxicity if ingested
Inhibits RNA polymerase in prokaryotes
Actinomycin D MOA
inhibits RNA polymerase in prokaryotes and eukaryotes
what is hnRNA
initially transcribed mRNA (mRNA without the processing)
what are anti-Smith antibodies and in which disease are they found?
found in SLE (highly specific!!!)
What are anti-U1 RNA antibodies associated with?
mixed connective tissue disease
hsp60 is an example of
chaperone protein - involved in facilitating/maintaining protein folding
hsp60 is expressed at high temps to prevent protein denaturing/misfolding
is Rb active when phosphorylated or dephosphorylated
examples of permanent cells (never go to G0)
2) skeletal and cardiac muscle
examples of stable (quiescent) cells
examples of labile cells
1) bone marrow
2) gut epithelium
4) hair follicles
5) germ cells
secretory cells are rich in what organelle?
What are Nissl bodies
RER in neurons (synthesize neurotransmitters)
DNA methylation where represses transcription
Rate limiting step of purine synthesis
Where is mRNA synthesized
Where is tRNA synthesized
Where is rRNA synthesized
5 functions of golgi apparatus
1) glycosylates core proteins to make proteoglycans
2) adds O-oligosaccharide to Serine and Threonine
3) adds N olgiosaccarides to Aspargine
4) adds m6P to lysosomal enzymes
5) adds sulfate to sugars and tyrosine
Coarse facial features, clouded corneas, restricted joint movements, high plasma levels of lysosomal enzymes
I cell disease - defect in N-acetylglucosaminyl-1-PHOSPHOTRANSFERASE. No phosphorylation of mannose = low M6P = no targeting of lysosomal enzymes to the lysosome
What does a signal recognition particle do
cytosolic ribonucleoprotein that traffics proteins from ribosome to RER
What happens if you have absent/deficient signal recognition particle?
buildup of proteins in the cytosol
What does a peroxisome break down
defects in the ubiquitin proteasome system have been implicated in what disease?
synthesis of what occurs in peroxisomes?
plasmalogens - phospholipid found in myelin! No peroxisomes = neurodegenerative disorder.
vimentin stains what type of cells
connective tissues - sarcoma
desmin stains what type of cells
muscle - rhabdomyosarcoma or leiomyosarcoma
cytokeratin stains what type of cells
epithelial cells (keratin) = CA
GFAP stains what type of cells
seen in glioblastoma
neurofilaments stain what type of cells
nuclear lamins stain what
nuclear envelope and dna within (implicated in progeria)
inhibits NA-K ATPase by binding to K+ site
inheritance of OI
OI is from a problem with
type I collagen
can't form the triple helix
what part of collagen synthesis requires vitamin C?
what part of collagen synthesis requires copper?
lysyl hydroxylase = cross-linking of procollagen (triple helix crosslinking)
brittle, kinky hair, growth retardation, hypotonia
menkes (copper deficiency)
difference between elastin and collagen in terms of structure?
elastin is rich in nonhydroxyylated proline, glycine, and lysine
collagen has hydroxylated proline/glycine/lysine
what gives elastin its elastic properties
southern blot detects what?
dna probe used to detect DNA
northern blot detects what?
dna probe to detect rNA
western blot detects what?
labelled antibody to identify protein sample
southwestern blot detects what?
oligonucleotide probe to detect DNA binding proteins (like transcription factors)
gene inserted randomly into a genome
gene inserted to a target place in a genome
mccune albright snydrome is a problem with what?
G protein signaling
unilateral cafe au lait spots
polyostotic fibrous dysplasia
mccune albright syndrome
example of locus heterogeneity
example of allelic heterogeneity
using hardy weinberg to calculate x-linked recessive disorders?
males = q
females = q^2
prader willi and angelmans occur because of mutations and deletions on what chromosome
defects in structural genes are often what type of inheritance?
enzyme deficiencies are what type of inheritance?
What is hypophosphatemic rickets
X linked dominant disorder where there is phosphate wasting in the PCT - resistant to vit. D. Presents like rickets
gomori trichrome stain
used to stain ragged red fibers which are part of the mitochondrial myopathies
reticulonodular pattern on xray
cf is what inheritance and found on what chromosome
AR, found on chr. 7
most common cause of death in duchenne muscular dystrophy
pathogenesis of myotonic dystrophy
CTG trinucleotide repeat in the DMPK gene - abnormal expression of myotonin protein kinase - causes myotonia, muscle wasting, cataracts, testicular atrophy, balding, arryhtmia (testicles, toupee, ticker, myoTonia)
fragile x pathogenesis
CGG trinucleotide expansion in the FMR1 gene on X chromosome
X-tra large testes, jaw, ears
low AFP, high beta-HCG, low estriol, high inhibin A
low ATP, low beta-HCG, low estriol, low/normal inhibin A
trisomy 18 (edwards)
low beta-hCG, low PAPPA, high nuchal translucency
Patau trisomy 13 (downs has high beta-HCG)
clenched hands with overlapping fingers
edwards (trisomy 18)
clift lip/palate, polydactyly, holoprosencephaly
patau (trisomy 13)
what chromosomes can undergo robertsonian translocation
13 14 15 21 22
cri du chat is due to what
microdeletion of short arm of chromosome 5 (5p)
deletion of long arm of chr. 7 that contains elastin gene
von hippel lindau chromosome number
renal cell carcinoma chromosome number
ADPKD with PKD2 defect chromosome number
cri du chat chromosome
freidreich ataxia chromosome
wilms tumor chromosome