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First Aid Biochem part 1
5.22.12
261
Medical
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05/22/2012

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Term
How many times does DNA loop around histone octamers to form the nucleosome "bead"?
Definition
twice
Term
What amino acids primarily compose the octamer subunits of histone proteins?
Definition
arginine and lysine
Term
What are the nucleosome core histones?
Definition
H2A, H2B, H3 and H4
Term
Which DNA bases are methylated to allow mismatch repair enzymes to distinguish between old and new strands?
Definition
cytosine and adenine
Term
Which nucleotide basse has a ketone?
Definition
guanine
Term
What nucleotide base has a methyl?
Definition
thymine
Term
Name the amino acids necessary for purine synthesis?
Definition
glycine, aspartate and glutamine
Term
Describe the bond that links nucleosides?
Definition
3'-5' phosphodiester bonds
Term
Describe the process of de novo purine synthesis?
Definition
start with sugar + phosphate then add base
Term
Describe the process of pyrimidine syntehsis?
Definition
make temporary base (orotic acid), add sugar + phosphate (PRPP), modify base
Term
Which is synthesized first, ribonucleotides or deoxyribonucleotides?
Definition
ribonucleotides (converted to deoxyribonucleotides by ribonucleotide reductase)
Term
What two metabolic pathways is carbamoyl pohsphate involved in?
Definition
de novo pyrimidine synthesis and the urea cycle
Term
ornithine transcarbamylase deficiency leads to an accumulation of what?
Definition
carbamoyl phosphate which is then converted into orotic acid
Term
What drug inhibits ribonucleotide reductase?
Definition
hydroxyurea
Term
What is the MOA of 6-mercaptopurine?
Definition
blocks de novo purine synthesis
Term
What is the MOA of 5-flourouracil?
Definition
inhibits thymidylate synthase (decrease dTMP)
Term
What is the deficiency of orotic aciduria?
Definition
inability to convert orotic acid to UMP due to defect in either orotic acid phosphoribosyltransferase or orotidine 5'phosphate decarboxylase
Term
What are the findings associated with orotic acidemia?
Definition
increased orotic acid in urine, megaloblastic anemia that does not improve with administration of folate or B12, failure to thrive
Term
How do you differentiate between orotic aciduria and OTC deficiency with labs?
Definition
both will have increased orotic acid; OTC deficiency will also have hyperammonemia
Term
How do you treat orotic aciduria?
Definition
oral uridine administration
Term
How does adenosine deaminsae deficiency cause SCID?
Definition
excess ATP dATP imbalances nucleotide pool via feedback inhibition of ribonucleotide reductase which prevents DNA synthesis and thus decreases lymphocyte count
Term
What was the first disease to be treated by experimental human gene therapy?
Definition
SCID
Term
What is teh deficiency in Lesch-Nyhan syndrome?
Definition
hypoxanthine guanine phosphoribosyltransferase (HGPRT) deficiency
Term
How is Lesch Nyhan inherited?
Definition
x linked recessive
Term
What are the symptoms of Lesh Nyhan?
Definition
retardation, self-mutilation, aggression, hyperuricemia, gout, choreoathetosis
Term
What does it mean to say the genetic code is unambiguous?
Definition
each codone specifies only 1 amino acid
Term
What does it mean to say the genetic code is degenerate or redundant?
Definition
more than 1 codon may code for the same amino acid
Term
What does it mean to say the genetic code is "commaless" or "nonoverlapping"?
Definition
read from a fixed starting point as a continuous sequence of bases
Term
Name an exception to the rule that the sequence of bases in mRNA is "nonoverlaapping"
Definition
viruses
Term
Which amino acids are only coded for by 1 codon?
Definition
methionine (AUG), and tryptophan (UCG)
Term
What does it mean to say the genetic code is "universal"?
Definition
conserved throughout evolution
Term
What type of mutation results in an early stop codon?
Definition
nonsense
Term
What is a missense mutation?
Definition
changed aa (convservative-new aa is similar in chemical structure
Term
Where does eukaryotic replication begin?
Definition
consensus sequence of base pairs
Term
What is the replication fork?
Definition
Y shaped region along DNA template where leading and lagging strands are syntehsized
Term
What prevents the ssDNA from reannealing after helicase has broken the hydrogen bonds?
Definition
single-stranded binding proteins
Term
What is the MOA of flouroquinolones?
Definition
inhibit DNA gyrase (prokaryotic topoisomerase II)
Term
What is primase?
Definition
makes an RNA primer on which DNA polymerase III can initiate a replication
Term
T/F DNA polymerase III is found in eukarotes.
Definition
false; prokaryotic only
Term
What is the function of DNA polymerase III?
Definition
elongates leading strand by adding deoxynucleotides to the 3' end; elongates lagging strand until it reaches primer of preceding fragment; 3' to 5' exonuclease activity profreads each added nucleotide
Term
What is the function of DNA polymerase 1?
Definition
prokaryotic only; degrades RNA primer and fills in the gap with DNA (DNA polymerase 1 excises RNA primer with 5' to 3' exonuclease)
Term
What is the function of telomerase?
Definition
enzyme adds DNA to the 3' ends of chromosomes to avoid loss of genetic material with every duplication
Term
What links the okazaki fragments?
Definition
DNA ligase
Term
What process can not take place in patients who have xeroderma pigmentosum?
Definition
specific endonucleases release thymidine dimers created by UV light exposure and DNA polymerase and ligase fill and reseal the gap
Term
What enzyme is used by prokaryotes to excise thymidine dimers?
Definition
photolyase
Term
What enzyme is deficient in xeroderma pigmentosa?
Definition
UV endonuclease
Term
By what process is DNA repaired if there is spontaneous/toxic deamination/
Definition
base excision repair
Term
How is base excision repair preformed?
Definition
specific glycosylases recognize and remove damaged bases; Ap endonuclease cuts DNA at apyrimidinic site; empty sugar is removed and the gap is filled and resealed
Term
What is mismatch repair?
Definition
when unmethylated, newly synthesized string is recognized, mismatched nucleitides are removed and the gap is filled and resealed
Term
Mismatch repair is mutated in what disease?
Definition
hereditary nonpolyposis colorectal cancer
Term
What is mutated in ataxia telangiectasia?
Definition
nonhomologous end joining
Term
What type of DNA repair repairs both strands of DNA?
Definition
nonhomologous end joining
Term
Where does the energy for DNA and RNA synthesis come from?
Definition
triphosphate on the 5' end of the incoming nucleotide
Term
In what direction is mRNA read?
Definition
5' to 3'
Term
In what direction are amino acid synthesized?
Definition
N to C
Term
Drugs blocking DNA replication often have a modified ____, preventing addition of the next nuclotide (chain termination).
Definition
modified 3' OH
Term
What is the most abundant type of RNA?
Definition
rRNA
Term
What is the longest type of RNA?
Definition
mRNA
Term
What is the smallest type of RNA?
Definition
tRNA
Term
What is the mRNA start codon?
Definition
AUG (or rarely GUG)
Term
What does AUG code for?
Definition
methionine in eukaryotes; formyl methionine in prokaryotes
Term
What are the stop codons?
Definition
UAG, UGA, UAA
Term
Promoter sequences are rich in what nucleotides?
Definition
A and T (TATA and CAAT)
Term
What's another name for the TATA box?
Definition
pribnow or hogness box
Term
Where are promoter sequences located?
Definition
upstream of gene locus (TATA is at -25; CAAT is at -70)
Term
What binds to teh promoter sequence?
Definition
RNA polymerase and multiople other transcription factors to initiate transcription
Term
What types of sequences that regulate gene transcipriton can be found close to, far from, or even within the gene whose expression it regulates?
Definition
silencers and enhancers
Term
What do you call the site where negative regulators (repressors) bind?
Definition
silencer
Term
What binds the enhancer?
Definition
transcription factors
Term
What is the MOA of alpha amanitin?
Definition
inhibits RNA polymerase II causing liver failure
Term
What is the name of the poison found in death cap mushrooms?
Definition
alpha amanitin
Term
Which RNA polymerase opens DNA at the promoter site?
Definition
RNA pol II
Term
Does RNA polymerase have proofreading functions?
Definition
no
Term
Describe the difference between eukaryotic and prokaryotic RNA polymerase.
Definition
there are three different types of RNA polymerase that make the different kinds of RNA in eukaryotes; prokaryotes have 1 RNA pol that makes all types of RNA
Term
The initial transcript by RNA pol II is called...
Definition
heterogenous nuclear RNA
Term
How is transcription terminated?
Definition
rho dependent (uses Rho factor, an ATPase), or rho independent (GC rich reagion forms a hairpin loop and bumps off RNA pol at a weak AT rich region)
Term
What is the polyadenylation signal??
Definition
AAUAAA
Term
How is a lariat created?
Definition
G attacks an A which forms UGA and then breaks off at the OH group and the two exons join together
Term
What effect does glucose have on the lac operon?
Definition
glucose inhibits the activated by decreasing cAMP (cAMP binds to the CAP which can then bind to the CAP binding site and allow transcription to take place)
Term
What is the activator for the lac operon?
Definition
CAP (catabolite activator protein) which binds with cAMP in order to bind to the CAP binding site and help RNA polymerase to bind to the promoter
Term
What effect does lactose have on the lac operon?
Definition
inhibits the repressor protein by binding to it and not allowing it to bind to the lacl sequence upstream of the lac genes
Term
What are the lac genes?
Definition
Z, Y and A
Term
What do the lac genes encode?
Definition
beta galactosidase which breaks down lactose into glucose and galactose
Term
What do you call it when different exons can be combined by alternative splicing to make unique proteins in different tissues?
Definition
alternative splicing
Term
Where is the anticodon end of a tRNA?
Definition
opposite the 3' aminoacyl end
Term
What is located at the three prime end of all tRNAs both eukaryotic and prokaryotic?
Definition
CCA at the 3' endalong with a high percentage of chemicall modified bases
Term
What enzyme puts an amino acid on tRNA?
Definition
aminoacyl-tRNA synthetase
Term
T/F Aminoacyl-tRNA synthetase has proofreading ability.
Definition
true; scrutinizes aa both before and after covalently binding aa to tRNA
Term
What is the MOA of tetracyclines?
Definition
bind the thirty S subunit, preveting attachment of aminoacyl-tRNA
Term
What are the subunits of the prokaryotic vs eukaryotic subunits?
Definition
prokaryotic (30 + 50 = 70)
eukaryotes (40 + 60 = 80)
Term
What is the energy source for tRNA charging?
Definition
ATP
Term
Describe how initiation occurs?
Definition
activated by GTP hydrolysis, initiation factors (eIFs) help assemble the 40S ribosomal subunit with the initiator tRNA and are released when the mRNA and the ribosomal subunit assemble with the complex
Term
What are the different tRNA sites of the ribosome?
Definition
a= incoming aminoacyl-tRNA; p= peptide chain; e= holds empty tRNA as it exits
Term
What is the MOA of aminoglycosides/
Definition
bind the thirty S subunit and inhibit formation of the initiation complex and cause mimsreading of mRNA
Term
How does translation termination occur?
Definition
stop codon is recognized by release factor and complete protein is released from ribosome
Term
What is the MOA of chloramphenicol?
Definition
inhibits 50S peptidyltransferase
Term
What is the MOA of streptogramins?
Definition
inhibits 50S peptidyltransferase
Term
What is the MOA of macrolides?
Definition
block translocation by binding the 23 subunit of 50S
Term
What is the MOA of clindamycin?
Definition
block peptide bond formation
Term
what is the MOA of linezolid?
Definition
bind to 23 subunit of 50S
Term
What are the elongation factors in eukaryotes versus prokaryotes?
Definition
euk= EF2; pro= EFG
Term
What is the shortest phase of the cell cycle?
Definition
mitosis
Term
Which is cell cycle specific: cyclins or CDKs?
Definition
cyclins are phase specific while CDKs are constitutive and inactive
Term
What is a "permanent" cell type?
Definition
remain in G0, regenerate from stem cells; ex= neurons, skeletal and cardiac muscl, RBCs
Term
What are stable/quiescent cells?
Definition
enter G1 from G0 when stimulated (hepatocytes, lymphocytes)
Term
What are labile cells?
Definition
never go to G0; divide rapidly with a short G1 (bone marrow, gut epithelium, skin, hair follicles)
Term
Name two cell types that are rich in RER?
Definition
plasma cells; globlet cells
Term
What kinds of post translational modifications can occur in the RER?
Definition
n-linked oligosaccharide addition
Term
What is RER in neurons called?
Definition
nissl bodies
Term
Where are organellar proteins made?
Definition
free floating ribosomes
Term
What types of cells are rich in SER?
Definition
liver hepatocytes (detox of drugs and poisons) and adrenal cortex (site of steroid synthesis)
Term
What does the golgi do to modify proteins?
Definition
modifies N-oligosaccharides on asparagine; adds O-oligosaccharides on serine and threonine; adds mannose-6-phosphate for trafficking to lysosomes
Term
What is COPI?
Definition
vesicular trafficking protein that moves retrograde (golgi --> ER)
Term
What is COPII?
Definition
vesicular trafficking protein that is responsible for anterograde movement (RER --> cisGolgi)
Term
What is trans versus cis golgi?
Definition
trans is on the side of the plasma membrane; cis is on the side of the ER and nucleus
Term
What is the defect in I cell disease?
Definition
lysosomal storgae disorder d/t failure of addition of mannose 6 phosphate to lysosome proteins (enzymes are secreted outside the cell instead of being targetted to the lysosome)
Term
What are the symptoms of I cell disease?
Definition
coarse facial features; clouded corneas, restricted joint movement, and high plasma levels of lysosomal enzymes
Term
What is the prognosis of I cell disease?
Definition
fatal in childhood
Term
What is the function of a peroxisome?
Definition
membrane enclosed organelle involved in catabolism of very long chain fatty acids and amino acids
Term
What is a proteasome?
Definition
barrel shaped protein complex that degrades damaged or unnecessary proteins tagged for destruction with ubiquitin
Term
Describe the structure of a microtubule?
Definition
cylindrical structure composed of a helical array of polymerized dimers of alpha and beta tubulin (each dimer has 2 GTp bound)
Term
What are the drugs that act on microtubules?
Definition
mebendazole/thiabendazole, griseofulvin, vincristine, vinblastine, paclitaxel, colchicine
Term
Name a disease caused by a microtubule polymerization defect?
Definition
chediak higashi syndrome
Term
What are the symptoms of chediak higashi syndrome?
Definition
recurrent pyogenic infections, partial albinism, and peripheral neuropathy
Term
What is the ATPase located around cilia?
Definition
axonemal dyneine (links peripheral nine doublets and causes bending of cilium by differential sliding of doublets)
Term
What cytoskeletal element is responsible for microvilli?
Definition
actin and myosin
Term
What cytoskeletal element is associated with cytokinesis?
Definition
actin and myosin
Term
What cytoskeletal element is responsible for adherens junctions?
Definition
actin and myosin
Term
What cytoskeletal element is associated for cell movement?
Definition
microtubules
Term
What cytoskeletal muscle makes up cilia and flagella?
Definition
microtubules
Term
What cytoskeletal elements are responsible for axonal trafficking?
Definition
microtubules
Term
What cytoskeletal elements are associated with centrioles?
Definition
microtubules
Term
What is the function of intermediate filaments?
Definition
structure
Term
What are the different types of intermediate filaments?
Definition
vimentin, desmin, cytokeratin, lamins, glial fibrillary acid proteins, neurofilaments
Term
T/F There are more phospholipids than cholesterol in the plasma membrane?
Definition
false; they are 50/50
Term
What composes the plasma membrane?
Definition
phospholipids, cholesterol, sphingolipids, glycolipids, and proteins
Term
What effect does high cholesterol have on plasma membrane?
Definition
increases melting temperature; decrease fluidity
Term
What effect does long saturated fatty acid content ahve on cell membrane?
Definition
increases melting temperature; decreases fluidity
Term
A vimentin stain stains...
Definition
connective tissue
Term
Desmin stains...
Definition
muscle
Term
ytokeratin stains..
Definition
epithelial cells
Term
GFAP stains...
Definition
neuroglia
Term
neurofilaments stain...
Definition
neurons
Term
In order to pump 3 Na out and 2 K in, the Na/K ATPase must be...
Definition
phosphorylated by ATP to allow Na out; depohsphorylated to bring K in
Term
What is the most abundant protein in the human body?
Definition
collagen
Term
Where is type I cartillage found?
Definition
bone, skin, tendon, dentin, fascia, cornea, late wound repair
Term
Where is type II cartilage found?
Definition
vitreous body, cartilage, nucleus pulposus
Term
Where is type III collagen found?
Definition
reticulin= skin, blood vessels, uterus, fetal tissue, granulation tissue
Term
Where is type IV collagen found?
Definition
basement membrane
Term
What
Definition
Term
What is the amino acid sequence characteristic of collagen?
Definition
Gly-X-Y (X and Y can be proline, hydroxyproline, or hydroxylysine)
Term
Where does hydroxylation of proline and lysine residues of collagen molecule take place?
Definition
RER
Term
Where does glycosylation of collagen take place?
Definition
ER
Term
How is procollagen formed?
Definition
hydrogen and disulfide bonds (tripple helix of three collagen alpha chains)
Term
Where does the formation of procollagen take place?
Definition
ER
Term
What form of collagen is exocytosed by the fibroblast?
Definition
procollagen
Term
What happens to procollagen once it leaves the fibroblast?
Definition
cleavage of terminal regions of procollagen transforms it into insoluble tropocollagen; reinforcement of many staggered tropocollagen molecules by covalent lysine-hydroxylysine cross linkage (by lysyl oxidase) to make collagen fibrils
Term
What is the final form of collagen called?
Definition
collagen fibrils
Term
What are the symptoms of osteogenesis imperfecta?
Definition
multiple fractures; blue sclerae, hearing loss, dental imperfections
Term
What type of OI is fatal in utero or in the neonatal period?
Definition
type II
Term
What is the incidence of OI?
Definition
1/10,000
Term
What is the pathogenesis of ehlers danlos syndrome?
Definition
type III collagen is most frequently affected
Term
What are the symptoms of Ehlers Danlos?
Definition
hyperextensible joints, stretchy skin, tendency to bleed, joint dislocation, berry aneurysms, organ rupture
Term
What is the inheritance pattern of ehlers danlos?
Definition
there are six types and they can be either autosomal dominant or recessive
Term
What is the inheritance pattern of alport syndrome?
Definition
most common form is x linked
Term
What are the symptoms of alport syndrome?
Definition
progressive hereditary nephritis and deafness; may be associated with ocular disturbances
Term
Where is elastin particularly important?
Definition
lungs, large arteries, elastic ligaments, vocal cords, ligamenta flava
Term
Elastin is rich in which amino acids?
Definition
proline and glycine, nonglycosylated forms
Term
What is the function of fibrillin?
Definition
provide scaffolding for tropoelastin
Term
What causes Marfan's?
Definition
fibrillin defect
Term
What causes the wrinkles of aging?
Definition
decreased collagen and elastin production
Term
What is a southern blot?
Definition
DNA is electrohporesed on a gel and then transferred to a filter; filter is soaked in a denaturant and subsequently exposed to a radiolabeled DNA probe that recognizes and anneals to its complementary strand; the resulting double stranded labeled piece of DNA is visualized when the filter is exposted to film
Term
What is a southern blot for RNA called?
Definition
northern blot
Term
What is a western blot?
Definition
sample protein is separated via gell electrophoresis and transferred to a filter; labeled antibody is used to bind to relevant protein
Term
What is a southwestern blot?
Definition
identifies DNA binding proteins (trnascription factors) using labeled oligonucleotide probes
Term
What is the purpose of microarrays?
Definition
profile gene expression levels of thousands of genes simultaneously to study certain diseases and treatments; able to detect SNPs
Term
T/F the specificity and sensitivity aof ELISA approach 100%.
Definition
true
Term
What is the "cre-lox system"?
Definition
can inducibly manipulate genes at specific developmental oints using an antibiotic controled promoter (e.g. to study a gene whose deletion causes embryonic death)
Term
How do you make trnasgenic mice?
Definition
random insertion of gene into mouse genome (constitutive); targeted insertion of deletion of gene through homologous recombintation with mouse gene (conditional)
Term
What is RNAi?
Definition
dsRNA syntehsized that is complementary to the mRNA sequence of interest. when transfected into human cells; dsRNA separates and promotes degradation of target mRNA, knocking down gene expression
Term
What kinds of body tissues do you need to perform karyotyping?
Definition
sample of blood, bone marrow, amniotic fluid, or placental tissue
Term
What is codominance?
Definition
neither of 2 alleles is dominant
Term
What is variable expression?
Definition
nature and severity of phenotype vary from 1 individual to another
Term
What is pleiotropy?
Definition
1 gene has > 1 effect on an individuals phenotype
Term
What is imprinting?
Definition
differences in phenotype depend on whether mutation is of maternal or paternal origin
Term
What types of genes can cause tumor syndromes due to loss of heterozygosity?
Definition
tumor suppressor genes
Term
What is a dominant negative mutation?
Definition
exerts a dominant effect; a heterozygote produces a nonfunctional altered protein that also prevents the normal protein from functioning
Term
What is linkage dysequilibrium?
Definition
tendency for certain alleles nearby in a gene to occur more often than expected by chance (measured in population not ina family and often variies in different populations)
Term
What causes mosaicism?
Definition
postfertilization loss of genetic information during mitosis
Term
What is lyonization?
Definition
random X inactivation in females
Term
What is lyonization?
Definition
random X inactivation in females
Term
What is a chimeric individual?
Definition
an individual whose genetic make up resutls from two zygotess that subsequently fuse
Term
What do you call it when mutations at different loci can produce the same phenotype?
Definition
locus heterogeneity
Term
Name three different diseases that can cause a marfanoid habitus?
Definition
marfans, homocysteinuria, MEN 2B
Term
What is heteroplasmy?
Definition
presence of both normal and mutated mtDNA, resulting in variable expression in mitochondrial inherited disease
Term
What is uniparental disomy?
Definition
offspring recieves 2 copies of a chromosome from 1 parent and no copies from the other parent
Term
What is the hardy weinberg equation?
Definition
p2 + 2pq + q2 = 1
Term
What are the assumptions of the hardy weinberg law?
Definition
no mutation occuring at the locus, no selection for any of the genetypes of the locus, completely random mating, no migration
Term
What is the abnormality of prader willi syndrome?
Definition
individual has normally inactivated maternal allele on chr 15; paternal allele should be active but is deleted
Term
What is the defect in angleman's syndrome?
Definition
individual has normally inactivated paternal allel; maternal allel on chr 15 should be active but is deleted
Term
What are the symptoms of prader willi syndrome?
Definition
mental retardation, hyperphagia, obesity, hypogonadism, hypotonia
Term
What are the symptoms of angel man syndrome?
Definition
mental retardation, seizures, ataxia, inappropriate laughter (happy puppet)
Term
Defects in structural genes often cause disease with what mode of inheritance?
Definition
AD
Term
If ALL female offspring of an affected father are affected, the inheritance is likely...
Definition
x linked dominant
Term
Name a disease that is x linked dominant?
Definition
hypophophatemic rickets
Term
What is the defect of hypophosphatemic rickets?
Definition
increased phosphate wasting at proximal tubule
Term
What are the symptoms of Leber's hereditary optic neuropathy?
Definition
acute loss of central vision
Term
What is teh defect in achondroplasia?
Definition
cell signaling defect of fibroblast growth factor receptor 3
Term
What genetic disease is associated with advanced paternal age?
Definition
achondroplasia
Term
What is the presentaiton of ADPKD?
Definition
flank pain, hematuria, hypertension, preogressive renal failure
Term
What is the mutation associated with ADPKD?
Definition
90% due to mutation of PKD 1 on chr 16
Term
What other pathology besides polycystic kidneys is associated with ADPKD?
Definition
polycystic liver disease, berry aneurysms, mitral valve prolapse
Term
What is teh mutation that causese familial adenomatous polyposis?
Definition
APC gene on chr 5
Term
What is the MOA of familial hypercholesterolemia?
Definition
elevated LDL due to defective or absent LDL receptor
Term
What's another naem for familial hypercholesterolemia?
Definition
hyperlipidemia type IIA
Term
What is the cholesterol of someone with familal hypercholesterolemia?
Definition
heterozygote= 300 mg/dl; homozygote= 700+ mg/dl
Term
What rae teh symptoms of familal hypercholesterolemia?
Definition
severe atherosclerotic diesease early in life and tendon xanthomas 9classically in the achilles tendon); MI may develop before age 20
Term
What's another name for osler-weber-rendu?
Definition
hereditary hemorrhagic telangiectasia
Term
What are the findings in herditary hemorrhagic telangiectasia?
Definition
telangiectasia, recurrent epistaxis, skin discoloration, ateriovenous malformations
Term
Hereditary spherocytosis is due to a defect in..
Definition
spectrin or ankyrin
Term
What are the lab findings of hereditary spherocytosis?
Definition
increased MCHC
Term
What disease can be cured with splenectomy/
Definition
hereditary spherocytosis
Term
What are the changes in neurotransmitter in the brain associated with huntingtons?
Definition
decreased levels of GABA and ACh
Term
What is the mutation associated with huntingtons disease?
Definition
trinucleotide repeat of CAG on chromosome 4
Term
What are the symptoms of marfans?
Definition
tall with long extremities, pectus excavatum, hyperextensive joints, arachnodactyly; cystic medial necrosis of aorta leading to aortic insufficiency and dissecting aortic aneurysms; floppy mitral valve, subluxation of lenses
Term
T/F Scoliosis is a symptom sof NF type 1?
Definition
true
Term
What are the finidngs of neurofibromatosis type 1?
Definition
cafe au lait spots, neural tumors, lisch nodules , scoliosis and other skeletal disorders, optic pathway glioma
Term
What chromosome is affected by NF 1?
Definition
chr 17q
Term
What are the symptoms of NF2?
Definition
bilateral acoustic schwannomas, juvenile cateracts
Term
Where is the mutaon for NF 2?
Definition
chr 22 (NF2 gene)
Term
What are the findings for tuberous sclerosis?
Definition
facial lesions (adnoma sebaceum), hypopigmented "ash leaf spots" on skin, cortical and retinal hamartomas, seizures, mental retardation, renal cysts, and renal angiomyolipomas, cardiac rhabdymomas, increased incidence of astrocytoma
Term
What is the incidence of astrocystoma?
Definition
Term
What accounts for the variable presentation of tuberous sclerosis?
Definition
incomplete penetrance
Term
What are the findings of vHL disease?
Definition
hemangioblastoma of retina/cerebellum/medulla; about half of affected individuals develop bilateral renal cell carcinoma and toher tumors
Term
What is the mutation associated with vHL
Definition
deletion of VHL gene (tumor supressor) on chr 3p; this results in constitutive expression of HIF (transcription factor) and activation of angiogenic growth factors
Term
What is the inheritance of hemochromatosis?
Definition
AR
Term
Name the only sphingolipidosis that is not AR?
Definition
fabry's
Term
Where is the mutation for CFTR?
Definition
chr 7
Term
What is the most common mutation of CF?
Definition
deletion of phe 508
Term
What is the function of CFTR?
Definition
secretes Cl- in teh lung and resorbs cloride in sweat
Term
What is the most common lethal genetic disease of caucasians?
Definition
cystic fibrosis
Term
What is the MOA of N-acetyl cystine for CF/
Definition
cleaves disulfide bonds within mucous glycoproteins
Term
What types of organisms cause recurrent respiratory infections in CF patients?
Definition
pseudomonas and S. aureus
Term
How does the mutation of CF cause abnormal CFTR?
Definition
mutation causes abnormal protein folding, resulting in degradation of channel before reaching cell surface
Term
What is the inheritance pattern of ocular albinism?
Definition
x linked recessive
Term
What is the pathogenesis of duchenes?
Definition
x linked fram shift mutation causes deletion of dystrophin gene; dystrophin gene is responsible for anchoring muscle fibors primarily in skeletal and cardiac muscle; absence causes accelerated muscle breakdown
Term
What is the presentation of duchenne's
Definition
weakness beginning in pelvic girdle muscles and progressing superiorly; pseudohypertrophy of calf muscles due to fibrofatty replacement of muscle; cardiac myopathy
Term
At what age does Duchene's start to present?
Definition
before 5 yoa
Term
What is the mutation of becker's muscular dystrophy?
Definition
x linked mutated dystrophin gene (no frameshift)
Term
At what age does Becker's present?
Definition
adolescence or early adulthood (less severe than Duchenne's)
Term
What is the mutation associated with fragile X syndrome?
Definition
X linked defect (CGG repeat)What is the repeat affecting the methylation and expression of the FMR1 gene
Term
What is the trinucleotide repeat associated with friedreich's ataxia?
Definition
GAA
Term
What is the trinucleotide repeat associated with myotonic dystrophy?
Definition
CTG
Term
Gap between the first two toes is associated with what syndrome?
Definition
down syndrome
Term
Down syndrome patients are at an increased risk of what cancer?
Definition
ALL
Term
What are teh results of the pregnancy quad screen for Down's?
Definition
decreased AFP, increased B-hCG, decreased estriol, increased inhibin A
Term
What are the ultrasound findings of Downs?
Definition
increased nuchal translucency
Term
What is the risk of Down's after woman is over 45?
Definition
1/25
Term
What is the chromosomal abnormality responsible for Downs?
Definition
95% due to meiotic nondisjunction of homologous chromosomes; 4% Robersonian trnaslocation; 1% due to Down mosaicism
Term
What mutation that causes DOwn's is NOT associated with AMA?
Definition
mosaicism
Term
What are the findings associated with edward's syndrome?
Definition
severe mental retardation, ricker bottom feet, micrognathia (small jaw), low-set ears, clenched hands, prominent occiput, congenital heart diesease
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