Biochemistry Flashcards
Dihydroorate dehydrogenase is involved in addition of _______ to _______ and blocked by _________
Dihydroorate dehydrogenase is involved in addition of Aspartate to Carbamoyl phosphate and blocked by Leflunomide
What converts dUMP to dTMP and what inhibits this enzyme?
Thymidylate synthase
Inhibited by 5-FU
What is the function of HGPRT?
Purine salvage - converts hypoxanthine to IMP and guanine to GMP
What happens with a deficiency of HGPRT?
Lesch-Nyhan syndrome - results in excess uric acid production and de novo purine synthesis
Hyperuricemia Gout Pissed off (self mutilation) Retardation dysTonia
What amino acids are necessary for purine synthesis?
Glycine
Aspartate
Glutamine
Which amino acids are encoded by only 1 codon?
Methionine (AUG) and tryptophan (UGG)
Origin of replication is single in ______ but multiple in ________
Origin of replication is single in prokaryotes but multiple in eukaryotes
What is the difference between DNA polymerase I and III?
III: Leading strand and lagging strand; 5’ to 3’ synthesis and 3’-5’ proofreading
I: Degrades RNA primer and replaces it with DNA - excises RNA primer with 5’-3’ exonuclease
Duchenne Muscular dystrophy is due to a _______ mutation
Sickle cell disease is due to a ________ mutation
Duchenne Muscular dystrophy is due to a frameshift mutation
Sickle cell disease is due to a missense mutation
RNA polymerase I makes _RNA
RNA polymerase II makes _RNA
RNA polymerase III makes _RNA
Which is inhibited by amanita phalloides?
1: rRNA
II: mRNA - Inhibited by Amanita Phalloides
III: tRNA
What is responsible for quality control after mRNA is transported out of the nucleus?
P-bodies - contain exonucleases, decapping enzymes, and microRNAs
Antibodies to snRNPs are highly specific for ___
SLE
What is the function of the following parts of tRNA
T-arm:
D-arm:
3’CCA end:
T-arm: necessary for tRNA ribosome binding
D-arm: Necessary for tRNA recognition by correct aminoacyl tRNA synethetase
3’CCA end: Amino acid acceptor site
What catalyzes the binding of amino acid to tRNA?
What happens if it is malfunctioning?
Aminoacyl-tRNA synthetase
A mischarged tRNA reads usual codon but inserts wrong amino acid
What are the functions of ATP and GTP in protein synthesis?
ATP - tRNA activation
GTP - tRNA gripping and going places - translocation
RER is for protein secretion and addition of _______ to many proteins
Where is RER abundant?
N-linked oligosaccharide
RER is abundant in mucus-secreting goblet cells of the small intestine and antibody-secreting plasma cells
SER is the site of steroid synthesis and ________ of _______
Where is it found?
Detoxification of drugs and proteins
Liver hepatocytes and steroid hormone producing cells of adrenal cortex and gonads are rich in SER
What is the function of the following Golgi associated proteins... Signal recognition particle (SRP): COPI: COPII: Clathrin:
Signal recognition particle (SRP): traffics proteins from ribosome to RER
COPI: Golgi to Golgi (retrograde) and Golgi to ER
COPII: Golgie eto Golgi (anterograde) and ER to Golgi
Clathrin: trans-Golgi to lysosomes or plasma membrane to endosomes
What parts of collagen synthesis occur inside fibroblasts?
1) Synthesis (Gly-X-Y)
2) Hydroxylation of proline and lysine residues
3) Glycosylation of pro-alpha chain hydroxylysine residues and formation of pro-collagen (hydrogen and disulfide bonds)
4) Exocytosis
What parts of collagen synthesis occur outside of fibroblasts?
5) Cleavage of disulfide-rich terminal regions of procollagen transforming it into insoluble tropocollagen
6) Reinforcement of staggered tropocollagen molecules by covalent lysine-hydroxylysine cross-linkage to make collagen fibrils
Osteogenesis imperfecta is due to a defect in which stage of collagen synthesis?
Formation of triple helix
Menkes disease is due to impaired absorption and transport of _______
copper
What is pleiotropy?
One gene contributes to multiple phenotypic effects
What is heteroplasmy?
Presence of both normal and mutated mitochondrial DNA resulting in variable expression in mitochondrial inherited disease
Uniparental disomy:
Which type indicates a meiosis I error?
Which type indicates a meiosis II error?
Uniparental disomy - offspring receives 2 copies of a chromosome from 1 parent and no copies from the other parent
Heterodisomy/heterozygous indicates a meiosis I error
Isodisomy/homozygous indicates a meiosis II error
In Hardy-Weinberg population genetics, the frequency of an x-linked recessive disorder in males = __ and in females = __
Males = q Females = q^2
What is imprinting?
At some loci, only one allele is active; the other is inactive (methylation) - if the active allele is deleted there is disease
Prader-Willi and Angelmann syndrome are due to mutation or deletion of genes on chromosome __
15
What are the features of Prader-Willi syndrome
Hyperphagia Obesity Intellectual dysability Hypogonadism Hypotonia
What are the clinical features of Angelman syndrome?
Inappropriate laughter
Seizures
Ataxia
Severe intellectual disability
What are the features of hereditary hemorrhagic telangiectasia (AKA Osler-Weber-Rendu syndrome)?
Inherited disorder of blood vessels Telangiectasia Recurrent epistaxis Arteriovenous malformation GI bleeding Hematuria
What is the normal function of the chloride channel affected by cystic fibrosis?
Secretes Cl- in the lungs and GI tract and reabsorbs Cl- in sweat glands
What is the consequence of increased intracellular Cl- in cystic fibrosis?
Compensatory increase in Na+ reabsorption via epithelial Na+ cells leading to increased H2O reabsorption leading to abnormally thick mucus secreted into lungs and GI tract
*Also increased Na+ reabsorption causes more negative transepithelial potential difference
A CTG trinucleotide repeat expansion in the DMPK gene causes __________ which involves an abnormal expression of ________ _________ ________
A CTG trinucleotide repeat expansion in the DMPK gene causes Myotonic Type I which involves an abnormal expression of Myotonin protein kinase
Fragile X syndrome is due to defect affecting the methylation and expression of the _____ gene
What are the findings?
FMR1
Fragile X - eXtra large testes, jaw and ears
Cri-du-chat syndrome is a congenital microdeletion of the short arm of chromosome __
5
Williams syndrome is a congenital microdeletion of the long arm of chromosome __ which includes the ________ gene
7; elastin
Vitamin A prevents _________ _________ and is used to treat measles and ___ subtype M3
Vitamin A prevents squamous metaplasia and is used to treat measles and AML subtype M3
What TCA cycle reaction requires FAD as a cofactor?
Succinate dehydrogenase reaction
How does niacin treat dyslipidemia
Lowers levels of VLDL and raises levels of HDL
Facial flushing in Vitamin B3 deficiency is induced by ________
Prostaglandin
What liver products are an example of transamination reactions (which require vitamin B6)?
ALT and AST
What neurotransmitters require vitamin B6 for synthesis?
Serotonin, Epinephrine, Norepinephrine, Dopamine, and GABA
What is the function of Vitamin B9 (folate)?
What happens with B9 deficiency?
Function: Converted to THF and serves as coenzyme for 1-carbon transfer/methylation reactions
Deficiency: Macrocytic, megaloblastic anemia; hypersegmented neutrophils; glossitis
What are the consequences of the increased NADH/NAD ratio in ethanol metabolism?
Pyruvate to lactate (lactic acidosis)
Oxaloacetate to malate (prevents gluconeogenesis)
Glyceraldehyde-3-phosphate to glycerol-3-phosphate (which combines with fatty acids to make triglycerides leading to hepatosteatosis)
Disulfiram inhibits acetaldehyde dehydrogenase
_________ inhibits alcohol dehydrogenase
Fomepizole (for methanol or ethylene glycol poisioning)
Name the following types of bacterial genetics…
Ability to take up naked DNA (from cell lysis) from environment:
Segment of DNA (transposon) jumps from one location to another:
Lytic phage infects bacterium→ DNA packaged in viral capsid → gene transfer:
Ability to take up naked DNA (from cell lysis) from environment: Transformation
Segment of DNA (transposon) jumps from one location to another: Transposition
Lytic phage infects bacterium→ DNA packaged in viral capsid → gene transfer: Transduction
