biochem/genetics Flashcards by Unknown Unknown

nucleoside =

nucleotide =

nucleoside = base + sugar

nucleotide = base + sugar + phosphate

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deamination:

guanine -> _____
5-methylcytosine -> _____
cytosine -> ______
adenine -> ______

guanine -> xanthine
5-methylcytosine -> thymine
cytosine -> uracil
adenine -> hypoxanthine

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methylation of _____ -> thymine

uracil

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Lesch Nyhan syndrome is due to absent _____ which converts _________

inheritance pattern?

HGPRT. purine salvage pathway
hypoxanthine -> IMP
guanine -> GMP

x-linked recessive

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enhancer, promotor, or operator?

can be located upstream downstream or within introns of a gene, does not have to be close to the gene

enhancer

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enhancer, promotor, or operator?

must be located upstream, pretty close to the gene
directly binds RNA polymerase and transcription factors
required for transcription

promotor (TATA and CAAT boxes)

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which DNA repair happens in G1 phase?

nucleotide escision repair

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which DNA repair happens in S phase?

mismatch repair

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which DNA repair fixes spontaneous/toxic deamination?

base excision repair

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which DNA repair is defective in xeroderma pigmentosum?

nucleotide excision repair

pyrimidine dimers accumulate (formed from UV light)

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which DNA repair is defective in Lynch syndrome?

mismatch repair

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which DNA repair is defective in ataxia telangiectasia?

double strand nonhomologous end joining

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which DNA repair is defective in breast/ovarian cancers w/ BRCA1 mutation?

double strand homologous recombination

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guy eats death mushrooms. what is the problem?

alpha-amanitin. inhibits RNA polymerase II + sever ehepatotoxicity

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what end does 7-methylguanosine cap go on of mRNA?

5’ end

A357 mnemonic

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SLE has anti-Smith antibodies. what are these against?

snRNPs (spliceosomes)

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protein synthesis is intiated by _____(reaction)

GTP hydrolysis

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lysosomal storage disorder: 
courase facial features
clouded corneas
restricted joint mvt
high plasma levels of lysosomal enzymes
often fatal in childhood

dx? pathogenesis?

I cell disease

defect in N=acetylglucosaminyl-1-phosphotransferase -> Golgi can’t phosphorylate mannose residues => decreased mannose-6-phosphate on glycoproteins -> proteins are secreted extracellularly rather than delivered to lysosomes

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signs/sx of peroxisome dz?

reason for the neuro sx?

scaly skin, ataxia, cataracts/night blindness, shortening of 4th toe, epiphyseal dysplsia

hypotonia, seizures, hepatmegaly, early death

neuro sx are from dec synthesis of PLASMALOGENS, important for phospholipids in myelin

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based on the primary structure of collagen, what is the best reflector of collagen synthesis? (amino acid)

Glycine

remember sequence is Gly-X-Y where x and y are proline or lysine

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In Menkes dz, defective menkes protein (ATP7A) leads to what?

pattern of inheritance?

leads to decreased activity of lysyl oxidase, which cross links collagen in final step of synthesis -> kinky hair, growth retardation, hypotonia

x-linked recessive

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Marfan syndrome is autosomal dominant. FBN1 gene mutation on chromosome 15 results in defective _______

can have subluxation of lenses ___ and ____

fibrillin

lens up and out (temporal)

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definition of locus heterogeneity and example?

Albinism

mutations at different loci can produce a similar phenotype

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definition of allelic heterogeneity and example?

different mutations in the same locus produce the same phenotype

B-thalassemia

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heteroplasmy definition

presence of both normal and mutated mitochondrial DNA, resulting in variable expression in mitochondrially inherited dz

what test is used for newborn screening of Cystic fibrosis?

elevated immunoreactive trypsinogen

X-linked recessive disorders: Oblivious Female Will Often Give Her Boys Her x-Linked Disorders

``` OTC deficiency Fabry dz Wiskott-Aldrich syndrome Ocular albinism G6PD deficiency Hunter syndrome Bruton agammaglobulinemia Hemophilia A and B Lesch-Nyhan syndrome Duchenne and Becker muscular dystrophy ```

Lyonization definition

x inactivation. female carriers | variably affected depending on the pattern of inactivation of the X chromosome carrying the mutant vs normal gene.

in muscular dystrophies, esp Duchenne, there is increased CK and ______

aldolase

in myotonic dystrophy, there is _____ trinucleotide repeat expansion in ____ gene -> abnormal expression of ______

CTG DMPK gene myotonin protein kinase

in fragile X syndrome, trinucleotide repeat expansion in FMR1 gene leads to _________

hypermethylation -> decreased expression

what inherited syndromes/dz can predispose to MVP? (4)

fragile X Marfan Ehlers-Danlos AD PKD

trinucleotide repeat expansion in fragile X syndrome

CGG

trinucleotide repeat expansion in Friedreich ataxia

GAA

of the trisomies, which one has increased B-hCG?

Downs 21. the other 2 are decreased

of the trisomies, which one has increased PAPP-A?

none. all decreased

of the trisomies, which one has decreased inhibin A?

Down 21.

of the trisomies, which one has normal levels of stuff in 2nd trimester?

13, Patau syndrome

severe intellectual disability, rocker- bottom feet, microphthalmia, microcephaly, cleft liP/Palate, holoProsencephaly, Polydactyly, cutis aPlasia, congenital heart disease, Polycystic kidney disease. Death usually occurs by age 1. which trisomy?

13 Patau syndrome

Prominent occiput, Rocker-bottom feet, Intellectual disability, Nondisjunction, Clenched fists (with overlapping ngers), low-set Ears, micrognathia (small jaw), congenital heart disease. Death usually occurs by age 1. which trisomy?

18, Edward syndrome

if trisomy 21 is due to unbalanced Robertsonian translocation, which 2 chromosomes is it most commonly between?

14 and 21

if a fetus has Down's, 1st semester ultrasound will show what?

nuchal translucency and hypoplastic nasal bone.

microcephaly, moderate to severe intellectual disability, VSD or other cardiac abnormality deletion of short arm of chromosome 5 what is it?

Cri du chat syndrome

Congenital microdeletion of long arm of chromosome 7 (deleted region includes elastin gene). Findings: distinctive “elfin” facies, intellectual disability, hypercalcemia ( sensitivity to vitamin D), well-developed verbal skills, extreme friendliness with strangers, cardiovascular problems (eg, supravalvular aortic stenosis, renal artery stenosis) dx?

Williams syndrome william for will ferrel in the movie Elf (elfin facies and super friendly)

which 2 cardiac defects are associated w/ catch22?

truncus arteriosis | tetralogy of fallot

alopecia, dry skin (eg, scaliness), hepatic toxicity and enlargement, arthralgias, and pseudotumor cerebri these are from chronic toxicity of what vitamin?

vit A

4 enzymes/reactions that thiamine B1 is cofactor for

1. Pyruvate dehydrogenase (links glycolysis to TCA cycle) 2. α-ketoglutarate dehydrogenase (TCA cycle) 3. Transketolase (HMP shunt) 4. Branched-chain ketoacid dehydrogenase (valine, leucine, isoleucine, maple syrup dz)

what test confirms diagnosis of vitB1 thiamine deficiency?

increased RBC transketolase activity after vitB1 administration

Wernicke-Korsakoff syndrome is due to damage to mammillary bodies and _________

medial dorsal nucleus of thalamus

facial flushing, hyperglycemia, and hyperuricemia are signs of toxicity of what vitamin?

B3. niacin.

Dermatitis, enteritis, alopecia, adrenal insufficiency. are signs of deficiency of what vitamin?

vit B5 pantothenic acid note: alopecia is also sign of vit A EXCESS

vit B3 niacin is derived from ______. thus, Hartnup dz can lead to pellagra b/c ________

tryptophan Hartnup dz is missing neutral amino acid transporters (tryptophan is neutral)

which rx in TCA ccle is vit B2 (riboflavin) a cofactor for?

``` succinate dehydrogenase (requires FAD which riboflavin is used to make) the rxn is succinyl - > fumarate ```

Converted to pyridoxal phosphate (PLP), a cofactor used in transamination (eg, ALT and AST), decarboxylation reactions, glycogen phosphorylase. Synthesis of cystathionine, heme, niacin, histamine, and neurotransmitters including serotonin, epinephrine, norepinephrine (NE), dopamine, and GABA. is function of what vitamin?

B6 pyridoxine

avidin in egg whites binds _______ | sx of deficiency:

B7 biotin dermatitis, alopecia, enteritis

how does vitC facilitate iron absorption?

reduces it to Fe2+ state (can also be used as ancillary tx for methemoglobinemia

which skin layer forms D3 cholecalciferol

stratum basale

Hemolytic anemia, acanthocytosis, muscle weakness, posterior column and spinocerebellar tract demyelination. signs of deficiency of what vitamin?

vit E looks like B12 deficieny but is hemolytic anemia, not megaloblastic. also b12 def has increased serum methylmalonic acid

S/Sx of Kwashiorkor dz (protein malnutrition): MEALS

``` Malnutrition Edema Anemia Liver (fatty_ Skin lesions (hyperkeratosis, dyspigmentation) ```

Fomepizole inhibits ____(enzyme). use?

alcohol dehydrogenase antidote for alcohol OD

disulfiram inhibits _______ enzyme

acetaldehyde dehydrogenase

where in cell does ketogenesis and acetyl-coA production occur?

mitochondria

where in cell does HMP shunt, steroid synthesis, and synthesis of a lot of other things happen?

cytoplasm

which vitamin is essential compononent for coenzyme A (coA) and fatty acid synthase?

vit B5 pantothenic acid

hexokinase vs glucokinase: 1. which one is mostly in liver and beta cells of pancreas? 2. which one has higher Km aka lower affinity, but higher Vmax aka capacity for substrate? 3. which one is NOT feedback inhibited by G6P? 4. which one induced by insulin?

all glucokinase

essential fructosuria is defect in _____ enyzyme, where as hereditary fructose intolerance is deficiency of _______ enzyme, so _______ accumulates tx?

essential fructosuria is defect in fructokinase enyzyme. benign. hereditary fructose intolerance is deficiency of aldolase B -> fructose 1 phosphate accumulates. decreased availabel phosphate - > inhibition of glycogenolysis and gluconeogenesis tx is decrease intake of BOTH glucose and fructose,..

infant has neuro defects, lactic acidosis, and in creased serum alanine. dx? tx?

pyruvate dehydrogenase complex deficiency tx: increase intake of ketogenic nutrients (high fat content or lysine and leucine which are the purely ketogenic amino acids)

FAB GUT mnemonic

Fructose is to Aldolase B, as Galactose is to UridylTransferase missing aldolase B -> fructose intolderance missing G1P uridyltransferase -> classic galacosemia

galactose appears in blood (galactosemia) and urine (galactosuria); infantile cataracts. May present as failure to track objects or to develop a social smile dx? missing what enzyme?

galactokinase deficiency

Symptoms develop when infant begins feeding (lactose present in breast milk and routine formula) and include failure to thrive, jaundice, hepatomegaly, infantile cataracts, intellectual disability. Can predispose to E coli sepsis in neonates. dx? missing what enzyme? tx?

absent galactose-1-phosphate uridyltransferase exclude galactose and lactose (galactose + glucose) from diet

PKU pts must avoid _______, an artificial sweetener that contains phenylalanine

aspartame

PKU is missing _____ OR ________ tx? (increase intake of what?)

phenylalanine hydroxylase or BH4 (tetrahydrobiopterin) cofactor tx is decreased phenylalanine and increased tyrosine + BH4 supplementation

bluish-black connective tissue, ear cartilage, and sclerae (ochronosis); urine turns black on prolonged exposure to air. May have debilitating arthralgias (homogentisic acid toxic to cartilage) dx? pathogenesis?

Alkaptonuria: deficiency of homogentisate oxidase in the degradative pathway of tyrosine to fumarate pigment-forming homogentisic acid accumulates in tissue aka improper tyrosine degradation

presentation of homocystinuria: HOMOCYstinuria

``` Homocysteine in urine, Osteoporosis, Marfanoid habitus, Ocular changes (downward and inward lens subluxation), Cardiovascular effects (thrombosis and atherosclerosis stroke and MI), kYphosis, ``` bonus: intellectual disability

kid has cystinuria (hexagonal cystine stones). this is b/c of a hereditary defect in renal PCT and intestinal aminoa acid transporter that prevents reabsorption of _____

``` COLA Cystine Ornithine Lysine Arginine ```

diagnostic test for cystinuria

urinary cyanide nitroprusside test

``` glycogen storage dz: increased glycogen in liver, hepatomegaly increased uric acid -> gout increased blood lactate and TAGs severe fasting hypoglycemia ``` what enzyme is deficient?

glucose 6 phosphatase

glycogen storage dz: cardiomegaly, hypertrophic cardiomyopathy hypotonia, exercise intolerance early death which enzyme is deficienty?

LYSOSOMAL acid alpha-1,4-glucosidase, alpha-1,6-glucosidase (acid maltase)

glycogen storage dz: milder form of type 1 (hepatomegaly, gout, etc) what enzyme deficient? accumulation of what structures in cytosol?

deficient in debranching enzyme alpha-1,6-glucosidase GLUCONEOGENESIS IS INTACT limit dextrin-like structures in cytosol

glycogen storage dz: painful muscle cramps, myoglobinuria (red urine) with exercise 2nd win phenomenon due to increase blood flow to muscles which enzyme deficient? are blood glucose levels high low or normal?

skeletal muscle glycogen phsophorylase aka myophosphorylase blood glucose levels typically unaffected

``` lysosomal storage disorder: progressive neurodegeneration, developmental delay lysosomes with onion skin cherry red macula NO hepatosplenomegaly ``` deficient enzyme? accumulated substrate?

Tay Sach's heoxsaminidase A enzyme deficient GM2 ganglioside accumulates

all the lysosomal storage dz are autusomal recessive except

fabry dz (x-linked recessive)

fanconi anemia has what signs/sx besides aplastic anemia? what is pathogenesis?

problem is DNA repair defect causing bone marrow failure | incidence of tumors/leukemia, café-au-lait spots, thumb/radial defects