Biochemistry Flashcards
RNA polymerase I
restricted to nucleolus as it synthesizes majority of rRNA
produces 18S, 5.8S, & 28S
forms essential ribosomal components
mRNA
Produced by RNA pol II
translated by ribosomes to form specific proteins
small nuclear RNA
Produced by RNA pol II
involved in mRNA splicing & transcription regulation
micro RNA
Produced by RNA pol II
cause gene silencing via translation arrest or mRNA degradation
RNA pol III
produces tRNA and 5S ribosomal RNA (essential component of 60S ribosomal subunit)
vitamin A deficiency
sx = night blindness, complete blindness, xerophthalmia, Bitot’s spots (abnromal squamous cell proliferation and keratinization of conjunctiva), corneal perforation, keratomalacia, derm abnl, damage to phagocytes and TC lymphocytes, death
common in Asia, Africa, South America
associated with malnourishment and fat malabsorption (eg CF, cholestatic liver disease)
Give to all children with measles from area with vit A def or with measles mortality >1%
Transformation
Direct uptake of naked DNA from the environment by bacT that are naturally able
- strep pneumo
- Haemophilus influenza
- Neisseria gonorrhoeae & meningitidis
*this is how non-virulent non-capsule-forming strains of s. pneumo can obtain genes that code for capsule and gain virulence
Conjugation
one-way transfer of DNA between bacT cells through direct physical contact
donor cells contain an extra segment of DNA = F factors coding for sex pilus and other prot necessary for transfer to F- recipients
Transduction
transfer of DNA via bacteriophage
during lytic infection when random bacT genes accidentally packaged into viral capsid
lyosgenic infection when selected bacT genes near viral insertion site are excised and packaged into virion
Dry beriberri
think ber1 ber1 –> B1 deficiency
polyneuritis, symmetrical muscle wasting
Wet beriberi
high-output cardiac failure (dilated cardiomyopathy), edema
B1 deficiency
impaired glucose breakdown –> ATP depletion worsened by glucose infusion with highly aerobic tissues affected first (brain, heart)
Thiamine
found in thiamine pyrophosphate (TPP) = cofactor for:
- pyruvate dehydrogenase (links glycolysis to TCA)
- alpha-ketoflutarate dehydrogenase = TCA cycle
- Transketolase (HMP shunt responsible for NADPH production)
vitamin B2
riboflavin
cofactor in oxiation and reduction (eg FADH2)
Mneumonics:
-Fad and Fmn derived from riboFlavin (B2 = 2ATP)
B2 deficiency
Cheilosis
Crneal vascularization
“2 C’s of B2”
B3
niacin
constituent of NAD+, NADP+ (using redox reactions).
Derived from tryptophan – need B6
“NAD derived from Niacin (B3 = 3 ATP)
Niacin deficiency
glossitis
severe = pellagra = diarrhea, dementia, dermatitis
c/b Hartnup dz (dec tryptophan absorption), malignant carcinoid syndrome (inc tryptophan metabolism), INH (dec B6)
niacin excess
flushing - seen at doses used to tx HLD
B5 function and deficiency presentation
pantothenate
essential part of CoA and fatty acid synthase
deficiency = dermatitis, enteritis, alopecia, adrenal insufficiency
B6
pyridoxine
converted to pyridoxal phosphate = cofactor used in transamination (ALT, AST), decarboxylation reactions, glycogen phosphorylase
Needed to make:
- cystathionine
- heme
- niacin
- histamine
- NTs = 5HT, E, NE, GABA
B6 deficiency
convulsions, hyperirritability, peripheral neuropathy, sideroblastic anemia due to impaired Hb synthesis and iron excess
B7 (biotic)
cofactor for carboxylation enzymes (add 1-carbon group):
- pyruvate carboyxlase: pyruvate (3C) –> oxaloacetate (4C)
- acetyl-CoA carboxylase: acetyl-CoA (2C) –> malonyl-CoA (3C)
- Propionyl-CoA carboxylase: propionyl-CoA (3C) –> methylmalonyl-CoA (4C)
deficiency is rare but causes dermatitis, alopecia, enteritis. Occurs if consume too many raw eggs (Avidin binds biotin) or abx.
B9
converted to tetrahydrofolate (THF) = coenzyme for 1-C transfer/methylation rxns
needed to make nitrogenous bases in DNA and RNA
found in green leafy vegetables (“folate in foliage”)
small reserve pool in liver
drugs that cause folate deficiency
MTX, phenytoin, sulfonamides
*remember no neuro sx like in B12 deficiency