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523 Cards in this Set

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which resembles substrate: competitive or noncompetitive inhibitors?
competitive
what type of inhibitor binds at the active site and is overcome by increasing substrate?
competitive
what effect do competitive inhibitors have on Vmax?
none
what effect do noncompetitive inhibitors have on Vmax?
decrease it
what effect do competitive inhibitors have on Km?
increase it
what effect do noncompetitors have on Km?
none
the lower the Km, the higher the _____?
affinity
when does Km = [S]?
at 1/2Vmax
in the cell cycle, which phase is usually the shortest?
mitosis
most cells are at what point in the cell cycle?
G0 - quiescent G1 phase
rapidly dividing cells have a shorter ____?
G1 (growth)
this is the site of synthesis of secretory proteins and N-linked oligosaccharide addition to many proteins
RER
mucus-secreting goblet cells of SI and Ab-secreting plasma cells are rich in what cellular organelle?
RER
nissl substance is not found where?
axon or axon hillock
what do nissl bodies do?
synthesize enzymes (e.g. ChAT) adn peptide neurotransmitters
what is SER for?
site of steroid synthesis and detoxification of drugs and poisons
lipid hepatocytes and steriod-producing cells of the adrenal cortex are rich in what?
SER
where is mannose-6-phosphate added, and what does it do?
golgi - added to specific lysosomal proteins, which targets them to the lysosome
what is I cell disease?
failure of addition of man-6-P to lysosome proteins, causing them to be secreted outside the cell instead of targeted to the lysosome; coarse facial features and restricted joint movement
this is the distribution center of proteins and lipids from the ER to the plasma membrane, lysosomes, and secretory vesicles
golgi
the golgi modifies N-oligosaccharides on what amino acid?
asparagine
golgi adds O-oligosaccharides to residues of what?
serine and threonine
what organelle assembles proteoglycans from proteoglycan core proteins?
golgi
this organelle performs sulfation of sugars in proteoglycans and of selected tyrosine on proteins
golgi
what is the diameter of a microtubule?
24 nm
each dimer in microtubules has how many GTP bound to it?
2
mebendazole/thiabendazole, taxol, griseofulvin, vincristine/vinblastine, and colchicine all act on what structure?
microtubules
this syndrome is characterized by decreased phagocytosis as a result of a microtubule polymerization defect
chediak-higashi syndrome
microtubules are involved in what type of axoplasmic transport?
slow
how many polymerized tubulin dimers are there per circumference in microtubules?
13
this structure consists of a 9+2 arrangement of microtubules
cilia
dynein is reponsible for what direction of movement?
retrograde
kynesin is responsible for what direction of movement?
anterograde
this is an ATPase that links peripheral 9 doublets and causees bending of cilium by differential sliding of doublets
dynein
a high cholesterol or long saturated fatty acid content does what to melting temperature?
increases it
this is the only side of the plasma membrane that contains glycosylated lipids or proteins
noncytoplasmic
this is a major component of RBC membranes, myelin, bile, surfactant, and is also used in the esterification of cholesterol
phosphatidylcholine
H1, alpha1, V1, M1, & M3 are linked to which class of G protein?
Gq (HAVe 1 M&M)
Gq initiates what cascade?
phospholipase C - PIP2 - IP3 - increased intracellular calcium (also PIP2 can yield DAG-PKC)
beta1, beta2, D1, H2, V2 are linked to which class of G protein?
Gs
M2, alpha2, and D2 are linked to what class of G protein?
Gi (MAD 2s)
Gs/Gi stimulate/inhibit what cascade?
adenylyl cyclase - cAMP - PKA
what is the most abundant protein in the body?
collagen
90% of collagen is what type?
type I
this type of collagen is found in bone, tendon, skin, dentin, fascia, cornea, late wound repair
type I
this type of collagen is found in cartilage, vitreous body, nucleus polposus
type II
this type of cartilage is found in skin, blood vessels, uterus, fetal tissue, granulaltion tissue
type III
this type of cartilage is found in basement membrane or basal lamina
type IV
this type of cartilage is found in the epiphyseal plate
type X
where are collagen alpha chains (preprocollagen) translated?
on RER
preprocollagen has the structure Gly-X-Y - what are X and Y?
proline, hydroxyproline, or hydroxylysine
hydroxylation of specific proline and lysine residues in the synthesis of collagen occurs where and requires what?
ER; vitamin C
in collagen synthesis, where does glycosylation of pro-alpha-chain lysine residues and formation of procollagen occur?
golgi
what is procollagen?
triple helix of 3 collagen alpha chains
what is formed when procollagen peptidases cleave terminal regions of procollagen? where does this occur?
tropocollagen; occurs outside fibroblasts
collagen fibrils are composed of what?
many staggered tropocollagen molecules that are reinforced by covalent lysine-hydroxylysine cross linkages
the step between pro-alpha-chains and triple helix formation/procollagen does not occur in what disease?
osteogenesis imperfecta
the step between peptide cleavage and collagen fibrils with crosslinks doesn't occur in what syndrome?
ehlers-danlos
vimentin stains what?
connective tissue
what does desmin stain?
muscle
what does cytokeratin stain?
epithelial cells
what do glial fibrillary acid proteins (GFAP) stain?
neuroglia
what do neurofliaments stain?
neurons
fatty acid oxidation (beta-oxidation), acteyl-CoA production, Krebs cycle occur where?
mitochondria
glycolysis, fatty acid synthesis, HMP shunt, protein synthesis (RER), steroid syntheis (SER) occur where?
cytoplasm
where do gluconeogenesis, urea cycle, and heme synthesis occur?
both mitochondria and cytoplasm
the 2 phosphoanhydride bonds in ATP have how many kcal/mol each?
7 kcal/mole
aerobic metabolism of glucose produces how many ATP via malate shuttle?
38 (malate - mal8)
aerobic metabolism of glucose produces how many ATP via G3P shuttle?
36
how many ATP per glucose does anaerobic glycolysis produce?
2
what is ATP composed of?
base (adenine), ribose, 3 phosphoryls, 2 phosphoanhydride bonds
ATP + methionine = ?
S-adenosyl-methionine (SAM)
what does S-adenosyl-methionine do?
transfers methyl units to a wide variety of acceptors (SAM the methyl donor man)
regeneration of methionine (and thus SAM) is dependent on what?
vitamin B12
this yields CAMP via adenylate cyclase
ATP
this yields cGMP via guanylate cyclase
GTP
what is the intermediate between glutamate and GABA? what does it require?
glutamate decarboxylase - requires vitamin B6
choline -> ACh via what?
choline acetyltransferase
arachidonate yields what products via cyclooxygenase/lipoxygenase?
prostaglandins, thromboxanes, leukotrienes
what is the rate-limiting enzyme of glycolysis?
phosphofructokinase (PFK)
phosphofructokinase catalyzes fructose-6-P to what?
fructose-1,6-bis-P
what reaction does bisphosphoglycerate mutase catalyze?
1,3-BPG to 2,3 BPG
what is NADPH used in?
1. anabolic processes, 2. respiratory burst, 3. P450
this is usually used in catabolic processes to carry reducing equivalents away as NADH
NAD+
this is used in anabolic processes (steroid and fatty acid synthesis) as a supply of reducing equivalents
NADPH - product of the HMP shunt
where is hexokinase found?
throughout the body
where is glucokinase found?
primarily in the liver (gLucokinase-Liver)
this enzyme phosphorylates excess glucose to sequester it in the liver as G6P
glucokinase
what enzyme is feedback inhibited by G6P?
hexokinase
how do RBCS metabolize glucose? what do they depend on?
anaerobically (no mitochondria) - therefore depend solely on glycolysis
what catalyzes D-glucose -> G-6-P?
hexokinase/glucokinase
what catalyzes fructose-6-P -> fructose 1,6-BP?
phoshofructokinase (rate-limiting step)
what inhibits fructose-6-P -> fructose 1,6-BP?
ATP, citrate
what promotes fructose-6-P -> fructose 1,6-BP?
AMP, frucotse-2,6-BP
what catalyzes phosphoenolpyruvate -> pyruvate?
pyruvate kinase
what inhibits phosphoenolpyruvate -> pyruvate?
ATP, alanine
what promotes phosphoenolpyruvate -> pyruvate?
fructose-1-6-BP
what catalyzes pyruvate -> acetyl-CoA?
pyruvate dehydrogenase
what inhibits pyruvate -> acetyl-CoA?
ATP, NADH, acetyl-CoA
chronic granulomatous disease is related to a deficiency of what?
NADPH oxidase
deficiencies in hexokinase, glucose phosphate isomerase, aldolase, triosephosphate isomerase, phosphate glycerate kinase, enolase, and pyruvate kinase are associated with what?
hemolytic anemia
what does the pyruvate dehydrogenase complex require?
first 4 B vitamins plus lipoic acid: 1. pyrophosphate (B1, thiamine, TPP) 2. FAD (B2, riboflavin), 3. NAD (B3, niacin), 4. CoA (B5, panthotenate), 5. lipoic acid
pyruvate + NAD+ + CoA -> ???
acetyl-CoA + CO2 + NADH
what happens in pyruvate dehydrogenase deficiency?
causes backup of substrate (pyruvate and alanine), resulting in lactic acidosis - neuro defects
what is the treatment for pyruvate dehydrogenase deficiency?
increase intake of ketogenic nutrients, e.g. high fat content or increased lysine and leucine
what are the only purely ketogenic amino acids?
lysine and leucine
B1 deficiency in alcoholics can lead to what other deficiency?
pyruvate dehydrogenase
how many ATP equivalents are needed to generate glucose from pyruvate?
6 ATP
what serves as a carrier of amino groups from muscle to liver in pyruvate metabolism?
alanine
what does the Cori cycle do?
transfers excess reducing equivalents from RBCs and muscle to liver, allowing muscle to function anaerobically - net 2 ATP
what complex requires the same cofactors as the pyruvate dehydrogenase complex?
alpha-ketoglutarate dehydrogenase complex
how many ATP/acetyl-CoA does the TCA cycle produce?
12
how many NADH per acetyl CoA does the TCA cycle produce? per glucose?
3, 6
how many FADH2 and GTP does the TCA cycle produce per acetyl CoA?
1 of each (2 per glucose)
how many CO2 does the TCA cycle produce per acetyl CoA?
2 (CO2); 4 per glucose
in the electron transport chain, 1 NADH yields what?
3 ATP
in the electron transport chain, 1 FADH2 yields what?
2 ATP
what do rotenone, antimycin A, CN-, CO do?
directly inhibit electron transport, causing a decrease of proton gradient and block of ATP synthesis
what does oligomycin do?
directly inhibits mitochondrial ATPase, causing an increase of proton gradient, but no ATP is produced because electron transport stops
what do uncoupling agents, e.g. 2,4 DNP, do to oxidative phosphorylation?
increase permeability of membrane, causing a decrease of proton gradient and increased O2 consumption; ATP synthesis stops, electron transport continues
what are the irreversible enzymes in gluconeogenesis?
Pathway Produces Fresh Glucose: pyruvate carboxylase, PEP carboxykinase, fructose-1,6-bisphosphatase, glucose-6-phosphatase
what does pyruvate carboxylase catalyze? where does it occur?
pyruvate -> oxaloacetate; in mitochondira
this step of gluconeogenesis requires biotin and ATP, and is activated by acetyl-CoA
pyruvate -> oxaloacetate
what catalyzes oxaloacetate -> phophoenolpyruvate? where does this step of gluconeogenesis occur?
PEP carboxykinase; cytosol
what catalyzes fructose 1,6-bisphophate -> fructose-6-P? where does it occur?
fructose-1,6-bisphosphatase; cytosol
what reaction does glucose-6-phosphatase catalyze?
glucose-6-P -> glucose (in cytosol)
where are the enzymes of gluconeogenesis found?
liver, kidneys, intestinal epithelium (muscle cannot participate in gluconeogenesis)
what do deficiencies of the key gluconeogenesis enzymes cause?
hypoglycemia
what is the role of the pentose phosphate pathway (HMP shunt)?
1. produces ribose 5P from G6P for nucleotide synthesis 2. produces NADPH from NADP+ for fatty acid and steroid biosynthesis and for maintaining reduced glutathione inside RBCs
all reactions of the HMP shunt occur where?
cytoplasm
how much ATP is used and produced in the HMP shunt?
none
in what sites does the HMP shunt occur?
lactating mammary glands, liver, adrenal cortex - all sites of fatty acid or steroid synthesis
what are the ketogenic essential amino acids?
leucine, lysine
what are the glucogenic/ketogenic essential amino acids?
Ile, Phe, Trp
what are the glucogenic essential amino acids?
Met, Thr, Val, Arg, His
which amino acids are required during periods of growth?
Arg, His
what is the most basic amino acid?
arginine
arginine and lysine are found in high amounts where?
histones, which bind to negatively charged DNA
at body pH (7.4), acidic amino acids aspartic acid (Asp) and glutamic acid (Glu) have what charge?
negative
at body pH, basic amino acids Arg and Lys have what charge?
positive
what net charge does basic amino acid histidine have at body pH?
no net charge
what amino acids have an extra NH3 group?
Arg and Lys
what cycle degrades amino acids into amino groups?
urea cycle
the urea cycle accounts for what percent of nitrogen in urine?
90%
where in the body does the urea cycle take place?
liver
where in the cell does carbamoyl phosphate incorporation (in urea cycle) take place?
mitochondria
all steps of the urea cycle except for carbamoyl phosphate incorporation occur where?
cytosol
histamine is derived from what amino acid?
histidine
porphyrin -> heme comes from what amino acid?
glycine
creatine, urea, and nitric oxide all come from what amino acid?
arginine
GABA is derived from what amino acid?
glutamate
tyrosine (->thyroxine) -> dopa (->melanin) -> dopamine -> NE -> epi originates from what amino acid?
phenylaline
niacin, serotonin, melatonin all come from what amino acid?
tryptophan
what coenzyme is used by pyruvate dehydrogenase to convert pyruvate to acetyl CoA (in the absence of this, pyruvate accumulates and can be converted by lactate dehydrogenase to lactate, which is spilled in the blood causing lactic acidosis)
thiamine
waht do exopeptidases do?
can remove amino acids from the amino- or carboxyl-terminus of a protein
what do endopeptidases do?
cut AA bond within a molecule
what is the rate-limiting enzyme of glycolysis?
phosphofructokinase
what are the essential amino acids?
lysine, isoleucine, leucine, threonine, valine, tryptophan, phenylaline, methionine, histidine (& tyrosine b/c synthesized from phenylaline; arginine required for growth)
what areas of the body don't need insulin for glucose uptake into cells?
brain, RBCs, intestine, cornea, kidney, liver
BRICK L
where are GLUT2 receptors found?
beta cells
where are GLUT4 receptors found?
muscle and fat
what are the anabolic effects of insulin?
(1) increases glucose transport, (2) increases glycogen synthesis and storage, (3) increases TG synthesis and storage, (4) increases Na retention in kidneys, (5) increases protein synthesis
what does glucagon do to glycogen synthase and phosphorylase?
glucagon phosphorylates stuff : turns glycogen synthase OFF and phosphorylase ON
what does insulin do to glycogen synthase and phosphorylase?
insulin dephosphorylates stuff - turns glycogen synthase ON and phosphorylase OFF
where does fatty acid degradation take place?
where its products will be consumed - in the mitochondrion
urine test for ketones does not detect what?
beta-hydroxybutyrate (favored by high redox state)
what are ketone bodies made from?
HMG-CoA
what are ketone bodies metabolized into by the brain?
2 molecules of acetyl-CoA
what catalyzes the rate-limiting step in cholesterol synthesis?
HMG-CoA reductase, which converts HMG CoA to mevalonate
2/3 of plasma cholesterol is esterified by what?
lecithin-cholesterol acyltransferase (LCAT)
what is the role of pancreatic lipase?
degradation of dietary TG in the small intestine
what degrades TG in circulating chylomicrons and VLDLs?
lipoprotein lipase
what is the role of hepatic TG lipase?
degradation of TG remaining in IDL
what degrades TG in stored adipocytes?
hormone-sensitive lipase
what is the role of alipoprotein A-I?
Activates LCAT (A-activate)
which apolipoprotein binds to the LDL receptor?
apo B-100
what is the role of apo C-II
cofactor for lipoprotein lipase
what apolipoprotein mediates extra (remnant) uptake?
apo E (E-extra)
this lipoprotein delivers dietary triglycerides to peripheral tissues and cholesterol to the liver; secreted by intestinal epithelial cells
chylomicron
excess of this lipoprotein causes pancreatitis, lipemia retinalis, and eruptive xanthomas
chylomicron
what apolipoprotein mediates secretion of chylomicrons?
apo B-48
what lipoprotein delivers hepatic triglycerides to peripheral tissues? what is it secreted by?
VLDL - secreted by liver
this lipoprotein is formed in the degradation of VLDL & delivers TG and cholesterol to the liver, where they are degraded to LDL
IDL
what is the role of LDL?
delivers hepatic cholesterol to peripheral tissues
what lipoprotein is formed by lipoprotein lipase modification of VLDL in the peripheral tissue?
LDL
excess of this lipoprotein causes atherosclerosis, xanthomas, and arcus corneae
LDL
what is the role of HDL?
mediates transport of cholesterol from periphery to liver; acts as a repository for apoC and apoE
from where is HDL secreted?
both liver and intestine
what is the first step in heme synthesis? what catalyzes it?
succinyl CoA + glycine … catalyzed by ALA synthetase
what occurs in lead poisoning?
inhibition of ferrochelatase and ALA dehydrase
what accumulates in urine in lead poisoning?
coproporphyrin and ALA
what is deficient in acute intermittent porphyria?
deficiency in uroporphyrinogen I synthetase
what accumulates in acute intermittent porphyria?
porphobilinogen and delta-ALA
what is the deficiency in porphyria cutanea tarda?
uroporphyrinogen decarboxylase
waht accumulates in urine in porphyria cutanea tarda? what else is this associated with?
uroporphyrin accumulates (tea-colored urine); associated with photosensitivity
painful abdomen, pink urine, polyneuropathy, psych disturbances, precipitated by drugs?
symptoms of porphyrias
which form of hemoglobin has a higher affinity for O2?
relaxed form (300x affinity of taut form)
increased Cl-, H+, CO2, 2,3-BPG and temp favor what form of Hb? Which way does the O2 curve shift?
R form; shifts to right, leading to increased O2 unloading
this is an oxidized form of Hb (ferric, Fe3+) that does not bind O2 as readily but has an increased affinity for CN-
methemoglobin
what do you administer in cyanide poisoning?
nitrates to oxidize Hb to methemoglobin form
with what do you treat toxic levels of methemoglobin?
methylene blue
CO2 binding to Hb favors what form?
T (taut)
phospholipids and sphingolipids are what type of molecules? what type of vesicles do they form?
ampiphathic molecules - two hydrophobic tails; form bilayer vesicles
where does beta-oxidation of very long chain fatty acids occur?
peroxisomes
where does degradation of DNA occur?
lysosomes
where does oxidative phosphorylation occur?
mitochondria
where does post-translational modification of proteins occur?
golgi
when NO is released and diffuses into a smooth muscle cell, what does it turn on?
guanylate cyclase, which makes the second messenger cGMP, which triggers smooth muscle relaxation
what synthesized nitric oxide from arginine?
nitric oxide synthase - produces citrulline as a by-product
this is used to form nucleotids by adding a phosphoribosyl group to a nitrogenous base
phosphoribosyltransferase
what covers most microvilli & apparently helps to prevent them from trauma?
layer of glycocalyx
what is glial fibrillary acidic protein?
intermediate filament found in astrocytes
how are chromatids pulled apart during anaphase?
kinetochore microtuules from each of the two spindle poles attach to teh kinetochore plates of the centromere to pull the chromatids apart during anaphase
gap junctions are made of a hexagonal lattice of tubular rotein subunits called what?
connexons - form hydrophilic channels connecting the cytoplasm of adjacent cells
what structure are sealing strands found in?
tight junctions
what are tonofilaments found in?
desmosomes and hemidesmosomes
what contains type IV collagen, glycoproteins including laminin, and proteoglycans, including heparan sulfate?
basal lamina
what involves unfolding a fully translated protein, transporting it into the mitochondria, and then refolding it using other HSP proteins?
import of mitochondrial proteins from the cytosol into the mitochondria
what type of gene is the Rb gene?
tumor suppressor
what is the role of calreticulin?
binds to misfolded proteins and prevents them from being exported to the golgi
where does synthesis of the LDL receptor begin?
in cytosol on free ribosomes - completed on ribosomes bound to RER
what happens if a protein cannot refold properly?
it is targeted for degradation by proteases
the formation of a junctional complex relies on what?
homotypic interaction between E-cadherin proteins on adjacent cells - initiates the formation of zona adherens, including signaling pathways, which are then activated to initiate the formation of zona occludens and desmosomes
what are microvilli made of?
extensions of bundles of actin filaments, or microfilaments; myosin is associated
during contraction of a skeletal muscle, what maintains its uncontracted length?
A band
what quality control chaperone in the RER binds to misfolded membrane proteins and prevents them form proceeding to the golgi?
calreticulin
what quality control chaperone binds to misfolded soluble proteins and prevents them from going to the golgi?
calnexin
what do antibodies attack in pemphigus vulgaris?
desmoglein
what is the transmembrane cadherin that forms intercellular linkages at desmosomes?
desmoglein
what organelle is responsible for sorting and packaging of proteins?
RER
what protein property is birefringence related to?
beta-pleated sheet secondary structure
the crystalline core of an eosinic granule contains what?
major basic protein - appears to function in the destruction of parasites
name 3 sites where elastic fibers are found
large arteries (esp. aorta), vocal cords, and ligamenta flava (which connect the vertebrae); small amounts also found in skin
acini in what salivary gland are almost pure mucous cells?
sublingual, submandibular, parotid
acini in what salivary gland are a mixture of serous and mucuous cells?
submandibular
acini in what salivary gland are mostly pure serous cells?
parotid
striated muscle under voluntary control is found in what part of the esophagus?
upper third; middle third is roughly half striated and half smooth; lower third contains only smooth
primordial eggs remain stopped in what stage from before birth until ovulation?
diplotene stage of first meotic division
what is the appropriate stain for pneumocystis?
methenamine silver
what cells of the anterior pituitary stain pink?
somatotropes - GH, mammotropes - prolactin
what cells of the anterior pituitary stain blue on H&E?
corticotropes - ACTH, gonadotropes - FSH & LH, thyrotropes - TSH
what is the only site of the kidney in which epithelial cells have a brush border made of microvilli?
proximal convoluted tubule
how do fascial straps (retinacula) and fascial coverings of muscles or muscle groups attach to nearby bones?
blending with the covering periosteum; no deep attachments are made by fascia
what are the three phases of spermatogenesis?
spermatocytogenesis, meiosis, spermiogenesis
what type of cell is the germ cell closest to the basal lamina in the seminiferous tubule?
spermatogonia
what ear structure contains hair cells?
organ of corti (from the cochlear branch of CN VII)
what is a good stain for fungi?
methenamine silver
why is cartilage particularly vulnerable to infection?
because it is relatively avascular - immune system cannot access it effeciently
calcification of what is notorious for producing 'phantom' lung lesions?
hyaline cartilage of the costal cartilages
what type of cell is spindle-shaped like a fibroblast but contains several bundlese of microfilaments in its cytoplasm?
myofibroblast
where is fenestrated epithelium seen?
liver
what is responsible for producing the majority of new bone after a fracture?
periosteum
what catalyzes the irreversible conversion of pyruvate to acetyl CoA?
pyruvate dehydrogenase
if pyruvate dehydrogenase is absent, what will it be converted to?
alanine via alanine aminotransferase;
lactate via lactate dehydrogenase
what is the porphyrin ring of heme derived from?
TCA cycle intermediate succinyl-CoA and AA glycine; this initial synthetic step, which is rate-limiting, is catalyzed by aminolevulinic acid synthase
vitamin K is an important coenzyme for what?
gamma-gluyamylcarboxylase, an enzyme that catalyzes a post-translational modification of a group of calcium-binding proteins
how does vitamin K deficiency manifest in infants?
GI bleeding, skin hemorrhages, intracranial hemorrhage
late-onset vitamin K bleeding can occur between 1-6 months after birth - risk factors include exclusive breast feeding because human milk is low in vitamin K
absence of vitamin B12 results in the accumulation of what?
methylmalonyl-CoA (B12 is a cofactor in the conversion of methylmalonyl-CoA to succinyl-CoA)
what is the clinical picture associated with galactokinase deficiency?
very mild disease - only significant complication is cataract formation
what does homozygous deficiency of galactose-1-phosphate uridyltransferase lead to?
severe disease, culminating in death in infancy: impaired renal tubular absorption leading to aminoaciduria, GI symptoms, hepatosplenomegaly, cataracts, bleeding diatheses, hypoglycemia, and MR
what is the process of glycolysis?
converts glucose into pyruvate with concomitant production of ATP
name three ketone bodies
acetoacetate, beta-hydroxybutyrate, and acetone
when/how are ketone bodies produced?
produced by liver in the fasting state by beta-oxidation of fatty acids
this condition is associated wth MR, hepatosplenomegaly, foam cells in bone marrow, cherry red spots, and neuro deficits - death by 3 years of age is common
Niemann-Pick
what is the mechanism of cipro?
inhibits DNA gyrase (prokaryotic topoisomerase II) essential for DNA replication
what is the mechanism of statins?
HMG-CoA reductase inhibitors
this syndrome is characterized by MR, nervous system malformations, rocker-bottom feet, polydactyly, and cleft lip and palate
Trisomy 13/Patau syndrome
where does the clinically important degradation of ethanol to acetaldehyde occur in humans?
peroxisomes and SER (P450)
where is acetaldehyde oxidized to acetate?
mitochondria
what is the defect in von Gierke's?
glucose-6-phosphatase
what is Smith-Lemli-Opitz syndrome?
recessive genetic disease - first single-gene disease to be associated with multiple malformations
microcephaly, MR, hypotonia, incomplete development of genitalia, high forehead, pyloric stenosis, syndactyly of 2nd and 3rd toes are characteristic of what syndrome?
Smith-Lemli-Opitz
what technique is used to identify a specific protein that may be present in very small concentrations in a complex protein mixture?
Western blotting
what technique utilizes DNA-RNA hybridization to determine the size and abundance of RNA for a specific gene?
Northern blotting
what technique utilizes DNA-DNA hybridization?
Southern blotting
what technique involves DNA-protein interactions?
Southwestern blotting - a protein sample is subjected to electrophoresis, transferred to a filter, and exposed to labeled DNA
following treatment of ALL, patients often have a high level of what? how do you treat them?
urate (secondary to breakdown of nucleic acids) - Rx: allopurinol to decrease plasma urate levels (inhibition of xanthine oxidase)
what is the best technique for determining whether a gene is expresed in a particular cell type?
Northern blot
what is the most common technique used to screen for cystic fibrosis?
PCR
what is the primary source of ketones in diabetic ketoacidosis?
free fatty acid breakdown
severe neonatal jaundice, elevated indirect bilirubin, and exchange blood transfusion suggest what?
hemolysis
increased levels of 2,3 BPG, 3-PG, 2-PG, and PEP correspond with what type of hemolytic anemia?
one induced by pyruvate kinase deficiency
perifollicular hemorrhages, fragmentation of hairs, purpura, ecchymoses, splinter hemorrhages, and hemorrhages into muscle are characteristic of what?
vitamin C deficiency
nearly 90% of cases of hereditary nonpolyposis colorectal cancer are linked to mutations in what?
mismatch repair genes - e.g. hMLH1 & hMSH2
hypolglycemia with hypoketosis after fasting suggests what? accumulation of organic dicarboxylic acids suggests what?
a block in fatty acid oxidation - fatty acyl CoA dehydrogenase deficiency: most commonly medium chain acyl CoA dehydrogenase (MCAD) deficiency
dementia, ataxia, ophthalmoplegia?
wernicke encephalopathy
in what people does wernicke encephalopathy typically develop? what is it a result of?
alcoholics; thiamine deficiency
what are the four major enzymes requiring thiamine pyrophosphate?
pyruvate dehydrogenase, alpha-ketoglutarate deydrogenase, branched-chain ketoacid dehydrogenase, transketolase
a child with ketotic hypoglycemia following a period of fasting most likely has a defect in what?
gluconeogenesis (or pathway providing substrates for gluconeogenesis)
under fasting conditions, what is the primary substrate for gluconeogenesis?
alanine (derived from muscle protein)
in a child with ketotic hypoglycemia, if alanine rapidly increases blood glucose, what is the likely defect?
defect in protein catabolism (rules out defect in gluconeogenesis)
what LOD score is required to establish linkage between two loci?
3.00 or higher
what LOD score is required to rule out linkage between two loci?
-2.00 or less
what two red cell enzyme deficiencies are characterized clinically by long 'normal' periods interspersed with episodes of hemolytic anemia triggered by infections and oxidant drug injury?
pyruvate kinase deficiency and G6PD deficiency
primers in PCR must pair up with what?
the 3' sequences of the two strands (sequence of left primer is identical to that of top strand and sequence of right primer is identical to bottom strand written 5'to 3')
alopecia is related to deficiency of what vitamin?
vitamin A
what begins the HMP shunt?
conversion of glucose-6-phosphate to 6-phosphogluconate
what pathway increases the ratio of NADPH/NADP+?
HMP shunt
proteins destined to be secreted are synthesized where?
on ribosomes associated with RER
proteins destined for the cytosol and several organelles are synthesized on what?
'free' ribosomes
what are the characteristics of abetalipoproteinemia?
rare AR disorder characterized by very low levels of serum cholesterol and triglyceride
what is absent in abetalipoproteinemia?
ApoB-containing lipoproteins (chylomicrons, VLDL, LDL)
what enzyme is closely related to the role of folate in lowering the risk of CV disease?
homocysteine methyltransferase
what does cyanide inhibit?
cytochrome oxidase - causes loss of all ATP production associated with oxidative phosphorylation
on what chromosome is the Wilms tumor suppressor gene located?
chromosome 11
a higher Km means a lower what?
affinity
liver and steroidogenic tissues have a scavenger receptor that recognizes HDL and mediates transfer of cholesterol into these tissues - what is it called?
SR-B1
triad of ophthalmoplegia, ataxia, and global confusion?
Wernicke encephalopathy - requires immediate administration of B1/thiamine
where is ribosomal RNA manufactured?
nucleolus
ingestion of alcohol and what else can exacerbate hyperuricemia/gout?
nucleic acids - foods rich in DNA (caviar) or RNA (liver pate and sweetbreads (pancreas)) are sources of purines
what is MELAS?
mitochondrial encephalomyopaty, lactic acidosis, and stroke-like episodes
what is seen on muscle biopsy in patients with MELAS?
ragged red muscle fibers and disrupted mitochondria
what high-energy compound is formed when succinate thiokinase catalyzes the cleavage of the succinl-CoA thoiester bond?
GTP
what is the energy source used in protein synthesis (formation of activated elongation factor to which tRNA binds & in transfer of elongating chain from P to A site in ribosome)
GTP
proteins that fail to achieve normal tertiary and quaternary structures are retained where?
RER
vitamin B12 deficiency causes an increase in what in urine?
methylmalonate (due to low activity of methylmalonyl CoA mutase)
1 gram of protein or carbs produces how many kcal of energy?
about 4
one gram of fat produces how many kcal of energy?
9
deletion of two nucleotides will lead to what type of mutation?
frame-shift
children with this disease are generally healthy for the first two years but develop progressive hepatosplenomegaly with accumulation of glucocerebroside in macrophages
Gaucher's
flaring of the distal femur is common in this disease - may be described as having an Erlenmeyer flask appearance
Gaucher's
what binds to receptors with zinc finger motifs?
steroid hormones
what amino acid can partially take the place of niacin?
tryptophan - about 2% can be converted to quinolinate, which can then be used in place of niacin in NAD synthesis
if misfolded proteins accumulate in large quantities, where will they be found?
ER
weakness accompanied by difficulty in relaxation that is most pronounced in hands and feet; cataracts, testicular atrophy, heart disease, dementia, baldness?
myotonic dystrophy
the affected gene in myotonic dystrophy is located on what chromosome? how is it inherited?
19; autosomal dominant
the DNA polymerase used in PCR is highly resistant to what?
heat - comes from bacteria that grow in hot springs
during intense exercise, in what form will carbons derived from glucose enter the TCA cycle?
acetyl-CoA
what syndrome is due to a defect in copper transporting P-type ATPase?
Ehlers-Danlos
this contributes to hyperlipidemia in type I diabetes (and thus the risk for lipid deposition in the retina)
overactive hormone-sensitive lipase
dideoxycytidine (an antiviral) works by preventing what?
formation of a phosphodiester bond during viral DNA synthesis
how is Leber hereditary optic neuropathy inherited?
mitochondrial
about 20% of patients with 13q syndrome develope what?
retinoblastoma
what is the deficiency in fructose intolerance?
aldolase B
what accumulates in fructose intolerance, and what is the result?
fructose-1-phosphate accumulates, causing a decrease in available phosphate, which results in inhibition of glycogenolysis and gluconeogenesis
what are the symptoms of fructose intolerance?
hypoglycemia, jaundice, cirrhosis, vomiting
what is the treatment for fructose intolerance?
decrease intake of both fructose and sucrose (glucose + fructose)
what is the defect in essential fructosuria?
defect in fructokinase - benign, asymptomatic condition
what are the symptoms of essential fructosuria?
fructose appears in blood and urine
what is absent in galactosemia? what is the mode of inheritance?
absence of galactose-1-phosphate uridyltransferase; autosmal recessive
how is damage caused in galactosemia?
accumulation of toxic substances (including galactitol) rather than absence of an essential compound
what are the symptoms of galactosemia?
cataracts, hepatosplenomegaly, MR
what is the treatment for galactosemia?
exclude galactose and lactose (glucose + galactose) from diet
what does galactokinase deficiency cause?
galactosemia & galactosuria; galactitol accumulation if galactose is present in diet
what is decreased in PKU?
phenylaline hydroxlase or tetrahydrobiopterin cofactor
this disorder is characterized by excess pheylketones in urine (phenylacetate, phenyllactate, phenylpyruvate)
PKU
how is PKU inherited; what is the approximate incidence
autosomal-recessive; 1:10,000
what are the findings in PKU?
MR, growth retardation, fair skin, eczema, musty body odor
what is the treatment for PKU?
decrease phenylaline and increase tyrosine in diet
this is a congenital deficiency of homogenistic acid oxidase in the degradative pathway of tyrosine
alkaptonuria
what disease is characterized by urine that turns black on standing? what causes this?
alkaptonuria; alkapton bodies, connective tissue is also dark
although alkaptonuria is considered benign, it may be associated iwth this debilitating symptom
arthralgias
congenital deficiency of tyrosinase results in what?
albinism - inability to synthesize melanin from tyrosine
albinism may be caused by 2 deficiencies - what are they?
1. deficiency of tyrosinase or 2. defective tyrosine trasnporters
what may be the cause of albinism?
lack of migration of neural crest cells
what becomes essential in homocystinuria?
cysteine
cystathionine synthesis deficiency is a form of what?
homocystinuria
what is the treatment for cystathionine deficiency?
decrease Met and increase Cys in diet
decreased affinity of cystathionine synthase for pyriodoxal phosphate is a form of what?
homocystinuria
what is the treament for decreased affinity of cystahionine synthase for pyriodoxal phosphate?
increase vitamin B6 in diet
what are potential symptoms of homocystinuria?
MR, osteoporosis, tall stature, kyphosis, lens subluxation (downward and inward), and atheroscleorsis (stroke and MI)
how common is cystinuria?
1:7000
what is cystinuria?
inherited defect of renal tubular AA transporter for cystine, ornithine, lysine, arginine (COLA)
how do you treat cystinuria?
acetazolamide to alkalinize urine
what is a potential complication of cystinuria?
cystine kidney stones
what is the defect in maple syrup urine disease?
blocked degradation of branched amino acids due to decreased alpha-ketoacid dehydrogenase
what are the branched AA's?
Ile, Val, Leu (I Love Vermont)
what happens in maple syrup urine disease?
increased alpha-ketoacids in the blood, especially Leu -- causes severe CNS defects, MR, and death
a deficiency in what enzyme can cause SCID?
adenosine deaminase
what was the first disease to be treated by experimental gene therapy?
adenosine deaminase deficiency
what is absent in Lesch-Nyan syndrome?
HGPRTase, which converts hypoxanthine to inosine monophosphate (IMP) and guanine to guanosine monophosphate (GMP)
how is Lesch-Nyan inherited
X-linked recessive
retardation, self-mutilation, aggression, hyperuricemia, gout, and choreoathetosis are findings in what syndrome?
Lesch-Nyan
this syndrome is marked by a purine salvage problem
Lesch-Nyan
in this syndrome, excess ATP and dATP imbalances nucleotide pool via feedback inhibition of ribonucleotide reductase, which prevents DNA synthesis and thus decreases lymphocyte count
adenosine deaminase deficiency
what gycogen storage disease is due to a deficiency in glucose-6-phosphatase? what type is it?
Von Gierke's; type I
severe fasting hypoglycemia, marked increase of glycogen in liver, hepatomegaly, and increased blood lactate are characteristic of what glycogen storage disease?
Von Gierke's
what is the deficiency in Pompe's disease? what type is it?
lysosomal alpha-1,4 glucosidase deficiency; type II
what glycogen storage disease is marked by cardiomegaly and systemic findings, leading to early cardiac death?
Pompe's - Pompe's trashes the Pump (heart, liver, and muscle)
what is the deficiency in Cori's disease?
debranching enzyme alpha-1,6-glucosidase; type III
this glycogen storage disease is a milder form of type I with normal blood lactate levels
Cori's disease; type III
what is the deficiency in McArdle's disease?
skeletal muscle glycogen phosphorylase; type V
painful cramps and myoglobinuria during exercise are characteristic of what glycogen storage disease?
McArdle's
what is the deficient enzyme in Fabry's disease, and what substate is accumulated?
alpha-galactosidase A; ceramide trihexoside (fAbry)
Fabry's disease and Hunter's syndrome are inherited in what manner?
X-linked recessive (Fabry the Hunter aims for the X)
peripheral neuropathy of the hands and feet, angiokeratomas, CV/renal disease are characteristic of what lysosomal storage disease?
Fabry's disease
hepatosplenomegaly, aseptic necrosis of femur, bone crises are characteristic of what lysosomal storage disease?
Gaucher's (AR)
what is the deficient enzyme in Gaucher's disease? what substrate accumulates?
beta-glucocerebrosidase; glucocerebroside
what is the deficient enzyme in Niemann-Pick disease? what subtrate accumulates?
sphingomyelinase; sphingomyelin (AR) (no man picks his nose with his sphinger)
progressive neurodegeneration, hepatosplenomegaly, cherry-red spot on macula are characteristic of what lysosomal storage disease?
Niemann-Pick
hexosaminidase A is deficient and GM2 ganglioside accumulates in what lysosomal storage disease?
Tay-Sachs (Tay SaX lacks heXosaminidase)
this lysosomal storage disease is characterized by progressive neurodegeneration, developmental delay, cherry-red spot, lysozymes with onion skin
Tay-Sachs
what enzyme is deficient in Krabbe's disease? what accumulates?
beta-galctosidase; galactocerebroside
name 3 characteristics of Krabbe's disease
peripheral neuropathy, developmental delay, optic atrophy
this lysosomal storage disease is marked by central and peripheral demyelination with ataxia, dementia
metachromatic leukodystrophy
in this lysosomal storage disease, arylsulfatse A is deficient and cerebroside sulfate accumulates
metachromatic leukodystrophy
developmental delay, gargoylism, airway obstruction, corneal clouding, hepatosplenomegaly are characteristic of what lysosomal storage disease?
Hurler's syndrome
alpha-L-iduronidase is deficient and heparan sulfate, dermatan sulfate accumulate in which lysosomal storage disease?
Hurler's syndrome (alpha-L-iduronidase - HurLer's)
the symptoms of this lysosomal storage disease are similar to Hurler's, but there is aggressive behavior and no corneal clouding
Hunter's (you have to see and be aggressive if you are a hunter)
in what syndrome is there a deficiency of iduronate sulfatase and accumulation of heparan sulfate/dermatan sulfate?
Hunter's (X-linked recessive)
what do the defectve LDL receptors in familial hypercholesterolemia recognize?
apo-B 100 protein (cotransported with cholesterol esters in LDL)
what pathway is altered in achondroplasia?
cell signaling (FGFR3)
what condition clinically resembles pellagra?
Hartnup's disease (diarrhea, dementia, dermatitis)
what is the underlying defect in Hartnup's disease?
defect in epithelial transport of neutral AA's, including tryptophan, which can act as a precursor of niacin - poor dietary absorption of AA's & excess AA secretion into urine
normal child at birth who begins to suffer from diminished responsiveness, deafness, blindness, loss of neuro function, seizures?
Tay-Sachs - death by 4/5
a defect in what enzyme would yield chylomicrons in plasma?
lipoprotein lipase
severe memory deficit with confabulation in an alcoholic?
thiamine deficiency
type of gall stones in patient with sickle cell?
calcium bilirubinate
B-complex deficiencies often result in what?
dermatitis, glossitis, diarrhea
thiamine: TPP
vitamin B1
riboflavin: FAD, FMN
vitamin B2
niacin: NAD+
vitamin B3
pantothenate: CoA
vitamin B5
pyridoxine: PP
vitamin B6
cobalamin
vitamin B12
this vitamin is a constituent of visual pigments
vitamin A/retiol
deficiency in this vitamin can lead to night blindness, dry skin, and impaired immune response
vitamin A
excess of this vitamin can cause arthralgias, fatigues, headaches, skin changes, sore throat, allopecia
vitamin A
deficiency of this vitamin is seen in beriberi and Wernicke-Korsakoff syndrome; seen in alcoholism and malnutrition
vitamin B1
which beriberi is associated with polyneuritis, muscle wasting?
dry
which beriberi is associated with high-output cardiac failure (dilated cardiomyopathy) and edema?
wet
in thiamine pyrophosphate, this vitamin serves as a cofactor for oxidative decarboxylation of alpha-keto acids (pyruvate, alpha-ketoglutarate) and as a cofactor for transketolase in the HMP shunt
vitamin B1
deficiency of this vitamin leads to angular stomatitis, cheilosis, corneal vascularization
vitamin B2 (the 2 C's)
this vitamin serves as a cofactor in oxidation and reduction (e.g. FADH2)
vitamin B2 (FAD and FMN are derived from riboFlavin (B2=2 ATP))
what are the symptoms of pellagra/vitamin B3 deficiency?
3 D's: diarrhea, dermatitis, dementia (also beefy glossitis)
Hartnup disease (increased tryptophan absorption), malignant carcinoid syndrome (increased tryptophan metabolism), and INH (decreased vit. B6) can all cause what vitamin deficiency?
pellagra (vitamin B3/niacin)
which vitamin is derived from tryptophan using vitamin B6 and is a constituent of NAD+ and NADP+?
vitamin B3/niacin (NAD derived from Niacin; B3 = 3 ATP)
deficiency of this vitamin can cause dermatitis, enteritis, alopecia, and adrenal insufficiency
vitamin B5 (pantothenate)
this vitamin is a constituent of CoA (a cofactor for acyl transfers) and component of fatty acid synthase
vitamin B5 (pantothen-A is in Co-A)
deficiency of this vitamin can cause convulsions, hyperirritability (deficiency inducible by INH and oral contraceptives), and peripheral neuropathy
vitamin B6 (pyridoxine)
this vitamin is converted to pyridoxal phosphate, a cofactor used in transamination (e.g. ALT, AST), decarboxylation, and heme synthesis
vitamin B6 (pyridoxine)
deficiency of this vitamin can cause macrocytic, megabloblastic anemia; neurologic symptoms (optic neuropathy, subacute combined degeneration, paresthesia); and glossitis
vitamin B12 (cobalamin)
where is vitamin B12 found?
only in animal products
this vitamin serves as a cofactor for homocysteine methylation (transfers CH3 groups as methylcobalammin) and methylmalonyl-CoA handling
vitamin B12
where is vitamin B12 stored?
primarily in the liver; synthesized only by microorganisms
what might the abnormal myelin seen in B12 deficiency be due to?
decreased methionine or increased methylmalonic acid (from metabolism of accumulated methylmalonyl CoA)
what is the most common vitamin deficiency in the U.S.?
folic acid
deficiency of this vitamin can cause a macrocytic, megaloblastic anemia often without neurologic symptoms
folic acid
this vitamin serves as a coenzyme 1-carbon transfer & is involved in methylation reactions; it is important for the synthesis of nitrogenous bases in DNA and RNA
folic acid
what is the folic acid precursor in bacteria? what kind of drugs are analogs of it?
PABA; sulfa drugs and dapsone are PABA analogs
deficiency of this vitamin is marked by dermatitis & enteritis, and is caused by antibiotic use and ingestion of raw eggs
biotin (avidin in eggs avidly binds biotin)
this vitamin is a cofactor for carboxylations:
biotin
pyruvate -> oxaloacetate
acetyl-CoA -> malonyl-CoA
proprionyl-CoA -> methylmalonyl-CoA
this vitamin is necessary for hydroxylation of proline and lysine in collagen synthesis
vitamin C (C Cross-links Collagen)
this vitamin facilitates iron absorption by keeping iron in Fe2+ reduced state (more absorbable) and is also necessary as a cofactor for dopamine -> NE
vitamin C
what form of vitamin D is found in milk?
D2 = ergocalciferol
what form of vitamin D is formed in sun-exposed skin?
D3=colecalciferol
what is the storage form of vitamin D?
25-OH D3
what is the active form of vitamin D?
1, 25 (OH)2 D3
deficiency of this vitamin causes rickets in children (bending bones), osteomalacia in adults (soft bones), and hypocalcemic tetany
vitamin D
this vitamin increases intestinal absorption of calcium and phosphate
vitamin D
excess of this vitamin causes hypercalcemia, loss of apetite, and stupor
vitamin D
what disease can be associated with vitamin D excess?
sarcoidosis - epitheliod macrophages convert vitamin D into its active form
deficiency of this vitamin is associated with increased fragility of erythrocytes
vitamin E (E-Erythrocytes)
deficiency of this vitamin can cause neonatal hemorrhage with increased PT and PTT but normal bleeding time
vitamin K
what are the vitamin K dependent clotting factors?
II, VII, IX, X, proteins C & S
what drug is a vitamin K antagonist?
warfarin
this vitamin catalyzes gamma-carboxylation of glutamic acid residues on various proteins concerned with blood clotting
vitamin K
what synthesizes vitamin K?
intestinal flora - deficiency can occur after prolonged broad-spectrum antibiotic use
deficiency of this vitamin is associated with delayed wound healing, hypogonadism, decreased adult hair, and may predispose to alcoholic cirrhosis
zinc
what is the rate-limiting reagent in ethanol metabolism?
NAD+
by what order kinetics does alcohol dehydrogenase operate?
zero-order
what does disulfiram inhibit? what accumulates?
inhibits acetaldehyde dehydrogenase; acetaldehyde accumulates, contributing to hangover symptoms
what is the result of the increased NADH/NAD+ ratio in the liver that is caused by ethanol metabolism?
causes diversion of pyruvate to lactate and OAA to malate - inhibits gluconeogenesis and leads to hypoglycemia
what is responsible for the hepatic fatty change seen in chronic alcoholics?
increased NADH/NAD+ ratio - shunts away from glycolysis and toward fatty acid synthesis)
this is protein malnutrition resulting in skin lesions, edema, liver malfunction (fatty change)
Kwashiorkor (small shild with swollen belly): MEAL (malabsorbtion, edema, anemia, liver (fatty))
this is protein-calorie malnutrition resulting in tissue wasting
marasmus
this type of chromatin is condensed and transcriptionally inactive
heterochromatin
this type of chromatin is less condensed and transcriptionally active
euchromatin
which type of chromatin ties nucleosomes together in a string (30-nm fiber)?
H1
what histones make up the nucleosome core?
H2A, H2B, H3, H4
what are the purines, and how many rings do they have?
A, G; 2 rings
what are the pyrimidines and how many rings do they have?
C, T, U; 1 ring (pyramids were CUT)
which nucleotide has a ketone?
guanine
which nuclotide has a methyl?
thymine (THYmine has a meTHYl)
deamination of cytosine makes what?
uracil
which bond is stronger: G-C or A-T? why?
G-C is stronger because it has 3 H bonds
what happens to the melting temperature when you increase the G-C content?
increases (b/c more H bonds)
what is it called when a purine is substituted for a purine or a pyrimidine is substituted for a pyrimidine?
transItion (Identical type)
what is it called when a purine is substituted for a pyrimidine or vice versa?
transVersion (conVersion between types)
what are some exceptions to the universality of the genetic code?
mitochonria, archaeobacteria, mycoplasma, some yeasts
what is a silent mutation
same amino acid - often base change in 3rd position of codon (tRNA wobble)
what is a missense mutation?
changed amino acid (conservative - new aa is similar in chemical structure)
what is a nonsense mutation?
change resulting in an early stop codon - stop the nonsense!
what are the stop codons?
UGA, UAA, UAG
what is the mRNA initiation codon and what does it code for in eukaryotes?
AUG, methionine (AUG inAUGurates protein synthesis
what does the initial AUG code for in prokaryotes?
formyl-methionine
what do DNA topoisomerases do?
create a nick in the helix to relieve supercoils
what does primase do?
makes an RNA primer on which DNA polymerase III can initiate replication
what does DNA polymerase III do?
elongates the chain by adding deoxynucleotides to the 3' end until it reaches primer of preceding fragment; 3' -> 5' exonuclease activity proofreads each added nucleotide
what does DNA polymerase I do?
degrades RNA primer with 5' to 3' exonuclease
what does DNA ligase do?
seals DNA
in which direction does DNA polymerase synthesis occur?
5' to 3'
in which direction does proofreading with exonuclease occur?
3' to 5'
after excision repair-specific glycosolase recognizes and removes a damaged base, what does endonuclease do?
makes a break several bases to the 5' side and removes a short stretch of nucleotidse - the n DNA polymerase fills gap and DNA ligase seals it
the 5' of the incoming nucleotide bears what?
the triphosphate/engergy sourse for bond
DNA, RNA, and protein synthesis all occur in what direction
5' to 3'
which is the largest type of RNA?
mRNA (massive)
which is the most abundant type of RNA?
rRNA (rampant)
whihc is the smallest type of RNA
tRNA (tiny)
RNA polymerase I makes what?
rRNA
RNA polymerase II makes what?
mRNA
what does RNA polymerase III make?
tRNA
alpha-amantin, a substance found in death cap mushrooms, inhibits what?
RNA polymerase II
this is the site where RNA polymerase and multiple other transcription factors bind to DNA upstram from gene locus
promoter
this is a stretch of DNA that alters gene expression by binding transcription factors
enhancer - may be located close to, far from, or even within (in an intron) teh gene whose expression it regulates
theis is the site where negative regulators (repressors) bind
operator
intervening noncoding segments of DNA are called what?
introns
where are introns spliced out of?
primary mRNA transcripts
these particles facilitate splicing by binding to primary mRNA transcripts and forming spliceosomes
snRNPs
where does RNA processing occur?
nucleus
what three events occur in RNA processing after transcription?
(1) capping on 5' end (7-methyl-G) (2) poly AAAs on 3'end (about 200 As) (3) splicing out of introns
what do all tRNAs have at the 3' end?
CCA along with a high percentage of chemically modified bases
in tRNA, the anticodon end is opposite what?
the 3' aminoacyl end
what does a mischarged tRNA do?
reads the usual codon but inserts wrong amino acid
what two things are responsible for the accuracy of amino acid selection?
aminoacyl-tRNA synthetase and binding of charged tRNA to the codon
during protein synthesis, in which site does Met sit?
in the P site - peptidyl
during protein synthesis, where does the incoming amino acid bind?
A site - aminoacyl; hydrolyzes Met's bond to its tRNA while simultaneously forming a peptidyl bond between the 2 amino acids