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USMLE Biochem

USMLE Step 1 Biochemistry

QuestionAnswer
What changes a cytosine into a uracil? a Deaminase
Which base nucleotides contain an extra amino group? AdenineCytosine
Which base nucleotide has an extra methyl group? Thymine(THYmine = meTHYl)
What are the purines?Pyrimidines? Purines: Adenine & Guanine (PURe As Gold)Pyrimidines: Cytosine, Uracil & Thymine (CUT the Py)
How does Methyltrexate work on DNA? prevents changing a uracil to a thymine
If a sample of DNA has 10% G, how much is the T %? 10% G + 10% C = 20%therefore 80%/2 = 40% T
Which DNA has a higher melting point?Why?Define melting point. CG bonds They have a triple H-bondMelting point = 50% double-stranded & 50% single-stranded DNA
What is the charge of Histones?What 2 AA are histones abundant in? PositiveArginine & Lysine
what causes chromatin to be tightly packaged?Name of this type of chromatin? (active or inactive)If it is not packed tightly, what is it sensitive to? H-1Heterochromatin - inactivenucleases
Endonuclease activation and chromatin fragmentation are characteristic of cell death by apoptosis. What nucleic cell structure would most likely be degraded first in an apoptotic cell? 10 nm fiber(this is the chromosome without the H-1; fiber b/t a nucleosome)
number of origins the prokaryote and eukaryote can begin with regarding DNA replication? Pro - oneEu - many
What is the same structure in DNA and RNA synthesis? both require a DNA template
Something that helps attach nucleotides via a PDE bond to make a new nucleic acid Polymerase(Polymer = glue)
What is needed to begin DNA synthesis?RNA synthesis? DNA: RNA primerRNA: nothing
What has the ability to proofread DNA?How and in what direction? DNA polymerase III3' -> 5' Exonuclease
What recognizes the Origin of replication in a prokaryotic and eukaryotic cell? Prokaryotic: DNA A proteinEukaryotic: nothing
Unwinds DNA in Prokaryotic and eukaryotic cells?What does it require? Helicase(requires ATP)
What stabilizes unwound template strands of DNA? SSB(Single-stranded DNA-binding protein)
What synthesizes RNA primers? Primase
Responsible for synthesis of Leading strand of DNA in the prokaryotic cell? Eukaryotic cell? Pro: DNA polymerase IIIEu: DNA polymerase Delta
Responsible for synthesis of Lagging strand of DNA in the prokaryotic and eukaryotic cell? Pro: DNA polymerase IIIEu: DNA polymerase Alpha
What is responsible for the REMOVAL of RNA primers in prokaryotic cells? In what direction/activity? Pro: DNA poly I 5' -> 3' exonuclease activity
What is responsible for replacement of RNA primer w/ DNA? DNA poly I
Joins Okazaki fragments DNA ligase
Removes positive supercoils ahead of advancing replication forks? DNA topoisomerase II
Synthesis of telomers in prokaryotic and eukaryotic cells? Pro: not required (circular)Eu: Telomerase
What requires an RNA template to direct the synthesis of new DNA? RNA-dependent DNA polymerase(Reverse Transcriptase)
DNA repair have two main enzymes that do all the REPAIR work...what are they? DNA polymeraseDNA ligase
What excises thymine dimers? Excision endonuclease
What phase of cell cycle does a mismatch base problem occur?What phase is it fixed? Occurs: SFixed: G2
What is used to proofread human DNA? 3' -> 5' Exonuclease activity of DNA poly Delta
What do each of the (3) eukaryotic RNA polymerases make? RNA poly I: rRNARNA poly II: mRNA, hnRNARNA poly III: tRNA, 5S rRNA
What DNA strand should you assume the boards mean if it is not labeled? Coding strand(strand you will build a template strand from)
During RNA synthesis, the DNA template sequence TAGC would be transcribed to produce which of the following sequences? GCUA(always write in 5'->3' direction)
What initiates the promoter in the prokaryotic cell?What may be required to terminate transcription? intiate: Sigmaterminate: Rho + stem & loop (or UUUUU + stem & loop)
What is the initiation codon on the CODING strand of a transcription unit? ATG(corresponding to AUG RNA)
What does the promoter consist of in a prokaryotic cell?What is the "number" of the starting site? (-35) sequence & (-10) TATAATstarting site: +1
What does the promoter consist of in a eukaryotic cell? (2)What binds the promoter? (-70) CAAT + (-25 TATA box) Transcription Factors
What is the portion just before the initiation codon of a prokaryotic cell called? What recognizes this? Shine-Dalgarno sequence16S RNA of prokaryotic ribosome
What is the term referred to as the creation of a single protein?What type of cell does this? monocistronicEukaryotic (polycistronic is prokaryotic)
3 posttranscriptional processing steps for eukaryotics 1. 5' Cap (7-MeG)2. 3' poly-A tail3. removing interons w/ splicesome
where does transcription and translation occur in the eukaryotic cell? transcription - nucleustranslation - cytoplasm
define:TransitionTransversion Transition - purine for purineTransversion - purine for pyrmidine
Mutation type in DNA that creates a new codon Missense
Mutation type in DNA that creates a stop codon Nonsense
3 stop codons UGA (U Go Away)UAA (U Are Away)UAG (U Are Gone)
What type of genetic problem is caused by a deletion or addition of a single base? Frameshift mutation
blood problem that is a result of a large segment deletion alpha-thalassemia
blood problem that is the result of a splicing of the donor or acceptor sites (beginning of interons/exons) beta-thalassemia
What is responsible for accuracy of the amino acid selection along with tRNA?what is needed to activate this? Aminoacyl-tRNA2 high-energy ATP bonds
What does the UCG anti-codon code for? CGA (remember to read anti-codon backwards: 5'->3')
What is the bond between two amino acids called? Where does this form? peptide bond occurs in the ribosome
What is the anti-codon for the start codon? CAU
What site in the rRNA does the tRNA bring the AA to? What amount of energy is needed to translate a protein? A-site (acceptor) 4 GTP
Describe the 4 levels of protein shape Primary - Amino Acids Secondary - folded AA into a-helix or b-sheet Tertiary - 3-D the secondary structures Quarternary - multiple subunits (ex - Hb: 2a2b)
Why is there "rough" ER? N-terminus (NH2) of newly translated protein is hydrophobic, so the rRNA will move to and attach to the ER to complete translation within the ER
What does the golgi do to the new protein? adds sugars to the N-terminus
What AA does the golgi add N-oligosaccharides to? O-oligosaccharides? (2)* N: Asparagine O: Serine and Threonine
What does the golgi do if it wants to send the new protein to the lysosomes? Adds Mannose-6-Phosphate via phosphotransferase
Dx: protein creation problem that accompanies the signs of coarse facial features, gingival hyperplasia, joint immobility, growth/psychomotor retardation, cardioresp failure in first decade. What is missing in protein creation? Dx: I-cell disease Missing: Phosphotransferase (can't send proteins to lysosomes)
2 cells rich in RER Goblet cells of the GI Ab-secreting Plasma cells
What cell organelle is responsible for steroid synthesis? What else is it responsible for? Smooth ER also responsible for: detoxification of drugs and poisons
Covalent modification to proteins by adding 2 negative charges to allow calcium to bind. What important function uses this method? What drug prevents this? Gamma-carboxylation Clotting factors 2, 7, 9, 10 (Warfarin prevents gamma-carboxy)
Most prevalent AA in collagen? Two other common AA in collagen? Glycine Proline & Lysine
Where does hydroxylation of preprocollagen occur? What is hydroxylated? What cofactor is needed for it to occur? Proline & Lysine are hydroxylated in the ER Vitamin C is required
What occurs to collagen after it is hydroxylated? In what part of the cell? What is formed here? Name? Glycosylated in Golgi Triple helix (Procollagen)
Following glycosylation of collagen, what is the next step and alteration of the structure? What is it now called? Procollagen is secreted from the cell. Then terminal ends are cleaved. Then called: Tropocollagen
What is needed to make the tropocollagen into fibrils and stabilizes this structure? (2) Lysyl Oxidase & Copper
(4)* Collagen synthesis deficiencies SOME: 1. Scurvy 2. Osteogenesis Imperfecta 3. Menkes Dz 3. Ehlers-Danlos
Dx: Petechiae, ecchymoses, bleeding gums, poor wound healing, poor bone development Deficiency? Scurvy Deficiency: hydroxylation of collagen deficiency secondary to lack of Vit-C
Dx: Skeletal abnormalities, multiple fractures, blue sclera Osteogenesis Imperfecta
Dx: Hyperextensible, fragile skin, hypermobile joints, vericose veins, arterial and intestinal ruptures Deficiency? Ehlers-Danlos Deficiency: Lysine hydroxylase collagen deficiency secondary to lack of copper
To compare collagen counts of several tissues, what could be measured? hydroxyproline or hydroxylysine (not Glycine--b/c it's prevalent in other tissues)
Dx: 6 month infant has fractured rib; subdural hematoma; thin, colorless, tangled hair; low serum copper; developmental delay. What enzyme is deficient? Menkes disease Lysyl Oxidase in collagen metabolism, which requires copper
What do pseudomonas and diphtheria toxins inhibit in eukaryotic translation? eEF-2: translocation factor
What sequence is found at the 3' end of the tRNA? CCA then the Amino acid
What intermediate is formed by the splicing of the interons out of the mRNA transcripts? What facilitates the splicing? Lariat-shaped intermediate snRNA ("Snurp") facilitates
With the lac opeon, what is on/off if only glucose is present? Only Lactose? Both? When is Z, Y, A made? Glucose: Repressor-ON; CAP-OFF Lactose: Repressor-OFF; CAP-ON (Z, Y, A, made) Both: Repressor-OFF; CAP-OFF (glucose causes CAP off and Lactose causes Repressor off)
What favors gene expresson--histone acetylases or deacetylases? Why? histone acetylases - open hisones anything that condenses or bulks chromatin does not favor gene expression
Where are enhancers located? may be upstream, downstream or within interon of gene they control (due to looping)
When you see "zinc fingers", "leucine zippers", or "helix-loop-helix", what are they talking about? What are the fingers? Enhancers (steroid receptors are fingers, while cAMP response elements are zippers)
If you have multiple abnormalities with a single gene point mutation, where is the mutatuion? HOX or PAX gene
Dx: childhood obesity and hyperphagia, hypogonadotrophic hypogonadism, small hands and feet, mental retardation, hypotonia Type of genetic problem? Prader-Willi syndrome Genetic Imprinting (father's gene only)
Dx: mental retardation, continuous laughing Type of genetic problem? Angelman syndrome "Happy Puppet syndrome" Genetic Imprinting (mother's gene only)
What does bacteria do to protect its DNA? How does it destroy foreign DNA (bacteriophage)? it Methylates its DNA Restriction endonucleases
What do restriction endonucleases recognize in the sequence? palindromes
Library made from nuclear DNA and is good for seeing all sequences in the cell. Which library is good for seeing proteins (exons) without introns? Genomic Libraries cDNA Libraries
Example of a key tissue for collagen types 1-4 Bone SCAB: I: bone, Skin II: Cartilage III: Arteries IV: Basement membrane (4 to the floor)
What is a key feature to a Dominant genetic problem in pedigree (vs. recessive)? Dominant - every generation is affected (not in recessive)
What is a key feature to Autosomal genetic problem in pedigree (vs. X-linked)? Autosomal - Male-to-male inheritance (x-linked has no male-to-male)
Dx: Lateral displacement of the innercorner of the eye; Pigment abnormalities; congenital deafness; limb abnormalities What gene is the problem? Klein-Waardenburg Syndrome HOX gene abnormality
If cystic fibrosis patient were to be treated with gene therapy, which type of cells should be targeted by the host cells? Epithelial cells
name 5 Autosomal Dominant diseases FH-MAN Familial Hypercholesterolemia; Huntingtons; Marfans; Acute Intermittent Porphyria; NF-1
What is usually the common problem in the Autosomal Dominant diseases? Structural protein damage
name 4 common Autosomal Recessive diseases SCriPT Sickle cell; Cystic Fibrosis; PKU; Tay-Sachs
What type of genetic diseases affect energy production? (Name 3) Mitochondrial Diseases: Leber's optic neuropathy; MELAS; MML
name 4 X-linked recessive common diseases Duchennes muscular dystrophy; Lesh-Nylan; G6PD; Hemophilia A & B
Paternal relationships b/t man and infant can best be determined by DNA fingerprinting. What about the DNA is analyzed? Tandem repeats
2 amino acids that are the precursors for catecholamines Phenylalanine Tyrosine
What NT does tryptophan form? What vitamin? Serotonin Niacin
3 branched-chained amino acids found in Maple Syrup Urine disease? I Love Vermont: Isoleucine; Leucine; Valine
name the (6)* nonpolar, non-aromatic hydrophobic amino acids VIP GAL: Valine; Isoleucine; Proline Glycine; Alanine; Leucine
Only amino acid with a phenol group? Tyrosine
name the 3 aromatic amino acids Phenylalanine Tyrosine Tryptophan
the amino acid that acts as a methyl donor methionine (SAM)
name 3 amino acid that are basic What is the pK of the R groups? HLA: Histidine (6.5) Lysine (10) Arginine (13)
name the 2 amino acids that are acidic What is the pK of the R groups? Glutamate (4) Aspartate (4)
What are the 2 pKs that every amino acid has? pk (COO-) = 2 pk (NH2) = 9
What is the net charge on the amino acid if the pH is less then the pI? positive
What is the pI? (equation) average of the pKs: (2+9)/2 = 5.5 for normal AA [average the 2 closest numbers for charged AA]
Main extracellular buffer bicarbonate
10 essential amino acids PVT TIM HALL: Phe-Val-Thr Trp-Ile-Met His-Arg-Leu-Lys
What 2 essential amino acids are required during periods of growth? Histidine Arginine
What is the sign of delta G in a spontaneous reaction? negative
Affect on Km & Vmax: 1) Competitive Inhibitor 2) Non-competative Inh Competitive: Km= Increase; Vmax= no change Non-competitive: Km= no change; Vmax= Decrease
what does the x and y axis measure on Lineweaver-burke plots? x-axis: -(1/Km) y-axis: (1/Vmax)
How does affinity relate to Km? low Km = high Affinity
amino acid precursor to GABA Glutamic Acid
amino acid precursor to Heme Glycine
the amino acid that is the precursor for: Creatine Urea Nitric Oxide Arginine
adds a phosphate to a substance Kinase
2 serine kinases cAMP cGMP
which receptor type has no g-protein and results in smooth muscle relaxation? Second messenger? cGMP Protein kinase G
What phosphorylates in the insulin/glucagon world? Which needs ATP? Glucagon - phosphorylates (needs ATP) Insulin - de-phosphorylates
removes a phosphate from a substance Phosphatase
What bug affects ADP-ribosylation at Gs receptors? What bug affects it at Gi? What do they both cause in the cell? stimulates Gs- Cholera (stimulates the stimulator) inhibits Gi- Pertussis (inhibits the inhibitor) Both cause: Increase in cAMP
What two Vitamins can be used in dehydrogenase reactions? Riboflavin (B2) Niacin (B3)
Vitamin that makes CoA? Pantothenic Acid (B5)
What (4)* things does the liver produce in a well-fed state? G-TAB: GLYCOGEN Triglyerides ATP Bile (from cholesterol)
What is the first step in a well-fed state for the following tissues: liver, RBC, brain, muscle, fat? GLYCOLYSIS
2 actions of RBC in a well-fed and fasting state? 1) glycolysis (for ATP) 2) Lactate production
What tissues use insulin receptors: GLUT 1 and 3? RBC Brain
What tissues use receptor: GLUT 2? Liver
What tissues use receptor: GLUT 4? Muscle Adipose
Once there is enough energy in liver during well-fed state, what 2 substances build-up? What is done with them? Glucose & Acetyl-CoA Glucose - added together to be stored as glycogen Acetyl-CoA - added together to become fatty acids (then transported to adipose via VLDL)
What does adipose do during well-fed states? takes in glucose and fatty acids to make ATP and fat
What (4)* substances enter the liver during a well-fed state? Where is each from? Goes to Liver And Grows: Glucose - food (blood) Lactate - RBC Amino Acids - food (blood) Glycerol - Chylomicrons (food)
What does the liver give to tissues during fasting states? To what tissues? Glucose - RBC & Brain Ketone bodies - muscle
What does muscle get during the fasting state? (2) From where? Ketone bodies - liver (once enough ATP is made and Aceytl-CoA builds-up) Fatty acids - Adipose (carried on albumin)
What does the muscle provide to the liver during fasting states? For what? (2) Amino Acids 1. to make Pyruvate (then glucose) 2. for Urea cycle
2 sources (& preliminary substances) to make pyruvate b/t meals for the liver to make glucose RBC - lactate muscle - Alanine
What 2 ways can the GLUT-4 receptor move to the surface of muscle? 1) Increased Insulin 2) Exercise
What are the 2 anaerobic steps of substrate level phosphorylation in glycolysis? 1,3BPG --> 3PG (via Phosphoglycerate kinase) PEP --> Pyruvate (via Pyruvate kinase)
What are two essential items needed to make ATP from NADH? 1) Oxygen 2) Mitochondria (for ETC)
What 2 steps of glycolysis use ATP? First and third step: Glucose --> G6P (via Hexokinase/Glucokinase) F6P --> F-1,6-BP (via PFK-1)
What is the rate-limiting step of glycolysis? Net ATP? PFK-1 2 ATP (net)
How does the RBC replenish NADH? With what essential enzyme? If enzyme was not there, what would occur? Pyruvate --> Lactate (Enzyme: Lactate DH) changes NAD+ --> NADH for glycolysis (lactate goes to liver) If Lactate DH not there, RBC would die
What enzyme of glycolysis is only in the liver and is induced by insulin? Level of affinity of this enzyme? Glucokinase Low affinity = High Km = high Vmax
How is PFK-1 controlled? Which form is active (dephosphorylated or phosphorylated)? Insulin (dephos) stimulates PFK-2 for: F6P --> F-2,6-BP to make PFK-1 Glucagon (phosphorylates) inhibits PFK-2
What (3)* metabolic events occur in the mitochondria? Fatty acid oxidation Acetyl-CoA production TCA cycle
What (5)* metabolic events occur in the cytoplasm? Glucose Found Here Protects Steroids: Glycolysis Fatty acid synthesis HMP shunt Protein synthesis (RER) Steroid synthesis
What (3)* metabolic events occur in both the mitochondria and the cytoplasm? Heme synthesis Urea cycle Gluconeogenesis
What 2 shuttles take NADH from the cytoplasm to the mitochondria? How many ATP does each yield? Which yields a FADH2 instead of the NADH in the mito? Malate/OAA Shuttle - 3ATP G3P Shuttle - 2ATP (creates FADH2)
If a patient has cataracts early in life, what is the underlying metabolic problem? What toxic substance accumulation causes this? Galactose metabolism Toxic: Galacititol
Dx: young patient with hepatosplenomegaly, cataracts, mental retardation. Which enzyme presents sx at birth? Which in early childhood? Galactosemia: Galactose-1-P uridyltransferase = at birth; Galactokinase = early childhood
Dx: lethargy, vomiting, liver damage, hyperbilirubinemia, hypoglycemia, jaundice, renal proximal tubule problems. What enzyme is deficient? Fructose Intolerance Enz: Aldolase B
What are the (5)* cofactors used for Pyruvate Dehydrogenase? TLC For Nipples: Thiamine (B1) Lipoic Acid Coenzyme A (B5) FADH2 (B2) NADH (B3)
What does Pyruvate DH change pyruvate into? Acetyl CoA
Overall net reaction of the TCA cycle? What makes the ATP in this reaction? Acetyl CoA --> 2 CO2 3NADH + FADH2 + GTP = 12 ATP (2x everything per one glucose)
Which enzyme in the TCA cycle is in the inner mitochondrial membrane versus the matrix of the mitochondria? Succinate Dehydrogenase
What enzyme has the same 5 cofactors as Pyruvate DH? Alpha-Ketogluterate DH
In order, what are the 8 steps in the TCA cycle? Can I Keep Selling Sex For Money Officer? Citrate-->Isocitrate--> (alpha)Ketogluterate--> Succinyl CoA-->Succinate--> Fumarate-->Malate-->OAA
What does a Pyruvate DH deficiency lead to? What can it be due to? How is it treated? Lactic Acidosis (from backup of substrates) Seen in Alcoholics (thiamine deficiency) Tx: Ketogenic acids (Lysine & Leucine)
What part of the TCA cycle is also part of the ETC? What does it provide to the ETC? Succinate Dehydrogenase (Complex II) Provides: FADH2
What part of the TCA cycle deals with Fatty Acid synthesis? Citrate
What part of the TCA cycle deals with Heme synthesis? Succinyl CoA
What part of the TCA cycle deals with the Urea cycle? Fumarate
What parts of the TCA cycle deals with Gluconeogenesis? OAA & Malate
What is the rate limiting step of the TCA cycle? What does it depend on? Isocitrate DH depends on NADH levels
What enzymes in the TCA produce the energy? (5)* KIM SUCkS: Ketoglutarate DH - NADH Isoglutarate DH - NADH Malate DH - NADH Succinyl CoA - GTP Succinate DH - FADH2
What does Complex I use in ETC? What drug class inhibits Complex I? NADH Barbiturates
What 3 reactions add FADH2 to Coenzyme Q? Which is considered Complex II? TCA (Succinate DH) [Complex II] Glycerol-P shuttle Beta-oxidation (Fatty Acyl CoA DH)
Which Complex in the ETC uses Oxygen? Another name for thtis complex? What else is needed for this Complex? What 2 compounds inhibit this Complex? Complex IV (Cyto a/a3) copper Cyanide & CO
Where is the ATP made in the ETC? What inhibits this? ATP Synthase Inhibitor: Oligomycin
What is a common Uncoupler? How does it work? Aspirin Brings H+ across the proton gradient, which inhibits the creation of ATP and increases Oxygen consumption
What is the rate limiting step in Glycogen creation? UDP-Glucose --> Glycogen (via Glycogen Synthase)
In which type of muscle fiber is glucose converted to Lactate? In which type is it completely oxidized? to Lactate: White (fast) fibers completely oxidized: Red (slow) fibers
What converts Glycogen back into Glucose 1-P? What stimulates it in the liver and muscle? (2 each) Glycogen Phosphorylase Stimulated by: Liver: Glucagon and Epinephrine Muscle: AMP and Epinepherine
What are the (4)* main Glycogen storage diseases? (in order I, II, III, V) Very Poor Carbohydrate Metabolism: Von Gierke Pompe Cori McArdles
Dx: Glycogen storage disease that causes severe hypoglycemia, hepatomegaly, hyperlipidemia & hyperuricemia What is the deficient enzyme? Von Gierke's (Glucose-6-Phosphatase) "LU Von Geirke is 6" [LU = hyper Lipidemmia and Uriceia]
Dx: Glycogen-like material in inclusion bodies, cardiomegaly, muscle weakness and death by age 2 What is the deficient enzyme? Pompe's (Lysosomal-alpha-1,4-glucosidase)
Dx: Glycogen storage disease that is similar, but milder then Type I. What is the deficient enzyme? Cori's (Alpha-1,6-Glucosidase) [Cori is A-16 yo-Girl]
Dx: Increased glycogen in muscle, painful cramps, myoglobinuria w/ exercise What is the deficient enzyme? McArdle's (Muscle Glycogen Phosphorylase)
What are the 3 irreversible steps in Glycolysis? Glucokinase PFK-1 Pyruvate Kinase
What are the (3)* ways Gluconeogenesis circumvents the irreversible glycolysis steps (in order)? Pathway Produces Fresh Glucose: Pyruvate Carboxylase/PEPCK F-1,6-Bisphosphatase Glucose-6-phosphatase
What are the (3)* cofators for Carboxylase reactions? ABC enzymes: ATP Biotin CO2
What is the rate-limiting enzyme in Gluconeogenesis? PEPCK
What enzyme converts Pyruvate to OAA? How does this OAA get to the cytoplasm to create Glucose? Pyruvate Carboxylase Malate/OAA shuttle
What is an easy test to see if patient has a glycogen storage disease? inject patient with glycerol; if patient does not increase blood glucose, there is a G6P deficiency
Cycle that Transfers excess reducing agents from RBC and muscle to the liver, allowing the muscle to function anaerobically What do the muscle and RBC distribute to the cycle? Cori Cycle RBC and Muscle give: Lactate
What enzyme changes lactate to and from pyruvate? Lactate DH
What is the function of the HMP shunt? What are the 2 important enzymes in this reaction? to regenerate NADPH and Ribose 5-P Enzymes: G6PDH Transketolase (TPP)
What are the 3 main roles of NADPH? Liver: Biosynthesis (FA, Cholesterol, DNA) RBC: Protect against ROS Neutrophil: NADPH oxidase (kill bugs)
What are the 2 essential Fatty acids? What is their nomenclature? Linoleic = C18:2(9,12) Linolenic = C18:3(9,12,15)
What cells have telemorase activity? (2) Embryonic (germ) cells Cancer cells
What strand is identical to the mRNA (except T for U)? What strand is Complementary and antiparallel to the mRNA (except T for U)? Identical: Coding Strand Complementary: Template Strand
What drug inhibits all transcription in prokaryotes and eukaryotes? Actinomycin D
What is 3 bases and antiparallel to mRNA w/ U instead of T? where is this attached? Anti-codons attached to tRNA
(2) steps of Collagen formation that occurs in the RER? What Dz can occur from a deficiency in these steps? 1. Removal of the "Pre" from Prepro-alpha to make Pro-alpha 2. Hydroxylation of the Pro-alpha with Vitamin C Dz: Scurvy (Vit-C deficiency)
(2) steps of Collagen formation that occurs in the Golgi? What Dz can occur from a deficiency in these steps? 1. Glycosylation 2. Triple Helix formation to make Procollagen Dz: Osteogenesis Imperfecta
(3) steps of Collagen formation that occurs in the ECM? What (2) Dz can occur from a deficiency in these steps? 1. cleavage of peptide ends to make Tropocollagen 2. Tropocollagen into fibrils w/ Lysyl Oxidase and copper 3. Fibrils to Collagen Fibers Dz: Ehlers-Danlos (Lysine hydroxylase deficiency) Menke's Dz (Copper digestion insufficiency)
Drug that is against Pertussis by inhibiting the translocation of peptidyl-tRNA on 50s ribosome Erythromycin
What effect does Exotoxin A of Pseudomonas have on the human cells? inhibits translocation factor: eEF-2
Define: 1. Plasmid 2. Vector 3. Phage Plasmid: circular DNA in bacteria Vector: carrier for human DNA to insert into a plasmid Phage: Larger vector
What type of Genetics: NO male to male; no male to female; if mother has it, all kids have it Mitochondrial inheritance
With Southern blot, how does the DNA align? (2) DNA (negative charge) moves to the positive Larger fragments at top and smaller at bottom
What does it measure? 1.Southern blot 2. Northern blot 3. Western blot Which is good to answer questions about gene expression? About the amount of antigens or antibodies? To determine specific restriction fragments? Southern = DNA (restriction fragments) Northern = RNA (gene expression) Western = Proteins (Antibodies/Antigens)
Type of receptors: 1. Gs 2. Gi 3. Gq What does each do? Gs = Beta receptors (stimulates Adenyl cyclase to inc cAMP) Gi = Alpha-2 receptors (Inhibits Adenyl cyclase to dec cAMP) Gq = Alpha-1 receptors (Stimulates Phospholipase C in PIP2 receptor system)
Which receptor is associated w/ Protein Kinase C? IP3 (Gq)
Which receptor is assoc w/ Protein Kinase A? cAMP (Gs and Gi)
What is the G-receptor for Vasopressin? Glucagon? Gq - IP3 system Gs/Gi - cAMP system
MCC of deficiency in: Thiamine Alcoholism
MCC of deficiency in: Folic Acid (2) Alcoholism Pregnancy
MCC of deficiency in: Cyanocobalamin (B-12) Pernicious Anemia
MCC of deficiency in: Pyridoxine Isoniazid therapy
What NT is always released w/i the eyes (in the dark) causing constant depolarization? What channels respond to light causing the cell to hyperpolarize? Glutamic Acid cGMP-PDE Na+ gated channels close
What vitamin is used to introduce Calcium to binding sites of several calcium-dependent proteins? With which mechanism? What drug inhibits this? Vitamin K Gamma-carboxylation of Glutamate Warfarin inhibits it
Bleeding time difference and PT difference b/t a deficiency in: Vit-C and Vit-K Vit C: Increased bleeding time normal PT Vit K: normal bleeding time Increased PT
If tissue is hypoxic, what enzymes will be increased in the blood? Any Glycolysis enzyme (not Lactate DH)
MC genetic deficiency that causes hemolytic anemia Pyruvate Kinase Deficiency
What amino acid is assoc w/ the Malate-OAA shuttle? Aspartate
What enzyme in glycolysis is activated after a big meal? What activates it? PFK-2 Activated by Insulin
What thiamine-dependent enzyme is essential for glucose oxidation in the brain? Pyruvate DH
After an overnight fast, what enxymes of what metabolic process would be insignificant? Glycolysis enzymes (b/c liver is producing glucose, not storing it)
What enzymes in the TCA cycle produce items but not NADH? (2) Succinates: Succinyl CoA Synthase = GTP Succinate DH = FADH2
Which is the only enzyme in the TCA that deals w/ substrate level phosphorylation? Succinyl CoA Synthase
Which direction do H+ flow in the ETC? In which complexes? In which complex is the flow the opposite direction? Which side does O2 -> H20? On which complex? Mitochondrial matrix -> cytoplasm: Complexes I, III and IV Opposite direction: ATP synthase O2 -> H20: mitochondrial matrix on Complex IV
What does Nitroprusside break down into? What complex in ETC does it affect? Cyanide Complex IV
What glycogen storage Dz has debranching enzymes? Cori's Dz
If FA beta-oxidation is occurring in the liver, what does pyruvate do? Carboxylates to OAA for entry into Gluconeogenesis
What do G6PDH deficient patients have resistence to? Malaria
What do the bilirubin levels in the blood and urine look like w/ hemolytic jaundice (from G6PDH deficiency)? Direct = normal Indirect = increased Urinary = absent
What type of bonds are there in alpha-helix and beta-sheet proteins? Peptide bonds that participate in H+ bonding
What property of water most contributes to its ability to dissolve compounds? Hydrogen bonds
What tissue has the highest concentration of Cystine? Keratin
What gives strength to the IgG structure? What can break these bonds? Disulfide bonds Urea (and reducing agents)
What is constant (the same) in each class of immunoglobulins? Constant regions of the heavy chains
How many antigen binding sites does each immunoglobulin have per molecule? 2
Which FA is cardio-protective? Linolenic (omega-3)
When is a FA considered "saturated"? when it has NO double bonds
Name and give the nomenclature for the FA that is the precursor to Prostaglandins, thromboxanes and Leukotrienes Arachidonic Acid: C20:4(5,8,11,14)
What is a good way to remember the placement of the double bonds for unsaturated FA? (3) 1. Double bonds occur every 3 carbons 2. "L's" start w/ 9 3. Arachidonic C20:4 - take 20/4 = 5. This starts at 5
Accumulation of what in the liver triggers it to make fat? What is needed? Acetyl CoA Need Energy (ATP)
In the mitochondria, there are (2) pathways to make fat depending on the fed or fasting state. What is the path for each to get to Citrate? Fed (insulin): Pyruvate -> PDH -> Acetyl CoA -> Citrate Fasting (glucagon): Pyruvate -> P Carboxylase -> OAA -> Citrate
What from the mitochondria leaves the TCA cycle to enter the cytoplasm for fat synthesis? What does it then turn into? Citrate Aceytl CoA
What is the essential enzyme to transform Acetyl CoA to Malonyl CoA? What else is needed? How many Acetyl CoA are needed to make one Palmitate? Acetyl CoA Carboxylase ATP/Biotin/CO2 8 Acetyl CoA are needed for 1 Palmitate (7 cycles)
What enzyme and substance is needed to convert Malonyl CoA to Palmitate (16:0)? (2) FA Synthase (2) NADPH
How many molecules of NADPH are needed for one Palmitate? 14 NADPH (2 x 7 cycles)
To transport FA from liver, what do you need to do to the molecule? What is needed for this? Convert it to a TG Need: Glycerol-3-P
(2) enzymes that are induced/activated by insulin in FA synthesis PDH Acetyl CoA Carboxylase
What is needed for every Carboxylase enzyme? Biotin
(2) ways to make TG in the liver 1. Glucose enters liver: Glucose -> DHAP + Glycerol-3-P DH -> Glycerol-3-P + 3 FA CoA -> TG 2. Glycerol enters liver: Glycerol + Glycerol Kinase -> Glycerol-3-P + 3 FA CoA -> TG
What in Adipose allows for the removal of FA from TG carried by chylomicrons and VLDL? With what "key"? Lipoprotein Lipase Key: ApoC-II
What is the only Apoprotein left on LDL? What is its use? ApoB-100 used as a key to LDL receptors in cell membranes to endocytose the LDL for cholesterol usage
What are the (2) Apoproteins on HDL? Use of each? ApoE - Key to liver ApoA-1 - Key to stimulate LCAT
What does the LCAT receptor of peripheral tissues do? Adds a FA from the periphery to HDL for it to take back to the liver
What are the main ingredients of the plaque on the vessel walls? (3) What is this called? "Fatty Streak" formation: Cholesterol Foam cells (sick macros) Smooth muscle (migrated)
What membrane transport shuttle is used in Beta-oxidation of FA? Carnitine shuttle
(2) main enzymes in B-oxidation of FA? Which is the rate limiting step? Carnitine Acyl Transferase (rate-limiting across shuttle) Fatty Acyl CoA DH
What is the end product of b-oxidation? Acetyl CoA
When is the only time FA can go back into glucose? What does it make in this case? When it is a FA w/ an odd number Makes: Succinyl CoA
What (2) enzymes are used in the breakdown of odd-chained FA? What is needed with each step? Propionyl CoA Carboxlase (biotin) Methylmalonyl CoA Mutase (Vit B-12)
What is the difference b/t a TG and a glycerophospholipid? glycerophospholipid has Inositol or choline attached
What are the (2) main ingredients in Sphingolipids? Precursor to all sphingolipids? Serine (not glycerol) + FA Precursor: Sphingosine
Sphingolipids extra ingredients for: 1. Sphingosine 2. Cerebrosides 3. Gangliosides 1. Sphingo = CHOLINE 2. Cerebro = SUGAR 3. Ganglio = SIALIC ACID and complex sugars
Deficient Lysosomal enzyme: Gaucher's Dz Glucocerebrosidase
Deficient Lysosomal enzyme: Niemann-Pick Sphingomyelinase
What is the actual enzyme that causes the increased amount of Galactose to be converted into Galactitol to cause Cataracts? Aldose Reductase
What are the enzymes for the (2) sources of ammonia that enter the Urea cycle in the liver? Both break down Glutamate: Glutaminase in the GI Glutamate DH in liver
What vitamin is essential for aminotransferase reactions? Vitamin B-6
If blood glutamate is increased in the blood, what is the possible problem? Deficiency in Urea cycle
What are the steps in the Urea cycle? (8)* Careless Crappers AlSo ARe Frivolous About Urination Outside: Carbamoyl Phosphate -> Citruline + Aspartate -> Argininosuccinate - Fumarate -> Arginine - UREA -> Ornithine
Which step in the Urea cycle is inside the mitochondria? Carbamoyl Phosphate
What is the enzyme deficiency with the following Sx? blood glutamine increased, BUN decreased, cerebral edema, lethargy, convulsions, Uracil and Orotic acid increase in blood and urine Ornithine Transcarbamoylase (OTC)
What reactions and AA enter at the Succinyl CoA part of the TCA? (5)* VOMIT SUCks: Valine; Odd-chain FA; Methionine; Isoleucine; Threonine
(2) enzymes in the body that need Vit B-12 Methylmalonic CoA Mutase Homocysteine Methyl Transferase
What are the (2) Ketogenic AA? Where do they enter the TCA cycle? Leucine Lysine enter at Acetyl CoA
What (2) AA enter the TCA cycle at Fumarate? Phenylalanine Tyrosine
If you see zinc in heme, what enzyme is inhibited? Ferrochelatase
Steps in Heme Synthesis (6)* GAP UP Here: Glycine + Succinyl CoA -> Aminolevulinic Acid (ALA) -> Porphobilinogen -> Uroporphyrinogen-III -> Protoporphyrin -> Heme
What enzyme is deficient in Acute Intermittent Porphyria? Uroporphyrinogen Synthase
Dx: Painful abdomen; Pink urine (Port-wine urine); Polyneuropathy; Psychological disturbances 4 P = Porphyria
Porphyria that also causes blistering of the skin from photosensitivity Porphyria Cutanea Tarda
Dx: Patient is given a barbituate and begins projectile vomiting, confusion, abdominal pain, paranoia. Acute Intermittent Porphyria
(3)* causes of Increased Indirect Bilirubin HCG: Hemolysis; Crigler-Najjar syndrome; Gilbert's syndrome
(2) conditions that increase Direct Bilirubin Hepatic damage Bile duct obstruction
What are the (2) required AA for Pyrimidine synthesis? Glutamatine Aspartic Acid
Blocking THF creation would lead to not being able to make what? What (3) drugs do this? What is the side effect of all of these drugs? Thymidine (dTMP) Drugs that block DHF reductase: METHotrexate (cancer); TriMETHoprim (PCP); PyriMETHamine (toxoplasmosis) Side effect: Bone marrow Suppression
What are the (3)* important enzymes in the conversion of UMP to dTMP (in order)? Which Anti-cancer med targets each? Right Here The Funky Drugs Mingle: Ribonucleotide Reductase (Hydroxyurea) Thymidylate synthase (5-FU) DHF reductase (Methotrexate)
What is Orotic Acid involved in? Pyrimidine synthesis
What is the additional AA that is used to make purines? Glycine
What enzyme in Purine synthesis is the rate-limiting step? What (2) drugs inhibit this step? PRPP Amidotransferase Drugs ("Purin"): AlloPURINol (Gout); 6-MercaptoPURINe (cancer)
What intermediate in purine synthesis is different from guanine and adenine by one amino group and is also an intermediate in the breakdown of purines? Hypoxanthine
Lack of the salvage pathway of purines leads to what syndrome? What is the missing enzyme? What is an unusual sign of this syndrome? LNS = Lacks Nucleotide Salvage: Lesch-Nyhan syndrome HGPRTase Sign: Self-mutilation
Adenosine Deaminase deficiency causes a lack of what product? Inosine
Dx: 48-yo man w/ recessive condition is at high risk for deep vein thrombosis and has had replacement of ectopic lenses; no evidence of anemia. Enzyme that is deficient? What AA would be in excess? Homocysteinuria Enzyme: Cystathionine Synthase AA: Methionine
Dx: Man has dark pigment of cartilage and arthritis, and dark urine What enzyme is deficient? Alkaptouria Enzyme: Homogentisate Oxidase [AL KAPT a HOMe]
How do you treat Cystinuria? Alkalinize the urine w: Acetazolamide
Precursor to Ketone body formation HMG-CoA
(4)* genetic Dz w/ Trinucleotide repeats Try HUNTING for MY FRIED X (eggs): Huntington's; Myotonic Dystrophy; Friedreich's Ataxia; Fragile X
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