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132 Cards in this Set

  • Front
  • Back
Name the histone not included in the nucleosome core.
What amino acids are the main components of histones?

(positively charged)
What reaction converts Cytosine to Uracil?
Deamination - conversion of NH2 to O
Which nucleotide has a methyl group?
Which nucleotide has a ketone group?
What amino acids are necessary for purine synthesis?
What amino acid is necessary for pyrimidine synthesis? What is the other component necessary?

Carbamoyl phosphate
What precursor molecule leads to purines? To pyrimidines?
Purines are made from IMP precursor

Pyrimidines are made from orotate precursor (PRPP added later)
What metabolic pathways require carbamoyl phosphate?
De novo pyrimidine synthesis

Urea cycle
What is the mechanism of action of hydroxyurea?
Inhibition of ribonucleotide reductase, resulting in decreased dUDP and decreased CTP
What is the mechanism of action of 6-mercaptopurine?
Blocking of de novo purine synthesis, so decreased AMP, GMP
What is the mechanism of action of 5-fluorouracil?
Inhibition of thymidylate synthase, thus decreasing dTMP
What is the mechanism of action of methotrexate?
Inhibition of dihydrofolate reductase, thus decreasing dTMP
What is the mechanism of action of trimethoprim?
Inhibition of bacterial dihydrofolate reductase, thus decreasing dTMP

to sit down
What reaction is catalyzed by thymidylate synthase?
dUMP --> dTMP


N5N10 Methylene Tetrahydrofolate --> Dihydrofolate
What amino acid is required for the reaction of orotic acid (plus PRPP) to UMP?
What amino acids are required for conversion of ribose-5-phosphate to PRPP?
Glycine, aspartate, glutamate

Also tetrahydrofolate
What reaction is catalyzed by ribonucleotide reductase?
What enzymes are defective in orotic aciduria?
Orotic acid phosphoribosyltransferase


Orotidine 5'-phosphate decarboxylase
What are the findings in orotic aciduria?
Increased orotic acid in urine, megaloblastic anemia (not corrected with folate or B12), FTT

NO hyperammonemia!!!
What reaction is not being catalyzed in adenosine deaminase deficiency?
Adenosine --> Inosine

Results in excess ATP and dATP imbalancing the nucleotide pool, and causes feedback inhibition of ribonucleotide reductase, which is necessary for pyrimidine synthesis
What reactions are catalyzed by xanthine oxidase?
Hypoxanthine --> Xanthine

Xanthine --> Uric acid
What reaction is catalyzed by HGPRT?
Hyopxanthine --> IMP

Guanine --> GMP

Results in excess uric acid production
What NT sequence codes for a start codon?

What three sequences code for stop codons?
Start: AUG

What is added to RNA post-transcription on the 5' end and the 3' end?
5' end: 7-methylguanosine cap

3' end: Polyadenylation (200 As)
What is the polyadenylation signal?
What NT sequence is found at the 3' end on all tRNA?
What is the mechanism of action of Tetracyclines?
They bind the 30S subunit, preventing attachment of aminoacyl-tRNA
What is the mechanism of action of Aminoglycosides?
Inhibition of the formation of the initiation complex, causing misreading of mRNA
What is the mechanism of action of Chloramphenicol?
Inhibition of 50S peptidyltransferase
What is the mechanism of action of Macrolides? Clindamycin?
Binding of 50S, thus blocking translocation
What two tumor suppressors inhibit G1-S progression?

What organs/tissues are rich in RER?
Mucus-secreting globlet cells of the small intestine
Antibody-secreting plasma cells
What are Nissl bodies?
RER in neurons, which synthesize enzymes and peptide neurotransmitters
What organs/tissues are rich in SER?
Liver hepatocytes

Steroid hormone-producing cells of the adrenal cortex
What is the role of COP I?

COP I - retrograde vesicular transport, from Golgi to ER

COP II anterograde vesicular transport, from RER to cis-Golgi
What is the role of Clathrin?
Clathrin helps form vesicles from the trans-Golgi to lysosomes, and to the plasma membrane
What is I-cell disease?
Inclusion cell disease - inherited lysosomal storage disorder.

Lysosomal enzymes are secreted outside the cell instead of inside because mannose-6-phosphate is not added to lysosome proteins

Results in coarse facial features, clouded corneas, restricted joint movement, high plasma levels of lysosomal enzymes. Often fatal
How does the Golgi apparatus affect asparagine? Serine? Threonine? Lysosomal proteins? Proteoglycans and tyrosine?
Addition of O-oligosaccharides to Serone, Threonine

Modification of N-oligosaccharides on Asparagine

Addition of Mannose-6-Phosphate to specific lysosomal proteins

Sulfation of sugars in proteoglycans and of selected tyrosine on proteins
List some drugs that act on microtubules.
What is Chediak-Higashi syndrome?
A microtubule polymerization defect resulting in decreasd phagocytosis. Results in recurrent pyogenic infections, partial albinism and peripheral neuropathy
What is the structure of microtubules?
24 nm thick
A cylindrical structure composed of a helical array of polymerized dimers of alpha and beta tubulin

2 GTP bound to each dimer
Where is Dynein ATPase located?
At the axonemal dynein

The ATPase links peripheral doublets of microtubule doublets
What is Kartagener's syndrome?
Immotile cilia due to a dynein arm defect

Results in male and female infertility, bronchiectasis, and recurrent sinusitis

Associated with situs inversus
Where do you find actin and myosin?
Muscle contractions
Adherens junctions
Where do you find microtubules?
Mitotic spindles
Where do you find intermediate filaments?
Glial fibrillary acid proteins
What stain do you use for Neuroglia?
What immunohistochemical stain do you use for neurons?
What immunohistochemical stain do you use for Epithelial cells?
What immunohistochemical stain do you use for Muscle?
What immunohistochemical stain do you use for connective tissue?
What is the mechanism of action of Ouabain?
Inhibition of NaK ATPase by binding to K+ binding site
What is the mechanism of cardiac glycosides?
Digoxin, Digitoxin

Directly inhibit the Na+K+ ATPase, leading to indirect inhibition of Na/Ca exchange - increased [Ca] = increased cardiac contractility
What is the most abundant type of collagen and where do you find it?
Type I

Bone, skin, tendon, dentin, fascia, cornea, late wound repair
Where do you find type II collagen?
Cartilage (including hyaline)
Vitreous body, nucleus pulposus
Where do you find type III collagen?
Reticulin - skin, blood vessels, uterus, fetal tissue, granulation tissue
Where do you find type IV collagen?
Basement membrane or basal lamina
Which step in collagen synthesis requires vitamin C?
Hydroxylation of specific proline and lysine residues
What is formed by cleavage of terminal regions of procollagen?
What enzyme is responsible for reinforcement of staggered tropocollagen molecules by covalent lysine-hydroxylysine cross-linkage?
Lysyl oxidase
In what disease is there an inability to cleave peptides from procollagen?
In what disease is there a failure to form the triple helix (procollagen) step in collagen formation?
Osteogenesis imperfecta
What disease mostly affects type III collagen?
Ehlers Danlos syndrome
What disease affects type I collagen?
Osteogenesis imperfecta
What disease affects type IV collagen?
Alport's syndrome
Usually XLR

Progressive hereditary nephritis and deafness - may have ocular disturbances
What disease is caused by a defect in fibrillin?
Marfan's syndrome
What disease results from excess elastase activity secondary to an enzyme deficiency?
Emphysema, secondary to alpha-1 antitrypsin deficiency
What disease has a cell-signaling defect of fibroblast growth factor receptor 3?
What disease has a deletion on chromosome 3 and results in constitutive expression of HIF and activation of angiogenic growth factors?
Von Hippel Lindau disease - findings include hemangioblastomas of retina, cerebellum, medulla; multiple bilateral renal cell carcinomas
List some of the X-linked recessive disorders.
Bruton's agammaglobulinemia
Wiskott-Aldrich syndrome
Fabry's disease
G6PD deficiency
Ocular albinism
Lesch-Nyhan syndrome
Duchenne's muscular dystrophy
Becker muscular dystrophy
Hunter's Syndrome
Hemophilia A, B
What disease is caused by a deletion of the dystrophen gene?
Duchenne's muscular dystrophy
What disease, associated with chromosomal breakage, is the second most common cause of genetic mental retardation after Down syndrome?
Fragile X Syndrome
What are the trinucleotide repeat segments for...

Huntington's Disease
Myotonic Dystrophy
Fragile X Syndrome
Friedreich's Ataxia
Huntington's: CAG
Myotonic dystrophy: CTG
Fragile X: CGG
Friedreich's ataxia: GAA
What would the pregnancy quad screen results be for Down syndrome?
Decreased AFP, Estriol, Inhibin A

Increased beta-HCG
What is the most common mechanism behind Trisomy 21?
Meiotic nondisjunction of homologous chromosomes associated with advanced maternal age
What disease is associated with a microdeletion of the long arm of chromosome 7, including the part that codes for the elastin gene?
William's syndrome
What metabolic disorder(s) are associated with William's syndrome?
Hypercalcemia (secondary to vitamin D sensitivity)

Cardiovascular problems
List the B vitamins...

Number, chemical name, and related cofactors/energy carrying molecules
B1 - Thiamine - TTP
B2 - Riboflavin - FAD, FMN
B3 - Niacin - NAD+
B5 - Pantothenic acid - CoA
B6 - Pyridoxine - PLP
B12 - Cobalamine
For what enzymes/reactions is Vitamin B1 a cofactor?
Thiamine pyrophosphate (B1) is a cofactor for...

Pyruvate dehydrogenase (glycolysis)
alpha-ketoglutarate dehydrogenase (TCA cycle)
Transketolase (HMP shunt)
Branched-chain AA dehydrogenase
What regions of the brain are damaged in Wernicke-Korsakoff?
Medial dorsal nucleus of thalamus
Mammillary bodies
From what amino acid is Niacin derived?
What vitamin is required for Niacin synthesis?
Vitamin B6
What are signs of pantothenate deficiency?
Dermatitis, enteritis, alopecia, adrenal insufficiency
What is the role of Vitamin B6?
It is converted to pyridoxal phosphate, a cofactor used in transamination, decarboxylation reactions, glycogen phosphorylase, cystathione synthesis, heme synthesis
For what two enzymes is cobalamin a cofactor?
Homocysteine methyltransferase

Methylmalonyl-CoA mutase
What reaction is catalyzed by homocysteine methyltransferase?
Homocysteine + N-methyl-tetrahydrofolate --> Methionine + Tetrahydrofolate
What reaction is catalyzed by methylmalonyl-CoA?
Methylmalonyl-CoA --> Succinyl-CoA
What is the role of folic acid?
It is converted to tetrahydrofolate, which is a coenzyme for 1-carbon transfer/methylation reactions - important for the synthesis of nitrogenous bases in DNA, RNA.
What is the role of S-adenosyl methionine?
It donates methyl groups, required for conversion of norepinephrine to epinephrine
For what enzymes is biotin a cofactor?
Pyruvate carboxylase (Pyruvate --> Oxaloacetate)

Acetyl-CoA carboxylase (Acetyl-CoA --> Malonyl-CoA)

Proprionyl-CoA carboxylase (Proprionyl-CoA --> Methylmalonyl-CoA)
What are the functions of Vitamin C?
1. Facilitates iron absorption by keeping iron in Fe2+ reduced state

2. Necessary for hydroxylation of proline and lysine in collagen synthesis

3. Necessary for dopamine beta-hydroxylase which converts dopamine to NE
What are signs of Vitamin E deficiency?
Increased erythrocyte fragility
Muscle weakness
Posterior column and spinocerebellar tract demyelination
What reactions are catalyzed by Vitamin K?
Catalyzes gamma-carboxylation of glutamic acid residues on various proteins concerned with blood clotting: Factors II, VII, IX, X, Protein C, Protein S
What are signs of Zinc deficiency?
Delayed wound healing
Decreased adult hair
What transcription factor motif relies on zinc?
Zinc fingers
What is the role of Fomepizole?
Inhibits alcohol dehydrogenase and is an antidote for methanol or ethylene glycol poisoning
What is the role of Disulfiram (Antabuse)?
Inhibits acetaldehyde dehydrogenase (acetaldehyde accumulates, contributing to hangover symptoms)
Where is alcohol dehydrogenase located?

Where is acetaldehyde dehydrogenase located?
Alcohol dehydrogenase - in cytosol

Acetaldehyde dehydrogenase - in mitochondria
What two reactions occur along with ethanol metabolism to replenish the NAD+ supply in the liver?
Pyruvate --> Lactate

Oxaloacetate --> Malate
What metabolic processes take place only in mitochondria?
Fatty acid oxidation (beta-oxidation)
Acetyl-CoA production
TCA cycle
Oxidative phosphorylation
What metabolic processes take place only in the cytoplasm?
Fatty Acid Synthesis
HMP Shunt
Protein synthesis (RER)
Steroid synthesis (SER)
What metabolic processes take place in both the cytoplasm and the mitochondria?
Heme synthesis
Urea cycle
What is the rate determining enzyme for...

TCA cycle?

HMP shunt?

De novo purine synthesis?

De novo pyrimidine synthesis?

Fatty acid synthesis?

Fatty acid oxidation?
TCA cycle - Isocitrate dehydrogenase

HMP shunt - G6PD

De novo purine - Glutamine-PRPP amidotransferase

De novo pyrimidine - CPS II

Fatty acid synthesis - Acetyl-CoA carboxylase

Fatty acid oxidation - Carnitine acyltransferase I
What reaction is catalyzed by galactokinase?

Name the deficiency disease?
Galactose --> Galactose-1 phosphate

Mild galactosemia
What reaction is catalyzed by galactose-1-phosphate uridyltransferase?

Name the deficiency disease?
Galactose-1 phosphate --> Glucose-1 Phosphate

Severe galactosemia
What reaction is catalyzed by hexokinase/glucokinase?
Glucose --> Glucose-6 Phosphate
What reaction is catalyzed by glucose-6-phosphatase?

Name the deficiency disease?
Glucose-6 Phosphate --> Glucose

von Gierke
What reaction is catalyzed by G6PD?
Glucose-6-Phosphate --> 6-Phosphogluconolactone
What reaction is catalyzed by Transketolase?
Ribulose-5-Phosphate --> Fructose-6-Phosphate
What reaction is catalyzed by Phosphofructokinase 1?
Fructose-6-Phosphate --> Fructose 1,6-bisphosphate
What reaction is catalyzed by Fructose 1,6 Bisphosphtatase?
Fructose 1,6 bisphosphate --> Fructose-6 phosphate
What reaction is catalyzed by Fructokinase?

Name the deficiency disease?
Fructose --> Fructose-1 Phosphate

Essential fructosuria
What reaction is catalyzed by Aldolase B?

Name the deficiency disease?
Fructose-1 Phosphate --> DHAP, Glyceraldehyde

Fructose Intolerance
What reaction it catalyzed by pyruvate kinase?
Phosphoenolpyruvate --> Pyruvate
What reaction is catalyze by pyruvate dehydrogenase?
Pyruvate --> Acetyl-CoA

(Requires Thiamine)
What reaction is catalyzed by HMG-CoA Reductase?
HMG-CoA --> Mevalonate
What reaction is catalyzed by pyruvate carboxylase?
Pyruvate --> Oxaloacetate

(Requires Biotin)
What reaction is catalyzed by phosphoenolpyruvate carboxykinase?
Oxaloacetate --> Phosphoenolpyruvate
What reaction is catalyzed by Citrate synthase?
Oxaloacetate --> Citrate
What reaction is catalyzed by isocitrate dehydrogenase?
Isocitrate --> alpha-ketoglutarate
What reaction is catalyzed by alpha-ketoglutarate dehydrogenase?
alpha-ketoglutarate --> Succinyl CoA

(Also requires thiamine)
What reaction is catalyzed by ornithine transcarbamoylase?
Ornithine --> Citrulline

(Requires Carbamoyl phosphate)
What is the effect of fructose 2,6 bisphosphate on glycolysis?
Activates phosphofructokinase 1
What is inhibited by arsenic?
Lipoic acid

Findings: vomiting, rice water stools, garlic breath
What cofactors are required by the pyruvate dehydrogenase complex?
Cofactors: Pyrophosphate (B1, thiamine - TPP), FAD (B2, riboflavin), NAD (B3, niacin), CoA (B5, pantothenate), Lipoic acid
What are the two purely ketogenic amino acids?
Lysine, Leucine
What are the different pathways of metabolism of pyruvate (4)?
Alanine - carries amino groups to the liver from muscle

Oxaloacetate - can replenish TCA cycle or be used in gluconeogenesis

Acetyl-CoA - Transition from glycolysis to the TCA cycle

Lactate - End of anaerobic glycolysis
What are four things that directly inhibit electron transport and block ATP synthesis?
Antimycin A
What directly inhibits mitochondrial ATPase, causing an increased proton gradient?
What two things are considered uncoupling agents, and increase permeability of the membrane, thus preventing a proton gradient from being set up?


Also thermogenin in brown fat