Exam 3 Review Flashcards
Which of the following statements about Purine and Pyrimidine biosynthesis and metabolism is correct (or True)? (Select all that apply)
A: Antifolate drugs and Glutamine analogs block purine nucleotide biosynthesis.
B: PRPP (phosphoribosylpyrophosphate) synthase phosphorylates the anomeric OH group of Ribose 5’-phosphate. C: cAMP and cGMP feedback regulate their formation from IMP (InosineMonophosphate).
D: Orotic aciduria is a consequence of the inability of severely damaged mitochondria to utilize carbamoyl phosphate.
A, B, and D
Which of the following statements is incorrect (or False)?
A: Thyroid hormones are transported by thyroid binding globulin.
B: Glucocorticoids are transported by corticosteroid binding globulin. C: Group I hormones are lipophilic.
D: Group II hormones have a long plasma half-life.
D
Which of the following are hormones that bind to cell surface receptors? (Select all that apply)
A: Angiotensin II B: Glucagon
C: PTH
D: ACTH
ABCD
4 Which of the following hormones bind to intracellular receptors? (Select all that apply) A: Glucocorticoids B: Insulin C: Mineralcorticoids D: Glucagon
A and C
Which of the following statements about Pyrimidine metabolism is correct (or True)? (Select all that apply)
A: Primary amine group in Cytosine is first oxidized to the oxo group to form (or synthesize) dihydrouracil B: Primary amine group in Cytosine is first oxidized to the oxo group to form (or synthesize) Uracil.
C: The final metabolic product of cytosine metabolism is beta alanine
D: The final metabolic product of Thymine is beta-aminoisobutyrate.
BCD
Which of the following statements about purine metabolism is correct (or True)? (Select all that apply)
A: Adenosine deaminase oxidizes the primary amine in adenine to an oxo group.
B: Purine nucleoside phosphorylase hydrolyzes the beta N glycosidic bond to form hypoxanthine. C: Xanthine is reduced to Uric acid.
D: Hypoxanthine is oxidized to Xanthine.
ABD
Which of the following disorders of purine catabolism is correct (or True)? (Select all that apply)
A: Lesch-Nyhan syndrome represents overproduction of hyperuricemia which is characterized by frequent episodes of self mutilation.
B: Purine overproduction and hyperuricemia is found in Von Gierke disease.
C: Hypouricemia and increased excretion of hypoxanthine and xanthine are associated with a deficiency in xanthine oxidase.
D: Adeosine deaminase deficiency is associated with an immunodeficiency disease.
ABCD
Xeroderma pigmentosum (XP) is an inherited defect that is related to inability to remove
which of the following?
A: TT dimer B: AT dimer C: GC dimer D: AA dimer
A
Which of the following enzymes will cleave the heterocyclic base from the sugar?
A: DNA ligase
B: Exonuclease
C: Beta N-glycosidase D: Endonuclease
C
Which of the following statements about the formation of the peptidyl bond in protein formation is True (or Correct)?
A: The alpha amino group of the incoming amino acid at the “A” site carries out a nucleophilic attack on the amide group of the peptidy-tRNA at the “P” site.
B: The alpha amino group of the incoming amino acid at the “A” site carries out a nucleophilic attack on the ester group of the peptidy-tRNA at the “P” site.
C: The alpha carboxyl group of the incoming amino acid at the “A” site carries out a nucleophilic attack on the amide group of the peptidy-tRNA at the “P” site.
D: The alpha carboxyl group of the incoming amino acid at the “A” site carries out a nucleophilic attack on the ester group of the peptidy-tRNA at the “P” site.
B
In DNA replication process, the key step in opening up the superstructure is acetylation of an amino acid residue in histones. Which of the following amino acids is acetylated?
A: Lysine
B: Asparagine C: Glycine
D: Glutamine
A
The mature m-RNA is capped by which of the following heterocyclic bases (or which of the following heterocyclic bases are present on the cap of a mature m-RNA?
A: 5-methyguanine triphosphate B: 7-methylcytosine triphosphate C: 7-methylguanine triphosphate D: 5-methylcytosine triphosphate
C
Which of the following types is a description of Two base alteration of DNA?
A: Depurination
B: UV light induced Pyrimidine dimer C: Ionizing radiation
D: Deamination of Cytosine to Uracil.
B
Which of the following arms of t-RNA is required for recognition of the t-RNA by its proper aminoacyl t-RNA synthetase?
A: D arm
B: T(psi)C arm
C: Acceptor arm D: Anti-codon arm
A
Which of the following reactions listed against each enzyme is incorrect (or False)?
A: DNA ligase catalyzes bonds between DNA molecules
B: Exonuclease III removes nucleotides from the 3’ ends of DNA
C: S1 nuclease degrades double stranded DNA
D: Lambda Exonuclease removes nucleotides from the 5’ ends of DNA
C
In DNA replication process, the phosphodiester bonds are formed between which two 1/1 carbons of the adjacent ribose sugars?
A: 3’ and 5’ B: 3’ and 4’ C: 3’ and 2’ D: 3’ and 1’
A
Which of the following motifs does not exist as dimers? A: Leucine zipper B: Helix-turn-helix C: Zinc finger D: Thymine-Thymine dimer
C
In DNA replication process, which of the following enzymes initiates nicks on one strand to remove supercoils and supertwists?
A: DNA topoisomerase I B: DNA toposiomerase II C: DNA gyrase
D: Helicase
A
In translation of an mRNA into a protein, the first amino acid that is attached to the start codon is which of the following?
A: Cysteine
B: O-formylmethionine C: N-formylmethione D: Serine
C
Which of the following is the action of SnRNA (snurps)?
A: Important in growth and development B: Knocks out a portion of the gene
C: Splices the introns out of m-RNA
D: Splices out the exons out of m-RNA
C
Pol II is active when its tail is phosphorylated. Which of the following amino acids is present in the tail that gets phosphorylated?
A: Serine
B: Cysteine C: Tyrosine D: Tryptophan
A
Which of the following descriptions refer to the Leucine Zipper Motif?
A: Consists of three antiparallel beta sheets and three alpha helices.
B: Consists of closely spaced Cysteine-Cysteine residues followed by 12 to 13 amino acids later by histidine- histidine pair.
C: Consists of a beta sheet in which there is a periodic repeat of leucine residues at every 7th position.
D: Consists of an alpha helix in which there is a periodic repeat of leucine residues at every 7th position.
D
Which of the following is an example of an unacceptable missense?
A: Hb A, is converted to Hb M (Boston) where the alpha chain Histidine at #58 is replaced by Tyrosine. B: HbA is converted to Hb Hikari, where the beta chain Lysine at #61 is replaced by Asparagine.
C: Hb A is converted to Hb S, where the beta chain Glutamate at #6 is replaced by Valine.
A
Which of the following statements is incorrect (or False)?
A: The lagging strand is replicated discontinuously in short pieces of 100-250 nucleotides by DNA polymerase in the 3’ to 5’ direction.
B: The DNA replication is initiated at special sites termed Ori’s to generate replication bubbles.
C: Each strand of the double helix is replicated simultaneously by by somewhat different mechanism.
D: A complex of proteins, including DNA polymerase, replicates the leading strand continuously in the 5’ to 3’ direction.
A
Which of the following statements about AcetylCholine (ACh) is correct (or True)? (Select all that apply)
A: Two molecules of ACh bind to the alpha subunits of the heteropentameric receptor (AChR).
B: ACh is removed from the receptor by the enzyme acetylcholinesterase.
C: When ACh binds to the ACh receptor, it opens up the ion channel where Na+ ions flow in and K+ ions flow out. D: ACh is inhibited reversibly by Phosphonates in nerve gas and some pesticides
ABC
Which of the following statements about hormones and neurotransmitters is correct (or True)? (Select all that apply)
A: The excitatory neurotransmitters are Glutamate, aspartic acid and cysteine.
B: The inhibitory neurotransmitters are glycine, taurine, beta alanine and Gamma aminobutyric acid.
C: To stop the action of Catechol amines, Monoamine Oxidases (MAOs) reduce the amine (or quarternary amine) group to to the corresponding aldehyde group.
D: Methionine encephalin is a pentapeptide that is present in certain nerve terminals that bind to specific pain receptors.
ABD
Which of the following statements about GPCR is correct (or True)? (Select all that apply)
A: G-proteins associated with GPCR are heterotrimeric where the gamma subunit is attached to the plasma membrane by an isoprenoid tail.
B: The alpha subunit, formed after activation, also has an intrinsic hydroylase (or GTPase) activity.
C: GPCR is a seven transmembrane receptor with the N-terminal on the outside of the cell and the C terminal on the inside of the cell.
D: Many of the Group I hormones bind to receptors that couple to effectors through a G protein.
ABC
Which of the following statements about hormones is correct (or True)? (Select all that
apply)
A: Diacylglycerol (DAG) is capable of activating Protein Kinase C (PKC).
B: cAMP dependent protein kinase A (PKA) phosphorylates Glycogen synthase a (active) into glycogen synthase b (inactive).
C: Protein kinase G (PKG) phosphorylates several smooth muscle proteins.
D: Pyruvate kinase, pyruvate carboxylase, glycogen synthase enzymes are regulated by Ca+2 and or phosphorylation.
ABCD
Which of the following statements about hormone action and signal transduction is correct (or True)? (Select all that apply)
A: Excessive, deficient, or inappropriate production and release of hormones and other regulatory molecules are major causes of disease.
B: Glucocorticoids diffuse through the plasma membrane and bind to the receptor in the cytoplasm before binding to the GRE on DNA, which has no corepressor attached to the GRE.
C: Thyroid hormones enter the nucleus and bind to its hormone response element but fails to activate transcription because it exists in complex with a corepressor.
D: Water soluble hormones have a transport protein that help them initiate a response by binding to the cell surface receptor.
ABD
The incorporation of fatty acid into lecithin occurs in three ways. Which one of the following is not one of the ways? (Select all that apply)
A: By complete synthesis of the phospholipid.
B: By transacylation between cholesteryl ester and lysolecithin C: By direct acylation of lysolecithin by acyl-CoA.
D: By phosphorylation of lysolecithin.
D
Which of the following statement is correct (or True)? (Select all that apply)
A: small ncRNA termed miRNA and siRNA typically inhibit gene expression
B: The D-arm or D-loop contains pseudo uridine.
C: snRNA are significantly involved in rRNA and mRNA processing and gene regulation. D: The acceptor arm in tRNA terminates in the nucleotides CCA.
ACD
Which of the following statements is correct (or True)? (Select all that apply)
A: When proteins bind to nucleotides they usually do not disrupt the base pairing between the DNA molecules. B: Endonucleases cleave internal phosphodiester bonds.
C: The cap on the 5’ terminal end of mRNA helps prevent attacks by 3’ exonucleases.
D: The 3’ end of tRNA carries the amino acid for protein synthesis.
ABD
What types of lipids are involved in Multiple sclerosis and Lipidosis? (Select all that apply)
A: Phospholipids B: Spingolipids C: Glycerolipids D: Glycolipids
AB
Which two molecules begin the acylglycerol biosynthesis of triacylglycerols and phosphoglycerols? (Select all that apply)
A: Glycerol-3-phosphate and dihydroxyacetone phosphate. B: Plasmalogen and Platelet activation factors.
C: Phosphotidate and diacylglycerol
D: Cardiolipin and Phosphatidylinositol
A
Which of the following statements about hormones and neurotransmitters is correct (True)? (Select all that apply)
A: Adrenergic catecholamines, Adrenocorticotropic hormones, glucagon, parathyroid hormones all use cAMP as secondary messenger.
B: Atrial natriuretic factor and nitric oxide use cGMP as secondary messenger.
C: Angiotension II, Oxytocin uses Ca+2 or PI as secondary messenger.
D: Polypeptides, proteins, glycoproteins and catecholamines are considered as Group I hormones.
ABC
Which of the following statements about biosynthesis of nutritionally nonessential amino
acids is correct (or True)? (Select all that apply)
A: Glutamine is formed from glutamate by amidation reaction, using the ammonium ion.
B: Transamination of pyruvate forms alanine and transamination of oxaloacetate forms aspartate. C: Aspartate is converted to Asparagine using the ammonium ion provided by Glutamine.
D: Phenylalanine hydroxylase converts Tyrosine into Phenylalanine
ABC
37 Which of the following statements about the urea cycle is correct (or True)? (Select all that apply)
A: Urea cycle disorders are characterized by hyperammonemia, encephalopathy, and respiratory alkalosis. B: Four of the five metabolic diseases result in accumulation of precursors of urea, principally ammonia and glutamine.
C: Carbamoyl phosphate synthase I initiates urea biosynthesis.
D: Cleavage of Arginine releases urea and re-forms Citrulline.
ABC
