UNE BIOCHEM - Question 1 An individual is autosomal...

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Unformatted text preview: Question 1 An individual is autosomal recgsive for a branched chain keto acid dehydrogenase deficiency. This deficiency may mull in the elevation of all of the following the following amino acids except: < S elected ArBwer. hom ocysteine Response Feedback: See figure 39.1 3 Maple syrup urine disease (branched chain amino acids; tie in with pyruvate dehydrogenase complex and alpha—ketoglutarate dehydrogenase complex, and the requirement for thiamine, lipoic acid, niacin, riboflavin and pantothenate). Question 2 One of the differencfi in pro vs. eukaryotic protein translation is in the procfis of initiation. In eukaryotfi, trarBlational initiation starts with the small ribosomal subunit associating with the 5' cap on the mRNA. In prokaryotes, translational initiation starts with the ribsomal recognition of which of the following sequences? Selected Answer'. a. The Shine-Dalgarno sequence Response Feedback: See table 15.3. Prokaryotic translational initiation begins with recognition of the Shine—dalgamo sequence Compare translational initiation in both prokaryotes and eukaryotes Question 3 ’5, The NaJK ATPase is an example of an ATP dependent ligand—gated channel that allows for the movement of sodium against its concentration gradient. This type of transport is best described as which of the following? Selected Answer: Active transport Response See figure 1 0.1!] Feedback: Objective: Name two examples each of passive diffusion, active transport, and facilitated transport via a channel or carrier and briefly summarize the differencfi between each Question 4 In eukarytoic orgnaisms, which of the following enzymes is responsible for DNA synthesis on the lagging strand? Selected Answer: DNA polymerase 6 (delta) Response Feedback: See figure 13.9 Table 13.2 DNA polymerase delta is the enzyme primarily responsible for DNA synthesis on the lagging strand. luestion 5 .~_ .< The anticodon is located on the and is complementary to the codon located on the _ Selected Answer: tRNA ; mRNA Response Feedback: The anticodon is on the tRNA and is complementary to the codon on the mRNA. luestion E Steroid hormone receptors bind glucocorticoid response elements (GRE) on DNA. This type of regulation is referred to as: Selected Answer: d. transcriptional regulation luestion T The transport of glucose from the intestinal lumen to the enterocytes is dependent on which of the following processes? Selected Answer: The maintenance of a sodium gradient across the intestinal lumen and the enterocyte. Response Feedback: See figure 10.11 Objective: Com pare and contrast active trans port with secondary active trans port luestion B 3 Selected Answer: a. Hydrolases Chymotrypsin is a protease that cleaves peptide bonds. It is characterized as which of the following classes of enzymes? Response page 131: Hydrolase Feedback: Objective: Describe the 6 major enzyme classifications and the basic type of reaction catalyzed, including: oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases Question 9 r .< Alternative splicing and mRNA editing are two forms of post transcriptional regulation. Which of the following is an example of mRNA editting? Selected Answer. c. The generation of a small transcript via splicing Raponse Feedback: See figure 1 6.1 9 Compare the process of mRNA editting with mRNA altemative splicing Question ‘1 D .< In prokaryotic organisms, many genes are regulated by the same upstream promoter. This allows for all the genes to be transcripted and translated together. This organizational structure of prokarytoic genes is refered to as which of the following? Selected Answer. c. Operon Response See figure 16.2 Bacterial genes are organized in an operon. Transcription of that operon is regulated from a single promoter and the genes Feedback: are transcribed into a polycistronic mRNA. Define operon Question 11 Purine biosynthesis starts with the activation of a 5 carbon sugar. In this initial reaction, ribose 5—phosphate is converted into which of the following compounds? Selected Answer. PRPP (5— phosphoribosylpyrophosphate) Response Feedback: Explanation: PRPP and glutamine are the first required substrates for the synthesis of purines. See figure 41.9 Explain the central role of 5'phosphoribosyl—1—pyrophosphate (PRPP) in nucleotide metabolism Question ‘1 2 ’_-“' What is the [OH] concentration in a 0.01 M = 10'2 M solution of HCI. j (10-14 = [H+] [OH—j) Selected Answer. d. 10—12 M Response Feedback: Page 44. Section II Objective: Calculate the [OI-l] OR [Ht] concentration if given the molarity of a solution. Question 1 3 '7." The Epo receptor is an example of a classical Jak — STAT type of receptor. All of the following are true statements with regards to this receptor family except: Selected Answer. Q Signaling can be termination through activation of phosphodiesterase Response See figure 11.15 Feedback: Objective: Provrde examples of each ofthe followrng major classes of receptors and compare and contrasttheir mechanism ofsignaling and termination: receptortyrosine kinases, serineflzhreonine linked receptors, G—Protein coupled receptors (heptahelical receptors), cytoplasmiclnuclear receptors and ion channel receptors Question 1 4 :3. A nucleotide is comprised of which of the following units? Selected Answen a nucleoside and a phosphate group Response Explanation: A nucleoside contains a base and a sugar group. A nucleotide contains all three portions: a base, sugar and phosphate Feedback: group. Question 1 5 :7." Ca2+ influx thm a channel that is activated by a change in the membrane potential across the plasma membrane is an example of a(n}: Selected Answer. d. Voltagegated channel Response Feedback: See figure in] Objective: Name two examples each of passive difiusion, acijve transport, and facilitated transport via a channel or carrier and briefiysummarize the difierences between each Describe and evaluate the role of ion gradients, co transporters, and ATP in active transport mechanisms Question 1 S ’_ ,-<. Under low energy conditions, AMP will bind to phosphofructokinase I and glycogen phosphorylase. This is an example of which of the follow types of enzyme ' a regulation? Selected Answer. c_ allosteric inhibition Response Feedback: See figure 9.8. Objective: Define and explain allosterism and the important physiological role of allosteric enzyme inhibition or activation (n SMAD proteins are downstream targets of serine threonine receptors. Phosphorylation of the SMAD proteins by the receptor is required for translocation to the _a nucleus. This type of covalent modification is referred to as: Selected Answer. post translation regulation luestion 13 ~25 In pyrimidine synthesis, uracil can feedback and inhibit which of the following enzymes? Selected Answer. Carbamoyl phosphate synthase II luestion 19 75 A competitive inhibitor competes with a substrate for binding at the enzymes active site. This interaction causes which of the following changes in the j enzymes activity? Selected Answer: c The addition of a competitive inhibitor will have no impact on the Vmax of the enzyme. Response Feedback: See figure 9.14 Objective: Evaluate tiie change in the Km or‘v'max otan ezyme with the addition oia oompetitve or noncompetitive inhibitor. luestion 20 ‘7.” Glucogenic amino acids can enter the TCA cycle as all of the following intermediates except: I Selected Answer. :1. acetyl CoA Response See figure 39.2. If the amino acid is fully metabolized to acetyICoA it does not provide excess carbons to generate glucose thn.| Feedback: gluconeogenesis. I ist the nrnr‘lurtts Of ketnnenir'. rir nlurznnenir. amino acid catahnlism Iuestion 1 f In pyrimidine synthesis, carbamoyl phosphate syntheta se 11 [CSPII] is the primary regulatory enzyme. This enzyme can be allostericallyactivated m by which of the following compounds? Selected Answer: Q 5—phosphoribosyl ‘l—pyrophosphate (PRPP) Response Feedback: See figure 41.14 Describe the biosynthesis of the purine and pyrimidine nucleotides with emphasis on the key regulated steps Iuestion 2 no The association of DNA and histories can be modified by histone acetylation. A decrease in histone acetylation will have which of the following impacts on the j assocation of DNA and histories? Selected Answer: b. Increase DNA: histone association Response Histone acetylation decreases the positive charge on the lysine residues of histories. This will decrease the interaction of DNA (negatively Feedback: charged) with histories (postively charged). If histone acetylation decreases this INCREASES the postive charge on histories and the association with DNA increases. Relate levels of histone acetlylation to DNA accessibility. luestion 3 .75 In prokaryotic organisms, many genes are regulated by the same upstream promoter. This allows for all the genes to be transcripted and translated together. in This organizational stmcture of prokarytoic genes is refered to as which of the following? Selected Answer: a. Operon Response See figure 16.2 Bacterial genes are organized in an operon. Transcription of that operon is regulated from a single promoter and the genes Feedback: are transcribed into a polycistronic mRNA. Define operon luestion 4 :’__.-fi A patient recently diagnosed with colon mncer isbeing treated with 5 —fluorouracil. “i‘hich of the following enzymes will this drug directly ‘ inhibit ? SElECIEU Answer: Q Thymidylate synthase Response Feedback: See figure 40.5 Objective: Explain the use otmeti'ioti'exate and 5 —tturouracil as an inhibitor oi nucleotide synthesis. luestion 5 .1 A Which amino acid has a side chain that has a pKa that can act as a buffer in a physiological pH range ("pH = 7.4)? The pH range over which a buffer is j effective is called the buffering range, usually defined as pKa + 1 to pKa — 1. Selected Answer: d. Histidine Response Feedback: See Figure 6.9 Objectiv e: List and name the 20 amino acids that commonly occur in proteins and classify them according to chirality, polarity, size, and charge luestion E r A In the process of protein translation, which of the following RNAs is responsible for delivering the amino acids to the translational machinery? Ld Selected Answer: tRNA (transfer RNA) Response Feedback: tRNAs carry amino acids on their 3' CCA tail. See figure 14.1]Ir which illustrates the amino acid attachement site. luestion if In eukarytoic orgnaisms, which of the following enzymes is responsible for DNA synthesis on the lagging strand? r K Selected Answer: DNA polymerase 6 (delta) Response Feedback: See figure 13.9 Table 13.2 DNA polymerase delta is the enzyme primarily responsible for DNA synthesis on the lagging strand. Iuestion 3 3’5 Ca2+ lr‘lflLD< thm a channel that is activated by a change in the membrane potential across the plasma membrane is an example of afn}: Selected Answer: a. VoltageLgated channel Response Feedback: See figure 10.? Objective: Name two examples each of passive difiusion,ac1jve transport, and facilitated transport via a channel or carrier and briefivsummarize 1h difierences between each Describe and evaluate the role of ion gradients, co transporters, and ATP in active transport mechanisms IUESIIDH 'I U - This figure depicts a segment of DNA, the transcriptional start site (T55) is labeled and transcription will tenninate at the terminator j highlighted in blue. TSS 5 ' - CTRTFfl" RGCCBTGCBTTRTCTAGATAGTAGGCTCTGAGMTTTBTCTCRCT- 3 ‘ Ililllilllllll|III|lll'lllrlllillllillllllllll TCGGTHCGTAATRGATCTATCETCCGAGACTCTTWTAGRGTGA- b ' promoter terminator Each strand has three putential reading fmes. Fnjm the T55, which ufthe reading frames shunld be used tIJ generate an inframe ATG? 39l9d9d Answer: a Frame 3: 2 hasepairs after the T55 starting with GCC Response Feedback: See figure 15.3 Frame 3 will generate an inframe ATG which can be transcribed into AUG to be used as a translational start. Iuestion 1 1 "a?“ Which ofthe following statements is true regarding theactivity ofthe ribonuoeltide reductase? Selected Answer: b. The enzyme is required to convert nucleotides from the ribose form to the deoxy'ribose form required for DNA synthesis Response Feedback: See page ?68 Section IV. Describe the requirement of the ribonucleotide reductase reaction and its regulation at both the allosten'c and effector sites luestion 12 In the absence of iron, the iron response eiement binding protein is bound to the iron response element on mRNA. Under these conditions: j Selected Answer: b. transcription of ferrit'rn in decreased Response Feedback: See figure 16.21 Relate how levels of iron can modulate the transcription and translation of different protein products Question 1 3 ’_:<. All ofthe following can be found within thetranscribed region ofa eukaryotic gene except: Selected Answer: a TATAhox Response Feedback: See figure 14.4 The TATA box is upstream of the transcriptional start site. Illustrate gene organizational structure and demonstrate how this relates to transcriptional initiation. Question 1-4 r5 In an inducible operon, in the absence of the inducer. Selected Answer: c. the repressor is bound to the operator Response Explanation: An inducible operon is shown in Fig 18.4. In the absence of the inducer the repressor binds the operators and transcription does not Feedback: occur When the inducer is prEent, it binds the reprasor and the operator is accasible to RNA polymerase. Question 1 5 r_,.< Platelet—derived growth factor is secreted from platelets aggregated at the site of an injury. This growth factor stimulates nearby smooth muscle cells to '—d proliferate. This type of signaling is best described as which of the following? Selected Answer: paracrine Response Feedback: See figure 11.4 Objective: Compare endocrine, paracrine, or autocrine signals Question 1 E {5 In a reprasible operon, when the co—reprfisor is absent which of the following statements is true? - Selected Answer: a. The repressor is inactive and the operon is transcribed Response A repressible operon is shown in figure 16.6. In this case, both the repressor and co—repressor must be present and associated with each Feedback: other before binding the operator. If one is absent, the operon is transcribed Compare the differences in inducible and repressible operons Question 17' At the base of a tRNA there is a trinucleotide sequence that is complementary to a trinud eotide sequence on mRNA and will determine what amino acids are added during the process of protein translation. “fhich ofthe following terms is used to describe this trinucleotide sequence on the tRNA? Selected Answen b. anticodon Response Feedback: See figure 14.17 the anticodon is the triplicate sequence at the base of a tRNA Describe the structure of tRNA including the addtion of a 3' amino acid attachement site and the necessity of the anticodon. Question 18 Under low energy conditions, AMP will bind to phosphofructokinase I and glycogen phosphorylase. This is an example of which of the follow types of enzyme regulation? Selected Answer: d. allosteric activation Response Feedback: See figure 9.8. Objective: Define and explain allosterism and the important physiological role of allosteric enzyme inhibition or activation Question 19 .55 Purine biosynthesis starts with the activation of a 5 carbon sugar. In this initial reaction, ribose 5—phosphate is converted into which of the following compounds? Selected Answer: PRPP (& phosphori bosylpyrophosphate} Response Feedback: Explanation: PRPP and glutamine are the first required substrates for the synthesis of purines. See figure 41.9 Explain the central role of 5'phosphoribosyl—‘l—pyrophosphate (PRPP) in nucleotide metabolism Question 20 To evaluate whether a protein is being translation the best method to use would be: Selected Answer: d. Westem blot Response Explanation: To evaluate if a protein product is being made you will need to look at protein levels. The only technique that looks at the level of Feedback: protein is a Western blot. Northern blot evaluates mRNA levels; Southern blot allows you to assess changes in genomic DNA and PCR can also be used to evaluate changes in DNA sequence. ...
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