Questions and Answers of Biochemistry Concepts And Connections

Why do some journals require the authors of articles describing DNA libraries to make those libraries available to other researchers?
Why is temperature control so important in the polymerase chain reaction?
What is qPCR?
What difficulties arise in the polymerase chain reaction if there is contamination of the DNA that is to be copied?
Why is DNA evidence more useful as exclusionary evidence than for positive identification of a suspect?
Give the DNA sequence for the template strand that gives rise to the following sequence gel, prepared using the Sanger method with a radioactive label at the 5' end of the primer. A T T с T I G T T
This is a conjectural question—there is no single “right” answer—that is good for discussion over tea and crumpets. In what ways might it be possible to prevent genetic discrimination due to
What is the difference between the genome and the proteome?
Has proteomic analysis been done on multicellular eukaryotes?
What is the genetic material of a virus?
How does a virus infect a cell?
What is the difference between the lytic pathway and the lysogenic pathway?
Is there a correlation between the speed of a viral infection and its potential mortality rate? Explain.
What might be the characteristics of cells of a human who is immune to HIV infection?
What is unique about the life cycle of a retrovirus?
What enzyme is responsible for the production of viral DNA from a retrovirus?
What are three reasons that retroviruses are studied so much these days?
What is meant by gene therapy?
What types of viruses are used for gene therapy, and how are they manipulated to make them useful?
What are the components of innate immunity?
What are the components of acquired immunity?
What is the purpose of a major histocompatibility complex?
What is clonal selection?
What type of viral RNAs from herpes viruses confound the immune system?
What is a tumor suppressor? What is an oncogene?
What is the difference between Prima-1 and nutlins in the way they would fight cancer?
What causes the majority of the mutations found in human melanomas and lung cancer?
Which cells are attacked by HIV?
How does HIV gain entry into the cells it attacks?
What types of therapy are used to fight AIDS?
Does the HIV virus kill a patient directly?
What is HAART?
Is there a connection between the free-energy change for a reaction and its equilibrium constant? If there is a connection, what is it?
What do the following indicators tell you about whether a reaction can proceed as written?(a) The standard free-energy change is positive.(b) The free-energy change is positive.(c) The reaction is
Consider the reactionThe Keq at pH 8.5 and 38°C is 122. Can you determine the rate of the reaction from this information? Glucose-6-phosphate + H₂O → Glucose + P₁ [glucose]
What conditions are necessary for the free-energy change to be used to predict the spontaneity of a reaction?
Why is it important that energy released by exergonic reactions can be used to provide energy for endergonic reactions?
Why is it necessary to define a modified standard state for biochemical applications of thermodynamics?
How can you tell if the standard Gibbs free energy given for a reaction is for chemical standard states or biological standard states?
Calculate ΔG°' for the following values of K'eq: 1 * 104, 1, 1 * 10–6.
Consider the reaction A ⇌ B + C, where ΔG° 5 0.00.(a) What is the value of ΔG (not ΔG°) when the initial concentrations of A, B, and C are 1 M, 10-3 M, and 10-6 M?(b) Try the same
Compare your answers for parts (a) and (b) with that for part (c) in Question 10. What do your answers to parts (a), (b), and (c) say about the influence of concentrations of reactants and products
The ΔG°' for the reaction Citrate → Isocitrate is + 6.64 kJ mol-1 = + 1.59 kcal mol-1. The ΔG°' for the reaction Isocitrate → α-Ketoglutarate is - 267 kJ mol-1 = -63.9 kcal mol-1. What is
Can you use the equation ΔG°' = -2RT ln K'eq to get the ΔG°' from the information in Question 3? Question 3Consider the reactionThe Keq at pH 8.5 and 38°C is 122. Can you determine the rate of
If a reaction can be written A → B, and the ΔG°' is 20 kJ mol-1, what would the substrate/product ratio have to be for the reaction to be thermodynamically favorable?
Organize the following words into two related groups: catabolism, energy-requiring, reductive, anabolism, oxidative, energy-yielding.
Comment on the statement that the existence of life is a violation of the second law of thermodynamics, adding concepts from this chapter to those we saw in Chapter 1.
Would you expect the production of sugars by plants in photosynthesis to be an exergonic or endergonic process?Give the reason for your answer.
Would you expect the biosynthesis of a protein from the constituent amino acids in an organism to be an exergonic or endergonic process? Give the reason for your answer.
Adult humans synthesize large amounts of ATP in the course of a day, but their body weights do not change significantly. In the same time period, the structures and compositions of their bodies also
What is the structural difference between NADH and NADPH?
How does the difference between NADH and NADPH affect the reactions in which they are involved?
Which coenzyme is a reactant in the oxidation of a nutrient, NAD+ or NADH? What is the reason for your answer?
Does the oxidation of glucose to carbon dioxide and water take place in one step or in several steps?
Which of the following statements are true? For each, explain why or why not.(a) All coenzymes are electron-transfer agents.(b) Coenzymes do not contain phosphorus or sulfur.(c) Generating ATP is a
The following half reactions play important roles in metabolism.Which of these two is a half reaction of oxidation? Which one is a half reaction of reduction? Write the equation for the overall
A biochemical reaction transfers 60 kJ mol-1 (15 kcal mol-1) of energy. What general process most likely would be involved in this transfer? What cofactor (or cosubstrate) likely would be used? Which
There is a reaction in carbohydrate metabolism in which glucose-6-phosphate reacts with NADP+ to give 6- phosphoglucono-d-lactone and NADPH.In this reaction, which substance is oxidized, and which is
Draw NAD+ and FAD showing where the electrons and hydrogens go when the molecules are reduced.
There is a reaction in which succinate reacts with FAD to give fumarate and FADH2.In this reaction, which substance is oxidized, and which is reduced? Which substance is the oxidizing agent, and
Show that the hydrolysis of ATP to AMP and 2Pi releases the same amount of energy by either of the two following pathways. Pathway 1 Pathway 2 ATP + H₂O → ADP + P₁ ADP + H₂O → AMP +
How does the release of chemical energy make metabolism possible?
Comment on the free energy of hydrolysis of the phosphate bond of ATP (-30.5 kJ mol-1; -7.3 kcal mol-1) relative to those of other organophosphates (e.g., sugar phosphates, creatine phosphate).
What structural feature do NAD+, NADP+, and FAD have in common?
A friend has seen creatine supplements for sale in a health-food store and asks why. What do you tell your friend?
Would you expect an increase or a decrease of entropy to accompany the hydrolysis of phosphatidylcholine to the constituent parts (glycerol, two fatty acids, phosphoric acid, and choline)? Why?
Explain and show why phosphoenolpyruvate is a high-energy compound.
Short periods of exercise, such as sprints, are characterized by lactic acid production and the condition known as oxygen debt. Comment on this fact in light of the material discussed in this chapter.
Why is the process of activation a useful strategy in metabolism?
What is the molecular logic that makes a pathway with a number of comparatively small energy changes more likely than a single reaction with a large energy change?
Why are thioesters considered high-energy compounds?
This is a conjectural question: If the reactive part of coenzyme A is the thioester, why is the molecule so complicated?
Name which, if any, of the following are epimers of D-glucose: D-mannose, D-galactose, D-ribose.
Name which, if any, of the following groups are not aldose–ketose pairs: D-ribose and D-ribulose, D-glucose and D-fructose, D-glyceraldehyde and dihydroxyacetone.
What is the difference between an enantiomer and a diastereomer?
How many possible epimers of D-glucose exist?
Why are furanoses and pyranoses the most common cyclic forms of sugars?
How many chiral centers are there in the open-chain form of glucose? In the cyclic form?
The sugar alcohol often used in “sugarless” gums and candies is D-sorbitol. Much of this alcohol is prepared by reduction of D-glucose. Compare these two structures and explain how this can be.
Two sugars are epimers of each other. Is it possible to convert one to the other without breaking covalent bonds?
How does the cyclization of sugars introduce a new chiral center?
What is unusual about the structure of N-acetylmuramic acid (Figure 16.18) compared with the structures of other carbohydrates?
What is the chemical difference between a sugar phosphate and a sugar involved in a glycosidic bond?
Define the term reducing sugar.
What are the structural differences between vitamin C and sugars? Do these structural differences play a role in the susceptibility of this vitamin to air oxidation?
Name two differences between sucrose and lactose. Name two similarities.
How does chitin differ from cellulose in structure and function?
How does glycogen differ from starch in structure and function?
What is the main structural difference between cellulose and starch?
What is the main structural difference between glycogen and starch?
How do the cell walls of bacteria differ from those of plants?
Advertisements for a food supplement to be taken by athletes claimed that the energy bars contained the two best precursors of glycogen. What were they?
Explain how the minor structural difference between α- and β-glucose is related to the differences in structure and function in the polymers formed from these two monomers.
All naturally occurring polysaccharides have one terminal residue, which contains a free anomeric carbon. Why do these polysaccharides not give a positive chemical test for a reducing sugar?
An amylose chain is 5000 glucose units long. At how many places must it be cleaved to reduce the average length to 2500 units? To 1000 units? To 200 units? What percentage of the glycosidic links are
Glycogen is highly branched. What advantage, if any, does this provide an animal?
No animal can digest cellulose. Reconcile this statement with the fact that many animals are herbivores that depend heavily on cellulose as a food source.
What is the difference between the core enzyme and the holoenzyme?
Put the following in linear order: UP element, Pribnow box, TSS, -35 region, Fis site.
Define inducer and repressor.

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