In studying a particular bio-molecule (a protein, nucleic acid, carbohydrate, or lipid) in the laboratory, the biochemist first needs to separate it from other biomolecules in the sample—that is, to purify it. Specific puri-fication techniques are described later in the book. However, by looking at the monomeric subunits of a biomolecule, you should have some ideas about the characteristics of the mole-cule that would allow you to separate it from other molecules. For example, how would you separate (a) amino acids from fatty acids and (b) nucleotides from glucose?

QUESTION 9

1. Drugs that aim to lower blood cholesterol work by

   		preventing recycling of bile salts.
   		All the alternatives
   		inhibiting hepatic cholesterol synthesis.
   		inhibiting its intestinal absorption.

2 points   

QUESTION 10

1. For marathoners, the ATP for sustained muscle contraction comes from the metabolism of which of the following substrates?

   		proteins and amino acids
   		fatty acids
   		All the alternatives
   		glucose

2 points   

QUESTION 11

1. Which of the following is TRUE about fasted-state metabolism?

   		it is catabolic
   		All the alternatives
   		leads to the formation of ketone bodies
   		maintains plasma glucose for the brain

2 points   

QUESTION 12

1. Which of the following is NOT true regarding type 2 diabetes?

   		incidence is related to poor lifestyle habits
   		accounts for 90% of all diabetes
   		tissues are insulin-resistant
   		is associated with beta cell destruction in the pancreas

2 points   

QUESTION 13

1. Generally, insulin and glucagon are released by opposing stimuli and have opposing effects on metabolism. However, both hormones are released by the stimulus of an increase in blood amino acids. Which answer below explains why this occurs?

   		Glucagon release is part of a positive feedback loop.
   		Both insulin and glucagon promote amino acid absorption at the small intestine.
   		Glucagon prevents hypoglycemia following ingestion of a pure protein meal.
   		Amino acids are present in the blood during both anabolism and catabolism.

2 points   

QUESTION 14

1. Individuals with diabetes who need to take insulin usually inject insulin rather than taking it as a pill because

   		injecting it means that the insulin reaches most cells before passing through the liver first.
   		injecting it helps it to cross the blood-brain barrier.
   		the hormone will be broken down in the digestive system if taken orally.
   		they need insulin to enter their bloodstream more quickly.

2 points   

QUESTION 15

1. The maintenance of plasma glucose concentration within its narrow range is achieved through which of the following?

   		glycogenesis
   		glycogenolysis
   		All the alternatives
   		oxidative metabolism

2 points   

QUESTION 16

1. The exocrine portion of the pancreas produces

   		insulin.
   		somatostatin.
   		digestive enzymes
   		glucagon.

2 points   

QUESTION 17

1. During the absorptive state in a person at rest,

   		the liver forms glycogen.
   		skeletal muscles have net glycogen catabolism.
   		gluconeogenesis takes place.
   		adipocytes dump fatty acids into plasma.

1. View the side groups in the model, with attention to the water channel. What do the numerous aromatic rings on the surface of the channel suggest about the chemical properties of the channel?

2. Conserved histidine, asparagine (blue), and cysteine (yellow) residues are present on the surface of the water channel. Which of the following is LEAST likely to hydrogen-bond with a water molecule?

3. What prevents glycerol from passing through the water channel?

4. Aquaporins allow water to pass through the channel but prevent other solutes and ions from also crossing the membrane. Protons can move with water using the same hydrogen bonding facillitated movement. What PREVENTS protons from passing through the water channel?

1. View the side groups in the model, with attention to the water channel. What do the numerous aromatic rings on the surface of the channel suggest about the chemical properties of the channel?

2. Conserved histidine, asparagine (blue), and cysteine (yellow) residues are present on the surface of the water channel. Which of the following is LEAST likely to hydrogen-bond with a water molecule?

3. What prevents glycerol from passing through the water channel?

4. Aquaporins allow water to pass through the channel but prevent other solutes and ions from also crossing the membrane. Protons can move with water using the same hydrogen bonding facillitated movement. What PREVENTS protons from passing through the water channel?

About utilization of fatty acids to generate ATP, which of the following is INCORRECT?

a). It is first activated by ATP to form fatty acyl-CoA in the cytosol
b). Fatty acyl-CoA needs carnitine acyltransferases to translocate to mitochondria c). Each round of beta-oxidation releases 1 acetyl CoA, 1 NADH and 1 NADPH
d). The translocation process is repressed by high levels of insulin
e). it is repressed by active fatty acid biosynthesis

16. Biosynthesis of fatty acids in mammalian hepatocytes needs NADPH. In addition to pentose pathway, which of the following biochemical processes can provide additional NADPH for biosynthesis?

a) An alternative glycolytic pathway, ED pathway, generates NADPH b) Malic enzyme-catalyzed dehydrogenation of malate
c) Dehydrogenation of pyruvate in cytosol
d) β-oxidation of fatty acids in the cytosol recovers NADPH

e) Dehydrogenate citrate in cytosol

17. Assume a type of lipase identified in adipose tissues which can be activated by an unknown hormone. Upon activation, it releases fatty acids into circulation as fuel supply. Functionally, this hormone is unlikely to be:

a). glucagon b). insulin
c). epinephrine d). T3
e). T4

18. Pancreas is important for metabolism because it produces the following, EXCEPT for:

a). insulin
b). glucagon c). lipases
d). thyroids e). proteases

19. Which of the following pathway in skeletal muscle will not be stimulated by AMPK?

a). glycogenolysis

b). glycolysis
c). gluconeogenesis

d). beta-oxidation

e). krebs cycle

30. Which one is a cofactor needed for the glycogenolysis?

For questions 37-40, refer choices given below:

a). Glut1 b). Glut2 c). Glut3 d). Glut4 e). SGLT

37. The one whose cell surface localization is enhanced by insulin signaling pathway is?
38. Which one is expressed abundantly on neuronal cells?
39. Which one has a large Km and expressed mainly in hepatocytes and pancreatic alpha/beta-cells? 40. Which one is abundantly expressed in red blood cells to ensure supply of glucose to erythrocytes?

You wish to make a buffer with a pH of 11.

A) Which of the following amino acids would you use to make your buffer: glutamine, aspartate, histidine, or tyrosine?

B) Why would your chosen amino acid be better than the others?

C) Start with 0.02M of the base form of your amino acid and calculate the concentration of the acidic form needed to have your buffer at the desire pH of 11. Show your work.

This is the third time I have posted this question. I believe the answer to A is histidine. I believe the answer to B is because histidine is basic. I really need the explanation for part C. However, please confirm that my answers for A and B are correct.

The enzyme Sucrase hydrolyzes sucrose into its two component sugars. Draw the entire pathway for the conversion of sucrose to pyruvate in the LIVER. Both of the component sugars of sucrose are labeled with 14C at positions 1 and 5. Show where the 14C labels would be found in the pyruvate that is produced. You must give the name of every enzyme and metabolite as well as draw the structure for each metabolite. Glyceraldehyde is produced as a metabolite in the pathway. There are two possible pathways for glyceraldehyde to continue down glycolysis to pyruvate; you must draw BOTH pathways. You do not have to draw the structures of any cofactors ( ATP, NAD etc) but you must include them in all of the appropriate reactions.

1. Are proteins, ATP, enzymes, or ribozymes responsible for doing work in the cell? Why?

2. Can glycolysis run in reverse?

3. Is the role of stomach acids to degrade, denature, synthesize, or inactivate proteins?

4. What is the sugar backbone of DNA generated by, phosphodiester bonds, peptide bonds, glycosidic bonds, or hydrogen bonds?

5. Proteins destined for cell export are synthesized in the nucleus, cytoplasm, mitochondria, or ER?