Biochem exam 3

Which enzyme removes H2O to form a cis carbon-carbon double bond?

Aconitase

Which of the following is an intermediate in a reversible step in the citric acid cycle?

Aconitase removes H2O from citrate to form the double bond of cis-aconitate

Which of the following fatty acids has the lowest melting point?

An 18 carbon trans-polyunsaturated fatty acid

Which two intermediates must oxaloacetate be reversibly converted to before the formation of phosphoenolpyruvate in gluconeogenesis

malate or aspartate

What is the system that can be used to transport cytosolic NADH into the mitochondria SPECIFICALLY in liver cells and mammalian tissue?

malate-aspartate shuttle

What enzyme is an integral component in the regulation of fatty acid synthesis?

acetyl CoA carboxylase

Which enzyme allows the stereospecific addition of water to trans double bond during the beta oxidation of saturated fatty acids?

enoyl-CoA hydratase

Calculate the delta Go' for the redox reaction of FMN and ubiquinene and state which complex this reaction takes place in. (F=96.5KJ/mol) Reduction Potentials: Coenzyme Q: 0.045V (ubiquinene + 2H+ +2e- -------> ubiquinol) FMN: -0.340V (FMN +2H+ +2e- -------->FMNH2)

-74.30 KJ/mol, Complex I

Which of the following enzymes, in gluconeogenesis, are metabolically irreversible? Glucose-6-Phosphatase Fructose 1,6-Bisphosphatase PEPCK Pyruvate Carboxylase Enolase

1, 2, 3, & 4

Which of the following fatty acids is the most unsaturated?

18:4Δ2,7,9,14

How many NADH are produced when one acetyl group is oxidized in the citric acid cycle?

3

Which of the following enzymes is in both glycolysis and gluconeogenesis?

3-Phosphoglycerate Kinase

For every pair of electrons, how many protons are translocated across the membrane in the Q cycle?

4

In the inner mitochondrial membrane there are five complexes that are used to fully make ATP. Complex I-IV are involved in electron transport, while complex V is ATP synthase. What is the NET number of protons that are produced from the first four complexes and which complex does not produce any H+.

8 H+, complex II

In regards to electron transport, which is false? A. Redox centers must come into contact in order to transfer electrons B.Cytochrome C oxidase catalyzes a four-electron REDOX reaction C.FAD may participate in either one or two electron transfer D.The heme prosthetic group in Cytochrome C can only participate in one electron transfer

A. Redox centers must come into contact in order to transfer electrons

Which of the following molecules is NOT produced with each round of B-oxidation of Acetyl CoA of saturated fatty acids?

ATP

Which conformation state, in the F1 subunit of the ATP synthase complex, releases ATP?

O

Which is true for gluconeogenesis? A. It requires the enzyme Phosphofructokinase-1. B. In humans, it can convert protein into blood glucose. C. The process involves the same enzymes and reactions as glycolysis, just in the reverse order. D. The final reaction of gluconeogenesis takes place in the mitochondria.

B. In humans, it can convert protein into blood glucose.

Which of the following is false regarding the beta oxidation of saturated fatty acids? A. One product is Acetyl CoA. B. The enzyme 3-L-hydroxyacyl-CoA dehydrogenase (HAD) reduces a ketone to an alcohol during the reaction sequence. C. The original fatty acyl CoA is shortened by 2 C atoms at the end of one cycle. D. Enoyl-CoA hydratase (EH) catalyzes the stereospecific addition of H20 to a trans double bond during the reaction sequence.

B. The enzyme 3-L-hydroxyacyl-CoA dehydrogenase (HAD) reduces a ketone to an alcohol during the reaction sequence.

Which of the following is not a derivative of cholesterol? A. Steroid hormones B.Vitamin E C.Bile salts D.Vitamin D

B. Vitamin E

Which of the following molecules is NOT produced with each round of B-oxidation of Acetyl CoA? A. QH2 B. NADH C. ATP D. Acetyl CoA E. Fatty Acyl CoA

C. ATP

During vigorous exercise, what is broken down to produce energy?

Glycogen

How is GTP converted to UDP-glucose if glycogen synthesis is thermodynamically unfavorable?

Coupling of pyrophosphatase has a negative delta G that pulls the reaction forward.

Iron-Sulfur clusters in the electron transport chain proteins are bound via which amino acid?

Cysteine

In Complex IV, from which source do the electrons come from that are used to reduce molecular oxygen to two water molecules?

Cytochrome C

Which of the following is NOT true of Lipoprotein lipase? A. It is activated by App C-II B.It produces 3 FFA and a free glycerol C.It is extracellular and acts in the blood D.It removes triacylglycerol in HDL

D. It removes triacylglycerol in HDL

Which of the following is true about the products of lipoprotein lipase? A. The products of lipoprotein lipase is a chylomicron, 3 fatty acids, and a free glycerol. B. The products of lipoprotein lipase are 2 fatty acids and a free glycerol. C. The products of lipoprotein lipase are 3 fatty acids, low density lipoprotein, and a monoacylglycerol. D. The products of lipoprotein lipase are 3 fatty acids and a free glycerol.

D. The products of lipoprotein lipase are 3 fatty acids and a free glycerol.

Which of the following is NOT a function of lipids? A. long term energy storage B. biological signals C. membrane structures D. lowering the activation energy of chemical reactions

D.lowering the activation energy of chemical reactions

What is the function of thiamine pyrophosphate (TPP) cofactor of the pyruvate dehydrogenase enzyme?

Decarboxylates pyruvate yielding a hydroxyethyl-TPP carbanion

Which prosthetic group(s) from complex I pass electrons to ubiquinone (Q), and how many electrons can they carry?

FMN carries one or two electrons; Fe-S Clusters carry one electron

Pyruvate is ...

Formed in the cytosol by glycolysis and must be transferred to the mitochondria for oxidative catabolism.

The conversion of an L-site to a T-site is driven by which energy source?

Free Energy

What is the main product of glycogen degradation?

Glucose-1-phosphate

All of the following are true about McArdles's Disease except?

Glycogen synthesized has an abnormal structure

A 43 year old man visiting the hospital complains of chest pain and when checking his vitals, the doctor realized the man's cholesterol levels were very high and could potentially be causing a heart attack. Which of the following treatments would help lower the mans cholesterol?

HDL drip

How do lipids play a major role in biology? I- biological signals II- as components of lipid bilayers in biological membranes III- non soluble in fat and dissolve in water IV- act as energy stores

I, II, IV

Lipoproteins are spherical particles containing lipids and protein which help transport fat throughout the body. However, mutations in the body can prohibit successful transport of these fats, causing diseases such as Tangier disease. Which of the following results from Tangier disease? I. Severe reduction of the amount of HDL in the body. II. Reduced amount of fat absorbed in the cells. III. Increase in the amount of LDL in the body.

I, III

Which enzyme catalyzes the first Oxidation Reduction reaction in the Citric Acid Cycle?

Isocitrate Dehydrogenase

Which lipoprotein acts as a cholesterol delivery lipoprotein?

LDL

Via a series of dehydration reaction reactions a sample unsaturated fatty acids now contain 5 double bonds for each fatty acid tails. The addition of the double bonds

Lowers the melting point

Which of the following is a characteristic of a saturated fatty acid?

No C=C double bonds

What enzyme in gluconeogenesis forms Phosphoenol-pyruvate from oxaloacetate and GTP?

PEPCK

Which of the following enzymes help digest lipids and help release the fatty acid chains from the membrane phospholipids?

Phospholipase

Which of these complexes is a key regulator of the citric acid cycle?

Pyruvate Dehydrogenase Complex

Phosphoglucomutase uses this residue to phosphorylate the 6 carbon and dephosphorylate the 1 carbon in the conversion of G1P to G6P.

Ser

A disadvantage to having a highly branched glycogen structure is that...

Significant de-branching is needed.

Chylomicrons are synthesized in:

Small Intestine

What group are bile salts derived from?

Sterols

There are eight enzymes used in eight different reactions for the citric acid cycle. Which of the following enzymes is not a rate-determining step in the citric acid cycle?

Succinyl-CoA synthetase

The cholesterol delivery lipoprotein, LDL, moves cholesterol bound to its receptor into the cell. What synthetic mechanism(s) (is)are altered once this occurs?

The production of cholesterol in the liver is shut off via HMG-CoA reductase and cholesterol is esterified inside the cell for storage via ACAT

Which of these is NOT a derivative of cholesterol?

Thromboxane

What is the function of the iron sulfur cluster of Aconitase?

To orient the OH group of Citrate

Fatty Acyl CoA is converted to Acylcarnitine in _________ and then is converted back to Fatty Acyl CoA in _______.

cytosol, mitochondrial matrix

In complex IV of the electron transport chain, through which protein do the electrons come that are used to reduce molecular oxygen to two water molecules?

cytochrome c

During the oxidation of isocitrate, _____ is decarboxylated to form alpha-ketoglutarate.

oxalosuccinate

The two enzymes needed in gluconeogenesis to bypass the highly irreversible step catalyzed by pyruvate kinase in glycolysis are:

pyruvate carboxylase and PEP carboxokinase

Which of these is not a rate determining step in the citric acid cycle:

pyruvate dehydrogenase