Biochemistry Flashcards by Sarah Gillen

Which hydrophobic amino acid is susceptible to oxidation due to sulfur groups?

Cysteine

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Which type of amino acids are the only ones found in proteins?

L-amino acids

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Protein folding is hierarchical and occurs in a certain order. When would disulfide bonding occur, before or after folding is complete?

Can occur before OR after - Disulfide bonds are not required for early determinants of folding.

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What are the 3 primary conditions that can affect protein denaturation?

Heat
pH extremes
Agitation

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Describe the structure of hemoglobin

Tetramer made up of 4 globin chains, makes a porphyrin ring with iron

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If you see 2,3-BPG on the exam, what biological molecule are we dealing with?

Hemoglobin

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What class of enzymes participates in group transfer reactions?

Transferases (i.e., NMP kinase)

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Which class of enzyme participates in the transfer of functional groups to water?

Hydrolases (i.e., chymotrypsin)

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What does it mean to have a negative value for the Gibbs free energy of activation?

The reaction is favorable and will likely occur spontaneously

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In _____________ inhibition, when the inhibitor is present, the substrate cannot bind to the EI complex

Competitive

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In ____________ inhibition, the inhibitor binds to free and substrate-bound enzyme

Noncompetitive

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Describe the effects of noncompetitive inhibitors on enzyme kinetics. Specifically Vmax, Km, and the effect of increasing [S]

Vmax = lowered
Km = unchanged

Increasing [S] will not allow the substrate to outcompete the inhibitor

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Describe the effects of competitive inhibitors on enzyme kinetics. Specifically Vmax, Km, and the effect of increasing [S]

Vmax = unchanged
Km = increased

If [I] is fixed, increasing [S] would allow the substrate to outcompete the inhibitor

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Between glucose and fructose, which one is a ketose and which one is an aldose?

Glucose = aldose
Fructose = ketose

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When glucose folds into a 6-membered ring structure, it is referred to as a ________

Pyran

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When fructose folds into a 5-membered ring structure, it is referred to as a ________

Furan

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Name 2 disaccharides

Sucrose

Lactose

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Name 3 monosaccharides

Glucose
Fructose
Galactose

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Which of the following disaccharides would be involved in a hydrolase reaction?

A. Glucose
B. Fructose
C. Lactose
D. Galactose

C. Lactose

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Glycosidic bonds determine polysaccharide structure. A _________ polysaccharide is unbranched, or has one branch every 30. A __________ polysaccharide has a branch every 10.

Starch

Glycogen

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Starch/glycogen polysaccharides are not broken down the same as cellulose. What is different about the bonding pattern between the two?

Cellulose has beta bonding pattern

Starch/glycogen has alph bonding pattern

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Which is more stable, a glycosylated protein (glycoprotein) or unglycosylated protein?

Glycosylated is more stable

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Name the 3 essential fatty acids

Linoleic
Linolenic
Arachidonic

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The 3 main forms of modified fatty acids in the lipid bilayer are phospholipids, glycolipids, and cholesterol. Of those 3, which is most important for fluidity of the membrane?

Cholesterol

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Which ion is in highest concentration in the ECF? What about ICF?

Highest in ECF = sodium Highest in ICF = potassium

A calcium channel opening when a ligand binds would be what type of transport? A sodium/potassium exchanger would be what type of transport?

Primary Secondary

What membrane transport system involves the flow of ions down a gradient, and provides facilitated transport via passive diffusion?

Ion channels

What membrane transport system involves the flow of ions against a gradient and is coupled to an energy source, where a chemical reaction in a protein leads to conformational changes?

Primary transporters

What membrane transport system derives energy from existing ion gradients to transport a second molecule?

Secondary transporters

Which one has a 2-ring structure, purines or pyrimidines?

Purines

Is IMP a precursor to a purine or pyrimidine?

Purine

Is PRPP necessary for the activation of purine or pyrimidine synthesis?

Both!

Is UMP a precursor for purines or pyrimidines?

Pyrimidines

What enzyme is responsible for the formation of uric acid from xanthine in purine nucleotide catabolism?

Xanthine oxidase

True or false: gout results from excess production of xanthine oxidase, which forms excess uric acid in joint spaces

FALSE, gout is not a problem with xanthine oxidase!!

Which enzyme would be a good target for gout in the purine nucleotide salvage pathway?

HGPRT

An elevated lactate level in the blood indicates that the body is in what state?

Fasting, we are burning glucose an anaerobic conditions like a sprint, resulting in lactic acid buildup

Pyruvate and lactate can be salvaged by being resynthesized into glucose in the metabolic process of _________________

Gluconeogenesis

What metabolic state is the body in if you have increased levels of glucose-1-phosphate?

Glycogenolysis - generating glucose from glycogen stores for use by other tissues [you also have glucose-1P in glycogenesis]

What is the main glucose transporter in the liver? Does it have high or low affinity for glucose?

GLUT2, low affinity with no regulation

What is the main glucose transporter in skeletal muscle, heart, and adipose tissue? What is this transporter dependent on?

GLUT4, dependent on insulin

Is the GLUT4 transporter found in the liver?

NO, the only glucose transporter found in the liver is GLUT2

What enzyme is the primary regulator of glycolysis in terms of a fed vs. fasting state?

PFK

What is the main 3-carbon sugar that gets turned to fat?

DHAP

________________ is an especially important metabolic process during a longer period of fasting, starvation, or exercise. You burn through your free glucose in seconds and need to make more to send to the brain. This requires ____________ which you can get from fatty acids

Gluconeogenesis; pyruvate

The pentose phosphate pathway is an alternate pathway for the oxidation of glucose. What are 2 main products of the PPP?

Riboses and NADPH

When glycogen is broken down during glycogenolysis, what is the first thing it becomes? What enzyme does this require?

Glucose-1-phosphate, requires glycogen phosphorylase

What enzyme is responsible for breaking the glycosidic bonds during glycogenolysis?

Debranching enzyme (alpha-1,6-glucosidase)

During glycogenesis, what is the first thing that glucose is converted to?

Glucose-6-phosphate, then to glucose-1-phosphate [note that in glycogen breakdown, the FIRST product is glucose-1-phosphate)

The conversion of glucose-1-phosphate to UDP-glucose occurs in what metabolic process? Does this require ATP?

Glycogen synthesis; yes requires ATP

What is the status of glycogen metabolism in conditions of increased glucagon or epinephrine?

Glycogenolysis (glycogen breakdown), so you will be utilizing glycogen phosphorylase

In what cellular compartment would you find pyruvate dehydrogenase (PDH)?

Mitochondria

From the following list of cofactors, which is NOT involved in the PDH complex? A. FAD B. Lipoamide C. TPP D. NADH

D. NADH

Which of the following is responsible for inhibiting E2 of the PDH? A. NADH B. NADPH C. FAD D. Acetyl CoA

D. Acetyl CoA

Of the four complexes involved in the electron transport chain, which one involves the utilization of oxygen and electron release? A. Complex I B. Complex II C. Complex III D. Complex IV

D. Complex IV

Of the four complexes involved in the electron transport chain, which one utilizes coenzyme Q? A. Complex I B. Complex II C. Complex III D. Complex IV

B. Complex II

Of the four complexes involved in the electron transport chain, which on utilizes cytochrome C? A. Complex I B. Complex II C. Complex III D. Complex IV

C. Complex III

Of the four complexes involved in the electron transport chain, which one utilizes NADH? A. Complex I B. Complex II C. Complex III D. Complex IV

A. Complex I

Of the four complexes involved in the electron transport chain, which one involves the utilization of FADH2? A. Complex I B. Complex II C. Complex III D. Complex IV

B. Complex II

Of the four complexes involved in the electron transport chain, which one does NOT involve the transport of protons? A. Complex I B. Complex II C. Complex III D. Complex IV

B. Complex II

Triacylglycerols (TAGs) are the major lipids present in the human diet. What are the 2 ways that energy can be harvested from TAGs?

Fatty acids can be utilized in beta oxidation Glycerol backbone can be directly fed into glycolysis

True or false: fatty acids can be utilized in glycolysis

False, glycerol can. Fatty acids are utilized in beta oxidation

If you see acyl CoA dehydrogenase, is the body in a fasting or fed state?

Fasting, we need the energy! This enzyme is utilized in beta oxidation (catabolism), fatty acids are being broken down for energy

The formation of __________ __________ such as acetoacetate, D-3-hydroxybutyrate, and acetone are associated with a state of starvation. This may also occur in a disease state, such as ___________

Ketone bodies; diabetes (untreated)

When ketone bodies are synthesized in a fasting diabetic, oxaloacetate may be formed intermediate to the TCA cycle. What role does this have in metabolism?

Feeds into ability to make glucose from fatty acids (beta oxidation to gluconeogenesis) --Oxaloacetate is essential for acetyl coA oxidation. Oxaloacetate is used for glucose synthesis, therefore OAA is depleted during fasting or diabetes. The liver produces more acetyl coA than can be oxidized in TCA.

Fatty acid synthesis occurs in conditions of excess energy. It occurs primarily in the _________, but also occurs in the brain, kidneys, and ___________ tissue. The components of fatty acid synthesis are located in the cytoplasm, including enzymes, _________ carrier proteins, co-factors, reducing power, and ___________.

Liver Adipose Acyl Energy (ATP)

The rate limiting step in fatty acid biosynthesis is the conversion of acetyl coA to ______________, which is catalyzed by _________.

Malonyl CoA Acetyl CoA Carboxylase (ACC)

Describe fatty acid biosynthesis regulation in terms of hormones like insulin.

Acetyl CoA is dependent on insulin signaling. Insulin causes the DEPHOSPHORYLATION of acetyl coA

Plasma lipoproteins have different functions. ___________ serves as the carrier for TAGs. ____________ is the highest in cholesterol.

Chylomicrons | LDL

What enzyme is the target for regulation of intracellular cholesterol by statin drugs?

HMG CoA Reductase

Amino acids generated by protein breakdown in the proteosome are eventually converted to urea, which requires what enzyme?

Aminotransferases (like ALT and AST)

What amino acid is the key to starting the urea cycle?

Glutamate, which then becomes NH4

Where does the urea cycle occur?

The liver

Ornithine is combined with what other product (made up of carbon dioxide and ammonia) to produce citrulline?

Carbamoyl phosphate

What type of enzymes help to funnel nitrogens into the urea cycle?

Aminotransferases

Of all the amino acids, which 2 are strictly ketogenic?

Leucine and lysine

Inosine 5'monophosphate (IMP) is the initial product of purine nucleotide anabolism. Which nucleotides are subsequently synthesized from IMP, after additional enzymatic steps? A. AMP and CMP B. TMP and CMP C. AMP and GMP D. None of the above

C. AMP and GMP

Which of the following is not an intermediate in the glycolytic pathway by which glucose is oxidized to pyruvate? A. Glucose 6-phosphate B. Glucose 1-phosphate C. Fructose 6-phosphate D. Fructose 1,6-bisphosphate

B. Glucose 1-phosphate

Which of the following enzymes is most likely to be deficient in gout (caused by an excess of uric acid)? A. Hypoxanthine-guanine phosphoribosyl transferase (HGPRT) B. Xanthine oxidase C. PRPP D. Hypoxanthine phosphatase

A. HGPRT

Biochemistry Flashcards

(79 cards)