Scott Ong OS201 Exam2 Flashcards
Gibb’s free energy is the combination of the combination of the first and second laws of thermodynamics. What does Gibbs’ free energy measure?
A. measurement of the redox potential
B.mesurement of dicorder
C. rate of reaction and formation of products
D. measurement of useful work
Answer: D
The Gibbs free energy is the maximum amount of non-expansion work that can be extracted from a closed system; this maximum can be attained only in a completely reversible process.
What is thermodynamic term for a metabolic reaction that is favorable? A. negative free energy charge B. positive free energy charge C. small enthalpy charge D. positive entropy charge
Answer: A
Because of the laws of enthalpy and entropy, free energy is always increasing. However, in endothermic reactions, or chemical reactions that require energy to occur, net free energy is negative because the energy is “lost” to the environment as it is bonded in the reaction.
Energy is often defined in reference to something else, and the sign of the energy is a function which direction is flowing. If energy (heat) flows from a system to the environment, the ethalpy change is negative (exothermic), whereas if energy flows from the environment to the system, the ethalpy change is positive (endothermic
4. How are endergonic reactions driven to completion? A. Increase enzyme concentration B. Coupled with exergonic reaction C. Increase temperature D. Dehydration of ATP
Answer B
Since exergonic reactions is spontaneous.
Which of the following is/are identified from the standard free energy change?
A. A positive H
B. pH 7.0 and 25 degrees centigrade
C. 1M concentration of both reactions and products
D. All of the above
E. b and c only
Answer: B
Conditions of standard change in G is at pH 7.0 and 25 degrees centigrade
6. ATP is the energy currency of the cell. This function can be attributed to some structural properties of ATP molecule. Which of the ff. structural component/feature is not found in ATP? A. A dinucleotide moiety B. An adenosine residue C. A ribosyl -5- triphosphate D. A pyrophosphate bond
Answer: A
ATP consists of adenosine — composed of an adenine ring and a ribose sugar — and three phosphate groups (triphosphate).
- Which of the following best describes the Krebs cycle?
A. …of the ETC
B. catabolic and anabolic
C. final common pathway of FA, carbohydtates, protein metabolism
D. all of the above
Answer: C
The citric acid cycle — also known as the tricarboxylic acid cycle (TCA cycle), the Krebs cycle, or more rarely, the Szent-Györgyi-Krebs cycle— is a series of enzyme-catalysed chemical reactions, which is of central importance in all living cells that use oxygen as part of cellular respiration.
In aerobic organisms, the citric acid cycle is part of a metabolic pathway involved in the chemical conversion of carbohydrates, fats and proteins into carbon dioxide and water to generate a form of usable energy. Other relevant reactions in the pathway include those in glycolysis and pyruvate oxidation before the citric acid cycle, and oxidative phosphorylation after it. In addition, it provides precursors for many compounds including some amino acids and is therefore functional even in cells performing fermentation
What 2 processes produce ATP through substrate level phosphorylation? A. glycolysis and kreb’s cycle B. ETC and glycolysis C. Kreb’s cycle and ETC D. none of the above
Answer: A
Substrate-level phosphorylation is a type of chemical reaction that results in the formation and creation of adenosine triphosphate (ATP) by the direct transfer and donation of a phosphoryl (PO3) group to adenosine diphosphate (ADP) from a reactive intermediate. While technically the transfer is PO3, or a phosphoryl group, convention in biological sciences is to refer to this as the transfer of a phosphate group. In cells, it occurs primarily and firstly in the cytoplasm (in glycolysis) under both aerobic and anaerobic conditions.
While the Krebs cycle is oxidative respiration, one more instance of substrate-level phosphorlyation occurs as Guanosine triphosphate (GTP) is created from GDP by transfer of a phosphate group during the conversion of Succinyl CoA to Succinate. This phosphate is transferred to ADP in another substrate-level phosphorylation event.
Mechanism of fluoracetate?
A. binds na competitive inhibition w/ citrate cyntax?
B. forms fluorocitrate and binding with acomtas??
C. Directly inhibits citrate synthase??
D. directly inhibits comple I of the ETC
Answer: B
Fluoroacetate disrupts the citric acid cycle (also known as the Krebs cycle) by combining with coenzyme A to form fluoroacetyl CoA, which reacts with citrate synthase to produce fluorocitrate. A metabolite of fluorocitrate binds very tightly to aconitase, thereby halting the citric acid cycle. This inhibition results in an accumulation of citrate in the blood which deprives cells of energy.
Below is the overall reactive catalyzed by the complex I of the ETC NADH + ubiquinone NAD + ubiquinol 14. What is the other name of complex I? A. NADH – Co G reductase B. CoQ – cyto C reductase C. succinate – Co Q reductase D. cyt AA3 reductase
Answer: A Complex I (NADH dehydrogenase, also called NADH:ubiquinone oxidoreductase) removes two electrons from NADH and transfers them to a lipid-soluble carrier, ubiquinone (Q).
What is the cofactor of complex I? A. NAD + B. FMN + FeS C. --- D. FC-S + Cu
Answer: B
NADH is oxidized to NAD+, reducing Flavin mononucleotide to FMNH2 in one two-electron step. The next electron carrier is a Fe-S cluster, which can only accept one electron at a time to reduce the ferric ion into a ferrous ion. In a convenient manner, FMNH2 can be oxidized in only two one-electron steps, through a semiquinone intermediate. The electron thus travels from the FMNH2 to the Fe-S cluster, then from the Fe-S cluster to the oxidized Q to give the free-radical (semiquinone) form of Q. This happens again to reduce the semiquinone form to the ubiquinol form, QH2. During this process, four protons are translocated across the inner mitochondrial membrane, from the matrix to the intermembrane space. This creates a proton gradient that will be later used to generate ATP through oxidative phosphorylation.
What is the role of ADP in cellular respiration?
A. participates in glycolysis & TCA cycle
B. signals low energy
C. key role as “acceptor”
D. AOTA
Answer: D
17-21 Match the compounds with their corresponding rates in the electron transport chain
- inhibits ADP transport into mitochondria
- site specific inhibitor of ETC
- ??
- inhibitor of ATP synthetase
- an uncoupler
A. DNP B. iron-porphyrin compound C. oligomycin D. atractyloside E. carbon monoxide
Answer: D, E, B, C, A
Which of the following is consistent with the mechanism/theory (chemiogmatic coupling theory) for oxidative phosphorylation?
A. the existence of higher ph in the cisternae of endoplasmic reticulum than in the cytosol
B. the high-E electrochemical gradient drives the flow of proton through the FuFi ATPase into the matrix
C. the membrane proteins undergoes high energy confoational changes
D. the synthesis of ATP is coupled with the hydrolysis of high energy “phosphate transfer potential
Answer: B
it relates to the generation of ATP by the movement of hydrogen ions across a membrane during cellular respiration.
An Ion gradient has potential energy and can be used to power chemical reactions when the ions pass through a channel
Hydrogen ions (protons) will diffuse from an area of high proton concentration to an area of lower proton concentration.
Which of the following is correct? A. carbonic anhydrase is a hydrolase B. catalase is a hydrolase C.Tissue plasminogen is a hydrolase D. carbonic anhydrase is a carboxylase
Answer: C
Carbonic anhydrase is a dehydratase. Catalase is a heme-containing oxidoreductase.Tissue plasminogen activator is a hydrolase.
Which of the following statements is correct?
A. pyridoxal phosphate serves as co-enzyme for methyltransferases
B. S-adenosyl methionine serves as co-enzyme for aminotransferases
C. certain inorganic cations are coenzymes
D. apoenzymes consists purely of proteins
Answer: D
SAM is a carrier of methyl groups(cofactor of transmethylase or methylase). Pyridoxal phosphate carries amino group and acts as a cofactor for an aminotransferase. Apoenzymes are purely protein component of an enzyme. Coenzymes are inorganic cofactors.
Which of the following characterize/ s glucose transporters in general?
A. They have distinct substrate specificities.
B. They transport glucose using the sodium co-transport system.
C. They use facilitated diffusion down glucose concentration gradients.
D. All of the above
Answer: D
The consequence of the phosphorylation of glucose in somatic cell leads to:
A. cell trapping of the phosphorylated glucose because it cannot readily pass through cell membrane.
B. The positive charge of the phosphorylated glucose enhances efficient interaction with water inside the cell.
C. The phosphorylated glucose is recognized by kinase enzyme which requires a binding site
D. AOTA
Answer: A
B is wrong cause it becomes negatively-charged.
Difference between hexokinase and glucokinase?
A. glucokinase is found in muscle
B. glucokinase is synthesized in response to glucagon
C. glucokinase is …. Sorry I forgat
D. glucokinase has ↑km for glucose
E. glucokinase readily phosphorylates fructose and galactose
Answer: D
Glucokinase is found in hepatic tissues, while hexokinas is found in extrahepatic tissues. Glucokinase functions only when the intracellular concentration of glucose in the hepatocyte is increased. It facilitates phosphorylation of glucose. Glucokinase also has a much higher Km, requiring a higher glucose concentration for half-saturation.
Which occurs in the second half of glycolysis?
A. Phosphorylation of a hexose
B. Isomerization of a hexose phosphate
C. Formation of triose phosphates from a hexose diphosphate
D. Substrate level phosphorylation of ADP
Answer: D
Phosphorylation is in the first half (glu -> glu-6-P). So is the isomerization of a hexose phosphate (glu-6-P -> fruc-6-P).
What is true regarding the direct conversion of phosphoenol pyruvate from pyruvate?
A. —
B. it occurs in the cytosol
C. it requires pyruvate kinase
D. it is impossible for the reaction: pyruvate PEP (phosphoenol pyruvate)
Answer:
Hmm…magulo ang tanong, magulo ang choices..pero ito na lang ang tandaan:
PEP-> pyr occurs in the cytosol, requires pyruvate kinase, and is the third irreversible reaction in glycolysis.
