midtem 1 quizzes

Question 1

Life is a result of chemical interactions of various elements in the environment. Reactions in the living system occur due to

Answer 1

Interaction of electrons in the outer orbit of the atom.

Question 2

The most complex creation of nature, a human body is

Answer 2

a molecular assembly of mostly a few elements found in and on earth’s atmosphere.

Question 3

b. If there is an increase in entropy during this reaction, in what form it is occurring?

Answer 3

A. Increase due to the loss of mass

Question 4

reaction by measuring….?

Answer 4

concentration of product and substrate, voltage/reduction potential

Question 5

The original source of energy on this planet is

Answer 5

Nuclear energy

Question 6

universe or increases the entropy. Plants synthesize different compounds and create beautiful orders from disorder like flowers (e.g. Glucose from CO2, leaves, flowers, and fruits).

Answer 6

Disorder of energy is created in solar plasma

Question 7

nourishment. Which of the following is true?

Answer 7

Disorder is created in the surroundings (via breathing out CO2)

Question 8

Suppose you are running on the road for exercise. Write down the energy conversions from the source to the last form of energy in this process.

Answer 8

Chemical energy to kinetic energy to heat energy and sound energy

Question 9

Which of the above are nucleophiles?

Answer 9

C -> carbonyl carbon -> carbon is electron

Question 10

how and why?

Answer 10

Yes. Burning of wood is a reaction between O2 and a hydrocarbon. Because of O electronegativity and reactivity, it will be very desperate to react with the hydrocarbon. Spontaneous reactions are exergonic, meaning they produce/release lots of energy (in the form of heat).

Question 11

Absolute temp T = 298 K

Answer 11

G0 = -RTln([C][D]/[A][B])

Question 12

reaction with the concentration of different ingredients at equilibrium are A= 10 mM, B= 10 mM, D and C are 1M

Answer 12

G0 = -RTln([C][D]/[A][B])

Question 13

R-CHO + NAD+ + PO4– = R-COO-PO4 + NADH + H+

Answer 13

Oxidizing agent = NAD+ -> grabs the electron from the NADH+

Question 14

Calories (8360 KJoules). How much ATP (in grams) is hydrolyzed in one day by Dr. Pandey? Presume that free energy change in human physiological system is -50kJ/mole and molecular wt of ATP is approximately 500 dalton.

Answer 14

1M ATP = 500 g

Question 15

If the reaction product in any reaction is resonance stabilized i.e. if it has different electronic configurations for the same compound, the reaction proceeds spontaneously in forward direction. Give a thermodynamic explanation for this phenomenon.

Answer 15

Resonance stabilization means more configurations. The more confirgurations means increase in entropy therefore spontaneous.

Question 16

at equilibrium?

Answer 16

Zero because the reaction isn’t going backwards or forwards. Therefore concentration is not changing.

Question 17

Explain entropy change in this reaction.

Answer 17

When water cools it releases heat into the air. Upon becoming heated, the air molecules will begin to move very fast. This is an overall increase of entropy. The air increased in entropy at the cost of a decrease in entropy in the water.

Question 18

ATP in this condition?

Answer 18

G = G0 + RTln([prod][react])

Question 19

converted to CO2.

Answer 19

In both scenarios we have a polymer of glucose. The difference is the type of energy released. In wood burning it is released as heat and light. In respiration heat is held in the chemical bonds of ATP. Another difference is that the body maintains costant temperature and pressure. Another difference is that O2 and the wood interact directly while in respiration the breakdown is stepwise.

Question 20

Is the reaction in combustion engine favorable? If so, Why?

Answer 20

Yes. First, O is very electronegative so it is very desperate to react with the hydrocarbon, therefore the reaction will be spontaneous. Also in this type of combustion you go from liquid to gas, which is a more organized state to a less organized state.

Question 21

Fe+++ is involved in many redox reactions, it has different standard reduction potential ranging from very positive to very negative. Explain why?

Answer 21

Iron is never free, it is always surrouned by a protein. Different amino acids surrounding the element means that different ions/electrons can interact with it therefore different reduction potentials.

Question 22

standard temp and pressure) without measuring concentrations?

Answer 22

Yes by using standard reaction potential (voltage). This is for oxidation because of the movement of electrons.

Question 23

Which one is favorable reaction?

Answer 23

Catabolism = breaking down. Anabolism = creating molecules. Catabolism has an increase in energy because as you break down a compound you release energy and increase disorder. Therefore catabolism is more favourable.

Question 24

Special Question: Hunters who chased the rabbits for extended time and killed them for food, complained that the meet was sour. Why?

Answer 24

Under emergency conditions, the rabbits muscles will be undergoing lactic acid fermentation to significantly increase ATP production. Lactic acid fermentation product is Lactate which will build up in the muscles, lower the pH (make it more acidic) and create a sour taste.

Question 25

Which reaction of glycolysis requires inorganic phosphate?

Answer 25

Inorganic phosphate is a substrate in the GAPDH rection, the most critical reaction in glycolysis. If you don’t add it then this reaction cannot go through.

Question 26

g) CO2 during all the three pathways

Answer 26

A. 2

Question 27

c. How many grams of net ATP and CO2 will be produced?

Answer 27

a. 342 g = 1 mol sucrose = 2 glucose = 4 alcohol. 4x 46=184 g alcohol. Alcohol relative density is 0.8. 184/0.8 = 230 mL -> 0.23 L 0.23/10 = 0.023 x 100 = 2.3 %

Question 28

Name all the kinases involved in glycolysis

Answer 28

Hexokinase, phosphofructokinase-1, pyruvate kinase, phosphoglycerate kinase (4)

Question 29

Name the substrates in forward direction of each kinase reaction.

Answer 29

Glucose, F6P, 2 phosphoglycerate, 1,3 bisphosphoglycerate

Question 30

Name the reaction involving oxidation-reduction reaction in glycolysis.

Answer 30

glyceraldehyde 3 phosphate dehydrogenase

Question 31

Which compound is reduced in the reaction in reaction

Answer 31

NAD+ is reduced into NADH

Question 32

How many reactions of glycolysis involve phosphoryl group transfer? Provide the names of enzymes.

Answer 32

Six. 2 require ATP (hexokinase and phosphofructokinase). 4 have ATP involved (hexokinase, pfk, pyruvate kinase, phosphoglycerate kinase). GAPDH adds phosphate with no ATP, phosphoglycerate mutase also doesnt require ATP involved.

Question 33

Which reaction in glycolysis is responsible for the net gain of ATP during this pathway?

Answer 33

glyceraldehyde 3 phosphate dehydrogenase (coupled with phosphoglycerate kinase)

Question 34

Name the reactions in glycolysis involving phosphate group transfer without any involvement of ATP or ADP.

Answer 34

glyceraldehyde 3 phosphate dehydrogenase, phosphoglycerate mutase

Question 35

Lactic acid, which lowers the pH causing fatigue. There is no ATP production during this step of the reaction. Why should this reaction be there?

Answer 35

To regenerate NAD+ in emergency situations so that we can allow the last 4 steps of glycolysis to persist at a fast pace and produce ATP.

Question 36

reaction?

Answer 36

Nucleophilic attack on carbonyl carbon by the sulfur from sulfhydryl group on cysteine from active site of enzyme

Question 37

Despite the low amount of ATP generated during glycolysis. Why this is the preferred pathway in muscle during fast movement?

Answer 37

Because it is substrate level phosphorylation and we can produce lots of ATP by catabolising glucose. Aerobic conditions cannot be accelerated at this rate. It is accelerated 100x

Question 38

c. This reaction does not require ATP hydrolysis.

Answer 38

a) Phosphatase chops of phosphate and the enzyme becomes inactive

Question 39

Why is glucose phosphorylated in the first step of glycolysis?

Answer 39

We do not want glucose to leave the cell. Glucose is phosphorylated by ATP to become gluose-6-phosphate, which now is charged. This charge does not allow it

Question 40

positive. How does this reaction proceed in forward direction?

Answer 40

It is coupled to reaction 7 which is very exergonic, the product is immediately taken up by reaction 7

Question 41

glycolysis?

Answer 41

phosphofructokinase

Question 42

The substrate cycle is also called futile cycle, Why?

Answer 42

Occurs when two metabolic pathways run simultaneously in opposite directions

Question 43

Is futile cycle really a futile exercise? If not what is the importance of this cycle.

Answer 43

It is used to control the flux of glycolysis.

Question 44

iii. In both the lactate DH and alcohol dehydrogenase reaction during homolactic and alcoholic fermentation.

Answer 44

ii. NADH is being oxidized to NAD+

Question 45

Yeast carry out alcoholic fermentation pathway to

Answer 45

Regenerate NAD+ for glycolysis reactions producing ATP under anaerobic

Question 46

Why is glucose stored in the form of glycogen in muscle andliver as emergency stock?

Answer 46

Glycogen can be catabolized very fast into glucose and can be metabolized to make lots of ATP

Question 47

What is the difference between glycogen and starch and what is the significance of this structure?

Answer 47

They are both polymers of glucose, they both have chains of 1-4 linkage and 1-6 linkage

Question 48

What is the name of the cofactor in Glycogen phosphorylase reaction

Answer 48

Pyridoxal phosphate that is covalently linked to the enzyme

Question 49

What kind of nucleophilic substitution takes place in glycogenphosphorylase reaction? Provide evidence for your answer

Answer 49

It is an SN1 reaction, meaning one step at a time. The leaving nucleophile is substituted with the attacking nucleophile. We know this because of the presence of a carbocation semi chair intermediate. Also there is no confirmation change between substrate and product. When gluconolactone, a similar product was added, then the reaction was inhibited.

Question 50

Phosphorylated Glycogen phosphorylase (“a”, the active form)is independent of allosteric effectors. Explain need for such regulation

Answer 50

It is activated via phosphorylation of its two dimer parts. It is phosphorylated by phosphorylase kinase. This happens under emergency conditions where we need to produce lots of glucose 6 phosphate and ATP. These emergency conditions are triggered by epinephrine and glucagon. Even in the presence of ATP and glucose 6 phosphate it will still stay active. It will also ignore AMP.

Question 51

Hormonal control of glycogen breakdown is necessary in muscle tissue to quickly generate energy in stress. What is the role of similar control in liver tissue?

Answer 51

The liver does not need to generate ATP to do anything. The liver makes sure there is sufficient glucose in the blood. The liver will break down glucose and secrete it into the blood. The emergency that the liver can work on but muscles can’t is the situation in which a person has not eaten for a long time and blood glucose levels are dropping. This is called a dietary emergency.

Question 52

What is the mechanism of Phosphoglucose mutase reaction?

Answer 52

Enzyme is phosphorylated. It lends its phosphate to the 6th carbon, then replenishes the phosphate with the one on the 1st carbon

Question 53

Why is Glucose 6 Phosphatase dephosphorelated (removal of phosphate) in liver?

Answer 53

Glucose 6 phosphate is charged and cannot be secreted into the blood. Therefore we dephosphorylate it to neutral glucose so that it can be secreted into the blood to maintain blood glucose levels.

Question 54

What are the two enzymatic activities og debranching enzyme?

Answer 54

First one is glycosidic transferase. Second is a 1,6 - glycosidase.