MCB 2000 Lecture 8: Chapter 8 Microbial Metabolism

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5 Oct 2017

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Metabolism is: collection of all biochemical reactions that take place within cell of an organism, the ultimate function of metabolism is to reproduce the organism. Metabolism includes the following processes: nutrient uptake, conversion of nutrients into cell components, conversion of nutrients into energy, excretion of waste products. Apoenzyme (protein) + cofactor - nonprotein (metal ion) or. Active site of enzyme: tertiary and quaternary structure of a protein molecules provide the active site - the sire where the substrate binds (groove) Enzyme-substrate interaction: substrate and enzyme make a temporary union, substrate is inserted into the active site, the process is reversible. The mechanism of enzymatic action: enzyme attached to the substrate at the active site, enzyme-substrate complex is formed, substrate molecule is transformed, products of the reaction are released, the unchanged enzyme can start a new reaction. Transfer reactions: oxidation-reduction reactions: oxidation - removal of electrons (+energy, reduction - gain of electrons, these reactions are always coupled.

Related Questions

Question 1 When energy changes from one form to another, some of the energy that can be used to do work is always lost. The loss of this energy is mostly in the form of _________.
a. heat
b. potential energy
c. kinetic energy
d. light energy
e. mechanical energy

Question 2 Which of the following is exergonic?
a. binding fatty acids and glycerol molecules together to form lipids
b. building proteins from amino acids
c. binding sugars molecules together to form glycogen
d. breaking bonds in starch to release glucose
e. adding a phosphate group to ADP to form ATP

Question 3 The first law of thermodynamics states that:
a. energy can neither be created nor destroyed.
b. the universe is increasing in entropy.
c. all living organisms must eat to derive energy.
d. energy is required to bring molecules into a cell against a concentration gradient.
e. in energy-yielding reactions, matter goes from a more-ordered to a less-ordered state.

Question 4 Which of the following is true of energy?
a. It can be transferred from one form to another with 100 percent efficiency.
b. It can be created.
c. It can be stored in chemical bonds.
d. It can never be stored.
e. It can be released by forming chemical bonds.

Question 5 Metabolism is:
a. the sum of all the energy a cell uses.
b. the sum of all the vitamins a cell contains.
c. the sum of all the enzymes a cell contains.
d. the sum of all the chemical reactions that an organism carries out.
e. the sum of all the ATP a cell contains.

Question 6 Entropy is the measure of ________ in a system.
a. disorder
b. order
c. energy
d. work
e. heat

Question 7 What percentage of the energy stored in glucose are humans cells able to use to do useful work?
a. 37%
b. 100%
c. 15%
d. 52%
e. 48%

Question 8 What is activation energy?
a. the energy gained by living things, allowing them to remain active
b. the energy produced by the breakdown of ATP to ADP.
c. the energy required to initiate or begin a chemical reaction
d. the energy created by enzymes during exergonic reactions
e. the energy lost by living things in the form of heat

Question 9 Which of the following is true of allosteric enzymes?
a. Their activity can be reduced when the product binds the enzyme.
b. Their activity can be reduced when a coenzyme binds to them.
c. Their activity can be reduced when the substrate binds the enzyme.
d. Their activity can be increased when the product binds the enzyme.

Question 10 Which of the following is a true statement about enzymes?
a. They are made of proteins.
b. They are altered by the reactions they catalyze.
c. They increase the energy of activation of chemical reactions.
d. All of the above are true.
e. None of the above is true.

Question 11 What is the energy currency of cells?
a. ADP
b. enzymes
c. glucose
d. vitamins
e. ATP

Question 12 Kinetic energy is ____________, while potential energy is _____________.
a. stored energy; energy that is being used
b. stored energy; energy that can't be used
c. energy that is being used; stored energy
d. energy that can't be used; stored energy

Question 13 The energy released during ________ reactions can be used to drive ________ reactions, and this is called ________ reactions.
a. exergonic; endergonic; coupled
b. endergonic; exergonic; coupled
c. exergonic; endergonic; mutually dependent
d. coupled; mutually dependent; independent
e. endergonic; exergonic; mutually dependent

Question 14 ADP + P + Energy --> ATP Which of the following is a true statement about the chemical reaction above?
a. This is a coupled reaction.
b. This is an exergonic reaction.
c. The product of the reaction contains more energy than that of all of the reactants combined.
d. This is an endergonic reaction.
e. This is an example of a catabolic reaction.

greychimpanzee211

Value: 1

Anabolic pathways of metabolism are pathways that:

a. build complex molecules from simple ones.

b. release stored chemical energy.

c. take place primarily in skeletal muscle

d. make large quantities of ATP.

Value: 2

The sum of all chemical reactions in a cell is referred to as _______________.

Value: 3

Organisms that derive both their energy and carbon from organic compounds are:

a. photoautotrophs.

b. chemoautotrophs.

c. chemoheterotrophs.

d. photoheterotrophs

Value: 4

It is often stated that the phosphate bonds in ATP are "high energy," but in fact, they are not notably high in energy. Rather, they are easy to break, and the âG of hydrolysis is a "useful" quantity of energy. What makes the phosphate bonds easy to break?

a. They are close to the destabilizing nitrogenous base adenosine

b. Positive charges on amino groups repel each other.

c. Negative charges on phosphate groups repel each other

d. High acidity attacks bonds between amino acids.

Value: 5

Which of the following describes ATP hydrolysis? Select all that apply

[mark all correct answers]
a. exergonic

b. spontaneous

c. often coupled to a reaction that has a positive ÎG

Value: 6

Which of the following describes catabolic reactions?

a. They are endergonic and have a negative change in free energy

b. They are exergonic and have a negative change in free energy

c. They are exergonic and have a positive change in free energy.

d. They are endergonic and have a positive change in free energy.

Value: 7

Why are cells not infinitely big?

a. Because they wouldn't fit in an organism

b. Because they would have a small surface area:volume ratio and substances would diffuse in and out too slowly

c. Because they would have a large surface area to volume ratio and substances would diffuse in and out too quickly

Value: 9

How is organelle movement around cells controlled?

a. the nucleus directs the movement of organelles in a cell

b. the cytoskeleton is like a monorail that moves organelles in a cell via motor proteins

c. organelles do not move, they have a fixed position in the cell

d. organelles move by facilitated diffusion in the cell

Value: 10

1. Prokaryotic cells lack:

a. a. A nucleus

b. organelles

c. cell membrane

d. DNA

e. A and B

Value: 11

Rough endoplasmic reticulum (rER)

a. a. Makes cell membranes

b. has ribosomes attached

c. are a site of protein synthesis

d. all of the above

Value: 12

Match the items.

The task is to match the lettered items with the correct numbered items. Appearing below is a list of lettered items. Following that is a list of numbered items. Each numbered item is followed by a drop-down. Select the letter in the drop down that best matches the numbered item with the lettered alternatives.

a. help to digest worn-out or damaged organelles.
b. Takes in molecules in transport vesicles, modifies them, and sends them back out in vesicles
c. makes sugar
d. makes ATP
e. assembles the ribosomes
f. gives the cell structure
g. move material around the cell

1. vesicles	a b c d e f g
2. cytoskeleton	a b c d e f g
3. the golgi apparatus	a b c d e f g
4. lysosomes	a b c d e f g
5. mitochondrion	a b c d e f g
6. chloroplast	a b c d e f g
7. nucleolus

1. C6H12O6 + 6O2 Ã 6CO2 + 6H2O Glucose is being _____ to _____ and oxygen is being _____ to _____. a. oxidized; carbon dioxide; reduced; water b. oxidized; water; reduced; carbon dioxide Incorrect c. reduced; water; oxidized; carbon dioxide d. reduced; carbon dioxide; oxidized; water

2. Which of the following stages in the breakdown of the piece of toast you had for breakfast generates the most ATP? a. the citric acid cycle Incorrect b. glycolysis c. the digestion of starch to glucose d. oxidative phosphorylation

3. Which of the following is a catabolic pathway? a. gluconeogenesis b. production of starch Incorrect c. glycolysis d. production of glycogen

4. Per molecule, the oxidation of a fatty acid results in _____ energy storage than the oxidation of glucose. a. the same b. less Incorrect c. more d. None of the above; fatty acids cannot be oxidized.

5. Of the eight reactions in the citric acid cycle, how many are oxidation-reduction reactions? a. one b. two c. three d. four e. five

6. The process of glycolysis transfers the energy in sugar molecules into the stored energy of activated carriers such as ATP and NADH. Which statement is true about glycolysis? a. Only eukaryotic organisms do glycolysis. b. The ten reactions of glycolysis are identical in all eukaryotic cells, but are different in prokaryotic cells due to their diverse metabolic strategies. Incorrect c. The ten reactions of glycolysis are identical in almost all living organisms on the planet. d. There are many ways to oxidize glucose and transfer energy into activated carriers; the diversity of organisms on the planet is reflected in the diversity of their mechanisms of glycolysis.

7. Referring to the sentence completed in #13 above, the purpose of the latter reaction (in active muscle cells) is to _____. a. accumulate lactic acid in the cell, which provides additional energy for the production of ATP Incorrect b. slow down glycolysis until oxygen becomes available again c. accelerate the Krebs cycle, which will restore the oxygen supply d. regenerate NAD+ so that glycolysis can continue in the absence of oxygen

8. What are the products of the citric acid cycle? a. carbon dioxide, NADH, FADH2 and GTP b. carbon dioxide, NAD+, FAD and GTP c. NADH, FADH2, and acetyl CoA Incorrect d. carbon dioxide and water

9. Which statement is true about enzymes? a. Enzymes catalyze chemical reactions because they make inherently endergonic reactions exergonic. b. Each enzyme in a cell can catalyze many different chemical reactions involving chemically different substrates. Incorrect c. Enzymes can only catalyze reactions in one direction. d. After catalyzing a reaction, an enzyme is permanently altered and can no longer bind substrate. e. None of the above is true. 1

10. âG measures the change in free energy in a system as it converts reactant (Y) into product (X). When [X] = [Y], âG is equal to _____. a. RT b. ÎGÂ° + RT c. ÎGÂ° d. ln [X]/[Y]

11. The âGÂ° for the hydrolysis of ATP is -7.3 kcal/mol. What conditions in the cell would lead to a âG for ATP hydrolysis of -11 kcal/mol? a. An increase in the ATP/ADP ratio b. An increase in anabolic activity in the cell c. Transport of ATP out of the compartment where the reaction is occurring Incorrect d. A decrease in the ATP/ADP ratio

12. In the first reaction of glycolysis, a phosphate transferred from ATP to a glucose molecule to produce glucose-6-phosphate and ADP. Under conditions existing in the cell, the free energy change for this reaction is -8.0 kcal/mole. Which of the following statements is true? Recall that the âGÂ° for the hydrolysis of ATP is -7.3 kcal/mol. a. Glucose concentrations in the cell are always low, making this reaction more favorable than would be expected. b. This reaction is less favorable than would be expected, given the âGÂ° of ATP hydrolysis. c. Glucose-6-P concentrations in the cell are very low relative to glucose concentrations, making the reaction more favorable than would be expected. d. The âGÂ° for the addition of a phosphate to glucose must be -0.7 kcal/mole.

13. Protein E can bind to two different proteins, S and I. The binding reactions are described by the following equations and values: E + S --> ES Keq for ES = 10 E + I> EI Keq for EI = 2 Given the equilibrium constant values, which one of the following statements is true? a. When S is present in excess, no I molecules will bind to E. b. E binds I more tightly than S. c. The binding energy of the ES interaction is greater than that of the EI interaction. d. Changing an amino acid on the binding surface of I from a basic amino acid to an acidic one will probably make the free energy of association with E more negative.

MCB 2000 Lecture 8: Chapter 8 Microbial Metabolism

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