ch 6 homework

Check all of the examples below that illustrate the first law of thermodynamics.

1. A plant uses sunlight to form a H+ gradient 2. A H+ gradient is used to produce ATP. 3. An animal uses ATP to move its muscles.

Rank these reactions from least to most energetically favorable.

1. Glucose to Glucose-6-P, +3.3kcal/mol 2. Glucose-6-P to Fructose-6-P, +0.4kcal/mol 3. ATP to ADP and Pi, -7.3kcal/mol 4. PEP to pyruvate, -14.8kcal/mol

The reaction: ATP to ADP + Pi releases 7.3 kcal/mol of energy. For each reaction indicate how much ATP the reaction would require or generate. 1. Glucose to Glucose-6- bisphosphate +3.3 kcal/mol. 2. Active transport of Na+ ion, +9.4 kcal/mol 3. Creatine to Creatine-Phosphate, +11 kcal/mol 4. 1,3 bisphosphoglycerate tp glyceraldhyde-3- phosphate, -12.5 kcal/mol 5. Phoshoenolpyruvate to pyruvate, -14.8 kcal/mol

1. Requires 1 ATP 2. Requires 2 ATP 3. Requires 2 ATP 4. Generates at least 1 ATP 5. Generates at least 1 ATP

If a chemical that inhibits Enzyme #3 was added to a system containing this biochemical pathway, which of the following would result?

1. Substrate #4 would be depleted in the system. 2. The final product would be depleted in the system. 3. Substrate #3 would accumulate in the system. 4. Product #2 would accumulate in the system.

1. Energetic molecules such as NADH and ATP are often reactants of blank reactions 2. Energetic molecules such as NADH and ATP are often products of blank reactions 3. In the reaction Pyruvate + NADH → Lactate + NAD+NAD+ , pyruvate is being (Click to select), while NADH is being (Click to select)

1. anabolic 2. catabolic 3. reduced, oxidized

1. The ______of a reaction is not affected directly by temperature. 2. If a reaction has a negative change in_______ then it will be exothermic. 3. An increase in disorder is a form of _______

1. enthalpy 2. free energy 3. entropy

Select the correct words to complete each sentence. 1. RNA exposed to a/an (Click to select) will release (Click to select) which the cell can recycle. 2. Protein exposed to a/an (Click to select) will release (Click to select) which the cell can recycle.

1. exonuclease, nucleotides 2. proteasome, amino acids

Determine if each statement about the molecules in the reaction below is true or false. 1. Phosphoenolpyruvate is a product 2. Mg2+ ion is a cofactor 3. Pyruvate kinase is an enzyme 4. Pyruvate is a substrate

1. false 2. true 3. true 4. false

ATP is used in the cell to transfer energy. Indicate if the following statements about ATP are true or false. 1. When ATP is used in a reaction, the last phosphate may be transferred to the substrate. 2. The release of the last phosphate from ATP is endergonic. 3. Once phosphates are released from ATP they can be added back in an endergonic reaction. 4. Once phosphates are released from ATP they can be added back in an endergonic reaction. 5. When ATP is hydrolyzed to form ADP, the energy is released into the cytoplasm where enzymes use it to run endergonic reactions.

1. true 2. false 3. true 4. true 5. false

Based on the graph, indicate if the following statements are true or false. 1. A is influenced by temperature 2. B is influenced by temperature 3. A is lowered by an enzyme 4. B is lowered by an enzyme

1. true 2. true 3. true 4. false

Consider the biochemical pathway below, where A, B, and C are substrates and products and E1 and E2 are the enzymes that catalyze the reactions. If Enzyme 1 (E1) is inactive, which of the following compounds will accumulate?

A only

Which of the following statements about enzymes is TRUE?

An enzyme can couple a nonspontaneous reaction to a spontaneous reaction so that anabolic processes will occur.

NAD+ is a coenzyme for many enzymes involved in redox reactions. This means that

Enzymes that use NAD+ as a coenzyme will not function properly if NAD+ is not available.

Based on the reaction in the animation, what can you say about the change in free energy of the cleavage of sucrose into glucose and fructose?

It is negative and the reaction is exergonic.

Molecules capable of enzymatic activity include

RNA and proteins

When a biological molecule is oxidized, the electrons are often captured by NAD+NAD+ , which is reduced to NADH. With that knowledge, identify if the substrate other than NADH or NAD+NAD+ in each reaction is being oxidized or reduced.

Reduced Pyruvate + NADH → Lactate + NAD⁺- Diphosphoglycerate + NADH → Glyceraldehyde phosphate + NADH⁺ Oxidized Isocitrate + NAD⁺ → alpha-ketoglutarate + CO₂ + NADH- Malate + NAD⁺ → Oxaloacetate + NADH- Ethanol + 2NAD → Acetic Acid + 2NADH

What happens to sucrase when it binds to sucrose?

Sucrase goes through a conformational change.

A mutation occurred in the gene that encodes the enzyme sucrase, resulting in a single amino acid substitution in the active site of the enzyme; a polar amino acid changed to a nonpolar amino acid. What is probably the result of this mutation.

Sucrase will not be able to bind sucrose in the active site.

Alzheimer's disease is characterized by an accumulation of proteins such as beta-amyloid protein in the cells. Beta-amyloid mRNA levels do not increase in people with Alzheimer's disease. Explain how beta-amyloid protein levels increase in these patients' cells.

The beta-amyloid proteins are not broken down and recycled.

L-Arabinose is a naturally occurring, non-caloric sweetener that is a noncompetitive inhibitor of sucrase. If L-Arabinose is consumed, what will happen to the Vmax of the reaction and Km of the substrate?

Vmax and Km will both increase

A hydrogen atom consists of

a proton and an electron

NAD+ is made from niacin, a B vitamin. Based on the animation, if someone is deficient in niacin, which of the following symptoms might they experience?

a reduction in energy

The enzyme in the animation is most likely catalyzing

an anabolic reaction.

Your body needs amino acids to build new proteins encoded by your genes. Many of these amino acids come from your diet through the _________blank of proteins you eat.

catabolism

An enzyme binds the product more tightly than the substrate.

false

An enzyme catalyzes a chemical reaction in the cell, but can only be used once.

false

Inhibiting one step in a biochemical pathway will not have any affect on the rates of the other reactions in the pathway.

false

What happens when the coenzyme NAD+ gains an H atom?

it also gains an electron causing it to be reduced.

How often can a sucrase molecule be used to hydrolyze sucrose?

many times

Where is sucrase found in the human body?

microvilli of the small intestine

Consider the biochemical pathway below, where A, B, and C are substrates and products and E1 and E2 are the enzymes that catalyze the reactions. Enzyme 1 (E1) can utilize

only A as substrate.

Cells obtain energy by _________blank food molecules such as glucose.

oxidizing

You are cooking beans over a campfire. By the light of the fire, you read that one serving of beans is 120 calories. After eating the beans, you go for a hike along a stream. All of the items described here have energy. Identify the form of energy each contains.

potential energy: beans and firewood kinetic energy: hiking, flames, moving water

Most enzymes are

proteins

Which of the following binds most tightly to the active site of an enzyme?

substrate

An enzyme may catalyze a reaction by stressing or destabilizing the bonds of the substrates. This critical point in the enzymatic reaction is known as the

transition state

In a biochemical pathway, the product released by the first enzyme becomes the substrate for the second enzyme.

true

Whenever a molecule is oxidized, another molecule must be reduced.

true

Sucrase uses _________blank to cleave sucrose into two monosaccharides.

water