physiology ch 4

An allosteric modulator binds to ANSWER: -the substrate. -a region of the enzyme other than the active site. -the active site. -the product. -the surrounding tissue.

-a region of the enzyme other than the active site.

Enzymes increase reaction rate by ANSWER: -increasing the free energy in the products. -converting an endergonic reaction to an exergonic reaction. -lowering the activation energy of a reaction. -raising the activation energy of a reaction.

-lowering the activation energy of a reaction.

The active sites of enzymes are ANSWER: -bonds between the substrate and certain amino acids. -products of an enzymatic reaction. -regions of an enzyme that are involved in bringing substrates together. -not necessarily involved in a reaction.

-regions of an enzyme that are involved in bringing substrates together.

A competitive inhibitor binds to ANSWER: -the substrate. -the product. -a region of the enzyme other than the active site. -the active site. -the surrounding tissue.

-the active site.

Activation energy is ANSWER: -the energy required for an endergonic reaction. -required to convert an endergonic reaction to an exergonic reaction. -the energy lost or gained in a reaction. -the energy required to bring molecules into a position where they can interact.

-the energy required to bring molecules into a position where they can interact.

A reversible reaction is one where ANSWER: -there is no change in the net free energy from substrate to product. -there are small changes in the net free energy from substrate to product. -a reaction between products is unlikely due to the high activation energy. -there are large changes in the net free energy from substrate to product.

-there are small changes in the net free energy from substrate to product.

Chemical reactions in a living system function to ANSWER: -transfer energy from one molecule to another or use energy stored in a molecule. -only use energy stored in a molecule. -create new energy. -only transfer energy from one molecule to another.

-transfer energy from one molecule to another or use energy stored in a molecule.

What type of molecule is an enzyme? ANSWER: A nucleic acid A lipid A protein A carbohydrate

A protein

When energy is released during catabolism, it is temporarily trapped in high energy bonds or electrons of certain compounds. Which of the following is NOT associated with carrying energy? ANSWER: DNA ATP NADPH NADH FADH2

DNA

Phosphate groups may be transferred from one molecule to another during ANSWER: addition and exchange reactions. dehydration reactions only. exchange reactions only. hydrolysis reactions only. addition reactions only.

addition and exchange reactions.

Isozymes ANSWER: -are enzymes with slightly different structure that catalyze the same reaction. -are the inactive form of an enzyme. -are inorganic molecules that bind to and thereby activate enzymes. -are enzymes with the same structure that catalyze different reactions.

are enzymes with slightly different structure that catalyze the same reaction.

he production of ATP starts with glucose. When glucose enters a cell, it is broken down via successive steps. Along the way, some ATP is produced directly. With regard to the breakdown of glucose, this is an example of _____________ pathways. anabolic both catabolic neither

catabolic

Organic molecules that act as receptors/carriers for the cleaved portion of the substrate are ANSWER: modulators. coenzymes. isoenzymes. vitamins.

coenzymes.

The reactions of glycolysis occur in the cell's ________; the reactions of the citric acid cycle occur in the ________. ANSWER: mitochondria, cytoplasm mitochondria, mitochondria cytoplasm, cytoplasm cytoplasm, mitochondria

cytoplasm, mitochondria

When an enzyme's activity is destroyed by heat or a change in pH, the enzyme is said to be ANSWER: toxic. conjugated. denatured. broken. tertiary.

denatured.

Which of these results in a REDUCED molecule? ANSWER: loss of phosphate gain of phosphate loss of electrons gain of electrons

gain of electrons

Compartmentation refers to ANSWER: -grouping related enzymes into specific organelles. -separating substrates into chemical classes. -pairing together isozymes that perform similar reactions. -dividing metabolic reactions into groups for better understanding.

grouping related enzymes into specific organelles.

An enzyme that adds or subtracts water molecules is a ANSWER: ligase. lipase. kinase. transferase. hydrolase.

hydrolase.

End-product inhibition describes the process whereby ANSWER: -increasing amounts of product reduce activity of all enzymes in the vicinity. -decreasing amounts of product reduce activity of the enzyme. -increasing amounts of product reduce activity of the enzyme. -increasing amounts of substrate reduce activity of the enzyme. -decreasing amounts of substrate reduce activity of the enzyme.

increasing amounts of product reduce activity of the enzyme.

An enzyme that transfers phosphates from ATP to a substrate molecule is a ANSWER: ligase. kinase. transferase. lipase. hydrolase.

kinase.

An enzyme that joins two substrates using energy is a ANSWER: hydrolase. ligase. kinase. lipase. transferase.

ligase.

The activity of an enzyme is changed by environmental factors such as temperature or pH; these factors are referred to as ANSWER: common bond. specificity. product. modulators. isozyme.

modulators.

A molecule that loses electrons during a reaction is ANSWER: reduced. oxidized. dehydrated. hydrated.

oxidized.

In the aerobic metabolism of glucose, ________ acts as the final electron acceptor. ANSWER: carbon dioxide oxygen ATP water lactate

oxygen

The addition of a phosphate group to a substrate is called ________. The enzyme that catalyzes this reaction is referred to as a ________. ANSWER: phosphorylation; phosphatase proteolysis; phosphatase phosphorylation; kinase proteolysis; kinase

phosphorylation; kinase

The general term that describes energy stored in chemical bonds is ANSWER: bioenergetics. thermodynamics. kinetic energy. potential energy. entropy.

potential energy.

Information stored in the nucleus is translated into ANSWER: phospholipids. proteins. lipids. carbohydrates. None of the answers are correct.

proteins.

Aerobic metabolism of glucose ANSWER: -requires oxygen. -is the fastest way to produce glucose. -produces more ATP per glucose than anaerobic pathways. -requires oxygen and produces more ATP per glucose than anaerobic pathways.

requires oxygen and produces more ATP per glucose than anaerobic pathways.

When an enzyme is working as fast as it can because its active site is continually refilled with substrate, the condition is referred to as ANSWER: saturation. the Ricardo-Mertz phenomenon. specificity. equilibrium. allosteric modulation.

saturation.

The ________ of glycogen from many glucose molecules is an ________ reaction. ANSWER: synthesis, exergonic decomposition, exergonic synthesis, endergonic decomposition, endergonic

synthesis, endergonic

According to the second law of thermodynamics, ANSWER: -entropy decreases in living systems that are not receiving energy. -the amount of entropy in living systems increases without the input of energy. -the total amount of energy in the universe never changes. -energy can be converted, but not be created nor destroyed.

the amount of entropy in living systems increases without the input of energy.

Energy is defined as ANSWER: the light and heat from the sun. the capacity to do work. doing tasks that make you tired. using glucose to synthesize ATP.

the capacity to do work.

When a chemical reaction is in equilibrium, ANSWER: -the reaction has stopped. -there is no net change in the amount of substrates or products. -there are equivalent amounts of substrates and products. -the reaction is proceeding at its maximum rate.

there is no net change in the amount of substrates or products.

An enzyme that transfers chemical groups among substrates is a ANSWER: transferase. lipase. hydrolase. ligase. kinase.

transferase.