Exam 3, Chapter 10,11,12 & 16

What reactions capture energy from the organisms energy source?

Cataolic

_____ is the total of all chemical reactions occurring in the cell

Metabolism

________ reactions build new organic molecules from smaller inorganic and organic compounds

Anabolic

In thermodynamic studies, energy changes are analyzed in a collection of matter called a _____. All other matter in the universe is called the _____

system; surroundings

________ is the science that analyzes energy changes in a collection of matter

Thermodynamics

A rxn in which the forward rate is equal to the reverse rate is said to be at ______

equilibrium

Cells must efficiently transfer energy from their energy-trapping systems to the systems actually carrying our work and also use various metabolic processes to replace the energy used in doing work. This is called the ______ _______

Energy cycle

In order for the cell to be able to input energy into necessary endergonic reactions, energy-generating processes such as photosynthesis, fermentation, and respiration are used to produce _____

ATP

A molecule that binds to an enzyme at a location other than active site and thereby alters the enzyme's shape, making it inactive or less active is a _______ inhibitor

noncompetitive

The molecules formed by an enzyme-catalyzed

Products

The reacting molecules in an enzyme-catalyzed reaction are called _______

Substrates

The _______ ________ is the substrate concentration needed for an enzyme to achieve half maximal velocity

Michaelis constant (Km)

A complex formed during a reaction that resembles both the substrate and the product is called the _____ state complex

transition

RNA molecules that have catalytic activity are known as ______

Ribozymes

Cells carry out three major types of work; which of the following involves the synthesis of macromolecules as well as the breakdown of substances for their energy?

Chemical work

Cells carry out three major types of work; which of the following involves nutrient uptake and waste elimination?

Transport work

Cells carry out three major types of work. Which of the following involves energy for cell motility and the movement of structures within cells?

Mechanical work

T/F Energy can be redistributed within a collection of matter (called a system) or can be redistributed between the system and its surroundings

True

______ is a measure of randomness or disorder of a system

Entropy

The _____ law of thermodynamic states that energy can be neither created nor destroyed

First

The _____ law of thermodynamics states that physical and chemical processes occur in such a way that randomness increases to a maximum.

Second

The amount of heat energy needed to raise 1 gram of water from 14.5 to 15.5 is called a ______

calorie

T/F The numerical value of the free energy change indicates how fast a reaction will reach equilibrium

False

_____ is the total energy change that accompanies a chemical reaction

Enthalpy

For the reaction A + B ---- C + D, the equilibrium constant is expressed as _______

[C][D]/[A][B]

The change in _____ _____ is the amount of energy in a system that is available to do work.

free energy

T/F The most commonly used practical form of energy used in cells is adenosine diphosphate

False

A reaction that releases energy is ______

Exergonic

T/F Some energonic reactions can be made to proceed forward if they are coupled to hydrolysis of one or more oh the phosphates of ATP

True

A chemical reaction that requires an input of energy in order to proceed is _____

Endergonic

The _____ is the electron acceptor in a redox reaction

Oxidant

The ____ is the electron donor in a redox reaction

Reductant

The standard reduction potential of a redox reaction is a measure of the tendency of the _____ to _____ electrons

Reductant, lose

T/F The equilibrium constant for a redox reaction is called the standard reduction potential

True

Which of the following is used as an electron carrier by a living organisms?

NAD+
NADP+
Ubiquinone

T/F The ETC is based on the principle that redox couples with more positive reduction potentils will donate electrons to couples with more negative potentials

False

T/F One of the components used during photosythetic electron transport is ferredoxin, a nonheme iron protein

True

ETC molecules that only transfer electrons includes _______

Ferredoxin

Which of the follow is/are true about enzymes?

All of the choices are correct

T/F Each enzyme normally has a specific pH and temperature optima at which they function best.

True

T/F The Michaelis constant (Km) of an enzyme is the substrate concentration that produces maximum velocity

False

T/F Enzyme activity can be greatly affected by the pH and the temperature of the environment in which the enzyme must function

True

T/F When the amount of enzyme present is held constant, the rate of reaction will continue to increase as long as the substrate concentration increases.

False

T/F Enzymes increase the rate of reaction but do not alter equilibrium constants

True

T/F Enzymes increase the rate of reaction by increasing molecular motion, thereby providing kinetic energy to drive the reaction

False

Enzymes are usually named based on _____

The substrated they act on and the type of reaction they catalyze

The most specific term used to describe a substance in a biological system that increases the rate of a reaction without being permanently changed by the reaction is a ______

enzyme

The substrate of an enzyme binds at the ______

active site

A complete enzyme that consists of a protein component and a nonprotein component is called a _____

holoenzyme

A nonprotein component of an enzyme that is loosely attached to the protein component is referred to as a _____

coenzyme

The nonprotein component of an enzyme that is firmly attached to the protein is called _____

prosthetic group

If an enzyme consists of a protein component and a nonprotein component, the protein component is referred as the _____

apoenzyme

If all available enzyme molecules are binding substrate and converting it to product as rapidly as possible, the reaction is said to be proceeding at __________ velocity.

Maximal

A _____ increases the rate of reaction without being permanently altered by the reaction

catalyst

Enzymes function as catalysts by ______

concentrating the substrates and correctly orienting them at the active site

Enzymes catalyze a reaction by _____

decreasing the activation energy of the reaction

The energy required to bring the substrated of a reaction together in the correct way to reach the T.S. is called ______

activation energy

T/F One important ribozyme responsible for catalyzing peptide bond formation during protein synthesis is located in the mitochondria

False

Which of the following is a reason for metabolic regulation?

All of the choices are correct

In metabolic channeling, the regulation of metabolic pathways is controlled by the ____ of metabolites and enzymes involved in the pathway

Location

Metabolic channeling involves the localization of ___ in different parts of a cell in order to influence the activity of metabolic pathways

Susbstrates and enzymes

When the end product of a pathway inhibits the catalysis of the first step of that pathway, this phenomenon is called _____

Feedback inhibition

Enzyme activity can be controlled by _____

All of the choices are correct

In allosteric regulation, effector molecules usually bind ______

Reversible and non-covalently

In a branched pathway with many end products, an abundance of on of the end products will usually inhibit ______

The first committed step in the branch of the pathway leading to the production of that particular product

T/F Isoenzymes are different enzymes that catalyze the same reaction but can be regulated independently of one another

True

Which of the following are components of the ATP molecule?

Adenine
RIbose
Three phosphate

T/F In an ATP molecule, the phosphates are bonded to the adenine ring

False

Based on phosphate transfer potential, which is more likely to happen

Phosphoenolpyruvate will transfer phosphate to ADP

ATP has a phosphate transfer potential of 30.5, whereas glucose-6-phosphate has a phosphate transfer potential of 13.8. Based on these differences, which of the following will happen?

ATP will transfer phosphate to glucose-6-phosphate

The energy made available during cell respiration and fermentation is used to make ____, which is then available to provide energy for cellular work

ATP

What nucleoside triphosphate, other than ATP, provides some of the energy for protein synthesis?

GTP

What nucleoside trisphosphate provides energy for lipid synthesis?

UTP

As the difference in reduction potential between a redox pair increases, the amount of free energy made available _____

Increase

In a redox reaction involving NAD/NADH and pyruvate, ___ will be the electron donor and ___ will be the electron acceptor

NADH, pyruvate

Standard reduction potentials go in order from ____ to ____

least, greatest

Where is the ETC located in bacterial cells?

Plasma Membrane

In bacterial and archaeal cells, the ETC is located in the ____ whereas in eukaryotic cells, the ETC is located in the _____

Plasma membrane; inner mitochondiral membrane

T/F Enzymes decrease the overall free energy change in a chemical reaction

False

Until the discovery of ______, enzymes were the only recognized biological molecules that were catalytic

Ribozymes

Catalytic proteins are known as ____ whereas catalytic RNA molecules are known as ______

Enzymes; ribozymes

Which of the following reactions is catalyzed by a ribozyme?

Peptide bond formation during protein synthesis

Which strategy can be used for regulation of metabolism?

All of the strategies may be used

Feedback inhibition, covalent modification, and allosteric regulation are all examples of _____

Posttranslational regulation

T/F The regulatory site in an allosteric enzyme is found within the catalytic site

False

How does the binding of a regulatory molecule to the allosteric site affect the activity of an enzyme?
A) It causes the enzyme to denature and become inactive. B) It may change the affinity of the enzyme for its substrate.
C) It may cause the active site to disappear altogether.
D) It may change the maximum velocity of the enzyme.
E) It may decrease the activity of the enzyme.
F) It may increase the activity of the enzyme.
G) It may change the shape of the enzyme

B, D, E, F, G

A positive allosteric effector will ______ the activity of an enzyme while a negative effector will ____ the activity

Increase, decrease

The binding of a positive allosteric regulator molecule will _____

increase the ability of the substrate to bind to the catalytic site

Which three of the following groups are most commonly used to covalently modify an enzyme and its activity?
A) Phosphoryl group
B) Hydroxyl group
C) Methyl group
D) Adenyl group

A, C, D

T/F Covalent modification of enzymes most commonly uses phosphoryl, methyl, and adenyl groups

True

Consider a biochemical pathway with five steps that lead to the production of product Q. If there is an abundance of product Q, the most efficient way to slow down the entire pathway would be to regulate ______

The first enzyme in the pathway

A bacterial biosynthetic pathway synthesizes an amino acid in a series of steps, each catalyzed by a different enzyme. The bacteria is transferred to fresh media where the amino acid is present in abundance. The amino acid binds to a regulatory site on the first enzyme in the pathway, effectively shutting down the entire process. This is an example of ________.

Feedback inhibition

the total of all chemical reactions occurring in a cell is called ______

Metabolism

T/F Although most metabolic reactions are freely reversible, a few irreversible catabolic steps are bypassed during biosynthesis with special enzymes that catalyze the reverse reaction in order to allow for independent regulation of catabolic and anabolic pathways.

True

T/F Metabolic pathways can be either catabolic or anabolic but not both

False

_____ pathways are those that function both catabolically and anabolically

Amphibolic

T/F The catabolism of glucose begins with one or more of the glycolytic pathways that yield pyruvate

True

____ ___ is a process that can completely catabolize an organic energy source to CO2 using the glycolytic pathways and TCA cycle with O2 as the terminal electron acceptor for an ETC

Aerobic respiration

T/F Very few gram positive bacteria utilize the Entner-Doudoroff glycolytic pathway.

True

T/F Some aerobic bacteria lack the Entner-Doudoroff and Embden-Meyerhoff pathways and instead use the pentose phosphate pathway for glycolysis.

False