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BMSC 210 - Online Course > Chapter 10 > Flashcards

Chapter 10 Flashcards

1
Q

What is metabolism?

A

The total of all chemical reactions in the cell; almost all are enzyme catalyzed.

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2
Q

Cells carry out which 3 major types of work?

A

Chemical Work

Transport Work

Mechanical Work

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3
Q

Cellular energy is most commonly stored as?

A

ATP

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4
Q

What is the first law of thermodynamics?

A

Energy can be neither created nor destroyed.

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5
Q

What is the second law of thermodynamics?

A

Physical and chemical processes proceed in such a way that the entropy of the universe (the system & its surroundings) increases to the maximum possible.

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6
Q

What is Entropy?

A

A measure of the randomness or disorder of a system.

A measure of that part of the total energy in a system that is unavailable for useful work.

The greater the disorder, the greater its entropy.

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7
Q

What is a calorie?

A

The amount of heat energy needed to raise 1 gram of water 1 degree Celsius.

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8
Q

What are Joules?

A

The SI (International unit) unit of measure for energy or work. 1 calorie is equivalent to 4.1840 joules.

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9
Q

The combined useful equation relating the changes in energy that can occur in chemical reactions and other processes is?

A
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10
Q

What does G represent?

A

Change in free energy

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11
Q

What does H represent?

A

Change in enthalpy

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12
Q

What does T represent?

A

The Temperature in Kelvin (C + 273)

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13
Q

What does S represent?

A

The change in entropy occurring during the reaction.

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14
Q

What is enthalpy?

A

The heat content in the system

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15
Q

What happens to a reaction if the G (free energy of the system) is negative?

A

The reaction will occur spontaneously.

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16
Q

What is the equilibrium constant?

A

A value that relates the concentration of reactants and products to each other when a reaction is a equilibrium.

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17
Q

What happens if the Equilibrium constant is greater than 1?

A

The products are in greater concentration than the reactants at equilibrium.

The reaction tends to go to completion.

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18
Q

What is the standard free energy change?

A

The free energy change of a reaction at 1-atmosphere pressure when all reactants and products are present in their standard states: usually the temperature is 25C

The maximum amount of energy available from the system for useful work under standard conditions.

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19
Q

What is an exergonic reaction?

A

a reaction that spontaneously goes to completion as written.

The standard free energy change is negative, and the equilibrium constant is greater than 1.

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20
Q

What is an endergonic reaction?

A

A reaction that does not spontaneously go to completion as written

The standard free energy change is positive, and the equilibrium constant is less than 1.

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21
Q

What is the cell’s most practical form of energy?

A

ATP

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22
Q

What makes ATP suited for its role as energy currency?

A

ATP is a high-energy molecule

It is hydrolysed almost completely to the products Adenosine Diphosphate (ADP) and orthophosphate (P)

Strongly exergonic

The energy released is used to power endergonic reactions.

It readily donates a phosphoryl group to other molecules.

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23
Q

What is meant by high phosphate transfer potential?

A

A characteristic of a phosphorylated compound such that it readily transfers a phosphoryl group to another molecule concomitant with a large energy release.

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24
Q

What is meant by substrate-level phosphorylation?

A

the synthesis of ATP from ADP by phosphorylation coupled with exergonic breakdown of a high-energy organic substrate molecule.

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25
Q

What are redox reactions?

A

reactions involving electron transfers

the electron donor (reductant) gives electrons to an electron acceptor (oxidant)

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26
Q

How many electrons does a molecule of glucose have to donate?

A

24

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27
Q

Each redox reaction consists of 2 half reactions. What are they?

A

One half reaction functions as the electron-donating half (oxidation reaction)

The other functions as the electron-accepting half (reduction reaction)

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28
Q

What is the standard reduction potential?

A

A measure of the tendency of an electron donor to lose electrons in an oxidization-reduction (redox) reaction. The more negative the reduction potential of a compound, the better electron donor it is.

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29
Q
A
30
Q

Many of the electrons released from glucose are accepted by NAD+, reducing it to NADH, which in turn donates the electrons to O2. However it is not done directly. How are the electrons donated?

A

Electrons are transferred to O2 via a series of electron carriers called an electron transport chain.

31
Q

What is an electron transport chain?

A

A series of electron carriers that operate together to transfer electrons from donors to acceptors such as oxygen.

Molecules involved in electron transport include NAD+, NADP+, cytochromes, heme proteins, non heme proteins, coenzyme Q, FAD, and FMN.

32
Q

Where are ETCs located in bacterial and archaeal cells?

A

within or associated with plasma membranes and intracytoplasmic membranes.

33
Q

Where are ETCs located in eukaryotes?

A

localized to the internal membranes of mitochondria and chloroplasts.

34
Q

What are flavoproteins?

A

Proteins bearing FAD and FMN

35
Q

What are metabolites?

A

Chemical compounds produced by the metabolic activities of organisms.

36
Q

What are biochemical pathways?

A

Sets of chemical reactions performed by organisms that convert a starting substrate into one or more products.

37
Q

What type of biochemical pathway is shown?

A

Linear Pathway

38
Q

What type of biochemical pathway is shown?

A

Branched Pathway

39
Q

What type of biochemical pathway is shown?

A

Cyclical Pathway

40
Q

Metabolic pathways form a complex network and dynamic. The intermediates of one pathway may be diverted from one pathway to another pathway. They flow into and out of the many pathways that function in cells.

A
41
Q

What are enzymes?

A

a protein catalyst with specificity for the reaction catalyzed and its substrates.

42
Q

What is a catalyst?

A

a substance that increases the rate of a chemical reaction without being permanently altered itself.

43
Q

What are substrates?

A

A reacting molecule in a chemical reaction that is bound by an enzyme

The first molecule of a biochemical pathway

44
Q

What is an oxidoreductase?

A

a classification of an enzyme that catalyzes an oxidation-reduction reaction.

45
Q

What is a tranferase?

A

a classification of an enzyme that catalyzes a reaction involving the transfer to chemical groups between molecules

46
Q

What is a hydrolase?

A

a classification of an enzyme that catalyzes hydrolysis (break down) of molecules.

47
Q

What is a lyase?

A

a classification of an enzyme that breaks C-C, C-O, C-N and other bonds by means other than hydrolysis.

48
Q

What is an isomerase?

A

a classification of an enzyme that rearranges molecules to isomer form.

49
Q

What is a ligase?

A

a classification of an enzyme that joins two molecules together using ATP (or the energy of other nucleoside triphosphates)

50
Q

Many enzymes are composed only of proteins but some are composed of two parts - A protein component called a ______ and a nonprotein component called a _____

A

Protein component called an apoenzyme

nonprotein component called a cofactor

51
Q

What is a complete enzyme consisting of two parts called?

A

holoenzyme

52
Q

If the cofactor is tightly or covalently attached to the apoenzyme it is called a?

A

Prosthetic group

53
Q

If the cofactor is loosely attached and dissociate from the apoenzyme after other products are formed it is called a?

A

coenzyme

54
Q

What is the activation energy?

A

The energy required to bring molecules together to reach the transition state in a chemical reaction.

55
Q

How does an enzyme speed up a reaction?

A

They lower the activation energy

They bring substrates together at a specific location in the enzyme called the active site to form an enzyme-substrate complex.

56
Q

The more concentrated the substrate is, the faster the rate of product formation

A
57
Q

What is denaturation?

A

The loss of the 3d protein shape or nucleic acid structure.

58
Q

What is an enzyme inhibitor?

A

a molecule that inhibits enzyme activity by binding to the enzyme’s active site.

They usually resemble the structure of the normal substrates but they cannot be converted to products.

59
Q

What are noncompetitive enzyme inhibitors?

A

A chemical that inhibits enzyme activity by a mechanism that does not involve binding the active site of the enzyme.

60
Q

What are ribozymes?

A

an RNA molecule with catalytic activity

An important one is located in ribosomes and is responsible for catalyzing peptide bond formation between amino acids during protein synthesis.

61
Q

What 3 ways can metabolic pathways be regulated?

A

Metabolic channeling

Regulation of the synthesis of a particular enzyme (regulation of gene expression)

directly controlling the activity of enzyme (posttranslational regulation)

62
Q

What is metabolic channeling?

A

the localization of metabolites and enzymes in different parts of a cell.

63
Q

What is compartmentation?

A

The differential distribution of enzymes and metabolites to separate cell structures or organelles.

64
Q

How does regulation of gene expression work?

A

by changing the rate of transcription or translation to control the amount of an enzyme present in the cell.

65
Q

How does posttranslational regulation work?

A

it alters the activity of a protein after it has been synthesized by a structural modification, such as phosphorylation or a conformational change.

66
Q

What are allosteric enzymes?

A

An enzyme whose activity is altered by the noncovalent binding of a small molecule (allosteric effector) at a regulatory site separate from the catalytic site.

The effector binding prompts a conformational change in the enzyme’s catalytic site, causing enzyme activation or inhibition.

67
Q

Enzymatic activity can also be switched on and off by reversible covalent modification.

Usually occurs through the addition/removal of a chemical group like a phosphoryl, methyl, or adenylyl group.

A

The most studied regulated emzyme is E.Coli’s glutamine synthetase

68
Q

What is a pacemaker enzyme?

A

It is the enzyme that catalyzes the slowest or rate-limiting reaction in the pathway.

changes in the activity of this enzyme directly alter the speed at which the entire pathway operates.

69
Q

What is feedback inhibition?

A

A negative feedback mechanism in which an end product inhibits the activity of an enzyme in the pathway leading to its formation.

If the end product becomes too concentrated, it inhibits the regulatory enzyme and slows its own synthesis.

If the end product concentration decreases, pathway activity increases and more product is formed.

70
Q

What are isoenzymes?

A

an enzyme that carries out the same catalytic function but differs in terms of its amino acid sequence, regulatory properties, or other characteristics.

Endproduct P controls one isoenzyme, Endproduct Q controls a different one.

BMSC 210 - Online Course (3 decks)

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