Chapter 12 - Energetics and Redox Reactions

Question 1

Metabolism

Answer 1

The sum of chemical reactions that occur within a cell.

Question 2

Catabolism

Answer 2

breakdown of organic and inorganic molecules, used to release energy and derive molecules that could be used for reactions.

Question 3

Anabolism

Answer 3

synthesis of more complex molecules from simpler organic and inorganic molecules, requires energy

Question 4

Free Energy (G)

Answer 4

Energy available to do work

Question 5

Three types of work?

Answer 5

Chemical work (anabolism), transport work (nutrient uptake, and mechanical work (rotation of the flagellum)

Question 6

Change in free energy?

Answer 6

ΔG°’ - notation - which is the change in free energy under standard conditions

Question 7

Positive ΔG°’

Answer 7

indicates that the reaction requires energy - endergonic

Question 8

Negative ΔG°’

Answer 8

indicates that the reaction releases energy - exergonic - releases energy that can be conserved by the cell to do work

Question 9

Adenosine triphosphate (ATP)

Answer 9

high-energy molecule used by cells for energy currency, donates phosphoryl group to other molecules.

Question 10

What happens to ATP in exergonic reactions?

Answer 10

As the energy is released, the synthesis of ATP is driven from the addition of a phosphate molecule to adenosine diphosphate, or ADP

Question 11

Orthophosphate

Answer 11

Pi

Question 12

What happens to ATP in an endergonic reaction?

Answer 12

Requires energy and will couple the hydrolysis of ATP to ADP + Pi, using the released energy to drive the reaction.

Question 13

Activation Energy

Answer 13

Energy required to break bonds

Question 14

Catalyst

Answer 14

substance which assist the reaction to proceed without being changed themselves by the reaction

Question 15

enzymes

Answer 15

a catalyst used by cells

Question 16

Oxidation-Reduction reactions (Redox Reactions)

Answer 16

An electron is passed from an electron donor to an electron acceptor, as a way to conserve energy by coupling its synthesis to the release of energy

Question 17

Oxidation

Answer 17

Loss of its electrons

Question 18

Reduction

Answer 18

Gain of electrons

Question 19

Molecule being oxydized

Answer 19

This is the electron donor

Question 20

Molecule being reduced

Answer 20

This is the electron acceptor

Question 21

Energy Rich

Answer 21

Molecule with a lot of electrons to donate

Question 22

Conjugate Redox Pair

Answer 22

The acceptor and donor of a half reaction - every redox reaction consists of two half reactions - 1 donates (oxidized) and 1 accepts (reduced)

Question 23

Whats on the left of the the couple?

Answer 23

The oxidized form (acceptor)

Question 24

What is on the right of the couple?

Answer 24

The reduced form (donor)

Question 25

Name the donor and acceptor: O2/H2O

Answer 25

O2 is the acceptor, H2O is the donor

Question 26

Reduction Potential

Answer 26

E’o, (Volts) - measurement of the tendency of the donor in the reaction to give up electrons

Question 27

More Negative E’o

Answer 27

Greater tendency to donate electrons - very good electron donors in reduced form

Question 28

Less Negative or Positive E’o

Answer 28

Weak Tendency to donate electrons

Question 29

Redox Tower

Answer 29

lists redox couples in a vertical form based on E’o. Most negative go to top, most positive towards bottom. The reduced substance with greatest tendency to donate would be found at the top right. Oxidized substance w/ greatest tendency to accept on bottom left.

Question 30

ΔE’o

Answer 30

acceptor E’o minus donor E’o

Question 31

Larger ΔE’o

Answer 31

More potential Energy for the cell - larger vales are when there is a bigger difference

Question 32

Actual Formula to proportional ΔE’o and ΔG’

Answer 32

ΔG’=-nF (x) ΔE’o n= number of electrons, F is faraday constant

Question 33

Electron Carriers

Answer 33

Cellular intermediates that participate in the transference of electrons, with the possibility for energy capture occurring along the way. Go back and forth between reduced (carrying electron) and oxidized (after they passed electron on) forms.

Question 34

Organization of Electron Carriers

Answer 34

Must be arranged in order of their standard reduction potential. (Down Redox tower), with an electron passed from a carrier with the most negative E’o to a less negative E’o.

Question 35

NAD+/NADH

Answer 35

Nicotinamide adenine dinucleotide - a coenzyme that carriers both electrons and protons, two of each.

Question 36

NADP+/NADPH

Answer 36

Dinucleotide phosphate, closely related to NAD+, but accepts 2 electrons and only 1 proton.

Question 37

FAD/FADH and FMN/FMNH

Answer 37

Flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) - carry two electrons and 2 protons each.

Question 38

Flavoprotein

Answer 38

Proteins with FAD/FMN

Question 39

Coenzyme Q (CoQ/Uiquinone

Answer 39

2 electrons 2 protons

Question 40

Cytochromes

Answer 40

use iron atoms as part of a heme group, carry 1 electron

Question 41

Iron-Sulfur (Fe-S) protein

Answer 41

such as ferredoxin, use iron atoms not part of the heme group to carry 1 electron at a time

Question 42

Electron Transport Chain (ETC)

Answer 42

Starts with initial electron donor (substance from outside cell) and ends with final electron acceptor (another substance outside cell)

Question 43

Middle of ETC

Answer 43

electrons are passed from carrier to carrier as electrons move down tower

Question 44

Where are ETC’s located?

Answer 44

found within cell membranes of both bacteria and archaea, and mitochondrial membranes of eukaryotes