5-1: Energetics and Redox Reactions

Question 1

What is microbial metabolism essential for

Answer 1

Circulation of organic elements (carbon, nitrogen, etc) through environment

Question 2

What are the four metabolic requirements for all life

Answer 2

1. Liquid water
2. A source of energy to do work
3. Nutrients (e.g. sources of C, N, etc)
4. A source of electrons for biochemical reactions

Question 3

First law of thermodynamics

Answer 3

Energy is neither created nor destroyed

Question 4

Where is energy conserved/stored

Answer 4

High energy molecules (like ATP)

Question 5

Energy either comes from __________ or __________

Answer 5

chemicals, the sun

Question 6

Chemotrophs are…

Answer 6

Microbes that break down high energy molecules to lower energy molecules, use the excess energy to power cell functions

Question 7

Microbes that capture energy from sunlight are…

Answer 7

phototrophs

Question 8

Name for chemotrophs that use organic chemicals vs inorganic chemicals

Answer 8

Organic = chemoorganotrophs
Inorganic = chemolithotrophs

Question 9

Autotrophs vs heterotrophs

Answer 9

Autotrophs use CO2 (inorganic C) to build materials = primary producers

Heterotrophs obtain C from organic compounds (chemoorganotrophs)

Question 10

Hydrolysis of ATP to ADP used to…

Answer 10

power synthesis of cell components (proteins, membranes, CW) and power cell functions (transport)

Question 11

What do ATPase enzymes do

Answer 11

Couple energy from ATP hydrolysis to perform other cell reactions

Question 12

Catabolism vs anabolism

Answer 12

Catabolism = reactions used to obtain E and break down complex molecules

Anabolism = reactions used to synthesized cellular material (use E)

Question 13

What is metabolism

Answer 13

Series of biochemical reactions needed to sustain life

Question 14

What is Gibbs free energy

Answer 14

deltaG
Measurement of free E change of a reaction in kJ

Question 15

What is a negative gibbs free energy

Answer 15

Reactants have more energy than products, the reaction is exergonic (E released) and spontaneous

Question 16

What is positive gibbs free energy

Answer 16

Reactants have less energy than products, the reaction is endergonic (requires energy) and not spontaneous

Question 17

Gibbs free E equation

Answer 17

deltaG = deltaG0 + RTlnK

Question 18

what affects delta G

Answer 18

temperature, [substrates], [products]

Question 19

What does a high K value do

Answer 19

Increases deltaG (high [products]), reaction less favourable in that direction

Question 20

Equation for K

Answer 20

K = [products] / [substrates]

Question 21

How much energy does ATP production require

Answer 21

At least 31.8 kJ /mole

Question 22

How much energy does aerobic respiration of glucose release

Answer 22

2895 kJ

Question 23

What does the cell need nutrients for

Answer 23

Make up core molecules in the cell (DNA, proteins, lipids)
serve essential cell functions (Fe, Mg)

Question 24

What are redox reactions

Answer 24

Reduction/oxidation rxn
Electrons transferred from high E state to lower E state

Question 25

Redox rxns are the source of energy for…

Answer 25

Chemotrophs

Question 26

Electrons are at a lower E state when they are associated with…

Answer 26

More electronegative atoms

Question 27

When glucose loses electrons, it is _______
When O2 gains electrons, it is _________

Answer 27

Oxidized
Reduced

Question 28

How do redox rxns produce energy

Answer 28

E released when electrons move to lower energy state

Question 29

How do you write out a redox pair

Answer 29

(oxidized form/reduced form)
e.g. CO2/glucose

Question 30

what is reduction potential

Answer 30

E0’
The likelihood of a redox couple to act as an electron donor or acceptor

Question 31

Redox couples with more negative values will usually act as….

Answer 31

electron donors to be oxidized

Question 32

Redox couples with more positive values have strong tendency to act as….

Answer 32

electron acceptors, to be reduced

Question 33

What makes CO2/glucose a strong electron donor, with a negative reduction potential

Answer 33

C-H bonds in glucose = electrons in high energy state
Electrons close to oxygen in CO2 = lower energy state

Question 34

Why is O2/H2O a strong electron acceptor

Answer 34

Hydrogen wants to donate e
Oxygen highly electronegative
In H2O oxygen can steal electrons from H
Electrons associated with O2 = low energy state

Question 35

A redox pair lower on the redox tower/table will be a…

Answer 35

electron acceptor

Question 36

A redox pair higher on the redox tower will be a…

Answer 36

electron donor

Question 37

The larger the difference in redox potential of couples, the larger the…

Answer 37

amount of energy produced larger

Question 38

Increase in electronegativity =

Answer 38

decrease energy state of e

Question 39

Where do electrons end up after being transferred from initial e donor

Answer 39

Ultimate acceptor over many biochemical reactions

Question 40

What is used to shuttle electrons around cell

Answer 40

Soluble electron carriers (nicotinamide adenine dinucleotide (NAD+/NADH))

Question 41

NAD+ is the ___________ agent, whereas NADH is the ___________ agent

Answer 41

Oxidizing
Reducing (gets oxidized to NAD+)

Question 42

Enzymatic cofactors are…

Answer 42

non-protein chemical compound or metallic ion that is required for an enzyme’s role as a catalyst

Question 43

Last slide summary**

Answer 43

just look