BIOL 351 Exam 2 Study Set: Redox Terms and Definitions

Supply of monomers (or precursors of) required by cells for growth

Nutrients

Nutrients required in large amounts

Macronutrients

Nutrients required in trace amounts

Micronutrients

Required by ALL cells, Major element in ALL classes of macromolecules

Carbon (C)

what is required by ALL cells, Major element in ALL classes of macromoleculescarbon

carbon

____ use organic carbon, ______ use carbon dioxide (CO2)

Heterotrophs , Autotrophs

Typical bacterial cell is ~__% carbon (by dry weight)

50

Typical bacterial cell is ~__% nitrogen (by dry weight)

13

Key element in proteins, nucleic acids, and many more cell constituents

nitrogen

Synthesis of nucleic acids and phospholipids

Phosphorus

Sulfur-containing amino acids (cysteine and methionine)• Vitamins (e.g., thiamine, biotin, lipoic acid) and coenzyme A

sulfur

Required by enzymes for activity

Potassium

stabilizes ribosomes, membranes, and nucleic acids

• Also required for many enzymes

Magnesium

Helps stabilize cell walls in microbes

• Plays key role in heat stability of endospores

Calcium (Ca)

Required by some microbes (e.g., marine microbes)

Sodium (Na)

examples of macronutrients

carbon, hydrogen, oxygen, nitrogen, phosphorus

Key component of cytochromes and FeS proteins involved in electrontransport

iron

Organic compounds required in small amounts by certain organisms

• Examples: vitamins, amino acids, purines, pyrimidines

Growth factors

Most commonly required growth factors

• Most function as coenzymes

Vitamins

Examples of micronutrients are

vitamins, growth factors, iron

Nutrient solutions used to grow microbes in the laboratory

Culture media

precise chemical composition is known

defined media

composed of digests of chemically undefinedsubstances (e.g., yeast and meat extracts)

Complex media

Contain complex media plus additional nutrients(for nutritionally demanding organisms)

Enriched media

Contain compounds that selectively inhibit growth of some microbes but not others

Selective media

Contain an indicator, usually a dye, that detects particular chemical reactions occurring during growth

Differential media

culture containing only a single kind of microbe

Pure culture

unwanted organisms in a culture

Contaminants

Cells can be grown in ___ or ___ culture media

liquid , solid

Solid media are prepared by addition of a gelling agent ( ____ or ____ )

agar, gelatin

When grown on solid media, cells form isolated masses

colonies

The sum total of all of the chemical reactions that occur in a cell

Metabolism

Energy-releasing metabolic reactions

Catabolic reactions (catabolism)

Energy-consuming metabolic reactions, usually biosyntheses

Anabolic reactions (anabolism)

obtain energy from organic compounds

Chemoorganotrophs

obtain energy from inorganic compounds

Chemolithotrophs

obtain energy from light

Phototrophs

obtain energy from eating

Heterotrophs

obtain energy from themself

Autotrophs

In any chemical reaction, some energy is ___ as heat

lost

Energy is defined in units of____ , a unit for heat energy

kilojoules (kJ)

energy released that is available to do work

free energy (G)

The change in free energy during a reaction (under standard condition) is referred to as ____

ΔG^0′

Reactions with a negative _____ release free energy ( ____ )

ΔG^0′ , exergonic

Reactions with a positive ____ require energy (____ )

ΔG^0′ , endergonic

To calculate free-energy yield of a reaction, we need to know the _____ (Gf^0; the energy released or require during formation of a given molecule from the elements)

free energy of formation

: free energy that occurs under actual conditions

ΔG

ΔG = _________ (where R and T are physical constants and K is the equilibrium constant for the reaction in question)

ΔG^0′ + RT ln K

ΔG^0′ is ____ always a good estimate of actual free-energychanges

not

Free-energy calculations ___ provide information on reactionrates

do not

energy required to bring all molecules in achemical reaction into the reactive state

Activation energy

Catalyst ____ the activation energy of a reaction

Lowers

catalyst will ____ reaction rate

increase

catalyst does _____ energetics or equilibrium of a reaction

not affect

Biological catalysts

Enzymes

Enzymes are typically ___ some ___

proteins , RNAs

enzymes are _____ _____

highly specific

enzymes are __ than a substrate

larger

region of enzyme that binds substrate

Active site:

Bind tightly to enzymes, usually bind covalently and permanently (e.g., heme group in cytochromes)

Prosthetic groups

Loosely bound to enzymes

• Most are derivatives of vitamins(e.g., NAD+/NADH)

Coenzymes

the substance oxidized in a redox reaction

Electron donor:

electron donor is also called

energy source

the substance reduced in a redox reaction

electron acceptor

tendency to donate electrons

• Expressed as volts (V)

Reduction potential (E0′)

Reduced substance of a redox couple with a more negative E0′donates electrons to the oxidized substance of a ____ _____ with amore positive E0′

redox couple

The ____ ____ represents the range of possible reduction potentials

redox tower

The _____ substance at the top of the tower _____ s electrons

reduced , donate

The _____ substance at the bottom of the tower______ electrons

oxidized , accepts

The farther the electrons "drop," the greater the amount of energy released. So ΔE0′ is ____ to ΔG0′

proportional

electrons transfer from upper ___ to lower ____

right ; left

the reduced substance is on the ____ of the redox tower

right

the oxidized substance is on the ____ of the redox tower

left

given

A/B

C/D

make the redox equation (without balancing the reaction)

B + C = A + D

Electrons do _____ exist alone in solution

NOT

Redox reactions usually involve reactions between intermediates

carriers

Electron carriers are divided into two classes...

___ groups (attached to enzymes)

____ (diffusible)

• Examples: NAD+, NADP

Prosthetic , Coenzymes

NAD+/NADH ______ transport both protons and electrons, facilitating redox reactions without being consumed; they are recycled

(reducing power)

NAD+/NADH are common electron carriers among ____ reactions

NADP+/NADPH is are more common in ____ (biosynthesis) pathways

diverse, anabolic

Chemical energy released in redox reactions is primarily stored in certain _____ compounds

phosphorylated

Chemical energy also stored in

coenzyme A

what is the exception for energy rich bonds

thioester bond

____ involves insoluble polymers that can be oxidized to generate ATP

• Examples in prokaryotes

• Glycogen

• Poly-β-hydroxybutyrate (PHB) and other polyhydroxyalkanoates (PHA)

• Elemental sulfur

• Examples in eukaryotes

• Starch

• Lipids (simple fats)

Long-term energy storage

Two reaction series are linked to energy conservation in chemoorganotrophs: ____ and ____

fermentation, respiration

substrate-level phosphorylation; ATP is directly synthesized from an energy-rich intermediate

Fermentation

oxidative phosphorylation; ATP is produced from proton motive force formed by transport of electrons

Respiration:

in substrate level phosphorylation you must ____ ATP first

invest

in Oxidative phosphorylation you ____ ___ need to invest ATP first

do not

in Oxidative phosphorylation the cell surface is ___ charged and there are ___ on the surface

negatively, protons

(Embden-Meyerhof pathway) is

Glycolysis

in Glycolysis (Embden-Meyerhof pathway) the fermented substance is ____ an electron donor and an electron acceptor

BOTH

(Embden-Meyerhof pathway): a common pathway for catabolism of glucose, anaerobic process, three stages

Glycolysis

glycolysis has __ stages

3

glycolysis stage three can include:

anaerobic conditions, such as contracting muscle)

lactate

can carry both fermentation and respiration. Brewers like fermentation while bakers prefer respiration. Respiration generates more ATP, fermentation occurs when conditions are anoxic

Saccharomyces cerevisiae

O2 as terminal electron acceptor

Aerobic respiration

Use other electron acceptors and happens under anoxic conditions

Anaerobic respiration

Respiration: ___ ATP yield than fermentations

higher

ATP is produced at the expense of the proton motive force, which is generated by

electron transport

Oriented in cytoplasmic membrane so that electrons are separated from protons

• Electron carriers arranged in membrane in order of their reduction potential

• The final carrier in the chain donates the electrons and protons to the terminal electron acceptor (O2 in aerobic respiration)

Electron transport system