Unit 2 - Metabolic Processes

Metabolism

The totality of an organism’s chemical reactions

Metabolic pathway

Series of chemical reactions in which molecules are broken down or built up

Catabolic Pathway

Releases energy by breaking down complex molecules into simpler compounds

Anabolic Pathway

Consumes energy to build complex molecules from simpler ones

example of catabolic pathway

cellular respiration

example of anabolic pathway

photosynthesis

Bioenergetics

study of how energy flows through living organisms

3 cellular actions fuelled by ATP

Muscle contractions, cell movement, membrane pumps

energy

the capacity to cause change or do work

kinetic energy

energy associated with motion

Heat energy

kinetic energy associated with random movement of molecules or atoms

potential energy

energy matter possesses due to it’s location or structure

Chemical energy

potential energy available for release in a chemical reaction and held by chemical bonds in an atom

types of potential energy

gravitational, magnetic, elastic, chemical, nuclear, electrical

types of kinetic energy

light energy, electricity, heat energy

Weak bonds

require more energy to stay intact

Strong bonds

require less energy to stay intact

3 organic molecules rich in chemical energy

Carbs, Lipids, Proteins

Carbs, lipids and proteins (rich in chemical energy)

they have weak bonds

Structure of ATP

Adenine, 3 phosphates, ribose sugar

Macromolecule of ATP

Nucleic Acid

How ATP provides energy to other reactions

A phosphate group containing lots of chemical energy breaks, producing lots of energy used for reactions and turning ATP into ADP

First Law of Thermodynamics

Energy is never created nor destroyed, but only changed from one form to another

Second law of thermodynamics

Total entropy of a system will only increase

Entropy

Energy unavailable to do work, taking the form of an increase in disorder

Gibbs Free energy

energy available in a system to do useful work

What happens when cells use energy?

energy allows cells to reduce internal entropy and maintain organization, while increasing entropy of surroundings

Formula for Gibbs Free Energy

Free energy in products - free energy in reactants

Endergonic reactions

When free energy is greater in products than in reactants, meaning that the reaction requires energy (non-spontaneous).

Photosynthesis

an endergonic reaction where water and carbon dioxide react to form glucose and oxygen

Cellular respiration

an exergonic reaction where glucose and oxygen react to form water, carbon dioxide and energy (ATP)

Exergonic reactions

When free energy is greater in reactants than products, meaning that the reaction does not require additional energy (spontaneous)

Energetic coupling

when a spontaneous reaction drives a non-spontaneous reaction

phosphorylation

the addition of a phosphate group to a molecule

example of phosphorylation

phosphate group being added to an active pump

catalyst

substances increasing the rate of chemical reactions

3 unique properties of catalysts

• not consumed in a reaction

• don’t change equilibrium of a reaction

• specific and don’t participate in all reactions

enzyme

proteins increasing the rate of a chemical reaction in a cell by reducing activation energy

transition state

unstable intermediate state between reactants and products where old bonds break and new bonds are formed

activation energy

energy needed to reach transition state

active site

part of the enzyme that binds substrate and catalyzes its conversion to the product

optimal temperature

temperature at which the enzyme is the most active

chaperones

evolved proteins helping to protect denatured proteins until they attain proper 3D structure

optimal pH

pH at which enzyme is most active

how does pH affect function of enzymes

• affects charges of amino acids making up active site

• influences charge and shape of the active site

activator

increase the activity of enzymes

inhibitor

decrease activity of enzymes

irreversible inhibitor

form covalent bonds with enzymes & irreversibly inactivate them

reversible inhibitors

form weak bonds with enzymes and easily dissociate from them

competitive inhibitors

competes with substrate for the active site and are similar in shape to the substrate.

non competitive inhibitors

often bind to allosteric site, changing shape of the enzyme

anaerobic respiration

cellular respiration occurring in the absence of oxygen

aerobic respiration

cellular respiration occurring in the presence of oxygen

maximum amount of free energy released during cellular respiration

-686 kcal per mole

oxidization

loss of electrons

reduction

gaining of electrons

redox reaction

a chemical reaction between an oxidizing substance and a reducing substance

Why is cellular respiration a redox reaction

glucose is oxidized to form CO2 and oxygen is reduced to form H2O

Substrate level phosphorylation

Mechanism for ATP production when an organic molecule transfers a phosphate group directly to ADP. An enzyme is in charge of hydrolysis of an organic molecule to yeild a phosphate group and the addition of that phosphate group to ADP.

Oxidative phosphorylation

Mechanism for ATP production where the chemical energy of organic molecules is transferred first to electron carriers, which then carry electrons from one set of reactions to another.

NADH

Nicotinamide Adenine Dinucleotide

FADH2

Flavin adenine dinucleotide

Glycolysis 

The first step of cellular respiration involving the creation of pyruvate. It is anaerobic and occurs in the cytoplasm.

Products of glycolysis

2 pyruvate, 2 ATP, 2 NADH

Pyruvate Oxidation

The second step of cellular respiration involving the oxidization of 2 pyruvate to 2 Acetyl CoA. It is aerobic and occurs in the mitochondrial matrix.

Products of pyruvate oxidation

2 NADH, 2CO2, 2 Acetyl CoA

Kreb’s Cycle

The third step of cellular respiration where 2 Acetyl CoA is converted to 2 ATP, 6 NADH, 2 FADH2. It is aerobic and occurs in the mitochondrial matrix.

Electron Transport Chain (ETC)

The fourth step of cellular respiration where protein complexes within the inner membrane pass electrons from high energy molecules (NADH & FADH2), creating an electrochemical gradient and producing abundant ATP.

Name of electron shuttles

Ubiquinone (Q), Cytochrome C (Cyt C)

4 integral proteins in ETC

NADH dehydrogenase, succinate dehydrogenase, Cytochrome b-c, cytochrome oxidase

co-enzymes

A specific, organic molecule aiding in enzyme function

co-factors

a broad organic or inorganic molecule aiding in enzyme function

Examples of co-enzyme

NAD+, FAD, CoA

Example of co-factor

zinc

fermentation

An anaerobic process where microorganisms (e.g. yeast) convert carbs (e.g. glucose) to alcohols, acids and gasses.

alcoholic fermentation

when a microorganism converts pyruvate into CO2 and ethanol to produce alcohol. Acetaldehyde accepts electrons and oxidizes NADH to NAD+ for glycolysis to be carried out again.

lactic fermentation

when 2 pyruvate yield 2 lactate,