Bioenergetics

Metabolism

The sum of Catabolic and Anabolic reactions which occur in the cell [ Meta = Cata + Ana ]

Catabolism

Larger molecules breaking into smaller molecules (hydrolysis)

Anabolism

Smaller molecules breaking into larger molecules (dehydration synthesis)

Are catabolism and anabolism exergonic or endergonic?

Catabolism - Exergonic (releasing energy)

Anabolism - Endergonic (requiring energy)

Exergonic (or exothermic)

Something that releases energy and breaks bonds (negative delta G)

Endergonic (or Endothermic)

Something that requires energy and creates bonds (positive delta G)

Diving board energy analogy

As you climb up the diving board, energy gets STORED as potential energy and gets RELEASED as kinetic energy when you dive off the diving board

First law of thermodynamics

Energy cannot be created nor destroyed

Can energy change forms?

Yes, energy can change forms and ONLY change forms

Can energy change forms?

Yes, energy can change forms and ONLY change forms

Second law of thermodynamics

Energy only precedes to a less usable form. (Hot → Cold)

What eventually happens to energy?

It gets lost as heat and it will get lost in the universe (heat death)

Entropy

measurement of chaos & disorder

Levels of entropy

more entropy - more chaos & disorder

less entropy - less chaos & more order

What is true about entropy?

You CANNOT decrease the entropy of one system without increasing the other

Can life exist perpetually without energy?

No

Autotroph

Self feeders

Able to produce own food by converting solar energy into stored chemical energy in the form of glucose

photosynthesis

6 CO2 + 6 H2O (Sunlight) → C6H12O6v+ 6 O2

Heterotroph

CANNOT produce own food and rely on stored chemical energy from autotrophs

Cellular respiration

C6H12O6 + 6O2 (Enzymes) → 6 CO2 + 6 H2O + Energy (ATP)

• A series of chemical reactions in which energy is released from glucose (lipid, protein) and stored in ATP

• Each step involves an enzyme

• Many steps involve the transfer of H

What is special about plants?

They can undergo photosynthesis & cellular respiration. However, they dont produce enough ATP

Relationship of chloroplasts and mitochondria

Chloroplast - Stores ATP

Mitochondria - Makes ATP

Combustion

Reactions which involve the addition of oxygen

CH4 + 2O2 → CO2 + H2O

(combustion of methane, which is the byproduct of respiration)

Reduction

• Gains electrons

• Gains H

• Removes O2

• Stores energy

• photosynthesis

Reduction

• Gains electrons

• Gains H

• Removes O2

• Stores energy

• photosynthesis

Cellular respiration process

Process by which energy stored in organic molecules (glucose) is released in the cells

• Breaks bonds in glucose to strip H and of electrons will be carried with G= Energy

How much ATP in 1 glucose (perfect)

38 ATP

How much energy does aerobic respiration release

670kcal per mole

ATP

Energy

Structure: Adenine & Ribose → Adenosine

3 Phosphates: AMP, ADP, ATP

Whats important about cellular respiration?

Even though you lose energy due to the ATPs, you get more chemical reactions (less wasteful)

Coupled reactions

• Need energy to drive endergonic reactions

• If last bond on ATP is broke → Energy released

• ATP + H2O → ADP + Pi + Energy

Why is H2O combined with ATP?

• Uses released energy to drive endergonic reactions

• Use energy from exergonic reactions to run an endergonic reaction

What happens to Pi if it gets transferred to surrounding water?

• Energy is lost as heat

• Therefore, Pi is transferred to reactant molecule for reaction needing energy (the endergonic or couple reaction)

Coenzymes

• Reduced (oxidizing agents)

• Usually a redox reaction requires a coenzyme

• Temporarily bonds H+ (electrons)

• Acts as H+ or e- acceptors

• Usually vitamins

If a coenzyme picks up H, is it oxidized or reduced?

reduced - stored energy

• therefore, coenzyme possessed energy H will be used to make ATP

What are the names of the enzymes?

NAD & FAD

What is the coenzyme of NAD?

Niacin (B1 vitamin)

What is the coenzyme of FAD?

Riboflavin (B complex)

Anaerobic respiration

• Without oxygen

• Inefficient (not harnessing all the energy)

• Glucose only partially breaking down

• 6C → 2C3 (all carbons not broken - much energy left)

• Occurs mainly in prokaryotes (bacteria) and in eukaryotes when O2 is not available

Aerobic respiration

• With oxygen

• Can generate maximum amounts of ATP

• More efficient (complete breakdown of glucose)

• Strip off all H

• Occurs in most eukaryotes

Five Stage Process

• Stage 1 is common to both aerobic & anaerobic (almost all living things)

• Stage 2-5 is STRICTLY aerobic (many living things but not all)

  Definition: Process by which energy stored in glucose (organic molecule) is released to cells

Purpose of glucose breakdown

• To strip off H

• electrons will be carried with H

^^ Everything will result to energy

(NAD & FAD are pulling away energy from glucose to create ATP)

Glycolysis

IN: Glucose (6C)

• 2 ATP

• 2 PGAL (3C)

OUT: 2 pyruvic acid

• 2 ATP

• 2 NADH+

⭐️ANAEROBIC⭐️

More things about glycolysis

• Occurs in cytoplasm

• ALL enzymes are located there

• Contains coupled reactions, which are endergonic reactions paired with exergonic reactions (Ex: Hydrolysis of ATP)

Fate of Pyruvic Acid

• Happens when aerobic and anaerobic respirate, taking different pathways

• They deal with stripped H differently

• The H stored on NAD can only be temporary - it will be transferred to another molecule

Aerobic Respiration (Fermentation)

• Oxygen acts as a final electron respirator

• Pyruvic acid continues in a series of reactions to strip more H

• Eventually H is transferred to oxygen → splits & turns into H2O

• More ATP made

⭐️THE DECISION OF AEROBIC OR ANAEROBIC RESPIRATION DEPENDS ON OXYGEN LEVELS⭐️

Anaerobic Respiration (Glycolysis stops → No ATP production)

• Pyruvate can’t continue to be oxidized

• No available source electron acceptor, therefore cannot release more energy

• NADH+H+ must release H+ (must be recycled so glycolysis can continue)

• Small supply of enzyme

Alcoholic Fermentation

IN: 2 Pyruvates

• 2 NADH+H+

OUT: 2 CO2

• 2 ethanol

• 2 NAD+

Whole purpose of alcoholic fermentation

• To produce ATP from sugar without oxygen

• To turn coenzyme into NAD+

• To keep glycolysis running

Lactic Acid Fermentation

• Bacteria

• Muscles under oxygen debt

• Pyruvate → Lactic Acid

Purpose of Lactic Acid Fermentation

• To take in oxygen urgently

• Stiffen muscles

Inputs & outputs of Lactic Acid Fermentation

IN: 2 pyruvates

• 2 NADH+H+

OUT: 2 lactic acids

• 2 NAD+

Acetyl CoA Formation

Purpose: Move pyruvates into mitochondria

• Prepare pyruvate for Kreb’s cycle

Mitochondria

• Double membrane

• Outer - Smooth

• Inner - Highly folded (cristae)

• Foods increase surface area for respiratory reactions

Intermembrane space

• Compartmentalization is important

• Allows for storage of protons

• Builds concentration gradient = energy for ATP production

Inputs & Outputs of Acetyl CoA

IN:

• 2 pyruvates

• 2 CoA

• 2 NAD+

OUT:

• 2 CO2

• 2 Acetyl CoA

• 2 NADH+H+

Krebs Cycle

Purpose:

• To complete oxidation of carbon compounds to CO2

• Strip H & Store NAD

Location: Occurs in matrix