bio unit 4

Metabolism

All chemical reactions of a cell or organism that sustain life

Bioenergetics

The concept of energy flow through living systems

Metabolic pathways

A series of interconnected biochemical reactions that convert a molecule through a series of steps to eventually yield a final product(s)

Anabolic pathway

• require energy

• simpler TO complex

• Ex: photosynthesis

Catabolic pathways

• produce energy

• Degrade complex TO simple

• Ex: cellular respiration

ATP

adenosine triphosphate

• energy currency of all cells

where do carbs originate from

photosynthesis

Energy

The ability to do work

• electrical

• Light

• Heat

  
  

Kinetic energy

Energy an object possesses due to motion

Potential energy

Energy an object possesses due to position

• stored energy

(chemical energy in bonds)

Chemical energy

The potential energy that exists within chemical bonds that releases when those bonds break

• provide cells w energy from food

Potential energy in cells

Energy stored in the uneven distribution of ions across a membrane

Kinetic energy in cells

Movement of molecules against a concentration gradient using energy

Gibbs free energy (G)

usable energy available for work in a chemical reactions after accounting for entropy

Exergonic reactions

energy released during a reaction

• spontaneous - NO energy (slow)

Endergonic

Energy required

Non spontaneous

Products have more free energy than reactants

Endergonic reactions

Products have less free energy than the reactants

Exergonic reaction

entropy

the degree of disorder in a system

Cellular respiration

processes by which cells breakdown macromolecules (glucose) to produce ATP

Glycolysis takes place in

cytosol

glycolysis input

glucose and 2 ATP

Glycolysis output

4 ATP, 2 NADH, 2 Pyruvate

Net ATP production of glycolysis

2 ATP

acetyl CoA comes from

the pyruvate in glycolysis

where do citric acid cycle and pyruvate oxidation take place

mitochondrial matrix

Total citric acid cycle production

6 NADH, 2 FADH2, 2 ATP

ATP generated by cellular respiration

30-36 (90% from electron transport chain)

entropy

measurement of disorder

Activation energy

the energy needed to initiate a chemical reaction

what determines a reactions spontaneity

Changes in free energy (ΔG)

First law of thermodynamics

energy cannot be created or destroyed, only transferred

• total energy is constant

Second law of thermodynamics

every energy transfer increases the entropy (disorder) of the universe

• some energy is always lost as heat in transformations

ATP as energy currency

powers cellular processes by releasing energy when its phosphate bonds are hydrolyzed

Structure of ATP

Adenine base, ribose sugar, and three phosphate groups

Phosphorylation

transfer of phosphate group from ATP to another molecule, activating it!

Role of enzymes

biological catalysts the speed up chemical reactions by lowering activation energy

Enzyme-substrate interaction

enzymes bind to specific substrates at their active site, forming an enzyme substrate complex

Competitive inhibitors

Bind to the active site - competing with substrate

Noncompetitive inhibitors

Binds elsewhere, far away from active site - alters enzyme shape

Oxidation

loss of electrons

Reduction

gain of electrons

Glycolysis

first step of cellular respiration - breaks down glucose into 2 molecules of pyruvate

Steps of glycolysis

Energy Investment phase

Energy payoff phase

Energy investment phase

consumes 2 ATP

Energy payoff phase

Produces 4 ATP and 2 NADH

NADH

a coenzyme that acts as an electron carrier in cellular respiration

Oxidation of pyruvate

converts pyruvate into acetyl-CoA , releasing Co2 and generating NADH

Citric Acid Cycle

Completes the oxidation of acetyl-CoA

ATP is synthesized by substrate-level phosphorylation

What does the Citric acid cycle produce

2 CO2, 3 NADH, 1 FADH2, 1 ATP (per cycle turn)

Oxidative phosphorylation

The final stage of cellular respiration, producing the most ATP

Electron transport chain

transfers electrons from NADH and FADH2 to oxygen, pumping protons across the membrane

chemiosmosis

protons flow back through ATP synthase, generating ATP

Fermentation

anaerobic process that regenerates NAD+ for glycolysis

• takes place in cytoplasm

Lactic acid fermentation

produces lactate - occurs in muscle cells

• in bacteria and animals

Alcohol fermentation

produces ethanol and CO2 - in yeast

anaerobic respiration

uses alternative electron acceptors - instead of oxygen

Feedback inhibition

ATP and citrate inhibit key enzymes like phosphofructokinase to regulate glycolysis.

Allosteric regulation

activators and inhibitors modulate enzyme activity to match energy demands

glucose

has the greatest chemical potential energy

positive 🔺G

endergonic

Negative 🔺G

exergonic

Carbon-carbon covalent bonds

weak and have lot of potential energy

when is CO2 released as a waste product

Pyruvate oxidation and citric acid cycle

coenzyme Q and cytochrome c

transfer electrons between protein complexes of the ETC