Lecture 2 Outline (Ch. 8, 9)

I. Energy and Metabolism

II. Thermodynamics

III. Metabolism and Chemical Reactions

V. Cellular Energy - ATP

VI. Enzymes & Regulation

VII. Cell RespirationA. Redox Reactions

B. Glycolysis

C. Coenzyme Junction

VII. Preparation for next Lecture

What is Energy?

Energy

Where does energy on earth come from originally?

[equivalent of 40 million billion calories per second!]

Metabolism and Energy

Metabolism

Metabolism –chemical conversions in an organism

Types of Energy:

- Kinetic Energy = energy of movement - thermal

- Potential = stored energy - chemical

Potential energy can be converted to kinetic energy (& vice versa)

Potential Energy Kinetic Energy

ThermodynamicsThermodynamics – study of energy transformation in a system

Laws of ThermodynamicsLaws of Thermodynamics:: Explain the characteristics of energy

1st Law:

• Energy is conserved

• Energy is not created or destroyed

• Energy can be converted (Chemical Heat)

2nd Law: • During conversions, amount of useful energy decreases

• No process is 100% efficient

Thermodynamics

Energy is converted from more ordered to less ordered forms

• Entropy (measure of disorder) is increased

Potential vs. Kinetic Energy

Metabolic reactions: All chemical reactions in organism

Anabolic = builds

up molecules

Metabolism

Two Types of Metabolic Reactions:

Catabolic = breaks

down molecules

Chemical Reaction:

• Process that makes and breaks chemical bonds

+Reactants

+Products

Two Types of Chemical Reactions:

1) Exergonic = releases energy

2) Endergonic = requires energy

Chemical Reactions

Metabolic reactions:

• Chemical reactions in organism

Anabolic = build up

Metabolism

Two Types of Metabolic Reactions:

Catabolic = break down

Exergonic = release energy Endergonic = requires energy

Chemical Reactions

• Exergonic reaction • Endergonic reaction

-ΔG

release energy

spontaneous

+ΔG (or 0)

intake energy

non-spontaneous

Glucose CO2 + H20 CO2 + H20 Glucose

Question/Recall: Which has more order? Stores more energy? Polymer or Monomer, Diffused or Concentrated

H+? What is relationship between order and energy?

What type of energy is stored in a covalent bond?

A. Kinetic energy

B. Diffused energy

C. Heat energy

D. Potential energy

E. Conventional energy

Cellular Energy - ATP

• ATP = adenosine triphosphate

• ribose, adenine, 3 phosphates

• last (terminal) phosphate - removable

Be able to diagram ATP!

• ATP hydrolyzed to ADP

• Exergonic

ATP + H2O ADP + Pi

• Energy released, used in another reactions (endergonic)

Cellular Energy - ATP

• ATP regenerated

• cells power ATP generation by coupling to exergonic reactions

Like cellular respiration!

Cellular Energy - ATP

ATP Cycle

Making ATP from ADP + Pi is…

A. Exergonic because it releases energy

B. Endergonic because it requires energy

C. Exergonic because it requires energy

D. Endergonic because it releases energy

Chemical Reactions:

• Like home offices – tend toward disorder

Chemical Reactions

Chemical Reactions:

• Endergonic – energy taken in

• Exergonic – energy given off

Exergonic

Endergonic

Chemical Reactions

Self-Check

Reaction Exergonic or Endergonic?

Breaking down starches to sugars

Building proteins

Digesting Fats

Activation Energy: Energy required to “jumpstart” a chemical reaction

• Must overcome repulsion of molecules due to negative charged electrons

Nucleus Repel Nucleus

Nucleus Repel Nucleus

ActivationEnergy

ActivationEnergy

Chemical Reactions

Exergonic Reaction: – Reactants have more energy than products

Activation energy:

Make sugar and O2 molecules collide

Chemical Reactions

“Downhill” reaction

sugar + O2

water + CO2

Respiration (ch. 9) preview

Cellular Respiration Equation:

C6H12O6 + O2 CO2 + H2O

You will need to KNOW this equation.

Chemical Reactions and Enzymes

Enzymes

• lower activation energy only for specific reactions

• cell chooses which reactions proceed!

enzymes: cannot make rxns go that wouldn’t otherwise

Do speed up rxns that would occur anyway

Cannot change endergonic into exergonic rxns

Enzymes

• Enzymes – control rate of chemical reaction

• sucrase – enzyme sucrose breakdown

• sucrase – catalyst -speed up rxn, but not consumed

“-ase” enzyme

Enzymes

Enzymes

• enzyme – specific to substrate

• active site – part of enzyme -substrate

• binding tightens fit – induced fit

• form enzyme-substrate complex

• catalytic part of enzyme: converts reactant(s) to product(s)

Enzymes

• substrate(s) enter

• Enzymes lowers EA by:

• product(s) formed

-template orientation

-stress bonds

-microenvironment

• enzyme reused

• What factors might affect enzyme activity?

Enzymes

• inhibitors:

• Drug – blocks HIV enzyme at the active site

binds & blocks active site

binds allosteric site – alters conformation

If a competitive inhibitor is in an enzyme reaction, can you reverse the inhibition by adding more substrate?

A. Yes

B. No

C. I’m not sure

D. Wait, what’s a competitive inhibitor?

Cellular Respiration

Overall purpose:

• convert food to energy

• animals AND plants

• complementary to photosynthesis

Cellular Respiration:(Exergonic)

Cellular Respiration

• catabolizes sugars to CO2

• requires O2

• at mitochondrion

Redox Reactions

• as part of chemical reaction, e- are transferred

• e- transfer = basis of REDOX reactions(reduction) (oxidation)

Redox Reactions

• follow the H, e- move with them

Use “H rule” for reactions in this classReactant with more H’s = e donor, will be oxidized

Reactant with more O’s = e acceptor, will be reduced

ZH2 + O2 yields ZO + H2O

Self-Check

Reaction Molecule Reduced

Molecule Oxidized

ZH2 + O2 yields ZO + H2O

CH4 + 2O2 yields CO2 + 2H2O

C6H12O6 + O2 yields CO2 + H2O

Oxygen ZH2

Redox Reactions

Equation for respiration

• transfer of e- to oxygen is stepwise

Redox Reactions

• e- moved by NAD/H (from niacin/vit B3)

• NADH carry e- (reduced!)

Where do e- come from?

• NAD+ not carrying e- (oxidized!)

Where do e- go?

• glucose NADH ETC O2 (makes H2O)

Redox Reactions

In this equation is NAD+ to NADH oxidized or reduced?

A. Reduced, it gained electrons

B. Oxidized, it gained electrons

C. Reduced, it lost electrons

D. Oxidized, it lost electrons

NAD+ + H+ + 2e- NADH

1. glycolysis

- cytosol

- mitochondrial matrix

- inner mitochondrial membrane

• Steps of respiration:

2. Citric acid cycle

3. ETC

4. Chemiosmosis - inner membrane to intermembrane space

Steps of Respiration

Coenzyme Junction

4 CO2

2 CO2

• Stages of respiration:

1. Glycolysis – prep carbons

Cellular Respiration

1. Glycolysis

• 1 glucose (6C) 2 pyruvate (3C)

• Keep track of: - inputs

- NAD+/NADH

- ATP

Cellular Respiration

- CO2 and H2O

- outputs

• eukaryotes AND prokaryotes

ATP

ADP

1

Glucose

Glucose-6-phosphate

Glycolysis

2

Glucose-6-phosphate

Fructose-6-phosphate

Fructose-1, 6-bisphosphate

Dihydroxyacetonephosphate

Glyceraldehyde-3-phosphate

4

5

GlycolysisATP

ADP

2

2 ADP

2 ATP

Phosphoenolpyruvate

2 Pyruvate

10

Glycolysis

2 ATP

2 ADP

How many NET ATP are produced by glycolysis?

A. one

B. two

C. four

D. six

E. eight

-inputs:

CO2 = none yet

(2 H2O)

-outputs:

1 Glucose

2 ATP

4 ATP (2 net)

2 NADH

2 pyruvate

Where do the outputs go?

Glycolysis Cellular Respiration

Energy production

Mitochondria • energy from nutrients ATP

Coenzyme Junction • 2 pyruvate (3C) 2 Acetyl CoA (2C)

Cellular Respiration

• pyruvate joins coenzyme A (from vitamin B5)

• 2 carbons lost (as CO2)

• 2 NAD+ NADH

Things To Do After Lecture 2…Reading and Preparation:

1. Re-read today’s lecture, highlight all vocabulary you do not understand, and look up terms.

2. Ch. 8 Self-Quiz: #1-6 (correct answers in back of book)

3. Read chapter 9, focus on material covered in lecture (terms, concepts, and figures!)

4. Skim next lecture.

“HOMEWORK” (NOT COLLECTED – but things to think about for studying):

1. Describe the relationship between exergonic/endergonic, catabolic/anabolic, and “uphill”/”downhill” chemical reactions

2. Diagram one molecule of ATP and how ADP is different

3. Cut apart the boxes on the previous sheet – match up three (name, energy balance, basic reaction) for glycolysis and three for the coenzyme junction

4. Place the following molecules in order for when they are used/created during glycolysis: fructose-6-phosphate, glucose, glucose-6-phosphate, pyruvate, glyceraldehyde-3-phosphate

Self-check at home