Lecture 2 Outline (Ch. 8, 9). Energy Thermodynamics Metabolism and Chemical Reactions V. Cellular Energy - ATP Enzymes & Regulation Cell Respiration Redox Reactions Glycolysis Coenzyme Junction VII. Preparation for next Lecture. Energy. What is Energy?.
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What is Energy?
Where does energy on earth come from originally?
[equivalent of 40 million billion calories per second!]
Types of Energy:
- Kinetic Energy = energy of movement
- Potential = stored energy
Thermodynamics – study of energy transformation in a system
Potential energy can be converted to kinetic energy (& vice versa)
Laws of Thermodynamics: Explain the characteristics of energy
Energy is converted from moreordered to less ordered forms
Cells convert molecules chemically using cellular energy.
Metabolism – chemical conversions in an organism
Metabolic reactions: All chemical reactions in organism
Catabolic = breaks down molecules
Two Types of Metabolic Reactions
Two Types of Metabolic Reactions:
Catabolic = break down
Exergonic = release energy
Endergonic = requires energy
Glucose CO2 + H20
CO2 + H20 Glucose
+ΔG (or 0)
• Exergonic reaction
• Endergonic reaction
Question/Recall: Which has more order? Stores more energy? Polymer or Monomer, Diffused or Concentrated H+? What is relationship between order and energy?
A. Kinetic energy
B. Diffused energy
C. Heat energy
D. Potential energy
E. Conventional energy
• ATP = adenosine triphosphate
• ribose, adenine, 3 phosphates
• last (terminal) phosphate - removable
Be able to diagram ATP!
Cellular Energy - ATP
• ATP hydrolyzed to ADP
• Energy released, used in another reactions (endergonic)
• ATP regenerated
• cells power ATP generation by coupling to exergonic reactions
Like cellular respiration!
Activation Energy: Energy required to “jumpstart” a chemical
Make sugar and O2 molecules collide
sugar + O2
water + CO2
Cellular Respiration Equation:
C6H12O6 + O2 CO2 + H2O
You will need to KNOW this equation.
• lower activation energy only for specific reactions
• cell chooses which reactions proceed!
cannot make rxns go that wouldn’t otherwise
Cannot change endergonic into exergonic rxns
Dospeed up rxns that would occur anyway
• Enzymes – control rate of chemical reaction
• sucrase – enzyme sucrose breakdown
• sucrase – catalyst
-speed up rxn, but not consumed
• 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 lowers EA by:
• substrate(s) enter
• enzyme reused
• product(s) formed
• What factors might affect enzyme activity?
binds & blocks active site
binds allosteric site – alters conformation
• Drug – blocks HIV enzyme at the active site
If a competitive inhibitor is in an enzyme reaction, can you reverse the inhibition by adding more substrate?
• convert food to energy
• animals AND plants
• complementary to photosynthesis
• catabolizes sugars to CO2
• requires O2
• at mitochondrion
• as part of chemical reaction, e- are transferred
• e- transfer = basis of REDOX reactions
Use “H rule” for reactions in this class
Reactant with more H’s = e donor, will be oxidized
Reactant with more O’s = e acceptor, will be reduced
ZH2 + O2 yields ZO + H2O
• follow the H, e- move with them
Equation for respiration
• transfer of e- to oxygen is stepwise
• e- moved by NAD/H (from niacin/vit B3)
• NADH carry e- (reduced!)
• NAD+ not carrying e- (oxidized!)
Where do e- come from?
Where do e- go?
NAD+ + H+ + 2e- NADH
• Steps of respiration:
2. Citric acid cycle
• Stages of respiration:
1. Glycolysis – prep carbons
• 1 glucose (6C) 2 pyruvate (3C)
• Keep track of:
- CO2 and H2O
• eukaryotes AND prokaryotes
Step not shown
4 ATP (2 net)
CO2 = none yet
Where do the outputs go?
• energy from nutrients ATP
• 2 pyruvate (3C) 2 Acetyl CoA (2C)
• pyruvate joins coenzyme A (from vitamin B5)
• 2 carbons lost (as CO2)
• 2 NAD+ NADH