Lecture 2 Outline (Ch. 8, 9)
I.
Energy
II.
Thermodynamics
III. Metabolism and Chemical Reactions
V.
Cellular Energy - ATP
VI. Enzymes & Regulation
VII. Cell Respiration
A.
Redox Reactions
B.
Glycolysis
C.
Coenzyme Junction
VII. Preparation for next Lecture
Energy
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
Energy
Thermodynamics – study of energy transformation in a system
Potential energy can be converted to kinetic energy (& vice versa)
Potential Energy
Kinetic Energy
Thermodynamics
Laws 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
• Entropy (measure of disorder) is increased
Energy is converted from more ordered to less ordered forms
Potential vs. Kinetic Energy
Metabolism and Energy
Cells convert molecules chemically using cellular energy.
Metabolism
Metabolism – chemical conversions in an organism
Metabolic reactions: All chemical reactions in organism
Catabolic =
breaks down
molecules
Anabolic =
builds up
molecules
Two Types of Metabolic Reactions
Chemical Reactions
Chemical Reaction:
• Process that makes and breaks chemical bonds
+
+
Reactants
Products
Two Types of Chemical Reactions:
1) Exergonic = releases energy
2) Endergonic = requires energy
Metabolism
Metabolic reactions:
• Chemical reactions in organism
Two Types of Metabolic Reactions:
Catabolic = break down
Exergonic = release energy
Anabolic = build up
Endergonic = requires energy
Chemical Reactions
Glucose  CO2 + H20
CO2 + H20  Glucose
-ΔG
+ΔG (or 0)
release energy
intake energy
spontaneous
non-spontaneous
• 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?
What type of energy is stored in a covalent bond?
A.
B.
C.
D.
E.
Kinetic energy
Diffused energy
Heat energy
Potential energy
Conventional energy
Cellular Energy - ATP
• ATP = adenosine
triphosphate
• ribose, adenine, 3 phosphates
• last (terminal) phosphate
- removable
Be able to diagram ATP! 
Cellular Energy - 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!
ATP Cycle
Making ATP from ADP + Pi is…
A.
B.
C.
D.
Exergonic because it releases energy
Endergonic because it requires energy
Exergonic because it requires energy
Endergonic because it releases energy
Chemical Reactions
Chemical Reactions:
• Like home offices – tend toward disorder
• Endergonic – energy taken in; Exergonic – energy given off
Exergonic
Endergonic
Self-Check
Reaction
Breaking down
starches to sugars
Building proteins
Digesting Fats
Exergonic or Endergonic?
Chemical Reactions
Activation Energy: Energy required to “jumpstart” a chemical
reaction
• Must overcome repulsion of molecules due to negative
charged electrons
Nucleus
Repel
Nucleus
Activation
Energy
Nucleus
Repel
Activation
Energy
Nucleus
Chemical Reactions
Exergonic Reaction:
–
Reactants have more energy than products
Activation energy:
Make sugar and O2
molecules collide
sugar + O2
water + CO2
“Downhill” reaction
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
Cannot change endergonic into exergonic rxns
Do speed up rxns that would occur anyway
Enzymes
• Enzymes – control rate of chemical reaction
• sucrase – enzyme sucrose breakdown
• sucrase – catalyst
“-ase” enzyme
-speed up rxn, but not consumed
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
• Enzymes lowers EA by:
-template orientation
• substrate(s) enter
-stress bonds
-microenvironment
• enzyme reused
• product(s) formed
• What factors might affect enzyme activity?
Enzymes
• inhibitors:
binds & blocks
active site
• Drug – blocks HIV enzyme
at the 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.
B.
C.
D.
Yes
No
I’m not sure
Wait, what’s a competitive inhibitor?
Cellular Respiration
Overall purpose:
• convert food to energy
• animals AND plants
• complementary to
photosynthesis
Cellular Respiration
Cellular Respiration:
(Exergonic)
• 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
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
Self-Check
Reaction
ZH2 + O2 yields ZO + H2O
CH4 + 2O2 yields CO2 + 2H2O
C6H12O6 + O2 yields CO2 + H2O
Molecule
Reduced
Oxygen
Molecule
Oxidized
ZH2
Redox Reactions
Equation for respiration
Redox Reactions
• transfer of e- to oxygen is stepwise
Redox Reactions
• 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?
• glucose
NADH
ETC
O2 (makes H2O)
In this equation is NAD+ to NADH
oxidized or reduced?
NAD+ + H+ + 2e-  NADH
A.
B.
C.
D.
Reduced, it gained electrons
Oxidized, it gained electrons
Reduced, it lost electrons
Oxidized, it lost electrons
Steps of Respiration
• Steps of respiration:
1. glycolysis
2 CO2
Coenzyme Junction
2. Citric acid cycle
3. ETC
4. Chemiosmosis
4 CO2
Cellular Respiration
• Stages of respiration:
1. Glycolysis – prep carbons
Cellular Respiration
1. Glycolysis
• 1 glucose (6C)
2 pyruvate (3C)
• Keep track of: - inputs
- ATP
- NAD+/NADH
- CO2 and H2O
- outputs
• eukaryotes AND prokaryotes
Glycolysis
Glucose
Glucose-6-phosphate
ATP
1
2
ADP
Glucose-6-phosphate
Fructose-6-phosphate
Glycolysis
ATP
ADP
Fructose1, 6-bisphosphate
4
5
Dihydroxyacetone
phosphate
Glyceraldehyde3-phosphate
Glycolysis
2 ADP
2 ATP
2
Phosphoenolpyruvate
2 ADP
10
2 ATP
2
Pyruvate
Step not
shown
How many NET ATP are produced by glycolysis?
A.
B.
C.
D.
E.
one
two
four
six
eight
Glycolysis
Cellular Respiration
-inputs: 1 Glucose
2 ATP
-outputs:
2 pyruvate
4 ATP (2 net)
2 NADH
CO2
= none yet
(2 H2O)
Where do the outputs go?
Energy production
Mitochondria
• energy from nutrients  ATP
Cellular Respiration
Coenzyme Junction • 2 pyruvate (3C)
2 Acetyl CoA (2C)
• 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
Match each Step Name with Energy Balance and Basic Reaction