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 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!]
Metabolism and Energy
Metabolism
Metabolism –chemical conversions in an organism
Types of Energy:
- Kinetic Energy = energy of movement - thermal
- Potential = stored energy - chemical
Thermodynamics
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
Metabolic reactions: All chemical reactions in organism
Two Types of Metabolic Reactions:
Catabolic = breaks
down molecules
Anabolic = builds
up molecules
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
Chemical Reactions
Chemical Reactions:
• 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
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
- cytosol
Coenzyme Junction
2 CO2
2. Citric acid cycle
- mitochondrial
matrix
3. ETC
- inner
mitochondrial
membrane
4. Chemiosmosis
- inner membrane to intermembrane space
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
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