Download Bio 110 S.I. chapters 6 & 7

9/21/14
 ALL the chemical reactions occurring in the organism
including burning food molecules
 Linking molecules TOGETHER
 This STORES energy between the bonds
 BREAKING molecules apart
 This RELEASES energy
2 things that will determine what happens to a
chemical reaction
 Will the reaction proceed backwards (producing
more reactants) or forward (producing products)?
 IT DEPENDS ON:
 The amount of energy available
 This “energy” usually refers to ATP
 Catalysts (enzymes) can make the reaction proceed
faster
Ability to promote change
 Capacity to do work
 changing one molecule into another molecule
Energy
kinetic
potential
chemical
 associated with physical movement
 stored in an object due to its position
 in a:
 force field
 system due to its configuration
 molecular bond
1. First law
 Law of conservation of energy: Energy cannot
be created or destroyed
2. Second law
 Changing energy from one form to another
increases entropy (chaos)
 Biological processes are not 100% efficient --some energy is converted in heat rather than
work!
H=
Total energy
(enthalpy)
G +
Free energy
TS
Temperature (K) Unusable energy
(entropy)
 G is negative it is spontaneous
 This is called an exergonic reaction
 G is positive it is not spontaneous
 This is called an endergonic reaction
C(s,diamond) ----> C(s,graphite) delta G= - 693 calories
C(s,graphite) ----> C(s,diamond) DG= + 693 calories
A)
C(s,diamond) ----> C(s,graphite) delta G= - 693 calories
B)
C(s,graphite) ----> C(s,diamond) DG= + 693 calories
 The Gibb’s Free Energy change in the hydrolysis of
ATP is -7.3 kilocalories/mole
 It is exergonic
 Spontaneous
 Favors formation of products
 The initial amount of energy needed to get the reaction
started
Activation energy
 A spontaneous reaction is not necessarily a fast reaction
 Enzymes are catalysts
 Catalyst: a name given to something that makes the reaction go
faster
 Catalysts lower activation energy (Ea)
 Not all catalysts are enzymes- some are ribozymes
 Usually enzymes are protein
 Straining bonds in reactants to make it
easier to achieve transition state
 Positioning reactants together to
facilitate bonding
 Changing local environment
 Direct participation through very temporary bonding
1. Gene regulation
2. Cellular regulation
3. Biochemical regulation
1. Gene regulation
 Turn on or off genes = turning on and off metabolic
pathways
1. Cellular regulation
 Cell-signaling pathways, like hormones
 The hormones cause proteins and other molecules
in the cell to become active. The result may change
the cell permanently or temporarily
3. Biochemical regulation
 Competitive inhibitors- compete for access to an
enzyme’s active site
 Noncompetitive inhibitors- bind outside the active
site


When non-competitive inhibitors bind to an allosteric site
(somewhere outside active site) it changes the shape of the
active site
To prevent too much product from being made, non
competitive inhibitors stop production before it makes too
much
 Oxidation: Removal of electrons
 Reduction: Addition of electrons
 Redox: An electron removed from one molecule is added
to another
Ae
+B→A+
Be
Oxidation
Is
Losing
Reduction
Is
Gaining
 A is being oxidized
 It has lost its electron
 B is being reduced
 It has gained an electron
 NOW TO CONFUSE YOU:
 A is called the REDUCING AGENT
 B is called the OXIDIZING AGENT
Will need to know every detail of
 Glycolysis
 pyruvate reduction
 citric acid cycle
 electron transport chain
 fermentation
For the test
 How cells obtain energy from organic molecules (such as
sugar)
 Primary goal is to make ATP and NADH
 These molecules have high potential energy
Organic molecules + O2 → CO2 + H2O + Energy
1.
Glycolysis
2.
Breakdown of pyruvate to an acetyl group
3.
Citric acid cycle
4.
Oxidative phosphorylation

Can occur with or without oxygen

Happens in the cytoplasm

Steps are nearly identical in all living species

Happens in both eukaryotes and prokaryotes
Energy investment
1.


Steps 1-3
2 ATP hydrolyzed to create fructose-1,6 bisphosphate
Cleavage
2.


Steps 4-5
6 carbon molecule broken into two 3 carbon molecules of
glyceraldehyde-3-phosphate
Energy liberation
3.


Steps 6-10
Two glyceraldehyde-3-phosphate molecules broken down into two
pyruvate molecules producing 2 NADH and 4 ATP
Net yield: 2 ATP
Phosphorylated:
to add a
Phosphate group
to a molecule
PHASE 1: ENERGY INVESTMENT, Steps 1 - 3
GLUCOSE
1. Glucose is phosphorylated by ATP.
This changes glucose to Glucose 6
Phosphate.
2 ATP
2 ADP
2. Glucose 6 Phosphate
is rearranged to Fructose
6 phosphate.
3. Fructose 6 Phosphate is
FRUCTOSE 1-6
BIPHOSPHATE
phosphorylated to make
Fructose 1 6 biphosphate
PHASE 2: CLEAVAGE, Steps 4 & 5
FRUCTOSE 1 6
BIPHOSPHATE
4. Fructose 1 6 biphosphate is
cleaved into 2 molecules:
G3P and dihydroxyacetone
phosphate
Glyceraldehyde 3 Phosphate
Dihydroxyacetone phosphate
5. Dihydroxyacetone
phosphate is
isomerized to G3P
Glyceraldehyde 3 Phosphate
PHASE 3: ENERGY LIBERATION, Steps 6 - 10
Glyceraldehyde 3 Phosphate
6. G3P is oxidized to
make
NADH and 1 3
biphosphoglycerate
7. The phosphate is
removed from 1 3
biphosphoglycerate
to make ATP
Pyruvate
Glyceraldehyde 3 Phosphate
NAD+
NAD+
NADH
ADP
ATP
NADH
ADP
ATP
H20
ADP
ATP
8. 3 biphosphoglyerate
is rearranged
9. A water is removed
H20
ADP
ATP
10. A phosphate is removed
to make ATP and pyruvate
Pyruvate
GLUCOSE
2 ATP
2 ADP
FRUCTOSE 1-6
BIPHOSPHATE
Dihydroxyacetone phosphate
G3P
NAD+
NADH
ADP
ATP
G3P
NAD+
NADH
ADP
ATP
H20
ADP
ATP
Pyruvate
H20
ADP
ATP
Pyruvate
In eukaryotes:
 pyruvate in transported to the mitochondrial
matrix
 Broken down by pyruvate dehydrogenase
 Molecule of CO2 removed from each pyruvate
 Remaining acetyl group attached to CoA to make
acetyl CoA
 1 NADH is made for each pyruvate
CO2
NAD+ NADH
Pyruvate
Coenzyme A
Acetyl
CoA