Download UNIT 5 ENERGY AND LIVING CELLS

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CHAPTER ENERGY AND LIVING CELLS
“Life Requires Free Energy” ( Bozeman biology)
G= Free energy is the available(useable) energy to do
work in the system
Q.
So during an exothermic reaction does the G go
up or down?
Q.
As you move up a food chain does G go up or
down?
Gibbs Free Energy Equation
ΔG= ΔH – TΔS
ΔH= change in enthalpy(total energy)
ΔS = change in entropy (randomness)
C6H12O6 + 6O2 ----- 6CO2 + 6H20
Will a reaction be spontaneous or not?
-ΔH
+ ΔH
Spontaneous at
ΔG= ΔH – TΔS
+ ΔS Spontaneous
always
high temps only
at
Never
- ΔS Spontaneous
Low temps only
spontaneous
+ΔH gained enthalpy as reaction proceeded
-ΔS means we have decreased entropy
-ΔH means we have lost enthalpy(heat) (exergonic)
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Everything in the universe moves to a state of more
randomness or increasing disorder
This is called ENTROPY (S)
For equations when there are more particles in the products
than reactants, the amount of entropy of the system has
increases
C6H12O6 + 6O2 ----- 6CO2 + 6H20 + energy
What is this reaction?
( 2nd Law of Thermodynamics) : Everything moves to a state
of more disorder. In every energy exchange some
useable(Free) energy is lost as heat.
-Living organisms seem to run counter to this law. However
they are always using energy to maintain a balance. Their life
spans are finite and when they die become much more
disordered
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KEY CONCEPTS :
1. Energy enters the earth when green plants use solar
energy to photosynthesize to build food from CO2 + H20
Sun + CO2 + H20 -- Glucose + O2
2. Energy is released to be used during respiration as
glucose is broken down to carbon dioxide and water.
3. Organisms use energy to combat the universal tendency
toward entropy ( disorder)
ENERGY TRANSFORMATIONS:
What is energy?
The capacity to do work.
The capacity to cause change or motion.
Energy can be transformed , that is it can be changed from
one form to another.
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LAWS OF THERMODYNAMICS
1ST Law of Thermodynamics:
Energy can be neither created or destroyed but transformed
from one type to another.
( You can’t win)
2nd Law of Thermodynamics: ( Entropy)
In every energy transaction some energy is lost in the form of
heat ( You can’t even break even)
( Entropy: The degree of disorder)
( ex. Diffusion)
KINETIC ENERGY: Energy due to motion
POTENTIAL ENERGY: Stored energy due to position.
( chemical bonds)
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CHEMICAL REACTIONS AND ENERGY
- Free energy: useable energy
- Exergonic rxns - Release of energy
Decrease in free energy
- Endergonic rxns – Absorption of energy
Increase in free energy
Activation Energy:
The amount of energy needed to get a rxn to
run to completion.
Free
Energy
This is
endergonic rxn
products
Reactants
exergonic rxn
products
Time
EQUILIBRIUM :
The point at which no net rxn is occurring
Forward and backward rxns are equal
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2glucose
---- 1 sucrose
PHOTOSYNTHESIS AND RESPIRATION
Where does energy for cells come from?
Energy to run most cellular processes comes from
organic food molecules that contain chemical potential
energy in the bonds.
Breaking the bonds releases the energy.
Organic molecules made from Photosynthesis
Solar energy --- Chemical potential energy
(CH2O)n = carbs
Raw materials are low energy molecules
CO2 + water converted to high energy molecules
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All Photosynthetic or chemosynthetic organisms are
called (AUTOTROPHS)
(AUTO- SELF) ( TROPH- FOOD)
Ex. Plants, Algae, some protists ( euglena)
Archaea (chemosyn.)
HETEROTROPHS: ( Hetero- other)
- All organisms that must obtain (organic) food from
other organisms .
- Ex. Animals, some protists
CELLULAR RESPIRATION:
Process of breaking down food molecules to
energy for use by the cell.
(CH2O)n + O2 ------- CO2 + H2O + energy( ATP)
PHOTOSYNTHESIS :
CO2 + H2O + E ----- (CH2O)n + O2
PHOTOSYNTHESIS
CELL RESPIRATION
release
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OXIDATION – REDUCTION RXNS:
Reactions that require the transfer of one or more efrom one ion to another.
Oxidized: The molecule that loses eReduced: The molecule that gains eLeo goes Ger
LoseElectronOxidized GainElectronReduced
Simplest case. The oxidation of iron
+2 -2
Fe + O2 -------- FeO
As a general rule : ( O2 is an oxidizer)
Oxygen is reduced and thus gains or accepts e- from
another substance
( Oxygen is an oxidizing agent)
In respiration, Oxygen oxidizes sugars and thus sugar
reduce oxygen.
(CH2O)n + O2 ------- CO2 + H2O + energy( ATP)
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Respiration is the oxidation of small organic molecules
Photosynthesis is the reduction of carbondioxide
ENERGY INTERMEDIATES:
Cells need many endergonic rxns which go “uphill” in
terms of energy .
How are these rxns powered?
1. Enzymes lower activation energy
2. The rxns are coupled w/ exergonic rxns
The exergonic rxns. Must release more useful energy than the
endergonic ones require(2nd law OTD)
However releasing too much excess energy is.
1. Wasteful
2. Damaging to the cells enzymes 3 dim. Struct.
( denaturation)
A large burst of heat destroys enzymes .
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Therefore :Rxns that release a lot of heat , suc as oxid. –
reduct. Do so in small steps.
The conversion of lactate to pyruvate is catalyzed by lactate dehydrogenase.
In this reaction lactate loses two electrons (becomes oxidized) and is
converted to pyruvate. NAD+ gains two electrons (is reduced) and is
converted to NADH.
ENERGY INTERMEDIATES
At various steps energy releases are stored as “Energy Intermediates” .
These intermediates transfer middle sized amounts of energy.
ATP and GTP
ATP---- ADP ----AMP
GTP ---- GDP ---- GMP
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GTP is an energy intermediate for the production of ribosomes
ATP is an energy intermediate for Sodium-Potassium pumps
Making of proteins, Photosynthesis
Energy is released when phosphate bonds are broken
2 high energy bonds
ATPases : break down and build up atp
7kcals/ n of energy for each bond in ATP
Guanosine triphosphate
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Adenosine triphosphate
See picture pg 106 old b.
ENERGY INTERMEDIATES:
ATP and GTP
ATP is made up of
1. Nitrogenous base( adenine)
2. Ribose
3. 3 phosphate groups
When Phosphate of ATP split off…..
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ATPase
ATP + H2O -- ADP + Pi + 7Kcal/n
Note: ADP = Adenosine diphosphate
ATPase
ADP + H2O -- AMP + Pi + 7Kcal/n
Note: AMP = adenosine monophosphate
ELECTRON TRANSPORT SYSTEM:
Function: is to separate hydrogen atoms into electrons and
protons and carry the e- away.
( final electron acceptor is oxygen O2)
- All H+ is left on the inside of the membrane therefore
setting up a H+ gradient.
ATPases: Enzymes that act on ATP to make or break the
phosphate bonds.
How ATP is Made:
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1. Using large amounts of energy released by organic
molecules ( ex. Glucose) when they transfer a phosphate
group to ADP .
2. Most ATP is made using a membrane potential
Pg 107 fig 6-10 old pg 118 new
The energy to put the ATP together comes from hydrogen
ions (H+) moving across membranes .
1. Hydrogen molecule inside the cell is stripped of e- by
membrane
2. H+ is expelled to inside by electreon transport system
3. Channel proteins permit H+ to move down the conc.
gradient
4. ATP synthetase attaches phosphate to ADP or AMP
using the Kinetic energy of the moving hydrogen ion.
5. This process is called chemiosmosis or chemiosmotic
ATP synthesis. Phosphorylation
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WHERE DOES CHEMIOSMOSIS OCCUR IN THE CELL?
1. Bacterial cells: plasma membrane
2. Eukaryotes:
a. Mitochondria: inner membrane
b. Chloroplasts : inner membrane
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Oxygen must be replenished, otherwise electron transport cannot proceed.
Each carrier, once reduced, would have to stay that way because there would
be no place for the electrons to go. The need to deliver oxygen to the
electron transport system is why we have respiratory and circulatory
systems. Oxygen is necessary to "drain" electrons from the system,
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otherwise all of the carriers would remain reduced and electron transport
would have to stop.
Embedded in the inner membrane among the structures of the electron transport system are structures called the
ATP synthase complex. The complex consists of a proton channel and catalytic sites for the synthesis of ATP from
ADP and phosphate. When ADP and phosphate are available, they bind the catalytic sites on the ATP synthase.
When this happens, the channel opens, and protons can come whooshing back in. The energy released is used to
couple the phosphate to ADP, to make ATP.
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An Ion gradient has potential energy and can be used to power chemical
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INTERPRETING CLADOGRAMS :
Taxon 1
Taxon 2
Taxon 3
Taxon 4
C
B
A
Terminology :
Clade: includes the common ancestral population (node) plus all
its descendents Node A ( clade would include taxon 1-4)
Node: corresponds to a hypothetical ancestor. It is found at the
beginning of a group or taxon.
Terminal node: the end of the taxonomic group
Monophyletic group: One branch would make up a monophyletic
group
Polyphyletic group: more than one branch would be
Shared ancestor: The common ancestor is found at the
first node and is called the root
Outgroup: group that doesn’t include any of the traits of
the other groups
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When drawing cladograms you never leave an empty terminal node. It
should always end with a taxon . ( otherwise it will be marked as incorrect)
1. Taxon 1 is more closely related to Taxon 2 than to taxon 4.
2. Common ancestor b would include which taxon?
3. The universal ancestor for taxon 1,2,3,4 would be?