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Animal Body
Arthropods
Biochem
Cell Cycle
Cell Interactions
Cell Structure
Circulation
Respiration
Communities
Digestion
DNA
Ecosystems
Energy
Evolution Evidence
Future of
Biosphere
Genetic Engineering
Gene Function
Genetics
Hormones
Human Evolution
Immunity
Species
Interaction
Kidneys
Locomotion
Membranes
Mollusks
Mutation
Nervous
Non-Coelmic
Photosynthesis
Plant Physiology
Population Genetics
Population
Dynamics
Cellular Respiration
Sensory
Speciation
Taxonomy
Vertebrates
Vertebrate
Org
Vocabulary:
1,2,3,4,5,6,7,8,9,10,
11,12,13,14,15,
16,17,18,19,20,
21,22,23,24,25,
26,27,28,29,30,
31,32,33,34,35,
36,37,38,39,40,
41,42,43,44,45,
46,47,48,49,50,
51,52,53,54
Energy & Metabolism
I. Introduction A. Bioenergetics – behavior of
energy in living systems
B. Metabolism – sum of all chemical reactions in
a living organism
1. Anabolism – use of energy
to make/change chemical bonds
2. Catabolism – release of energy
when bonds are broken
II. Energy A. Definition – capacity to do work
B. Types
1. Kinetic – energy of motion
2. Potential – stored energy,
capacity to move
C. Can exist in many forms – heat, light, electricity,
sound, nuclear
D. Living organisms can/must transform P. E.
to K.E.
III. Thermodynamics A. Definition – The study of
energy
B. Energy is measured by first converting it to heat
C. Calorie – unit of measure
1. Amount of heat needed to raise
one gram of water one degree Celsius
2. 1,000 calories = 1kcal (food calories)
IV. Laws of Thermodynamics A. First Law of Thermodynamics
1. Energy cannot be created nor destroyed,
only transferred
2. Thus, the total amount of energy
in the universe remains constant
3. Animals transfer P. E.
from food into K.E.
4. Energy is stored in chemical bonds,
thus the more bonds the greater the energy released (i.e. Fat)
5. Energy loss cannot occur. It can
be changed to forms such as K.E., light, electricity
6. Some is transferred into the unusable
form of heat. When heat occurs, the heat is dissipated, but constantly
replaced by energy from the sun.
B. Second Law of Thermodynamics
1. Disorder (entropy) is increasing
(decay, decomposition)
2. Heat Energy – random motion
of molecules
a. Measured in degrees Celsius
b. Temp is a measure of AVG K.E.
3. Entropy = S.
V. Energy Transfer A. Mobile electrons can jump to higher
energy levels. When excited electron returns to natural level, energy
is released
B. Oxidation/Reduction Rxns:
1. Atom/Molecule gains or loses electrons
2. Oxidation – loss of electrons
a. O2 – most common acceptor
b. High electro negativity, more likely to accept electrons
3. Oxidation creates a positive charge
4. Reduction – gain of electrons,
becomes more negative
5. COENZYMES – electron carriers;
less EN than oxygen
a. NAD+ ~> NADH + H+
6. Photoelectric Effect – light
can cause electrons to become excited
7. Transfer of electrons often coupled
with transfer of protons in the form of H atoms
8. Thus, oxidation is removal of a
hydrogen atom and reduction is the gain of a hydrogen atom
9. Photosynthesis
a. Sun adds energy to a system and causes a transfer of H from H2O
to CO2
b. CO2 is reduced and forms glucose
c. 1 mole of glucose stores 686 kcal of energy
6 CO2 + Light Energy ~> C6H12O6 + 6 O2 + 6 H2O
10. Cell Respiration
a. H transferred from glucose to O2
b. Glucose is oxidized
c. **** Releases 686 kcal of energy *****
VI. Free Energy A. Bonds – hold molecules together
1. Free Energy – energy available
to make/break chemical bonds
2. Enthalpy – energy in all bonds
available to do work (H)
3. Temperature x entropy – thermal
energy (heat/unavailabl e)
at a given absolute temp (TS)
Absolute – K = (C-273)
B. Free Energy – ordering influences – disordering
influences
G = H-TS
C. Bonds constantly form/break which causes change in
free energy, thus under constant temp, pressure and volume \
DG = DH - DTS
D. Negative DG
1. Reaction is exergonic
2. Products have lower bond energy
than the reactants.
3. Excess energy is released as heat.
4. Occurs SPONTANEOUSLY!!!!!
E. Positive DG
1. Reaction is endergonic.
2. Products have higher bond energy
than reactants.
3. Does not occur spontaneously.
4. Requires energy to start.
VII. Activation Energy A. Energy required to destabilize
chemical bonds and initiate a chemical rxn
B. High A. E. rxns proceed slowly due
to an inability of some molecules to reach activation
C. Catalysis – stress chemical bonds to make them
easier to break, thus lowering the A.E.
1. Catalyst is the substance that
carries out catalysis
2. Cannot change the Laws of Thermodynamics
3. Accelerates rxns in both directions
4. Cannot force an endergonic rxn
to occur spontaneously
VIII. Enzymes A. Biological catalysts that carry out
catalysis in living organisms
B. Proteins with specialized shapes that allow temporary
associations with molecules that are reacting
C. Create a lower A.E.
D. End in – ase
E. Enzymes have specificity for types of rxns
F. Active Site 1.
Site where substrate binds to the enzyme
2. Creates an “induced fit”
(tertiary structure change)
G. Side groups chemically interact w/ substrate and
“steal” electrons
H. Substrate can act as an activator – enzyme complexes
I. Lock and Key Model // Enzyme – Substrate Model
J. Enzyme remains unchanged throughout the reaction
and are free to continue catalysis after each job
K. Factors affecting enzyme activity
1. Temperature
a. Most enzymes work at a optimum temp between 35-40°C
b. Denatures at high temperatures and protein shape is change along with
disruption of H bonds and hydrophobic interactions
2. pH
a. Optimum pH for every enzyme
b. Most work at pH of 6-8
c. Some maintain 3-D shape even in the presence of excess H+
d. More H+ ions create fewer negative and more positive changes, thus
disrupting bonds between oppositely charged A.A.’s
L. Inhibitors – bind to enzymes, change shape and
decrease activity
1. Feedback inhibition – endpoint
disrupts early stages of chemical pathways
2. Competitive inhibitors – compete
for the same active site as substrate, thus decreasing activity. Ex. O2
& CO2
3. Non-competitive inhibitors –
bind to enzyme on site other than active site (allosteric site, thus changing
enzyme shape and not allowing substrate to bin d)
(allosteric inhibitio n)
(switches enzyme between active and inactive configuration)
M. Activators – bind to allosteric site and keep
enzyme active, thus increasing activity
N. Cofactors – Additional chemical components that
help an enzyme to function normally. Metal groups that draw electrons
away from substrates (Heme groups / Fe2+, Fe3+
O. Coenzymes – Non-protein organic molecules that
aid in enzyme functioning. Includes vitamins and NAD+. Serve in redox
as electron carriers. Often paired with protons as hydrogen atoms
1. Nicotinamide adenine dinucleotide
(NAD+)
a. Very important hydrogen acceptor in the process of oxidation of energy
containing molecules and subsequent transfer of that energy to ATP
IX. Adenosine Triphosphate
A. Major energy unit of all living organisms. Developed
early on in the history of life.
B. Structure:
Adenine – Two C-N rings; nitrogen has unshared electrons and weakly
attracts H+ ions. Thus, acts as a base (nitrogenou s)
DNA.
C. ATP is hydrolyzed into ADP +Pi releasing 7.3 kcal/mole.
This energy is used to drive endergonic reactions. High energy due to
unstable bonds between phosphates and verylow A. E. (2x).
Body has only small reserves of ATP, but instead makes it constantly from
ADP + Pi. The energy to do this comes from Pi and oxidation of fats/carbos.
X. Biochemical Pathways A. Organized units of metabolism
in which the product of one rxn becomes substrate for another rxn allows
for control of various chemicals and often take place in specific organelles
B. Evolve backwards, one step at a time, rather than
forward. Probably due to loss of certain molecules and the need to synthesize
them to continue life
C. Most pathways controlled by feedback inhibition.
Final product binds to an allosteric site of an enzyme early in the process
and shuts down rest of pathway.