Microbial Metabolism
Energy
Metabolism
the chemical processes occurring within a
living cell or organism that allow it to get
and use energy.
anabolic (building up or synthetic)
catabolic (tearing down or degradative)
Anaerobic metabolism - occurs without
oxygen.
Aerobic metabolism - requires free oxygen
(which functions as the final electron
acceptor during the generation of ATP).
Metabolic pathways
1. Substrates enter the reaction
2. End products remain after the reaction
3. In some cases intermediates are formed
Energy - the ability to do work
Types include:
1. Kinetic - energy that is associated with
motion
2. Potential - energy that is stored as is
available for use. Chemical potential
energy is stored in the bond between
atoms of a molecule or compound.
3. Thermal- heat energy
LAWS OF
THERMODYNAMICS
The First Law of Thermodynamics states
that energy can neither by created or
destroyed but it can change from one form
to another
The Second Law of Thermodynamics states
that during transformations, some or all of
the energy is spontaneously converted
from more ordered forms to less ordered
forms (thus entropy or disorder increases).
Energy Transfer
Entropy
The ultimate source of energy for life on
Earth is the Sun.
Energy transfer is not complete (most is lost
as heat remember entropy increases) from
one tropic (feeding) level to another.
Thus energy is a limiting resource
Energy flow
ATP (adenosine triphosphate)
the universal energy currency of all cells
energy is stored within the bonds of this
energy intermediate (ADP + Pi ATP)
The formation of ATP occurs by a process
known as phosphorylation (oxidative or
substrate-level)
Enzymes Part I
Organic catalysts [a substance which speeds up a
reaction that would normally occur and that is
not used up in the reaction)].
Nearly all enzymes are proteins
Work by lowering the activation energy required for
a reaction to proceed
Promotes a reaction by serving as a physical site
upon which one or more substrates can be
positioned for various activities
Enzymes Part II
Each enzyme is associated with a specific substrate and
thus we have a “lock and key” mechanism.
Can lose their catalytic abilities if they are denatured (the
shape changes and they no longer “fit” the substrate).
So they are limited by factors e.g., temperature and pH
Some are exoenzymes that catalyze reactions outside of
the cell and other enzymes are endoenzymes that
catalyze reactions inside of the cell.
Some enzymes are constitutive which are always present,
and others are induced which are not always present.
Respiration
and
Fermentation
Aerobic Respiration
•
•
•
•
Occurs in the presence of Oxygen
Oxygen acts as the final electron acceptor
The cpe in glucose is transferred into cpe in ATP
The glucose is dismantled during the steps of
aerobic respiration: glycolysis, prep for the
Kreb’s cycle, Kreb’s cycle, and ETS
• Carbon and oxygen are lost as CO2
• The hydrogens are used in the ETS for ATP
formation
Glycolysis
Prep for the Kreb’s cycle
Kreb’s cycle
Electron Transport System
• http://video.google.com/videosearch?hl=en&q=
oxidation%20reduction%20reaction&gbv=2&ie
=UTF8&sa=N&tab=iv#q=glycolysis&hl=en&emb=0
• http://video.google.com/videosearch?q=cellula
r+respiration+animation&www_google_domain
=www.google.com&hl=en&emb=0&aq=2&oq=c
ellular+respiration#
• http://video.google.com/videosearch?q=cellula
r+respiration+animation&www_google_domain
=www.google.com&hl=en&emb=0&aq=2&oq=c
ellular+respiration#
Fermentation
• http://video.google.com/videosearch?q=fer
mentation&hl=en&emb=0&aq=f#q=fermen
tation+animation&hl=en&emb=0&start=20
Photosynthesis
The ultimate source of biological energy - the Sun
Plants, some protists, and some prokaryotes
capture sunlight energy with photosynthetic
pigments
1. Chlorophyll which is found in chloroplasts is the
most common pigment. It appears green
because it absorbs light of colors other than
green and allows green light to be reflected and
thus detected by other organisms.
2. There are also accessory photosynthetic
pigments that make plants appear yellow and
orange.
The primary photosynthetic organs of plants are
leaves ( know thylakoids, stroma, granuum, and
inner and outer membranes)
Chloroplast
Thylakoid
• Photosynthesis:
12H2O +6CO2 sunlight energy> 6O2 +C6H12O6 + 6H2O
Light dependent reactions
Light absorption. Photochemical reactions involve
the trapping of light. Light energy excites
pigment molecules and causes an electron to be
freed which begins moving through an ETS.
There are two photosystems [Photosystem I
(with chlorophyll a absorbing lightwaves of 700
most efficiently; P700) and Photosystem II (also
with chlorophyll a but absorbing lightwaves of
680 most efficiently; P680)] that are involved in
capturing the energy and the beginning of
electron transfer.
Electron transfer. The electron that is excited in
Photosystem I is sent along the ETS to NADP+
and as another electron is passed to NADP+,
the latter is reduced to NADPH (a coenzyme and
energy intermediate) which carries electrons.
Now light energy absorbed by Photosystem II is
transferred into an electron thus exciting it and
causing it to be sent to P700 (of Photosystem I)
which can now absorb more light energy
because of the replaced electron (note that
Photosystem II has electrons replaced from split
water molecules which also results in the
formation of O2).
Light Independent Reactions
• Chemiosmotic synthesis of ATP. This is the final phase
of energy capture and involves the movement of the
hydrogen ions along a series of membrane proteins with
the release of energy and finally the synthesis of ATP
from ADP.
• Carbon fixation
• 1. Carbon fixation occurs when a gas (CO2) is
incorporated into a solid (e.g., a carbohydrate)
• 2. During energy capture the energy and the hydrogen
needed for carbon fixation are required.
• 3. Carbon fixation involving atmospheric CO2 occurs
during the reactions of the Calvin-Benson Cycle
• http://video.google.com/videosearch?hl=e
n&q=photosynthesis%20light%20absorpti
on&ie=UTF8&sa=N&tab=iv#q=photosynthesis+animat
ion&hl=en&emb=0
• http://video.google.com/videosearch?hl=e
n&q=photosynthesis%20light%20absorpti
on&ie=UTF8&sa=N&tab=iv#q=Calvin+Benson+cycle+
animation&hl=en&emb=0
Metabolism - the chemical processes
occurring within a living cell or organism.
These include anabolic (building or
synthetic) and catabolic (tearing apart or
degradative) reactions
Energy - the ability to do work
Kinetic - energy that is associated with
motion
Potential is energy that is stored and ready
for use. Chemical potential energy is
stored in the bonds between the atoms of
a molecule or compound
Laws of Energy
1. The First Law of Thermodynamics states that
energy can neither be created nor destroyed,
but it can change from one form to another.
2. The Second Law of Thermodynamics states
that during energy transformations, some or all
of the energy is spontaneously converted from
more ordered forms to less ordered forms
(entropy or disorder increases).
The universal energy currency is ATP
(adenosine triphosphate). Energy is
stored within the bonds of the energy
intermediate (know the equation
associated with ATP).
Enzymes
An enzyme is an organic catalyst [a substance which speeds up a
reaction that would normally occur and that is not used up in the
reaction)].
Nearly all enzymes are proteins
Enzymes work by lowering the activation energy required for a
chemical reaction to proceed (fig. 6.5)
An enzyme promotes a reaction by serving as a physical site upon
which one or more substrates can be positioned for various activities
Each enzyme is associated with a specific substrate and thus we have
a “lock and key” mechanism.
Enzymes can lose their catalytic abilities if they are denatured (the
shape changes and they no longer “fit” the substrate). Thus
enzymes are limited by factors such as temperature and pH
Some enzymes are exoenzymes that catalyze reactions outside of the
cell and other enzymes are endoenzymes that catalyze reactions
inside of the cell.
Some enzymes are constitutive which are always present, and others
are induced which are not always present.
Glycolysis
Photosynthesis