3770769
Description
Mind Map by Alice Patterson, updated more than 1 year ago
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Created by Alice Patterson
about 9 years ago
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Bioenergetics of
the cell
- Definition of bioenergetics
- Part of biochemistry concerned with the energy
involved in making and breaking of chemical bonds
in the molecules found in biological organisms
- It can also be defined as the study of
energy relationships and energy
transformations in living organisms
- Part of biochemistry concerned with the energy
involved in making and breaking of chemical bonds
in the molecules found in biological organisms
- Gibbs' free energy
- For any process to be
possible, the change in
Gibbs' free energy must
be negative
- A negative Gibbs' free
energy indicates a
'spontaneous' process
- Spontaneity does not imply
that the reaction goes ahead, it
simply considers the possibility,
or feasibility, of a particular
reaction or process
- 'Free' indicates the
energy available in the
form of useful work
- Sometimes
a catalyst
is required
- OILRIG
- Oxidation is losing
[electrons]
- Reduction is gaining
[electrons]
- Oxidation is losing
[electrons]
- Change in Gibbs' free energy
- energy is liberated and
available for use
- Change in Gibbs' free energy
depends on difference in energy
between products and substrates
- Change in Gibbs'
free energy for
ATP hydrolysis
- ATP + H20 >> ADP + Pi
- Gibbs' change in free energy is -7.3kcal/mole
- Gibbs' change in free energy is -7.3kcal/mole
- Equimolar solution of product and
substrate favours the forward
reaction (hydrolysis of ATP)
- Change in Gibbs' free energy is negative
- Change in Gibbs' free energy is negative
- ATP + H20 >> ADP + Pi
- Change in Gibbs' free energy
outside standard conditions
depends on product and
substrate concentrations
- Reactions positive change in Gibbs' free
energy can occur in the forward direction if
there is enough substrate or if product is
reduced significantly
- Product can be very low if it is
rapidly used in another reaction
- Reactions positive change in Gibbs' free
energy can occur in the forward direction if
there is enough substrate or if product is
reduced significantly
- Change in Gibbs' free energy values of sequential reactions are additive
- For any process to be
possible, the change in
Gibbs' free energy must
be negative
- Structure of ATP
- Adenine
- Ribose
- Phosphate
- Has 2 phosphoanhydride bonds
- When the 1st is
hydrolysed it
produces ADP
- When the 2nd is hydrolysed it produces AMP
- When the 1st is
hydrolysed it
produces ADP
- Adenine
- Phosphoanhydride bonds are relatively weak
- Overall, more energy is released in
forming the products than used to
break bonds in the reactants
- Overall, more energy is released in
forming the products than used to
break bonds in the reactants
- Uses of ATP
- Mechanical work
- Muscle contraction
- Direct hydrolysis of ATP is the
source of energy in the
conformational changes in myosin
that produce muscle contraction
- The binding of ATP
dissociates myosin
from actin
- ATP is hydrolysed, inducing a
conformational change that
displaces the myosin head group
- The myosin head binds to
the new position on the
actin filament with the
release of ADP and Pi
- The return of myosin head
to its original conformation
drives actin filament sliding
- Direct hydrolysis of ATP is the
source of energy in the
conformational changes in myosin
that produce muscle contraction
- Quick synthesis of ATP
- Phosphocreatine serves as a
ready source of phosphoryl
groups for the quick synthesis
of ATP from ADP
- The phosphocreatine
concentration in
skeletal muscle
- Creatine kinase
catalysis this
reversible reaction
- Phosphocreatine serves as a
ready source of phosphoryl
groups for the quick synthesis
of ATP from ADP
- Muscle contraction
- Keeping us alive
- Transport e.g. sodium / potassium transporter
- Membrane active transport
- Accounts for 10-30%
of BMR in humans
- The pump binds ATP and binds 3 intracellular NA+ ions
- ATP is hydrolysed
- Conformational change in the pump which
exposes the Na+ ions to the outside
- The phosphorylated form of the pump has a low affinity
for Na+ ions, so they are released to the cell exterior
- The pump binds 2 extracellular K+ ions
- Dephosphorylation of the pump occurs,
and K+ is transported into the cell
- The unphosphorylated form of the pump has a higher affinity
for Na+ ions than K+ ions, so the 2 bound K+ ions are released
- ATP binds, and the process starts again
- ATP binds, and the process starts again
- The unphosphorylated form of the pump has a higher affinity
for Na+ ions than K+ ions, so the 2 bound K+ ions are released
- Dephosphorylation of the pump occurs,
and K+ is transported into the cell
- The pump binds 2 extracellular K+ ions
- The phosphorylated form of the pump has a low affinity
for Na+ ions, so they are released to the cell exterior
- Conformational change in the pump which
exposes the Na+ ions to the outside
- ATP is hydrolysed
- Functions
- Establish an intracellular
ion environment high in K+
and low in Na+
- Control of
cell volume
- Providing electrochemical
sodium gradient for driving
secondary active transport
systems e.g. glucose
- Establish a
resting potential
- Establish an intracellular
ion environment high in K+
and low in Na+
- Membrane active transport
- Anabolic or synthetic reactions
- Glycogen synthesis
- Fatty acid synthesis
- DNA synthesis
- Protein synthesis
- Cell division
- Glycogen synthesis
- Transport e.g. sodium / potassium transporter
- Mechanical work
- ATP regeneration
- There is a set amount of ATP
in the body at any one time
- ~100mg worth
- ~100mg worth
- If we were unable to
regenerate ATP, in the heart it
would last for 10 heart beats
- ATP generation
- Glycolysis
- Fatty acid oxidation
- Ketone acid oxidation
- Citric acid cycle (TCA cycle)
- Pentose phosphate pathway
- Individual pathways for
individual pathways
- Glycolysis
- Substrate level
phosphorylation
- Anaerobic
glycolysis
- Requires a source of energy
- A controlled series of chemical reactions
- Intermediates NADH and FAD2H produced
- Glycolysis
- Krebs cycle
- Glycolysis
- Creates some
ATP directly or
via electrons
- There is a set amount of ATP
in the body at any one time
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