Metabolism and Energy

flinkexistenceMechanics

Oct 27, 2013 (3 years and 9 months ago)

133 views

Metabolism

and

Energy

Chapters 8

Metabolism and Energy


Metabolism


Catabolism


Anabolism


Bioenergetics


Energy


Kinetic


Heat/Thermal


Light Energy


Potential


Chemical


Organisms are energy
transformers!

Metabolism and Energy


Metabolism


Metabolic pathway begins with a
specific molecule, which is then
altered in a series of defined steps
leading to a specific product


Each step is catalyzed by a
specific enzyme

Organisms are energy
transformers!

Metabolism and Energy


Metabolism


Catabolism


Energy
released (helps to drive
anabolic pathways)
.


Ex: cellular respiration


sugar put in to the body is broken
down to do work in the cell
(movement, active transport,
etc
).


Organisms are energy
transformers!

Metabolism and Energy


Metabolism


Catabolism


Anabolism


sometimes called biosynthetic
pathways
-



Ex: synthesis
of a protein from
amino acids.


Energy
required/absorbed.


Organisms are energy
transformers!

Metabolism and Energy


Metabolism


Catabolism


Anabolism


Bioenergetics


the study of how energy flows through
living systems.


Organisms are energy
transformers!

Metabolism and Energy


Metabolism


Catabolism


Anabolism


Bioenergetics


Energy



the capacity to cause change.


Some
forms of energy can be used to do
work
-

or
move matter against opposing
forces


Ex: (
friction and gravity
)


Ability to rearrange a collection of
matter



Organisms are energy
transformers!

Metabolism and Energy


Energy


Kinetic


Relative motion of objects


moving objects can perform
work by imparting motion to
other matter.


Ex: Moving
water through a dam
turns turbines, moving bowling
ball knocks over
pins

Organisms are energy
transformers!

Metabolism and Energy


Energy


Kinetic


Heat/Thermal


comes from the movement of
atoms or molecules associated
with kinetic
energy


Organisms are energy
transformers!

Metabolism and Energy


Energy


Kinetic


Heat/Thermal


Light Energy

Type of energy that can be harnessed
to perform work


Ex. Powering Photosynthesis


Organisms are energy
transformers!

Metabolism and Energy


Kinetic


Heat/Thermal


Light Energy


Potential


Non
-
kinetic energy


because
of location or
structure, height, chemical
bonds, etc.


Organisms are energy
transformers!

Metabolism and Energy


Kinetic


Heat/Thermal


Light Energy


Potential


Chemical


the potential energy available for
release by a reaction.


Ex:
Glucose is high in chemical
energy and the process of
glycolysis breaks it down. As bonds
are broken, energy is released, but
bonds also reform to make new
molecules, thus it uses some
energy.


Organisms are energy
transformers!

Metabolism and Energy

Organisms are energy
transformers!


All original energy comes
from light.
(photosynthesis
-

primary
producer
-

consumer
-

who changes it from
chemical to kinetic and
releases thermal.


Thermodynamics


What is Thermodynamics?

Thermodynamics


The energy transformations that occur in a
collection of matter

Thermodynamics


Thermodynamics


System vs. Surroundings


Isolated System vs. Open System


First Law of Thermodynamics

Thermodynamics


Two Laws of Thermodynamics govern
energy exchange:


First Law of Thermodynamics


Second Law of Thermodynamics

Thermodynamics


Two Laws of Thermodynamics govern
energy exchange:


First Law of Thermodynamics


energy cannot be created or destroy
-



Only transferred or transformed


Known as Principle of conservation of energy

Thermodynamics


Second Law of Thermodynamics


During energy transfer, some energy
become unusable energy (unavailable to
do work)


Entropy
(S
)


Measure of disorder or
randomness

Thermodynamics


So, What is the Second Law of
Thermodynamics?


Every energy transfer or transformation increases
the entropy of the universe


Thermodynamics


Spontaneous (Energetically Favorable) vs.
Nonspontaneous Processes


Leads to the second way we state the 2
nd

Law
of Thermodynamics:


For a process to occur spontaneously, it must
increase the entropy of the universe

Think
-
Pair
-
Share


How does the second law of
thermodynamics help explain the diffusion
of a substance across a membrane?


If you place a teaspoon of sugar in the
bottom of a glass of water, it will dissolve
completely over time. Left longer,
eventually the water will disappear and the
sugar crystals will reappear. Explain these
observations in terms of entropy.


Gibbs Free Energy


Free Energy


Portion of system’s energy that can perform work when
temp and pressure are uniform throughout system


ΔG = free energy of a system


-
ΔG = spontaneous reaction


+ΔG = nonspontaneous reaction


ΔG = 0 = Dead Cell (can do no work)


ΔG = ΔH


TΔS

ΔG =
ΔG
final



ΔG
initial



Enthalpy

Gibbs Free Energy


ΔG = ΔH


TΔS

ΔG =
ΔG
final



ΔG
initial



ΔH = he change in the system’s enthalpy


What is enthalpy?


Total energy


ΔS = change in system’s entropy


T = absolute Temperature in Kelvin


Gibbs Free Energy


ΔG = ΔH


TΔS

ΔG =
ΔG
final



ΔG
initial



Can think of this as difference in final state and initial
state


Gibbs Free Energy


Endergonic vs. Exergonic Reactions


+
ΔG






-
ΔG








Non
-
Spontaneous Spontaneous


Gibbs Free Energy



Reactions in isolates system eventually reach
equilibrium and then cannot do work


Metabolism reactions are reversible and eventually
will reach equilibrium


Living cell is not in equilibrium


Some reactions are constantly pulled in one direction
and this keeps them from reaching equilibrium

Warm Up Exercise


Glow in the dark necklaces are snapped in
a way that allows two chemicals to mix and
they glow. Is this an endergonic or
exergonic reaction? Explain.


In simple diffusion, H+ ions move to an equal
concentration on both sides of a cell
membrane. In
cotransport
, H+ ions are
pumped across a membrane to create a
concentration gradient. Which situation
allows the H+ ions to perform work in the
system?

ATP and Cellular Work


Three Types of Work


Chemical


Transport


Mechanical


Energy Coupling


Phosphorylated
Intermediate

Why is ATP such a good
energy molecule?


What is ATP?


Contains ribose sugar, nitrogenous base
adenine, and chain of 3 phosphate groups
bonded to it.


Bonds can be broken by hydrolysis

Why is ATP such a good
energy molecule?


When bond is broken , a molecule of
inorganic phosphate leaves the ATP


It become adenosine
diphosphate

(ADP)


Is Hydrolysis of ATP
endergonic and
exergonic? Anabolic or
catabolic?

Does it release
-
7.3 kcal
/
mol

in the cell?

ATP Hydrolysis


kh

ATP and Cellular Work

ATP Cycle


The body regenerates 10 million molecules
of ATP per second per cell!

Enzymes


Enzymes
-

biological catalyst


Substrates



reactants that bind to the
enzyme, usually in the active site


Enzymes


Activation Energy (E
A
)


the energy required to get a
reaction started.


Many times this energy is absorbed
as thermal energy from the
environment


Many times room temperature
may
be enough, but most reactants
need more energy than that to get
started. AKA = free energy of
activation



Enzymes


Activation Energy (E
A
)


the energy required to get a reaction
started.

How does heat effect an
enzyme?


Heat speeds a reaction by allowing
reactants to attain the transition state
more
often


T
his
solution is inappropriate for
biological systems because it would
denature proteins and kill cells.


Additionally
, it would speed up all
reactions, not just those that are
needed.

Enzymes


Enzymes catalyze reactions by lowering the
activation energy.

Enzymes


Enzyme + Substrate = Enzyme
-
Substrate
Complex










Enzyme Enzyme
-




Enzyme


+



Substrate



+

Substrate(s)


Complex


Product(s)


Enzymes


Active Site



pocket or groove
on the surface of
the enzyme where
the substrate binds
and catalysis
occurs
.

Enzymes


Induced Fit


When the substrate enters
the active site, it forms
weak bonds with the
enzyme, inducing a
change in the shape of
the protein. This change
allows additional weak
bond (
ie
: hydrogen
bonds) to form, causing
the active site to fit
around the substrate
snugly
-


Effects of Environment


Changes in the environment of
the enzyme can cause
inefficiencies or denaturation of
the enzyme:


Temperature


pH


Concentration of Enzyme


Concentration of Substrate

Enzymes


Cofactors


nonprotein

components that help in
catalytic activity.


Usually bound to enzyme (sometimes
permanently, sometimes loosely)


Coenzyme


If cofactor is organic


Many vitamins are important because they
are coenzymes or make up coenzymes


Enzyme Action


Competitive Inhibitors


Resembles normal substrate molecule


Reduce productivity of enzyme by blocking
substrates from entering active sites

Enzyme Action


Noncompetitive Inhibitors


Don’t directly compete with substrate


Impede enzymatic reactions by binding to
another part of the enzyme

Allosteric Regulation

Allosteric Regulation


Term used to describe any case in which a
protein’s function at one site is affected by
the binding of a regulatory molecule to a
separate site


Can be inhibition or stimulation


Generally constructed from two or more
subunits

Allosteric Site



regulatory site


Both activators and inhibitors can bind to
these sites:


Activator
stabilizes functional active site


I
nhibitors
stabilizes inactive
form


Shape change in one subunit affects shape
of other subunit

Cooperativity


A different type of allosteric activation in
which a substrate binds to an active site
stimulating the
catallytic

powers of a
multisubunit

enzyme by affecting other
active sites

Cooperativity


Amplifies the response of enzymes to substrates


An induced fit in one subunit can trigger the same
favorable shape change in other subunits

Feedback Inhibition


Metabolic pathway switched off by the
inhibitory binding of its end product to an
enzyme that acts early in the pathway

Feedback Inhibition