Download Introduction to Metabolism

Introduction to Metabolism
Metabolism: Energy and Life
__________________________ = totality of an organism’s chemical processes

Organized into pathways that are ordered series of _____________________
controlled reactions.

_____________________ pathways = release energy by breaking down
complex molecules into simpler compounds

_____________________ pathways = use energy to build complicated
molecules from simpler compounds.
Energy = ________________________________________________

Exists in many different forms (thermal, electrical, mechanical, etc.)

______________________ energy = energy in the process of doing work

______________________energy = energy that could do work

can be transformed from one form to another (follows laws of thermodynamics)
ex. Kinetic energy of sunlight is transformed into potential energy of chemical bonds
during photosynthesis
ex. Potential energy in chemical bonds of ATP is transformed into kinetic energy that
can drive biological processes.
Laws of Thermodynamics & Entropy
All energy changes are subject to two laws of thermodynamics:
1.
«1ST Law » = ________________________________________________________________
____________________________________________________________________________
2.
« 2nd Law » = ________________________________________________________________
____________________________________________________________________________
___________________ = quantitative measure of __________________ that is proportional
to randomness (designated by the letter `S`)

________________ systems = collection of matter under study which is isolated from
its surroundings.

________________ system = system in which energy can be transferred between the
system and its surroundings.
 The _________________ of a system may decrease, but the entropy of the system
plus its surrounding must always ________________.

Highly ordered living organisms do not violet the 2nd law because they are always
open systems. For example, animals;
o
o
o

Thus, combining the 1st and 2nd law of thermodynamics:
o The ____________________ of the energy in the universe is constanct, but it
________________________is not!
Organisms live at the Expense of Free Energy

___________________________ = the system’s energy that is available to do work.
o Is related to the system’s total energy, _____________________ and its
____________________ in the following way:
Where:
G = H - TS

Since, the maximum amount of usable energy that can be harvested from a
particular reaction is the system’s free energy change:
Helmholtz equation (at constant temperature and pressure)
G = H - TS
where:
Significance of Gibbs free energy:
o Indicates the maximum amount of a system’s energy is available to do work
o Indicates whether a reaction will occur spontaneously (reaction will occur
without a further input of energy) or not. How?

During a chemical reaction, _____________ molecules must _____________ energy for
their bonds to _______________, but energy is __________________ when bonds
______________ between the rearranged atoms of the products.

Consequently, reactions have a net energy _____________ or ______________.

In a spontaneous reaction,  G of a system _________________ (___________________)
 Gibbs free energy is being released and the reaction is said to be_______________

An ______________________________________ is not spontaneous and is accompanied
by an ________________in  G (_______________________________)  Gibbs free
energy is required to drive the reaction.
Metabolic Disequilibrium

Since metabolic reactions are reversible, they have the potential to reach
equilibrium.
o At equilibrium ___________, so the system can ___________________________
o
Maintaining disequilibrium is essential for life.
o In the cell, these potentially reversible reactions are __________________________
away from equilibrium, because the products of some reaction become the
reactants fro the next reaction in the metabolic pathway.
ATP Powers Cellular Work

ATP powers cellular work by coupling ______________________ and ___________________
reactions by acting as an intermediate
between them

ATP (________________________________)
= nucleotide with unstable phosphate
bonds.

ATP consists of:

____________________________ between phosphate groups can be _________________
in an exergonic reaction (releases energy)

The _____________________________________ of ATP is coupled with ________________
(energy requiring) reactions by transferring a phosphate group, and its 7.3
kcal/mol of energy to another molecule
Ex.
Glutamic acid + NH3  gluatmine
 G= +3.4 kcal/mol
Glu + NH3  Glu-P
Enzymes

Enzymes ____________________ metabolic reactions by ________________ energy
barriers in order to speed up the rate of the reaction.

Thus, enzymes acts as biological _________________________ = chemical agent that
increases the rate of reaction without being changed in the process

Before any reaction can occur, the reactants must absorb energy to break
chemical bonds. This initial energy investment is the
___________________________________.
effect of catalyst on
effect of catalyst on
exergonic reactions
endogonic reactions

___________________________ = unstable condition of reactant molecules t hat have
absorbed sufficient energy to react.