Transcript (1.3) METABOLISM • Make sure you read all of section 1.3 – in class I will touch on a few very important topics.

(1.3) METABOLISM
• Make sure you read all of section 1.3 – in
class I will touch on a few very important
topics from this chapter but will leave the rest
to you for reading!
• Topics I will cover
» activation energy
» adenosine triphosphate (ATP)
» redox reactions
METABOLISM
Metabolism is the sum of all
anabolic and catabolic
processes in a cell or
organism.
In order to live, organisms
must constantly capture, store
and use ENERGY!
Through an elaborate series of highly controlled chemical
reactions, cells manage the materials and energy they use to
keep themselves alive.
METABOLISM
• Activation Energy = the difference between
the potential energy level of the transition
state and the potential energy of the reacting
molecules.
» in other words, it is the energy necessary to be input into
a system before the reaction can occur.
Note: Energy is required to break a bond!
ATP
• Nature does not always provide energy in a
readily useable form…
» in many cases, energy in one form needs to be converted
to another form before it can be used!
• Plants convert the energy from sunlight
into glucose via photosynthesis
• Humans and animals convert the energy
in glucose to ATP via cellular
respiration
ATP
•
ATP = adenosine triphosphate
» is the primary source of free energy for living
cells!
ATP contains:
-the purine
nitrogenous base
adenine
- 5 carbon sugar
(ribose)
- a chain of 3
phosphate groups
ATP
• When the cell requires free energy to drive
an endergonic reaction, an enzyme called
ATPase catalyzes the hydrolysis of the
terminal phosphate of an ATP molecule
» this results in a molecule of ADP (adenosine
diphosphate), a molecule of inorganic
phoshphate and the release of free energy.
ATP
The hydrolysis of the terminal phosphate of
ATP is an exergonic process resulting in the
release of 54 kJ/mol of energy.
ATP + H2O  ADP + Pi
ATP
• The energy that is released in the hydrolysis
of ATP is usually coupled with an endergonic
process that attaches the inorganic
phosphate group to another molecule
directly associated with the work the cell
needs to do.
PHOSPHORYLATION
» this is called
=
the process of attaching a phosphate group to an organic
molecule
ATP
Active Transport is an example of phosphorylation. ATP
phosphorylates the protein carriers, which change their shape and move
ions against the concentration gradient.
ATP
• Some fun ATP facts!
» our cells use TONNES of ATP!
» a single working muscle cell uses about 600 million
ATP molecules PER MINUTE!!!
» an active human body consumes its own mass in
ATP daily.
The body does not need to get ATP from an external source,
because ADP and Pi are condensed into ATP in the process
of CELLULAR
RESPIRATION!
REDOX REACTIONS
• many chemical reactions involve the
transfer of electrons from one reactant to
another.
– The process of losing electrons is called
OXIDATION
– The process of gaining electrons is called
REDUCTION.
An electron transfer between two substances always involves an oxidation AND a
reduction – hence the name REDOX REACTION.
REDOX REACTIONS
The substance that gains the
electron is
reduced.
The substance that provides the
electron is the reducing
agent.
The substance that loses the
electron is oxidized.
The substance that takes the
electron is the oxidizing
agent.
REDOX REACTIONS
• The reaction between sodium and chlorine to
form sodium chloride is an example of a
redox reaction:
REDOX REACTIONS
• A redox reaction can also happen in a
reaction where electrons in a covalent bond
move closer to a more electronegative atom.
• An example of this is the combustion of
glucose in cellular respiration:
C6H12O6 + 6O2  6CO2 + 6H2O + 36 ATP