Respiration
Cellular respiration, the process in
which nutrients are converted into
useful energy in a cell.
ATP- an energy carrier
• ATP is Adenine
triphosphate
• Think of it like
rechargeable batteries
that are used to power
the reactions in cells.
• When reactions that
release energy happen
in cells, ATP stores the
energy
• When reactions need
energy to make them
happen, ATP supplies
the power.
• The amount of ATP is
a cell is small as it is
constantly being used
up.
• This means it
constantly needs to
be made.
• ATP is made in
respiration.
• Most energy is stored
in the 3rd bond.
• ATPase is the enzyme
that converts ATP to
ADP + P
The equation of respiration
Respiration occurs in the mitochondria
• Lots of
mitochondria in a
cell means lots of
energy.
• Muscle cells etc.
have lots of
mitochondria.
Respiration occurs in two stages
1.Glycolysis
• This occurs in the
cytosol of the
cytoplasm.
• Glyco means glucose
lysis means splitting
• 6 carbon glucose
molecules are broken
down in to 3 carbon
pyruvic acid
molecules.
Glycolysis
• 2 phosphate groups are
added to the glucose
molecule. This requires
energy.
• the 6C di-phosphate is
broken down into 2x 3C
pyruvate.
• Hydrogen is given off
(carried by NAD+)
• ATP is made
Glycolysis
2.Respiration occurs in the matrix of
the mitochondria (link reaction)
• Firstly pyruvate (pyruvic
acid ) is converted in to
Acetyl CoA ( a 2 carbon
substance) By
combining with CoA.
• CO2 is made
• Hydrogen is made. It is
used later.
Secondly the
Krebs cycle
• Each molecule of
Acetyl CoA travels
through a series of
reactions.
• CO2 is given off.
• ATP is made
• Hydrogen is produced
and may be ‘carried’ in
the form of NADH.
• CoA is recycled and
used again.
Thirdly- the Electron
transport chain
(oxidative
phosphorylation)
• This occurs in the inner
membrane of the
mitochondria (cristae)
• Oxygen is required (1
atom)
• The hydrogen made
before is converted into
water through a series
of reactions.
• Lots of ATP is made
Summary
Summary again
Energy yields per glucose
• the potential maximum energy produced is
38 ATP made up from
Glycolysis 2ATP
Krebs cycle 2 ATP
Electron transport 34 ATP
However each glucose probably makes less ATP
as some electrons may get lost during the
chemical reactions.
How is the rate of respiration
controlled?
Feedback inhibition.
• If there is too much
ATP or citrate then the
process is inhibited.
(stopped)
• if there is lots of AMP
or ADP then the process
is started.(stimulated)
Anaerobic respiration
• All organisms can
metabolise glucose
without using oxygen.
• Glycolysis occurs to make
2x pyruvate.
• In yeast and root cells
alcoholic fermentation
takes place
• In muscle cells lactic acid
fermentation makes lactic
acid
a closer look at alcoholic fermentation
• CO2 is made
• Hydrogen ions are
required.
• At above 15%
ethanol the yeast
is poisoned so it
cannot continue
indefinitely.
• Only 2ATP are
made so most
organisms cannot
live this way
• Ethanol is
CH3CH2OH
A closer look at lactic acid
fermentation
• The bodies last
attempts to make some
energy to keep muscles
going when you are
exercising and you
cannot get enough
oxygen to the muscle
cells.
• Lactic acid is toxic and
makes muscles hurt.
• Lactic acid is broken
down aerobically when
O2 is available.
(oxygen payback)
• Lactic acid is
CH3CHOHCOOH
The relationship between cellular
respiration and photosynthesis