Download Aerobic and Anaerobic Respiration

Aerobic and Anaerobic
Respiration
Intermediate 2 Biology
Unit 1: Living Cells
Learning Objectives
• Name the type of energy stored in
food.
• Describe the energy change when
food is burned.
• State the units used in measuring
energy content of food.
• Define the term respiration.
• Name the food molecule that is the
main source of energy in cells.
Energy Facts
• Energy facts
– Cannot be created or destroyed
– Can be converted from one form to
another
– Takes a variety of forms
– Measured in kilojoules
Energy
• Food is a store of chemical energy.
• When food is burned, chemical energy
is converted into heat and light
energy.
Energy in Living Organisms
• “Work”
–
–
–
–
–
–
–
Synthesis of complex substances
Active transport e.g. sodium-potassium pump
Movement
Bioluminescence
Maintenance of body temperature
Production of electricity
Maintenance, repair and division
Respiration
• The chemical process by which energy
is released from cells is called
respiration.
• The main source of energy for
respiration in cells is glucose.
• This process is controlled by a series of
enzymes.
Progress questions
• Fireflies can produce light in a process
called bioluminescence. Outline the
energy transformations that occur in
fireflies as they use energy from their
food to produce luminescence.
• Comment on the statement below.
– Respiration produces energy to form ATP.
Learning Objectives
• Give the full name of ATP and draw a
simplified diagram of its structure.
• Name the molecule from which ATP is
formed in cells and draw a simplified
version of its structure.
• Explain where the energy for the
formation of ATP in cells comes from.
• Explain what the energy from the
breakdown of ATP is used for.
Structure of ATP
• Adenosine triphosphate (ATP)
– Adenosine
– Three phosphate groups
• Diagram of ATP
ATP
• a high energy molecule
• continually being hydrolysed and
resynthesised.
Formation and breakdown of
ATP
• The combining of ADP + Pi to make ATP is
an energy requiring process.
• The breakdown of ATP to ADP + Pi is an
energy releasing process.
• The energy required for the formation of
ATP from ADP + Pi comes from the
respiration of glucose.
Transfer of chemical energy by
ATP
Role of ATP
• ATP is the energy source for:
– Muscle contraction
– Cell division
– Building up (synthesis) of proteins
– Transmission of nerve impulses
• If ATP is added to muscle tissue, it
causes the muscle fibres to contract.
The overall effect is that the muscle
tissue shortens in length.
Think!!
• Explain why ATP is known as the
universal energy currency.
Learning Objectives
• Describe aerobic respiration (using the
words glucose, pyruvic acid, glycolysis,
carbon dioxide and water).
Chemistry of Respiration
• Respiration is the process by which
chemical energy is released during the
breakdown of glucose
• It occurs in every living cell
• Involves the regeneration of ATP
Regeneration of ATP
Adenosine DiPhosphate (ADP)
Pi
A
Pi
+ Inorganic Phosphate (Pi)
Pi
Adenosine TriPhosphate
(ATP)
Takes in energy
A
Gives out energy
Pi
Pi
High
energy
bond
Pi
Glycolysis
• Splitting of
glucose into
two molecules
of pyruvic acid
• Results in the
production of
2ATP molecules
Glycolysis
C C C
C C C
C C C
2 Pyruvic Acid
1 Glucose
2 ADP + 2Pi
C C C
2 ATP
Aerobic breakdown of pyruvic
acid
• Pyruvic acid is broken down in a series
of enzyme controlled steps.
• Each pathway leads to formation of
– Water
– Carbon dioxide
– 18 molecules of ATP
• As this takes place twice for each
molecule of glucose the total gain of
ATP is 36
Aerobic breakdown of pyruvic
acid
Investigating the activity of
enzymes in aerobic respiration
Investigating the activity of
enzymes in aerobic respiration
• During respiration, glucose is broken down,
hydrogen is released at various stages
• This removal of hydrogen is controlled by an
enzyme
• Yeast contains stored food which can
be used as a respiratory substrate
• Resazurin dye changes colour when it
gains hydrogen)
blue
(no hydrogen)
pink
colourless
(lots of hydrogen)
Investigating the activity of enzymes in
aerobic respiration
• Set up the three test tubes as shown
below.
– 10ml glucose
– 10ml yeast
– 5 ml dye
Investigating the activity of enzymes in
aerobic respiration
• Shake tubes vigorously for 20 seconds,
and place in a water bath set at 37oC.
• Leave for a few minutes
• Draw a diagram of your results
• Can you explain your results.
Investigating the activity of
dehydrogenase enzyme in yeast
• Tube A
– Colour change from blue via pink to
colourless.
– Hydrogen has been rapidly released and
has reduced the dye.
– For this to happen – enzymes present in
yeast cells must have acted on the
glucose, the respiratory substrate, and
oxidised it.
Investigating the activity of
dehydrogenase enzyme in yeast
• Tube B
– Change from blue – pink – colourless
– Reaction is slower since no glucose was added.
– enzymes could only act on any small amount of
respiratory substrate already present in the yeast
cells.
• Tube C
– Boiling has killed the yeast and denatured the
enzymes.
AEROBIC RESPIRATION
EXPERIMENTS
Energy content of food
Release of heat energy during
respiration
Respirometer
do living things produce carbon dioxide?
Respirometer
Measuring the rate of respiration
Respirometer
• A respirometer measures the rate of
respiration
• Sodium hydroxide is a chemical that
absorbs carbon dioxide
• Oxygen taken in by the animal causes
a decrease in volume in the enclosed
gas, the coloured liquid rises up the
tube.
Learning Objectives
• Describe anaerobic respiration as the
breakdown of glucose to pyruvic acid by
glycolysis.
• State that anaerobic respiration in animals is
reversible and results in the production of
lactic acid.
• Describe the effect of lactic acid on muscle
cells and subsequent repayment of the
oxygen debt.
• State that anaerobic respiration in plants is
irreversible and results in the production of
ethanol and carbon dioxide
Anaerobic Respiration
• Partial breakdown of glucose in the
absence of oxygen
• Glycolysis occurs as normal
• 2ATP are produced
• Pyruvic acid then gets converted into
– Lactic acid in animals
– Carbon dioxide and ethanol in plants and
yeast (this is irreversible)
Anaerobic Respiration in
Animals
Anaerobic Respiration in animals
• In muscles cells, lactic acid is formed
during anaerobic respiration
• A build up of lactic acid reduces the
efficiency of muscles leading to muscle
fatigue
• Oxygen debt
– is the oxygen that needs to be repaid during
a rest period
– Lactic acid is converted to pyruvic acid and
respired aerobically
Anaerobic respiration in plants
and yeast
Anaerobic Respiration in plants
and yeast
• When oxygen is absent plants and
yeast respire anaerobically
– Carbon dioxide is lost from each molecule
of pyruvic acid
– Ethanol is formed
– This is irreversible
Learning Objectives
• Describe an experiment, including a
labelled diagram of the apparatus, to
investigate anaerobic respiration in
yeast and say what happens.
Comparing aerobic and
anaerobic respiration
Aerobic
respiration
Need for
oxygen
Energy yield
Degree of
breakdown of
glucose
End products
Anaerobic
respiration
Comparing aerobic and
anaerobic respiration
Need for
oxygen
Energy yield
Aerobic
respiration
Oxygen
required
38 ATP
Anaerobic
respiration
Oxygen
absent
2 ATP
Degree of
complete
partial
breakdown of
glucose
End products Carbon dioxide and Animals – lactic acid
water
Plants – ethanol and
CO2