Download Respiration

Respiration
How cells release energy
You must be able to:
• State that glucose is a source of energy
in cells.
• State that the energy in glucose is
released by a series of enzyme controlled
reactions called respiration.
Need for energy
• Why do we need energy?
Energy gain
• Where do we get the energy from?
Food
• What type of energy does it contain?
Chemical
Energy gain
• What organisms make the food?
• How?
Green plants
Energy gain
• What food is made by plants?
Glucose formed and changed to starch
• How do humans get the energy from the plants?
Energy in cells
• The chemical energy in glucose cannot be used
directly by cells.
• RESPIRATION = the process that releases
energy from food to be used by cells.
Controlling respiration
• Respiration is a series of chemical reactions.
• What controls the rate of the chemical reactions
in respiration?
• Respiration is
enzyme-controlled.
You must be able to:
• State the units energy content of food is
measured in.
• Compare the energy content of different foods.
Energy in food
• Look at any food or drink wrapper.
• What units is energy content measured in?
joules [J] or kilojoules [kJ]
Measuring energy in food
• Content measured in kilojoules (kJ).
• Unit of heat energy.
• How can we compare the energy content of
three different crisps?
Energy content of food practical
Aim
• To measure the energy content of food
Method described could be used
Method
1. Put 20 cm3 of cold water into a boiling tube.
2. Measure the starting temperature with a
thermometer.
3. Place boiling tube into a clamp and stand.
boiling tube
retort stand
Heatproof mat
heat proof mat
4. Place bunsen onto a heat proof mat and light.
Method
5. Hold food in tongs.
6. Set the food on fire and place it underneath
the boiling tube until it is completely burnt.
7. Measure the final temperature of the water.
8. Repeat this process using fresh water with
the same type of food.
Results
• Use the following sum to calculate the
change in temperature:
final
temperature
starting
=
temperature
rise in
temperature
Aim
• To compare the energy content of 3
different types of crisp.
Comparing energy in crisps
Design an experiment to compare the energy content.
Available apparatus:
•
•
•
•
•
Clamp and stand
Heat proof mat.
Boiling tube.
3 types of crisp.
Measuring cylinder.
•
•
•
•
Bunsen burner.
Tongs.
Water.
Thermometer.
Feed back ideas
Collect:
• Clamp and stand
• Heat proof mat.
• Boiling tube.
• 3 types of crisp.
• Bunsen burner.
• Tongs.
• Water.
• Thermometer.
• Measuring cylinder.
• Goggles
Method
1. Put 20 cm3 of cold water into a boiling tube.
2. Measure the starting temperature with a
thermometer. Complete first 2 columns in
results table.
3. Place boiling tube into a clamp and stand.
boiling tube
retort stand
Heatproof mat
heat proof mat
Method
4. Place bunsen onto a heat proof mat and light.
5. Hold one of the crisps in tongs.
6. Set the crisp on fire and place it underneath
the boiling tube until it is completely burnt.
Method
7. Measure the final temperature of the water
and write it into the results table.
8. Repeat this process using fresh water with
the same type of crisp.
9. Repeat the process for the other two crisps.
Results
• Use the following sum to calculate the
change in temperature:
final
temperature
starting
=
temperature
rise in
temperature
Results
• Work out the average rise for each of
the 3 types of crisp.
• How do you work out an average?
Questions
1 Which type of crisp caused the greatest
temperature increase?
2 Which type of crisp contained the least
energy?
3 Why is it unlikely that this technique
gives a very accurate measure of energy
content.
Measuring energy in food
• To make an experiment fair you can only change
one variable at a time.
• What variable have we changed?
• Type of crisp.
Comparing energy in food
• What variables were kept the same?
Controlled variables:
•
•
•
•
•
Volume of water.
Position of thermometer.
Position of flame underneath.
Crisp is completely burnt.
Mass of crisp.
A Food
Calorimeter.
This equipment makes
results more reliable
because:
Stirrer
Enclosed vessel
Oxygen supply
Chimney
Comparing energy in food
• How were the results made more reliable?
Revision
• What type of energy is in food?
Chemical
• What process allows this energy to be
released to be used by cells?
Respiration
• What unit do we use when discussing the
energy content of food?
joules
You must be able to:
• State that energy released from the
breakdown of glucose is used to synthesise
ATP from ADP and Phosphate.
• State that ATP can then be used by the
cell as an energy source.
Respiration
• A series of enzyme controlled reactions.
• Involves the breakdown of respiratory
substrates like glucose.
• Glucose is rich in energy
Respiration
Results in:
• Release of waste products.
• Release of ENERGY.
Respiration
• Energy release gradual to avoid cell damage.
Can be converted to:
• Heat energy or Chemical energy.
• Chemical energy stored in ATP molecules.
ATP
• Adenosine triphosphate.
• Found in all cells.
• Transfers chemical energy
that all cells can use
immediately.
ATP
Composed of:
• A molecule of adenosine.
• 3 inorganic phosphate (Pi)
molecules.
• Bonds between molecules
contain energy.
ATP breakdown
When the end Phosphate is removed by an enzyme:
• ADP (adenosine diphosphate) is formed.
ENERGY
RELEASE
• Phosphate is released.
• ENERGY is released – can be used by cells.
ATP synthesis
When energy becomes available:
• ATP is synthesised.
• Phosphate is used up.
• ENERGY is stored.
Energy
Stored
Summary
• Breakdown – energy is released as the bonds break.
• Synthesis – energy is stored as bonds form.
Revision
•
•
•
•
•
What does ATP stand for?
ATP is made of Adenosine and 3________?
What is stored in the bonds?
What is the function of ATP?
Describe what happens when ATP breaks
down.
You must be able to:
• State what energy is used for in cells.
Energy transfer
ATP transfers energy from respiratory substrates
(glucose) to cells allowing:
Cell Division
Synthesis of Proteins
Muscle Contraction
Transmission of nerve impulses
Energy transfer
Respiration
Energy transfer
Cell processes
Energy
releasing
reactions
Energy transferred by ATP
Energy
consuming
reactions
glucose
ADP
+ Pi
Energy
Muscular
contraction
Energy
Or
Waste
Products
ATP
Cell Division
ATP pupil demo
ADP
Pi released
as bonds
break
Respiration
Releases energy
Energy
requiring
reaction
Energy used to
add extra Pi
ATP pupil demo
You will need:
• 1 pupil to represent Adenosine
• 6 pupils to represent Phosphates
• 1 pupil to represent respiration (with 3
energy vouchers)
• 1 pupil to represent an energy requiring
reaction
ATP pupil demo
• Stick the appropriate cards on each
volunteer.
• Sit respiration and energy requiring reaction
at opposite ends of the room.
• Form ADP (3 pupils holding hands).
ATP pupil demo
• ADP travels to the respiration reaction and
second phosphate picks up energy voucher.
• This energy is used for a third Pi to join on =
ATP.
• ATP transfers the energy to the energy
requiring reaction.
ATP pupil demo
• As the bond between the second and third
phosphates break, energy is made available
for the reaction.
• The final Pi breaks off, leaving ADP ready to
start again.
Collect handout and make poster
• Cut out these key
points in ATP
production.
• Use them to make a
poster that shows the
synthesis and
breakdown of ATP.
Describe the structure, formation
and breakdown of ATP (5)
• ATP is composed of 1 adenosine and 3 inorganic
phosphate molecules
• Joined by chemical bonds which contain energy
• Respiration releases chemical energy from food
• Formation occurs when this energy is used to join
ADP and Pi together to make ATP
• ATP transfers chemical energy
• Breakdown involves final chemical bond breaking to
release energy
• Leaving ADP + Pi
Revision
• Why is respiration important?
• Name a substance that can be broken down to
release energy
• What does ATP stand for?
• What is the function of ATP?
• Where is the energy stored?
• When ATP breaks down what is left?
• Give 2 examples of energy consuming
reactions within a cell.
You must be able to:
• State that aerobic respiration yields 38
ATP molecules per glucose molecule
• State that anaerobic respiration yields
2 molecules of ATP per glucose molecule
Types of respiration
2 types of respiration:
• Anaerobic
• Aerobic
What is the difference?
Aerobic respiration
• Oxygen is required.
• Respiratory substrate completely broken down.
• Large amount of energy released.
• 38ATP are synthesised from 1 glucose molecule.
Anaerobic respiration
• Oxygen is not required.
• Respiratory substrate not completely broken down.
• Small amount of energy released.
• 2 ATP are synthesised from 1 glucose molecule.
Questions
• Why is respiration important?
• What are the 2 types of respiration?
• How many ATP molecules are gained in aerobic
respiration?
• How many ATP molecules are gained from
anaerobic respiration?
Chemistry of respiration
You must be able to:
• Describe the pathway of aerobic respiration.
• Describe GLYCOLYSIS (the first stage of
respiration) as the breakdown of glucose to form
pyruvic acid.
• State that glycolysis takes place in the cytoplasm.
Glycolysis
• Takes place in the
cytoplasm.
• Requires no oxygen.
Glycolysis
Glucose is broken down in a series of enzyme
controlled reactions to pyruvate.
• A little energy is released.
Glucose
Enzyme
controlled
reactions
2 ADP + Pi
+
Energy
2 ATP
Pyruvic Acid
Enough energy is released to give a net gain of 2ATP
Revision
• What is respiration that uses oxygen called?
• What is the net gain of ATP from the
breakdown of 1 glucose molecule in anaerobic
respiration?
• What is the first stage of respiration called?
• What is glucose converted to?
• What is the net gain of ATP?
You must be to:
• State that after glycolysis, pyruvic acid
is broken down to carbon dioxide and
water in the presence of oxygen.
Fate of pyruvic acid
• Fate of Pyruvic acid depends on
whether oxygen is present or absent.
• In which case do you think more energy
will be released?
Fate of pyruvic acid if O2 present
Each molecule of pyruvic acid enters a
mitochondrion.
Oxygen present
Aerobic respiration takes place.
• Pyruvic acid completely broken down to CO2 and
water.
• CO2 is a poisonous waste which is quickly removed.
• Energy released to synthesise further 36 ATP
molecules.
Aerobic respiration
Pyruvate
Many Enzyme controlled
reactions in mitochondrion
36 ADP + Pi
+
Energy
36 ATP
CO2
+
water
• How many ATP molecules are gained in total?
Write on boards
Aerobic respiration
• 2 ATP from Glycolysis
• 36 ATP from Pyruvic acid
=
38 ATP
Anaerobic respiration
• No oxygen present.
• Pyruvic acid stays in the cytoplasm.
Anaerobic respiration
• Oxygen is absent
Pyruvic acid
• Pyruvic acid not completely Many Enzyme
broken down.
controlled reactions
in cytoplasm
• NO EXTRA ENERGY.
• Waste products are poisonous
and not easily removed .
• May cause cell damage
(lactic acid in animals)
No
Extra
energy
Poisonous waste
Anaerobic respiration
• How many ATP Molecules are gained in total?
?
Write on board
Anaerobic respiration
• 2 ATP from Glycolysis
• 0 ATP from Pyruvic acid
=
2 ATP
Revision
• What is the first stage of respiration called?
• What are the 2 products?
• What substance must be present to allow aerobic
respiration to proceed?
• How many molecules of ATP are gained from the
complete breakdown of 1 glucose molecule in
aerobic respiration?
• Name the additional products of this aerobic
pathway?
• What is the function of ATP?
Anaerobic respiration in animal cells
You must be able to:
• Describe the reversible anaerobic conversion
of pyruvic acid to lactic acid in animals
• State that the build up of lactic acid leads
to muscle fatigue.
• Explain oxygen debt.
Anaerobic respiration in animal cells
• Occurs when no oxygen is available or when
oxygen runs out.
• e.g. vigorous exercise.
• Pyruvic acid converted to
lactic acid.
Anaerobic respiration in animal cells
Lactic acid causes:
• Muscle weakness
(fatigue)
• Muscle damage
(stiffness)
Removal of lactic acid
Removed from cells by converting it back to pyruvic
acid.
Requires extra oxygen.
Supplied by breathing heavily.
Removal of lactic acid
• The extra oxygen required to remove lactic acid
is called the:
• OXYGEN DEBT
Removal of lactic acid
• Anaerobic respiration in animals is reversible.
Pyruvic acid
Oxygen
absent
Oxygen debt Oxygen
present
repaid
Oxygen debt
Builds up
Lactic
acid
Describe anaerobic respiration in animals (5)
•
•
•
•
•
•
•
•
•
Enzyme controlled
Glucose converted to pyruvate
This is called glycolysis
Glycolysis occurs in cytoplasm
Energy is released to produce two ATP
No oxygen present
Pyruvate converted to lactic acid
Oxygen debt builds up
Incomplete breakdown of glucose/reversible
Anaerobic respiration in plants
You must be able to:
• Describe the irreversible anaerobic
conversion of pyruvic acid to ethanol
and carbon dioxide in plants and yeast.
• State that another name for
anaerobic respiration is fermentation.
Anaerobic respiration in plants
• In plant cells fermentation occurs when no O2 is
available.
• Pyruvate is broken down to ethanol and CO2.
Anaerobic respiration in plants
• Both are poisonous but the CO2 is easily and
quickly removed .
• How does it leave cells?
Anaerobic respiration in plant cells
• Accumulation of ethanol
will kill the cell.
• Anaerobic respiration in
plant cells is irreversible.
Pyruvic acid  ethanol and carbon dioxide
Describe anaerobic respiration in plants (5)
•
•
•
•
•
•
•
Enzyme controlled
Glucose converted to pyruvate
This is called glycolysis
Glycolysis occurs in cytoplasm
Energy is released to produce two ATP
No oxygen present
Pyruvate broken down to carbon dioxide and
ethanol
• Incomplete breakdown of glucose/irriversible
Revision
• Give another name for anaerobic respiration.
• When does fermentation occur.
• What are the products of fermentation in
plants?
• Give a use for each product.
• Is fermentation in plants reversible?
You must be able to:
• Describe where the different stages of
aerobic respiration and fermentation
occur.
• Give examples of cells that require large
numbers of mitochondria.
Mitochondrion
• Plural = mitochondria.
• Cell organelles involved in the process of
respiration.
Sites of respiration
Anaerobic respiration
(fermentation) occurs
in the cytoplasm.
Aerobic respiration
starts in the cytoplasm
and is completed in the
mitochondron.
Numbers of mitochondria
Large numbers are found in cells which
require large amounts of energy.
• e.g. Muscle cells for contraction, liver cells
for metabolic processes and sperm cells for
movement.
Revision
• Where in a cell does anaerobic respiration
occur?
• Name the stage of aerobic respiration that
occurs in the cytoplasm.
• Where is aerobic respiration completed?
• What type of cells require many
mitochondria?
• Give an example of such a cell.
Lactic acid build up practical
Aim
• To find out the effect of repeated
exercise on muscle strength.
Method
• Using 2 hands, squeeze the set of
bathroom scales with as much force as
possible.
• Write down the reading.
Method
• Hold your hands out in front of you.
• Raise them into a waving position with
fingers stretched back.
• Clench them into tight fists.
• Repeat this for 1 minute.
• Squeeze the scales again and write down the
reading.
Percentage change
• To work out a percentage decrease:
• Work out the difference between the
initial (first) and final (second) squeeze.
• Do this by: Initial – Final.
Percentage change
• Divide the difference you have just
worked out by the initial (first) squeeze.
• Multiply the answer by 100.
Results
• What did you find out?
• Why did you muscles have less force
the second time?
Conclusion
• A lack of oxygen during exercise
leads to the build up of Lactic acid.
• Lactic acid makes your muscles ache
and reduces their strength.
• This is called muscle fatigue.
• Fill in conclusion.
Make a colourful poster to show the
differences between aerobic and anaerobic
respiration in humans
G
O
CO
W
E
• 1 Glucose + oxygen  CO2 + Water + 38 ATP
• 1 Glucose  Lactic acid + 2 ATP
You must be able to:
• State that without oxygen, only a little
energy can be released from food.
• State that in yeast cells, alcohol and
carbon dioxide are also made.
• Describe industrial uses of the products of
fermentation.
Products from yeast
• Yeast is a living organism.
• It is a single-celled fungus.
• Yeast uses glucose as a food source to release
energy.
• Yeast carries out aerobic respiration in the same
way as all other living things.
Anaerobic respiration in yeast
• Yeast cells can also break down glucose to
release energy without using oxygen.
• The products in this case are very useful.
• Do you know any industries where yeast is
used in this way?
Anaerobic respiration in yeast
The products of anaerobic respiration in yeast are
used in:
• Beer making.
• Wine making.
• Bread making.
• But what are these products?
Anaerobic respiration in yeast
Yeast + glucose  CO2 +
Ethanol + energy
This process is also called fermentation.
Match product to use
Rising dough
Gassy beer
Wine
Fuel - Gasohol
Yeast + Glucose CO2 + Ethanol + energy
You must be able to:
• Describe how fermentation is used to
produce yoghurt.
How is yoghurt made?
Lactic acid bacteria
• Bacteria.
• Added to milk.
• Milk contains
lactose sugar.
Lactic acid bacteria
• Bacteria carry out fermentation.
• Convert lactose sugar to lactic acid.
• Produces yoghurt.
Revision
• Describe yeast.
• What is the fermentation (anaerobic
respiration) equation in yeast?
• Give 2 uses of the products of fermentation
in yeast.
• Which type of sugar is in milk?
• Describe how do bacteria make yoghurt?
Summary of respiration
Aerobic
respiration
In all organisms
Glycolysis
(cytoplasm)
Reactions if..
End
Products
Energy yield
Breakdown of
glucose
glucose
2 ATP
Pyruvic acid
Oxygen
36 ATP
present
CO2
&
Water
Anaerobic
respiration in
animals
Anaerobic
respiration in
plants/yeast
glucose
2 ATP
Pyruvate
Oxygen
absent
Lactic acid
38 ATP
2 ATP
Complete
Incomplete
glucose
2 ATP
Pyruvate
Oxygen
absent Ethanol
+
CO2
2 ATP
Incomplete
• Matching
• Make cards
• Torrance multichoice