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Cellular Respiration
The Chemistry of Respiration
energy and mitochondria clip
Adenosine triphosphate
►The energy released during respiration is not used directly by cells.
►Instead it is used to make a molecule called ATP which stores the energy until it is needed.
ATP = Adenosine triphosphate
What does ATP do?
►ATP supplies energy for all the processes that need it.
► For example: ► movement► chemical reactions ► growth.
slow twitch/fast twitch investigation
Structure of ATP
adenosine Pi Pi Pi
►How is ATP formed?
Formation of ATP
ATP is made when another molecule
called adenosine diphosphate (ADP) is
bonded to a third inorganic phosphate
(Pi) using the energy released from
glucose.
Pi
adenosine Pi Pi +
adenosine Pi Pi Pi
Enzymes
Energy from respiration
Energy Rich bond formed
Summarized as:
ADP + Pi ATP
The whole process is under the control of enzymes
The role of ATP
►ATP stores the energy in the third bond of the molecule
►How is energy released?
►The energy is released when that bond is broken to release the third inorganic phosphate (Pi) .
Pi
adenosine Pi Pi
+
Energy released to do work
ATP
ADP
Enzymes
adenosine Pi Pi Pi
Summary
ATP
ADP + Pi
energy (out)
energy (in)
cellular respiration
cell activities
ATP
energy (out)
cellular respiration
cell activities
The whole process is an enzyme controlled reaction.
Aerobic Respiration
Aerobic respiration = respiration with oxygen.
glucose + OXYGEN energy + carbon dioxide + water
(to make ATP)
Aerobic respiration happens in 3 stages:
Stage 1 – Glycolysis
glyco lysis
glucose splitting
In glycolysis, a glucose molecule is broken down into pyruvic acid.
energy released to make small quantity of ATP(2 molecules)
series of enzyme controlled reactions
2 pyruvic acid, 4 ATP (used 2), 2 NADH
glucose
Glycolysis does not require oxygen
►http://www.science.smith.edu/departments/Biology/Bio231/
GlycolysisSection 3 Cellular RespirationChapter 5
Stage 2 – Breakdown of pyruvic acid
The pyruvic acid made in glycolysis (stage1) still contains a lot of energy
It can only be broken down to release the rest of the energy in the presence of oxygen.
energy released to make largequantity of ATP(34 molecules)
series of enzyme controlled reactions
pyruvic acid
carbon dioxide + water
Kreb’s cycle AKA Citric Acid cycle
►Citric acid is the first compound formed
The Process- ► one C- atom is removed from
pyruvic acid► If the cell has enough ATP- the
new molecules are changed to fats for storage
► If the cell needs ATP- the new molecules are used in the Krebs Cycle.
► Krebs Cycle- produces 2 CO2, 1 ATP, NADH, and another carbon molecule that can repeat the cycle
►http://www.science.smith.edu/departments/Biology/Bio231/
Krebs CycleSection 3 Cellular RespirationChapter 5
►Electron Transport Chains- NADH can give electrons to move the electron transport chain.Proton pumps move protons outside the mitochondrial membranes.
As they cross the membrane again, they provide energy to make ADP into ATP
Extra Hydrogens join oxygen molecules to form water
►http://www.science.smith.edu/departments/Biology/Bio231/
Electron Transport Chain of Aerobic Respiration
Section 3 Cellular RespirationChapter 5
ATP production – summary
34 ADP + 34 Pi =34 ATP
glucose
pyruvic acid
carbon dioxide + water
2 ADP + 2 Pi =2 ATP
Summary of ATP production
►Stage 1, 2, and 3 release all the chemical energy in one molecule of glucose to make a total of 36 ATP molecules.
2 molecules ATP from glucose pyruvic acid
34 molecules ATP from pyruvic acid carbon- dioxide + water
Total 36 molecules ATP
Anaerobic Respiration(in animals)
anaerobic = in the absence of oxygen
In low oxygen conditions or during heavy exercise, when
not enough oxygen can be supplied, muscle cells swap to
anaerobic respiration
glycolysis still happens as it does not require oxygen
in absence of oxygen pyruvic acid is turned into lactic acid.
pyruvic acid
lactic acid
glucose
2 ADP + 2 Pi
2 ATP
A build up of lactic acid produces muscle fatigue.
Muscle fatigue makes muscles ache and contract less powerfully.
A recovery period is needed. During this time more oxygen is taken in to convert the lactic acid back into pyruvic acid again.
The volume of oxygen needed is called the
oxygen debt.
Summary
oxygen debte.g. during hard exercise
oxygen debtrepaid during recovery time
glucose
pyruvic acid
lactic acid
Anaerobic Respiration
in plants
The same process occurs in plants and yeast in low oxygen conditions, e.g. muddy, flooded soils.
glycolysis still happens, producing 2 ATP molecules
This time in absence of oxygen, pyruvic acid is turned into carbon dioxide and ethanol
glucose
pyruvic acid
ethanol + carbon dioxide
This is irreversible
2 ADP + 2 Pi
2 ATP
Aerobic respiration
Anaerobic Respiration
in animals in plants and yeast
Oxygen required?
Glycolysis occurs
ATP yield
Glucose completely broke down?
End products
Comparison of aerobic and anaerobic respiration
Aerobic respiration
Anaerobic Respiration
in animals in plants and yeast
Oxygen required? yes no no
Glycolysis occurs yes yes yes
ATP yield 36ATP 2ATP 2ATP
Glucose completely broke down? yes no no
End products Carbon dioxide and water
Lactic acid
Ethanol and carbon dioxide
Food for Thought…
►Humans store excess energy in the form of fat instead of carbohydrates. Why is this?
Helpful Hints
►When broken down by the body, each six-carbon fat molecule yields 51 ATP
►A six carbon carbohydrate would yield 36 ATP
►Carbohydrates store water when bound. Water yields zero ATP when metabolized. Fat stores no water.
Continued…
►An adult who weighs 70 kg can survive on the energy from fat for 30 days without eating.
►The same person would have to weigh nearly 140 kg to survive 30 days on carbohydrates.
►The End