Cellular Respiration. The Chemistry of Respiration energy and mitochondria clip.

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