respiration

29
BIOLOGY - 12 Advanced

Upload: firas-abdel-kareem

Post on 16-Aug-2014

118 views

Category:

Documents


4 download

DESCRIPTION

ppt presentation

TRANSCRIPT

Page 1: Respiration

BIOLOGY - 12Advanced

Page 2: Respiration

• Introduction :Organic compounds store potential energy.With the help of enzymes a cell systematically breaks-down

complex organic molecules ( E ↑ ) to simpler substances ( E↓ )Some of energy released can be used to do work. The rest ( most ) lost as heat.

Complex org. molec. ( E ↑ )

simple substances ( E↓ )

Systematic breaking-down energy

Cellular activities

Heat

UNIT–1 : Biological energetics

Page 3: Respiration

Mitochondria

Page 4: Respiration

• Respiration : breaking-down of food molecules to produce energy.

• There are two types of respiration :

Aerobic respiration Anaerobic respirationBreaking-down of food molecules Breaking-down of food molecules In the presence of oxygen in the absence of oxygen to produce energy to produce energy

Respiration

Glucose lactic acid + energyC6H12O6 2 C3H5O3 + energy

Glucose alcohol + CO2 + energyC6H12O6 2 C2H5OH + 2 CO2 + energy

Glucose + oxygen carbon dioxide + water + energy

C6H12O6 + O2 6CO2 + 6 H2O + 38 ATP

Page 5: Respiration

Respiration

Type of respiration Aerobic Anaerobic

Oxygen With Without

Oxidation of glucose Complete Incomplete

Energy yield High Low

Products CO2 and H2O Lactic acid or alcohol + CO2

Compare between aerobic and anaerobic respiration.

Page 6: Respiration

• Energy produced in respiration can be used in :1. Muscle working.

2. Active transport.

3. Nerve impulses.

4. Biosynthesis.

5. Keeping body temperature constant.• BUT

remember that : not all energy is used up a lot is lost as heat.

Respiration

Page 7: Respiration

• Compare respiration with combustion :

Respiration

Respiration Combustion

Inside the cell Outside the cell

Enzyme regulated No enzymes

Energy produced step-by-step

Energy produced at once

Slow Fast

Page 8: Respiration

• Occur in the absence of O2.

• Occur totally in cytoplasm.

• The cell is incompletely oxidize glucose.

• Produce little amount of energy ( 2 ATP ) so most of the energy remains in the organic molecule.

• It is a 2 stages process :1. Glycolysis.

2. Regeneration of NAD+.

• Two types :1. Lactic acid fermentation ( in animals ).

2. Alcoholic fermentation ( in plants ).

Anaerobic respiration• Occur in the absence of O2.

• Occur totally in cytoplasm.

• The cell is incompletely oxidize glucose.

• Produce little amount of energy ( 2 ATP ) so most of the energy remains in the organic molecule.

• It is a 2 stages process :1. Glycolysis.

2. Regeneration of NAD+.

• Two types :1. Lactic acid fermentation ( in animals ).

2. Alcoholic fermentation ( in plants ).

Page 9: Respiration

Regeneration of NADGLYCOLYSIS

• Note : only the first stage of anaerobic resp. produces ATP, so what is the importance of the second stage?[ If the supply of NAD stops anaerobic respiration stops ]

• The second step Regenerate NAD from NADH by reduction of pyruvate.so production of ATP continue.

Anaerobic resp.

NAD

NADH

Glucose

Pyruvic acid

Lactic acid

ATP

Page 10: Respiration

• Why does the athlete breathe heavily for several minutes after the race?

During the rapid exercise the body can`t supply enough oxygen to the muscle.

( developing oxygen dept )So, the muscle begin to produce ATP by lactic acid fermentation.Building of lactic acid cause a painful sensation.

• What is the fate of lactic acid?Oxidised by liver.

Lactic acid fermentation

Page 11: Respiration

ATP ( Adenosine triphosphate )- A nucleotide.- Acts as an energy currency of the cell.

( intermediary molecule between energy producing and energy consuming reactions )

- Structure :1. Adenine base.2. Ribose sugar.3. Three phosphate groups.

- How does ATP synthasize in respiration?1. Substrate level phosphorylation ( in glycolysis & krebs cycle )2. Oxidative level phosphorylation ( in electron transport chain )

ATP structure and function

Page 12: Respiration
Page 13: Respiration

Aerobic respiration

Page 14: Respiration

• Occur in the cytoplasm of all living organisms.

• No need for oxygen.

• Glucose is broken down into two pyruvates.

• This process consists of three stages:

1. Glycolysis

Page 15: Respiration

C C C C C C GlucoseATP

ADP

C C C C C C P

C C C C C C PP

Glucose phosphate

C C C PC C CP PGAl

PyruvateC C C

ATP

ADP

ATP

ADP

ATP

ADPNAD

NADH

NAD

NADH

Glycolysis

Fructose-1,6-diphosphate

C C C

Activation stage

Splitting stage

Oxidation anf rearrangement

C C C C C C P Fructose phosphate

Page 16: Respiration

1. Glucose molecule activated by 2 ATP to form hexose diphosphate.

2. The hexose diphosphate split into 2 triose phosphate.

3. The trioses oxidised in energy yielding phase to produce 2 pyruvate.

4. 4 ATP and 2 NADH2 produced

2 Pyruvate

Glucose 2 ATP ( 4 - 2 )

2 NADH2

Glycolysis

Page 17: Respiration

In the presence of oxygen pyruvic acid enters the matrix of mitochonderia and three things happen :1. Decarboxylation : CO2 molecule removed from the pyruvic acid.2. Dehydrogenation : hydrogen removed and transferred to NAD+ to form

NADH.H+.3. The resulting acetate ( 2C ) combines with coenzyme A ( CoA ) forming :

acetyle CoA which enters the krebs cycle.

The link reaction

Pyruvate ( 3C )

CO2 NAD+ NADH.H+

CoA

Acetyle CoA ( 2C )

Remember : - 2 pyruvate molecules are formed from each glucose molecule. - So, the reaction happen twice and 2 Acetyle CoA resulted with 2 NADH.H+

Page 18: Respiration

It takes place in the matrix of mitochondria and includes the following reactions :

1. Acetyle CoA combine oxaloacetate ( 4C ) to form 6C compound ( citrate ).

• A series of reactions takes place where the citrate both decarboxylated and dehydrogenated.

– CO2 is released as waste product.

– Hydrogen is picked up by 2 electron acceptors ( NAD & FAD )

• As a result the oxaloacetate is regenerated to combine with more acetyl CoA.

Krebs cycle

Page 19: Respiration

Krebs cycle

Page 20: Respiration

For each 1 turn of Krebs cycle : For each 2 turns of Krebs cycle :

- 3 NADH.H+ produced. - 6 NADH.H+ produced.

- 1 FADH2 produced. - 2 FADH2 produced.

- 1 ATP molecule produced. - 2 ATP molecule produced.

- 2 CO2 molecules released. - 4 CO2 molecules released.

Krebs cycle

Page 21: Respiration

Electron transport chain

Where does the energy that was in the glucose molecule has gone?

- Most is still in the reduced coenzymes ( NADH, FADH )

- Only 4 ATP molecules produced directly ( by substrate level phosphorylation )

from 1 glucose molecule ( 2 from glycolysis + 2 from krebs cycle )

What is the final stage of aerobic respiration? What is its importance?

electron transport chain ( e.t.c. )

importance : - couples the transport of electrons with the production of ATP

- most of ATP is produced during this stage

by oxidative phosphorylation

Page 22: Respiration

Electron transport chain

Where in the cell does e.t.c. occur?

in the cristae of the inner membrane of mitochondria.

Components of the e.t.c. :

- group of carrier proteins

( cytochromes )

- ATP synthase protein.

Cytochrome complexes

Page 23: Respiration

Electron transport chain

How does the mitochondria couple the transport of electrons with ATP synthesis?

( CHEMIOSMOSIS )

- High energy electrons from NADH and FADH2 are passed to e.t.c.

- These electrons are passed from carrier protein to the next .

- At the end of the chain there is an enzyme that combine these electrons with H+

and oxygen to form water.

- As the electrons passes along the chain, they lose most of their energy.

- This energy is used to pump hydrogen ions across the inner membrane

( from the matrix to the intermembrane space ).

- H+ gradient is created across the inner membrane.

- H+ diffuses down the proton gradient through the ATP synthase protein.

- The diffusion of H+ drives the phosphorylation of ADP to ATP

Page 24: Respiration

Chemiosmosis

Page 25: Respiration

Electron transport chain

How many ATP molecules produced for each :

- 1 NADH 3 ATP

- 1 FADH2 2 ATP

What is the function of oxygen in respiration?

oxygen serves as the final electron acceptor in the electron transport

chain.

so oxygen is essential for getting rid of low-energy electrons and hydrogen

ions, the wastes of cellular respiration.

What is the importance of e.t.c.?

1. release energy from NADH and FADH2 to be stored ( temporary ) in ATP.

1. Regenerate NAD and FAD so that the process of respiration proceeds

from glycolysis to link-reaction and krebs cycle.

Why does the an aerobic respiration stops after glycolysis ? ? ! !

Page 26: Respiration

TOTALS

Glycolysis

Link reaction

Krebs cycle

2 ATP 2 NADH

2 ATP 2 NADH

2 ATP 6 NADH 2 FADH2

2 ATP

e.t.c.

4ATP 18ATP 6ATP 6ATP

4 ATP directly produced 34 ATP indirectly produced

38 ATP is produced / 1 glucose

Page 27: Respiration
Page 28: Respiration

- Food gives us energy.

- Carbohydrates and fats are high energy foods.

- Energy of food is measured in kJ ( 1 kJ = 1000J ).

- To measure the amount of energy in food :

1. Burn the food to give-out energy.

2. Use energy to heat-up water.

3. The hottest water the more

energy content.

RESULTS

mass of peanut ( g ) Temp. of water ( start ) Temp. of water ( end )Temp. riseOf water

3.5 28.5 65.0 ??

3.5 g

65

28.5

20 ml

Page 29: Respiration

Calculations :

Temperature rise ( ΔT ) = end temp. – start temp.

= 65 - 28.5

= 36.5 C

Energy ( J ) = temperature rise X 20 X 4.2

= 36.5 X 20 X 4.2

= 3066 J

Energy content ( J/g ) = energy give ( J ) / weight of peanut ( g )

= 3066 / 3.5

= 876 J/g

= 0.876 kJ/g