Cellular respiration
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CELLULAR RESPIRATION. Cellular respiration is defined as the controlled release of energy from organic compounds to form ATP ( Adenosin Tri-Phosphate ) When ATP is split into ADP (adenosine diphosphate ) and phosphate, energy is released. Cell respiration. ADP + phosphate. ATP.

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CELLULAR RESPIRATION

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CELLULAR RESPIRATION


  • Cellular respiration is defined as the controlled release of energy from organic compounds to form ATP (Adenosin Tri-Phosphate)

  • When ATP is split into ADP (adenosine diphosphate) and phosphate, energy is released

Cell respiration

ADP +

phosphate

ATP

Active cell process


Glycolisis

  • The main organic compounds from which energy is released are carbohydrates (glucose) and lipids. These are the substrates.

  • The chain of reactions that take place in the cytoplasm of the cell to convert glucose to pyruvate is called glycolysis.

  • As a result, a small amount of ATP is produced.

    glucose  pyruvate

    ADP ATP

    Occurs in almost all organisms, in aerobic or anaerobic cell respiration


Anaerobic cell respiration

  • Under anaerobic conditions, pyruvate can go through one of the following paths:

    pyruvate  lactate

    Occurs in humans and some bacteria in anaerobic cell respiration

    pyruvate  ethanol +CO2

    Occurs in yeast in anaerobic cell respiration

  • No more ATP is produced

  • These substances are toxic in excess


Aerobic cell respiration

  • In the presence of oxygen, the pyruvate produced by glycolysis can be oxidized to release more energy.

  • In eukaryotic cells this occurs in the mitochondrion.

  • During this process more ATP is produced.

  • Carbon dioxide and water are also produced.

    MITOCHONDRION

    Glucose glycolysispyruvate

    Oxygen

H2O

CO2


Checking our knowledge

  • Cell respiration is:

    • Taking air into our lungs

    • Removing carbon dioxide from the lungs

    • Use of ATP in cells

    • Controlled release of energy in cells

  • What are the products of glycolysis?

    • Glucose

    • Glucose and ATP

    • ATP and pyruvate

    • Glucose, ATP and pyruvate

  • Which substances are produced by yeast in anaerobic cell respiration?

    • Carbon dioxide and lactate

    • Carbon dioxide and ethanol

    • Lactate and ethanol

    • Carbon dioxide, lactate and ethanol

  • Where is pyruvate used and produced in a cell respiring aerobically?

    • Cytoplasm / cytoplasm

    • Cytoplams / mitochondrion

    • Mitochondrion /cytoplasm

    • Mitochondrion / mitochondrion


HL

ONLY


Questions for the group activity

  • GROUP 1

    (2) Glycolysis:

    • Describe the complete process of glycolysis

    • Where glycolysis take place?

    • What is the net production of ATP of this process? Why?

    • Explain why NAD is needed for glycolysis

  • GROUP 2:

    (3) Krebs cycle

    • Describe the Krebs cycle

    • Where the Krebs cycle takes place?

    • What is the name of the reaction in which CO2 is removed?

    • What is the net production of ATP of this process? Why?

  • GROUP 3

    (1) Oxidation and reduction:

    • What is oxidation and reduction: give an example to show the processes

    • What are electron carriers in cells: explain how they work

      (4) Mitochondrion structure and function

    • Draw a mitochondria and label its parts

    • What can be found in the matrix of a mitochondrion?

    • How can you explain the presence of DNA and ribosomes in the Mitochondria?

  • GROUP 4

    (5) Oxidative phosphorilation

    • Describe the process of oxidative phosphorilation (electron transport system)

    • Why is oxygen important in this process?

    • How is the structure of a mitochondria related to its function?


Oxidation and Reduction

  • Oxidation is the loss of electrons from a substance

  • Reduction is the gain of electrons

    Example:

    NaOH + HCl NaCl + H2O

    sodium + hydrochloric sodium water

    hydroxide acid chloride

    In this equation:

    Sodium is oxidized, it gives away (losses) electrons

    Chlorine is reduced, it receives (gains) electrons


Electron carriers in cells

  • Substances that accept and give up electrons as required

    • NAD (nicotinamide adenine dinucleotide)

    • NADP (nicotinamide adenine dinucleotide phosphate)

    • FAD (flavin adenine dinucleotide)

  • How it works:

    NAD + 2 electrons NAD-2

    Processes:

    NAD+ + 2 H NADH + H+

    NAD+ + 2 H+ + 2 e- NADH + H+

reduced

The reduced substance

provides H atoms


  • Oxidation and reduction can also occur through the loss or gain of atoms of oxygen.

    C7 H15 ----- CH3 + ½ O2 C7H15 --- CH2 OH

    n - octane n- octanol

    NO2- + ½ O2  NO3-

  • Adding oxygen atoms is oxidation

  • Losing oxygen atoms is reduction.


Glycolysis

Glucose

Fructose

ATP

ADP

4 ATPs used

2 ATPs produced

2 NADH + H+ produced

Fructose Phosphate

P

ATP

ADP

Fructose Bi Phosphate

P

P

P

P

Glyceraldehyde 3-P

Glyceraldehyde 3-P

NAD+

NADH+ H+

NAD+

NADH+ H+

ATP

ADP

ATP

ADP

1-3diphosphoGlycerate

P

P

P

P

1-3 diphosphoGlycerate

2 ADP

2 ATP

2 ADP

2 ATP

Pyruvate

Pyruvate


The Krebs Cycle

Pyruvate

NAD+

NADH + H+

CO2

3 (2) CO2

1 (2) ATP

3 (2) H2O

4 (2) NADH + H+

1( 2) FADH2


Mitochondrion structure and function

  • Structures:

    • Outer smooth membrane

    • Inner membrane with cristae

    • Matrix

      • Enzymes

      • Ribosomes

      • Loops of DNA


Oxidative phosphorilation

  • Converts the energy in NADH + H+and FADH2 to ATP

  • It occurs in the mitochondrion membrane

Process:

Electrons are transferred from NADH, through a series of electron carriers, to O2.

The electron carriers are proteins embedded in the inner mitochondrial membrane.


Oxidative phosphorilation

  • Transfer of electrons by these carriers generates a proton (H+) gradient across the inner mitochondrial membrane.


Oxidative phosphorilation

  • When H+ spontaneously diffuses back across the inner mitochondrial membrane, ATP is synthesized.

  • The large positive free energy of ATP synthesis is overcome by the even larger negative free energy associated with proton flow down the concentration gradient.


Totals in respiration

  • Glycolysis: 2 ATP

  • Krebs cycle: 2 ATP

  • Oxidative phosphorilation: 32 ATP


Checking our knowledge:

  • What separates the matrix of the mitochondrion from the cytoplasm around the mitochondrion?

    • One wall

    • One membrane

    • Two membranes

    • One wall and one membrane

  • The mitochondrion matrix contains 70S ribosomes whereas the cytoplasm of eukaryotic cells contains 80S ribosomes. Which of these hypotheses is consistent with this observation?

    • Protein is synthesized in the mitochondrion

    • Ribosomes in mitochondria have evolved from ribosomes in bacteria

    • Ribosomes are produced by aerobic cell respiration

  • State the name of a compound in cell respiration that can:

    • Accept hydrogen atoms

    • Accept phosphate

  • Explain the reasons for a much lower ATP yield per glucose from anaerobic cell respiration than from aerobic cell respiration


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