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

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. 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 + adenosine Pi Enzymes Energy from respiration Energy Rich bond formed

Summarised 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 ► The energy is released when that bond is broken to release the third inorganic phosphate (Pi).

Pi adenosine Pi + Energy released to do work ATP ADP Enzymes adenosine 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 (in cytoplasm) glyco lysis glucose splitting

In glycolysis, a glucose molecule is broken down into pyruvic acid. energy released to make only 2 ATP and 2 NADH from NAD+ series of enzyme controlled reactions pyruvic acid glucose Glycolysis does not require oxygen But…if oxygen is present then….

Stage 2 – Kreb’s Cycle Happens in the mitochondrial matrix 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. It can only be broken down to release the rest of the energy in the presence of oxygen.

Energy carrying molecules NADH and FADH 2 series of enzyme controlled reactions pyruvic acid carbon dioxide Stage 2 – Kreb’s Cycle

ATP production – summary 8 NADH 2 FADH 2 2ATP glucose pyruvic acid carbon dioxide + water 2 NADH 2 ATP GLYCOLYSIS Kreb’s cycle

Summary of ATP production ► Cellular respiration releases all the chemical energy in one molecule of glucose to make a total of 36 molecules of ATP 36 molecules ATP from pyruvic acid  carbon- dioxide + water 36 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= 2ATP 2 NAD + to NADH 2 NADH to NAD+

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 debt e.g. during hard exercise oxygen debt repaid during recovery time glucose pyruvic acid lactic acid

Anaerobic Respiration in yeast, microorganisms The same process occurs in microorganisms 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 NADH to NAD+ 2 ADP + 2 Pi 2 ATP

Comparison of aerobic and anaerobic respiration Aerobic respiration Anaerobic Respiration in animals In microbes and yeast Oxygen required? yesnono Glycolysis occurs yesyesyes ATP yield 36ATP2ATP2ATP Glucose completely broke down? yesnono End products Carbon dioxide and water Lactic acid Ethanol and carbon dioxide

Task ► Prepare a series of PowerPoint slides which show the importance of anaerobic respiration in the brewing and bread-making processes. ► Prepare a couple of slides to show the role of anaerobic respiration in the production of cheese and yogurt. [Pages of your textbook will help you with these tasks if you are finding it difficult to find information on the internet].

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