Respiration Custard powder experiment Did the food contain

Respiration

Custard powder experiment Did the food contain energy? • • What kind of energy did it have to start with? • What kinds of energy was this released as?

Comparing energy in carbohydrates, proteins and fats Use different types of food to calculate which will give the most energy

Results Food Material Carbohydrate Protein Fat Mass of food (g) Starting temperature of water (0 C) Finishing temperature of water (0 C) Temperature rise (0 C)

Calculating energy in food ►A given amount of any substance always requires the same amount of energy to produce a particular increase in temperature. ► 1000 g of water needs………………. . 4. 2 k. J to make its temperature rise by 1 o. C

Calculating the energy content of foods ► The formula to calculate the energy release is M = mass of ► 4. 2 x M x T T=rise in 1000 ► Now water (g) temperature ( °C) calculate the energy content of your foods

Calorimeter

Gases and respiration ► A: Living Peas B: Dead Peas ► Burn a lighted splint in each gas jar.

Do other organisms respire? breathing and respiration

1 Which type of energy does food contain? 2 What is this energy converted to by other organisms? Give at least 3 examples. (i) (iii) 3 What name is given to the process by which organisms release energy? 4 What kind of energy is always released in 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

Formation of ATP is made when another molecule called adenosine diphosphate (ADP) is bonded to a third inorganic phosphate (Pi) using the energy released from glucose.

Energy from respiration adenosine Pi Pi + Pi Enzymes adenosine Pi Pi Pi 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 third inorganic phosphate (Pi).

adenosine Pi Pi Pi ATP Enzymes adenosine Pi ADP Pi + Energy released to do work Pi

Summary ATP cellular respiration energy (out) energy (in) energy (out) cell activities ADP + Pi 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 2 stages: Stage 1 – Glycolysis glyco glucose lysis splitting

In glycolysis, a glucose molecule is broken down into pyruvic acid. glucose energy released to make small quantity of ATP (2 molecules) series of enzyme controlled reactions pyruvic acid Glycolysis does not require oxygen

Stage 2 – Breakdown of pyruvic acid The pyruvic acid made in glycolysis (stage 1) still contains a lot of energy It can only be broken down to release the rest of the energy in the presence of oxygen.

pyruvic acid series of enzyme controlled reactions energy released to make large quantity of ATP (36 molecules) carbon dioxide + water

ATP production – summary glucose 2 ADP + 2 Pi = 2 ATP pyruvic acid 36 ADP + 36 Pi = 36 ATP carbon dioxide + water

Summary of ATP production ► Stage 1 and 2 release all the chemical energy in one molecule of glucose to make a total of 38 ATP molecules. 2 molecules ATP from glucose pyruvic acid 36 molecules ATP from pyruvic acid carbondioxide + water Total 38 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

glucose glycolysis still happens as it does not require oxygen pyruvic acid in absence of oxygen pyruvic acid is turned into lactic acid 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 glucose pyruvic acid oxygen debt e. g. during hard exercise lactic acid oxygen debt repaid during recovery time

Anaerobic Respiration in plants The same process occurs in plants and yeast in low oxygen conditions, e. g. muddy, flooded soils.

glucose 2 ADP + 2 Pi glycolysis still happens, producing 2 ATP molecules 2 ATP pyruvic acid This time in absence of oxygen, pyruvic acid is turned into carbon dioxide and ethanol This is irreversible ethanol + carbon dioxide

Comparison of aerobic and anaerobic respiration Anaerobic Respiration in animals in plants and yeast Oxygen required? yes no no Glycolysis occurs yes yes ATP yield 38 ATP 2 ATP Glucose completely broke down? yes no no End products Carbon Lactic acid dioxide and water Ethanol and carbon dioxide

Task ► Prepare a series of Power. Point 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 4 -14 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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