UNIT 1: Cell Biology Respiration

Energy release

Energy release Learning intention: State that living organisms need energy for many activities and that energy is released from food molecules. Why? Each cell requires energy for a huge range of processes and it is important to know where this energy comes from.

Energy release The energy released in respiration can be shown by the custard bomb and the screaming jelly baby experiments.

Complete Practical 1in the booklet. Watch the video of the screaming jelly baby. screaming jelly baby

Food and energy In this topic we will be investigating how energy is released from food molecules inside cells. Organisms need energy for lots of different activities: muscle contraction cell division synthesis of proteins transmission of nerve impulses

Food and energy We are going to investigate the energy content of food. What type of energy is stored in food? We can burn food and convert the chemical energy into heat energy. Different foods contain different quantities of energy.

Food and energy We are going to investigate the three main classes of food: Protein Carbohydrate Fat Which type of food would you expect to contain the most energy?

Measuring the energy content of food Heat energy is measured in joules (j) or kilojoules (kJ). It takes 4.2j to raise the temperature of 1000g of water by 1ºC.

Complete practical 2 in the booklet. Complete the what to do section under the energy release title in the booklet. .

Measuring the energy content of food Heat is lost to the surroundings Food may not burn completely Flame is near bulb of the thermometer and may give a distorted reading

Measuring the energy content of food

What is respiration?

What is respiration? Learning intention: State that respiration is the release of energy from food molecules. Describe that molecules of ATP are made during respiration. Why? Each cell requires energy for a huge range of processes from contracting muscles to transmitting nerve impulses.

Adenosine triphosphate (ATP) ATP is found in living cells. To form ATP the cell uses some of the energy from respiration. When the cell needs energy ATP can be broken down to release the stored energy.

Adenosine Triphosphate Pi 3 inorganic phosphates

ATP is made in cells from ADP and inorganic phosphate (Pi) Adenosine Pi Pi 2 inorganic phosphates

The role of ATP The formation of ATP allows the cell to store the energy released from respiration. The process of forming ATP uses energy from respiration to add an inorganic phosphate molecule to ADP.

Formation of ATP ENERGY Pi Adenosine Pi Pi Adenosine The energy released when glucose is broken down is stored as ATP. ENERGY Pi Adenosine Pi Adenosine Pi

The role of ATP ATP molecules have a high level of chemical energy (stored energy). If the cell needs energy it can breakdown ATP back into ADP and energy is released. Enzymes carry out the breakdown of ATP to ADP.

Breakdown of ATP ENERGY Adenosine Pi Pi Adenosine Pi The energy released when glucose is broken down is stored as ATP. Adenosine Pi Adenosine Pi Pi ENERGY

ADP + Pi are now ready to… Make more ATP! ATP Glucose ENERGY ENERGY Cell activities ADP + Pi

The role of ATP

The role of ATP Muscle contraction beating heart

The role of ATP Cell division mitosis

The role of ATP Protein synthesis

The role of ATP Transmission of nerve impulses nerve impulse

The role of ATP Movement of sperm cells movement of sperm

The role of ATP Action of companion cells

The role of ATP Muscle contraction Cell division Protein synthesis Transmission of nerve impulses Movement of sperm cells Complete the what to do section under the ATP title in the booklet.

Glucose ENERGY ATP ADP + Pi Cell activities

Aerobic respiration

Aerobic respiration Learning intention: Give the word equation for aerobic respiration Describe the chemistry of respiration Why? Respiration is a very important process which provides ATP for cell activities.

Respiration Respiration is the chemical process which releases energy from the food we eat. Do not mix up breathing with respiration. Breathing involves taking in oxygen and releasing carbon dioxide, whereas respiration is a chemical reaction.

Respiration Respiration is a series of reactions which breakdown glucose and release energy a little at a time. If all the energy stored in glucose was released at one time, this would damage the cell. Therefore different enzymes carry out different stages of the breakdown.

Word equation glucose + oxygen → carbon dioxide + water + ENERGY Raw materials Products

Aerobic respiration If oxygen is available in cells, aerobic respiration will take place. In aerobic respiration oxygen is used up in the breakdown of glucose. This is why living things must breathe in oxygen.

Glycolysis The first stage of aerobic respiration in the breakdown of glucose into two molecules of pyruvate. This reaction takes place by a series of enzyme controlled reactions. Glycolysis does not require oxygen and produces 2 ATP.

Glycolysis Respiration begins with each molecule of glucose being broken down to form 2 molecules of pyruvate. 2 molecules of ATP also produced for each glucose molecule broken down. glucose 2 ADP + Pi 2 ATP pyruvate pyruvate

First stage in aerobic respiration Complete the what to do section under the first stage in aerobic respiration title in the booklet.

The second stage of aerobic respiration There is still a lot of energy in pyruvate, therefore it is further broken down. During the second stage of respiration, pyruvate is broken down into carbon dioxide and water. This stage releases a large amount of ATP.

Breakdown of pyruvate The breakdown of pyruvate is also carried out by enzymes. This stage occurs in the mitochondria and requires the presence of oxygen. If oxygen is not available, the pyruvate cannot be broken down into carbon dioxide and water.

series of enzyme controlled reactions Breakdown of pyruvate pyruvate + oxygen 36 ADP + Pi series of enzyme controlled reactions 36 ATP carbon dioxide + water

pyruvate CO 2 H 2 H 2O 18 ATP O2

Breakdown of pyruvate Complete the what to do section under the second stage in aerobic respiration title in the booklet.

Respirometer Measures the rate of oxygen uptake by an organism. Soda lime absorbs carbon dioxide. Red dye moves up the tube. Worm Soda lime Red dye

Respirometer Your teacher will now demonstrate how to set up a respirometer. Worm Soda lime Red dye Complete the what to do section under the respirometer title in the booklet.

The great balloon race Place 5ml of yeast suspension and 5ml of yeast suspension in a test tube. Place a balloon over the mouth of the test tube. Have a race! balloon race

Enzymes and respiration

Enzymes and respiration Learning intention: I understand that enzymes control the reactions of respiration. Why? As the reactions of respiration are controlled by enzymes the rate will be affected by temperature.

Temperature and respiration The reactions of respiration are controlled by enzymes. How would you expect temperature to effect the rate of respiration?

You are going to investigate the effect of temperature on the rate of respiration in yeast cells.

You can use the indicator resazurin to measure the rate of respiration. During respiration in yeast glucose is oxidised and hydrogen released at various stages Resazurin dye changes colour when it is reduced(gains H2). Blue pink colourless no reduction partial reduction reduction The faster the resazurin dye changes colour the faster the rate of respiration.

Complete Practical 3 under the temperature and respiration title in the booklet.

Anaerobic respiration in animals and bacteria

Anaerobic respiration in animals and bacteria Learning intention: Describe anaerobic respiration in animals and bacteria. Why? It is important to understand why you get muscle fatigue.

Anaerobic respiration When oxygen is not available, anaerobic respiration (fermentation) takes place. For fish, the water they live in may not contain enough dissolved oxygen. The amount of oxygen in the blood can also be reduced if an animal is exercising vigorously and it cannot breathe fast enough to meet the demand.

Why wouldn’t oxygen be present? Exercising hard

Anaerobic respiration When oxygen is not present, glucose cannot be completely broken down into carbon dioxide and water. Glycolysis occurs as normal and glucose is broken down into 2 molecules of pyruvate, releasing 2 ATP. Because there is no oxygen, the pyruvate cannot be broken down.

If no oxygen is present… Pyruvate won’t be broken down. PYRUVATE

If no oxygen is available then this happens…. 1 x GLUCOSE 2 ADP + Pi 2 ATP Alternative Route PYRUVATE

Anaerobic respiration in animals and bacteria Glycolysis takes place, but without oxygen the pyruvate can’t be broken down any further. PYRUVATE LACTIC ACID NO OXYGEN

Anaerobic respiration glucose 2 ADP + Pi 2 ATP pyruvate lactic acid

Anaerobic respiration During anaerobic respiration 2 ATP are released when glucose is broken down into pyruvate. When pyruvate is broken down into lactic acid, 0 ATP are produced. This means anaerobic respiration only produces 2 ATP in total.

Anaerobic respiration Stage Aerobic Anaerobic No of ATP molecules Stage 1 Glycolysis 2 Stage 2 Breakdown of Pyruvate 36 Total 38

Effects of lactic acid on muscle cells Normally, muscle cells have a plentiful supply of oxygen and respire aerobically. If a person is carrying out gentle exercise, muscle cells usually get enough oxygen to respire aerobically.

Anaerobic respiration During vigorous exercise, the breathing rate cannot supply the muscles cells with enough oxygen. This means the muscle cells start to respire anaerobically. This means lactic acid builds up in the muscle cells causing the muscle to ache.

Anaerobic respiration When the anaerobic exercise stops, the muscles require a recovery period. The breathing rate continues at a high level. The oxygen taken in is used to convert the lactic acid back to pyruvate. The volume of oxygen needed to do this is called the oxygen debt.

pyruvate lactic acid Without, oxygen, pyruvate forms lactic acid b Without, oxygen, pyruvate forms lactic acid pyruvate OXYGEN DEBT PAID OXYGEN DEBT lactic acid Complete the what to do section under the anaerobic respiration in animals and bacteria title in the booklet.

Anaerobic respiration in plants and yeast

Anaerobic respiration in plants and yeast Learning intention: Describe anaerobic respiration in plants and yeast. Why? So you can appreciate the use of yeast in the biotechnological industries.

Anaerobic respiration The first stage of anaerobic respiration occurs as normal for animals. Glycolysis occurs and glucose is broken down into 2 molecules of pyruvate, releasing 2 ATP. In plants and yeast, the pyruvate is broken down into carbon dioxide and ethanol.

Anaerobic respiration Anaerobic respiration may occur in the root cells of plants if they are submerged in water. Some industries use yeast to make certain products i.e. beer.

Anaerobic respiration in plants and yeast

Anaerobic respiration in plants and yeast glucose 2 ADP + Pi 2 ATP pyruvate released carbon dioxide and ethanol

Anaerobic respiration in plants and yeast The second process of anaerobic respiration in plants and yeast releases 0 ATP. This means only 2 ATP are produced in total. The carbon dioxide is released from the plant as a gas, this means anaerobic respiration in plants and yeast is irreversible.

vacuum flask to reduce heat loss thermometer vacuum flask to reduce heat loss oil layer boiled and cooled glucose solution + live yeast cells lime Water

vacuum flask to reduce heat loss after 2 days live yeast cells thermometer vacuum flask to reduce heat loss oil layer boiled and cooled glucose solution + live yeast cells lime water cloudy

Anaerobic respiration in yeast Test Observation At start After 24 hours Smell of a sample from the flask yeasty alcohol Appearance of limewater clear cloudy (CO2 released) Temperature of mixture in the flask 20°C 26°C Complete the what to do section under the anaerobic respiration in plants and yeast title in the booklet.

Aerobic vs. anaerobic respiration Complete the comparing aerobic and anaerobic respiration section of the booklet.

Comparing aerobic and anaerobic respiration

Comparing aerobic and anaerobic respiration Learning intention: Compare aerobic and anaerobic respiration. Why? It is important to understand that more ATP is released by aerobic respiration and that is why many organisms require oxygen.

carbon dioxide and water carbon dioxide and ethanol glucose 2 ADP + Pi 2 ATP oxygen present pyruvate no oxygen present - animals 36 ATP no oxygen present – plants and yeast 36 ADP + Pi lactic acid carbon dioxide and water oxygen debt carbon dioxide and ethanol

Comparing aerobic and anaerobic respiration Using books, your notes and the internet make a poster to compare aerobic and anaerobic respiration. One half of the poster should detail aerobic and the other half anaerobic respiration.