National 5 Biology Unit 1 Section 6 - Respiration

Learning Intentions I will be successful if I can… State that glucose is a source of energy in the cell. State that the chemical energy stored in glucose is released by a series of enzyme-controlled reactions called respiration. State that some energy is released as heat from cells during respiration but most is used for cellular activities such as muscle contraction, cell division, synthesis of proteins and transmission of nerve impulses. State that energy released from the breakdown of glucose is used to synthesise ATP from ADP and Pi. The ATP can then be used by the cell as an energy source. State that aerobic respiration yields 38 molecules of ATP per glucose molecule. State that anaerobic respiration yields 2 molecules of ATP per glucose molecule. State that aerobic Pathway - breakdown of glucose to pyruvic acid by glycolysis. Further breakdown of pyruvic acid to carbon dioxide and water in presence of oxygen. State that anaerobic Pathway - breakdown of glucose to pyruvic acid by glycolysis. State that reversible anaerobic conversion of pyruvic acid to lactic acid in animals. State that the effect of lactic acid on muscle cells (i.e. muscle fatigue) and subsequent repayment of oxygen debt. State that the irreversible anaerobic conversion of pyruvic acid to ethanol and carbon dioxide in plants and yeast. State that glycolysis occurs in the cytoplasm whilst the aerobic stage of respiration occurs in the mitochondrion. State that anaerobic respiration takes place fully in the cytoplasm

Why do Living Organisms need Energy? Maintain body temperature Make your muscles work (movement) Synthesis and degradation of larger molecules Cells use energy from respiration to… Carry out chemical reactions Growth and repair of cells

Energy gain What food is made by plants? How do humans get the energy from the plants? Glucose formed and changed to starch

Energy in food Look at any food or drink wrapper. What units is energy content measured in? joules [J] or kilojoules [kJ]

Which Foods have the most Energy? Different types of food contain different amounts of energy. The three main food groups are: Carbohydrates Proteins Fats

Experiment 1 – Measuring the Energy Content of Different Foods Aim : To measure the energy content of different foods Dependent Variable: Independent Variable Variable to be kept constant:

Method 1. Put 20 cm3 of cold water into a boiling tube. 2. Measure the starting temperature with a thermometer. 3. Place boiling tube into a clamp and stand. 4. Place Bunsen onto a heat proof mat and light.

Method 5. Hold food in tongs. 6. Set the food on fire and place it underneath the boiling tube until it is completely burnt. 7. Measure the final temperature of the water. 8. Repeat this process using fresh water with the same type of food. .

Results Use the following sum to calculate the change in temperature: final - starting = rise in temperature temperature temperature

A Food Calorimeter. This equipment makes results more reliable because: Stirrer Enclosed vessel Oxygen supply Chimney

Revision What type of energy is in food? What process allows this energy to be released to be used by cells? What unit do we use when discussing the energy content of food? Chemical Respiration joules

ATP What is Respiration? A series of chemical reactions in our cells where energy is released from food Energy inside FOOD (glucose) Chemical Reactions Energy for the cell to use ATP

The Respiration Equation Glucose + Oxygen Energy + Carbon + Water (ATP) Dioxide From Our food Can be used for Cell activity eg Muscle contraction

Release of Heat Energy The source of the energy required to regenerate ATP is the chemical energy stored in food. The cellular process of releasing energy from food is called respiration. Some of the energy released is used to produce ATP. Some of the energy released is lost as heat.

ATP The energy produced during aerobic respiration is stored in a molecule called ATP (Adenosine triphosphate). Every molecule of glucose that is “burned” in the cell produces 38 ATP molecules.

Adenosine Tri Phosphate ATP Immediate energy source in a cell Formed from the energy that was in our food Adenosine Tri Phosphate Adenosine Pi Pi Pi Three inorganic phosphates

ADP: Adenosine Di Phosphate Adenosine Pi i Pi Adenosine Pi Pi Pi

ATP and Muscle Contraction Aim: To investigate if ATP or glucose is the source of energy in the cell used for reactions Add ATP Add Glucose Microscope slides Muscle tissue

Decrease in length (mm) ATP and muscle contraction Change Start X 100 Percentage Decrease: Solution Initial length (mm) Final length (mm) Decrease in length (mm) Percentage decrease % ATP 11 7 Glucose Conclusion: ATP is used as the energy source for reactions in the cell and not glucose

eg muscle contraction) The Role of ATP ENERGY NEEDED (comes from breakdown of food) + ENERGY RELEASED (can be used for cell activities eg muscle contraction) Pi

The Energy Cycle ATP ADP + Pi Used for ENERGY Cell ENERGY Respiration Activity ENERGY RELEASED Respiration Of glucose from food ENERGY PUT IN

ATP can rapidly convert to _________ and __________ to provide energy for: Heat (maintaining body temperature) Nerve impulse Muscle contractions (movement) Cell division (synthesis and degradation reactions)

Aerobic Respiration Using Oxygen Breakdown of glucose to release energy in the presence of oxygen is a two step process: Glycolysis: Glucose is split in two becoming pyruvic acid 2. Breakdown of pyruvic acid into simple products

This phase takes place in the cytoplasm of the cell. Stage 1: Glycolysis This phase takes place in the cytoplasm of the cell. Glucose Splitting Glucose (6C) 2ADP + 2Pi 2ATP A series of enzyme controlled reactions 2 x Pyruvic Acid/Pyruvate (3C)

Glycolysis Respiration should be seen as a series of enzyme controlled reactions in which 6-carbon glucose is oxidised (broken down) to form carbon dioxide this is accompanied by the synthesis of ATP from adenosine diphosphate (ADP) and inorganic phosphate (Pi). This process takes place within the cytoplasm does not require oxygen Glycolysis results in a production of 2ATP.

Stage 2: Breakdown of pyruvic acid Pyruvic acid + oxygen If there is oxygen available ( the normal situation), then the pyruvic acid produced by glycolysis diffuses into an organelle called mitochondrion for further breakdown if oxygen becomes available enzyme controlled reactions carbon dioxide + water

When is ATP produced? Glucose 2ADP + 2Pi 2ATP Pyruvic Acid + oxygen carbon dioxide + water

2 ATP 36 ATP Total = 38 ATP Glucose Pyruvic Acid + oxygen carbon dioxide + water

Mitochondria Structure This is the site of aerobic respiration. The inner membrane folds present a large surface area for aerobic respiration takes place. Sperm, liver, muscle, and neurones in animal cells together with companion cells in plants have large numbers of mitochondria.

Structure of a Mitochondrion Outer Membrane Inner Membrane Cristae Matrix Fluid

As a molecule to transfer energy in cells Glucose + Oxygen Carbon Dioxide Water Energy ATP ADP Pi e.g. Amino Acids Protein molecule RESPIRATION ENERGY TRANSFER WORK

Anaerobic Respiration No oxygen When would this happen to: An animal? Over exercising a muscle A plant? During a flood the plant gets submerged in water

Anaerobic Respiration in Animals Glucose same as in aerobic respiration Pyruvic Acid pyruvic acid can’t be completely broken down Lactic acid

2 ATP 0 ATP Total: 2 ATP ATP production Glucose 2ADP + Pi 2ATP Pyruvic Acid 0 ATP Total: 2 ATP Lactic acid

Effects of Lactic Acid in Muscle Glucose Pyruvic Acid + oxygen heavy exercise BUILD UP OXYGEN DEBT recovery period OXYGEN DEBT REPAID Lactic acid

Total 2 ATP Anaerobic Respiration in Plants and Yeast Glucose no oxygen Glucose 2ADP + Pi 2ATP Total 2 ATP Pyruvic Acid No ATP Ethanol and Carbon Dioxide

3.6 Uses of respiration in yeast Glucose Pyruvic Acid Ethanol and Carbon Dioxide Bubbles of gas Make dough rise (Bread making) Alcohol (Beer/Wine making)

Yeast Single celled organism Uses glucose for respiration Can carry out aerobic respiration Can carry out anaerobic respiration Both forms of respiration produce Carbon dioxide bubbles We use yeast to make dough rise

3.5.3 Comparing aerobic and anaerobic Aerobic respiration Anaerobic respiration animals Anaerobic respiration plants Glycolysis ATP yield Products Yes Yes Yes 2 38 2 Carbon dioxide & water Ethanol & Carbon dioxide Lactic acid

Word Meaning Adenosine Triphosphate ATP is an energy rich chemical compound. It is made of adenosine and 3 inorganic phosphates Aerobic Respiration Only occurs if oxygen is present. It happens in the mitochondria. Pyruvic acid  Carbon dioxide + Water + Energy Anaerobic Respiration Occurs if there is no oxygen present. In animals = Glucose Pyruvic Acid  Lactic Acid In plants = Glucose Pyruvate  Ethanol and Carbon Dioxide Chemical Energy Energy stored in chemical compounds that is released when the substance is broken down. Ethanol This is an alcohol Muscle Fatigue During strenuous activity there is a lack of oxygen so lactic acid builds up and lactic acid is formed Glucose 6 Carbon sugar molecule required for respiration Glycolysis 1st stage of respiration where glucose is broken down to pyruvic acid. This generates a net gain of 2ATP. It occurs in the cytoplasm of a cell Heat Energy The energy released when a substance is burned in a combustion reaction.

Word Meaning Kilojoule (kJ) unit of energy Lactic Acid Glucose Pyruvic Acid  Lactic Acid Produced in animal cells under strenuous exercise when muscle fatigue occurs and an oxygen debt builds up. Oxygen Chemical element formula O2 Oxygen Debt Built up when vigorous muscular activity results in there not being enough oxygen so debt builds up that is “owed back” Phosphorylation Addition of a phosphoryl group to a molecule Pyruvic Acid 3 carbon molecule formed from the breakdown of glucose during glycolysis.