Starter. Write down 6 things you know about energy

Transcription

1 Monday 13th June COPY BAT: - Explain that ATP provides the immediate source of energy for biological processes. - Describe the synthesis of ATP from ADP and phosphate and its role as the immediate source of energy for biological processes. Starter Write down 6 things you know about energy

2 Energy is defined as the ability to do work Variety of forms - e.g. light, heat, sound, electrical, magnets, mechanical, chemical and atomic Can be changed from one form to another Cannot be created or destroyed Measured in joules (J)

3 Make a list of the things organisms need energy for. metabolism - all the reactions that take place in living organisms movement - both within an organisms (e.g. circulation of blood) and of the organisms (e.g. locomotion)

4 active transport - of ions and molecules against a concentration gradient maintenance, repair and division - of cells and of organelles within the cells

5 production of substances - used within organisms e.g. enzymes and hormones maintenance of body temp - in birds and mammals. These organisms are endothermic and need energy to replace that lost as heat to the environment

6 Energy and metabolism Energy cannot be created or destroyed - so where does all the energy in living systems come from?

7 Light energy from the sun Plants convert light energy from the sun into chemical energy This chemical energy (in the form of organic molecules e.g. glucose) is converted into ATP during respiration IN ALL CELLS

8 ATP is then used by cells to perform useful work Write down everything you know about ATP

9 How Adenosine triphosphate - ATP stores energy ATP has 3 phosphate groups The bonds between these phosphate groups are unstable and low activation energy This means the bonds are easily broken

10 When these bonds break they release a considerable amount of energy USUALLY - in living cells it is only the terminal phosphate that is removed.

11 ATP + H2O > ADP + Pi + E Copy above equation and add names of molecules underneath What kind of reaction is this? P is the shorthand way of writing i H3PO4

12 Synthesis of ATP The conversion of ATP to ADP is a reversible reaction What do we need to make ATP? What kind of reaction is it?

13 1. energy 2. ADP + Pi It is a condensation reaction

14 The synthesis of ATP from ADP involves the addition of a phosphate molecule to ADP This occurs in 3 ways

15 Photophosphorylation This takes place in chlorophyll containing plant cells during photosynthesis (we will cover this when we do photosynthesis). Involves a chain of electron carrier molecules

16 Oxidative phosphorylation This occurs in mitochondria of plant and animal cells during the process of electron transport (we will cover this when we do respiration) Involves a chain of electron carrier molecules

17 Substrate-level phosphorylation This occurs in plant and animal cells when phosphate groups are transferred from donor molecules to ADP to make ATP. e.g. in the formation of pyruvate at the end of glycolysis (we will cover this when we do respiration)

18 Hint from text book Think of the unstable bonds that link the phosphates in ATP as coiled springs. Due to these spring-like bonds the end phosphate is straining to break away from it s nearest partner. Any small addition of energy and the end phosphate springs away releasing all the energy that is stored in the spring, that is, stored in the bond

19 Roles of ATP - why is ATP not used as a long term energy store? Because of the instability of the phosphate bonds Fats and carbohydrates such as glycogen, serve this purpose much better.

20 ATP is the immediate energy source of a cell Cells do not store large quantities of ATP They have just a few seconds of supply ATP is rapidly re-formed from ADP and inorganic phosphate (Pi)

21 ATP is a better immediate energy source than glucose for 2 reasons: 1. Each ATP molecule releases less energy than each glucose molecule. So the energy for reactions is released in smaller, more manageable quantities than it would be from a glucose molecule.

22 Q Why would the release of too much energy harm the cell? The release of energy involves changes within the whole molecule ATP + H2O > ADP + H3PO kJ mol -1 ADP + H2O > AMP + H3PO kJ mol -1 AMP + H2O > Adenosine + H3PO kJ mol -1 Remember P is the shorthand way of writing i H3PO4

23 Why is the amount of energy released from ATP breakdown always more than is required by the reaction to which it is coupled? 2. The hydrolysis of ATP to ADP is a single reaction that releases immediate energy. The breakdown of glucose is a long series of reactions and there fore the energy release takes longer.

24 Why do cells such as muscle fibres and the epithelium of the small intestine possess many large mitochondria? These cells require energy for movement and active transport. ATP cannot be stored so has to be constantly made in the mitochondria

25 What is the use of ATP in metabolic processes? It provides the energy to build up macromolecules from their basic units e.g. polysaccharides from polypeptides synthesis from DNA/RNA from

26 What is the use of ATP in movement? ATP provides the energy for muscle contraction. It provides the energy for the filaments of muscle to slide past eachother and so shorten the overall length of muscle fibre.

27 What is the use of ATP in active transport? ATP provides the energy to change the shape of the carrier proteins in. This allows molecules or ions to be moved against a.

28 What is the use of ATP in secretion? ATP is needed to form lysosomes necessary for the of cell products

29 What is the use of ATP in activation of molecules? When a phosphate molecule is transferred from ATP to another molecule it makes it more reactive and so lowers the activation energy of that molecule. ATP therefore allows enzyme catalysed reactions to occur more readily

30 Now answer the following questions fully: 1. ATP is sometimes referred to as an immediate energy source. Explain why. 2. Explain how ATP can make an enzyme-catalysed reaction take place more readily. 3. State 3 roles of ATP in plant cells.

31 Other useful Sources mitochondrial ATP synthesis ATP synthase cartoon Good little lecture on ATP References Glenn Toole, Susan Toole (2008). A2 Biology. Cheltenham: Nelson