Homework

N cycle x word

Law of limiting factors• Read pp41-43• Red 43• Green 44

Energy and ATP

AQA book p.28-31

Specification Reference: 3.4.2

Syllabus

• The synthesis of ATP from ADP and phosphate and its role as the immediate source of energy for biological processes.

Objectives

• What is energy and why do organisms need it?

• How does ATP store energy?• How is ATP synthesised?• What is the role of ATP in biological

processes?

What is energy and why do organisms need it?

1. Ultimately what is the source of energy for all living things?

2. How is energy trapped by plants?3. How do animals obtain energy?4. What are the different forms of energy?5. What is energy measured in?6. Why would it be wrong to say a plant

produces energy?7. What does transduction mean?

What is energy?

1. Ultimately what is the source of energy for all living things? sunlight

2. How is energy trapped by plants? Photosynthesis uses light to combine water and carbon dioxide

3. How do animals obtain energy? Break down organic molecules to release the energy in them

4. What are the different forms of energy? Light heat sound electrical magnetic mechanical chemical atomic

5. What is energy measured in? joules (J)6. Why would it be wrong to say a plant produces

energy? Cannot create or destroy energy – just change it from one form to another

7. What does transduction mean? Changing energy from one form to another e.g. in photosynthesis light chemical

Adenosine triphosphateadenine

ribosephosphates

ATP contains a sugar (ribose), a base (adenine) and three phosphate groups.

+ ++ 30.5 kJ

ATP H2O ADPinorganic

phosphate

When ATP is hydrolysed to form ADP and inorganic phosphate, 30.5 kJ of energy are released.

ATP

Label the diagram on your worksheet

How does ATP store energy?

• ATP = adenosine triphosphate• What breaks an ATP molecule to

release energy?• What are the products called?• Why does it break up so easily?• What type of reaction is involved?

Which molecule is bigger ATP or glucose?

Why ATP?Biological systems transfer the energy in glucose to ATP because unlike glucose…

ATP releases its energy instantly in a single reaction.

The hydrolysis of ATP releases a small amount of energy, ideal for fuelling reactions in the body.

glucose ATP

Comparing ATP and Glucose as an immediate source of energy for a cell

Glucose ATPNumber of steps in reaction to release energy

Speed energy becomes available

Amount of energy released

Reactivity of compound

Size of molecule and its consequences

Comparing ATP and Glucose as an immediate source of energy for a cell

Glucose ATPNumber of steps in reaction to release energy

Many One

Speed energy becomes available

slow Immediate

Amount of energy released

Too much – cell would burn

Just right for the energy needed for another reaction in a cell

Reactivity of compound unreactive Reactive – breaks down easily

Size of molecule and its consequences

Small – upsets osmosis in a cell and can leak out through cell membrane by facilitated diffusion

Larger – less effect on osmosis and trapped within cell membrane

What is respiration?

Respiration is the process by which organisms extract the energy stored in complex molecules and use it to generate adenosine triphosphate (ATP).

ATP provides the immediate source of energy for biological processes such as active transport, movement and metabolism.

In this way they obtain energy to fuel their metabolic pathways.

ATP

The addition of an inorganic phosphate group (Pi) to a molecule like ADP is called phosphorylation. ADP is phosphorylated during respiration.

Two types of phosphorylation occur during respiration:

1. Substrate-level: glycolysis & Krebs cycleA single reaction involving the direct transfer of a phosphate group from a donor molecule to ADP.

2. Oxidative: electron transport chain

A series of oxidation reactions that produce sufficient energy to form ATP from ADP and phosphate.

Phosphorylation of ADP

Adenosine triphosphate and phs

Adenosine triphosphate, or ATP, is an important molecule found in all living cells. It readily diffuses around the cell and provides energy for cellular processes.

ATP releases energy in the light-independent reaction when a bond between inorganic phosphate groups is broken, producing ADP and an inorganic phosphate group.

adenine

ribose

3 phosphate groups

ATP is made in the light-dependent reaction in photosynthesis from adenosine diphosphate (ADP) and an inorganic phosphate group (Pi). This requires energy.

Adding a phosphate molecule is phosphorylation. In this case, light is used as an energy source so the process is called photophosphorylation.

In the light-dependent reaction:

+ ®+ energy

In the light-independent reaction:

The use of water makes this a hydrolysis reaction.

Photophosphorylation and hydrolysis

ADP ATP

+ energy+®H2O ADPATP

How is ATP synthesised? P.30

• What type of reaction reforms ATP?• Photophosphorylation – in

photosynthesis• Oxidative phosphorylation – in

respiration in the electron transport chain

• Substrate level phosphorylation – in respiration when an inorganic phosphate is provided from the substrates of respiration

What is the role of ATP in biological processes?

• This is a very well used exam question for 3 marks.

• Active transport• Synthesising large molecules e.g. protein• Energy for filaments to slide past each

other in muscle contraction• Activation of molecules e.g. glucose in

glycolysis• Something specific to the type of cell in

the question e.g. liver cell = production of bile

• Mitosis

Coupled reactions

• Energy released in one reaction is used up in the other

• Some energy is always lost as heat

ATP video

• 20mins• Boulton Hawker – matter and energy

in living systems• Quiz at end of video• ATP song

http://users.rcn.com/fvirzi/atp.shtml