Chapter 2.3

Question 1

Where do all you get your energy from?

Answer 1

All energy you get comes from the Sun

Question 2

What do plants use the sun energy for?

Answer 2

ants used this energy to combine water and carbon dioxide into complex organic molecules (glucose) by the process of photosynthesis.

Question 3

Plants and animals then oxidise organic molecules (like glucose CHECK) to produce what?

Answer 3

Both plants and animals then oxidise these organic molecules (glucose CHECK) to make adenosine triphosphate (ATP), which is used as the main energy source to carry out processes within the cells.

Question 4

What’s the structure of ATP

Answer 4

• adenine – a nitrogen-containing organic base
• ribose – a sugar molecule with a 5-carbon ring structure (pentose sugar) that acts as the backbone to which the other parts are attached
• phosphates – a chain of three phosphate groups

Question 5

1. When there is three phosphate groups its called? 2.When there is 2 phosphate groups its called?
2. When there’s 1 phosphate group its called?

Answer 5

1.When there’s three phosphate groups: ATP (adenosine triphosphate)

Question 6

Is ATP a nucleotide?

Answer 6

ATP is nucleotide

Question 7

How many phosphate group does ATP have on it?

Answer 7

ATP contains three phosphate groups

Question 8

What in the phosphate molecule is key to how ATP stores energy

Answer 8

The three phosphate

Question 9

Why does ATP have a low activation energy?

Answer 9

The bonds between these phosphate groups are unstable and so have a low activation energy, which means they are easily broken. When they do break they release a considerable amount of energy.

Question 10

In living cells which phosphate molecule is removed to realise energy?

Answer 10

Using in living cells, only the terminal (3rd phosphate along) is removed. It is inefficient making the energy from this molecule any other way.

Question 11

What is the equation for ATP realising energy?

Answer 11

ATP + H2O -> ADP + Pi
+ E
inorganic phosphate molecule

Question 12

What type of reaction is used to convert ATP to ADP?

Answer 12

As water is used to convert ATP to ADP, this is known as a hydrolysis reaction.

Question 13

What enzyme catalyses the reacton of ATP to ADP

Answer 13

The reaction is catalysed by the enzyme ATP hydrolase (ATPase)

Question 14

Is the conversion of ATP to ADP reversible?

Answer 14

The conversion of ATP to ADP is a reversible reaction

Question 15

As the conversion to ADP to ATP is reversible what is added to ADP to reform ATP and what is used?

Answer 15

An inorganic phosphate is added to ADP to reform ATP and energy is needed and an enzyme ATP synthase

Question 16

What enzyme is used in the conversion of ADP to ATP?

Answer 16

ATP synthase

Question 17

What type of reaction is the conversion of ADP to ATP?

Answer 17

A condensation reaction as water is realsed

Question 18

What is the 3 ways the synthesis of ATP to ADP can occurs?

Answer 18

The synthesis of ATP from ADP involves the addition of a phosphate molecule to ADP. It occurs in three ways:

• in chlorophyll-containing plant cells during photosynthesis (photophosphorylation)
• in plant and animal’s cells during respiration (oxidative phosphorylation)
• in plant and animal cells when phosphate groups are transferred from donor molecules to ATP (substrate-level phosphorylation)

Question 19

Why is ATP a good energy donor, therefore used as a immediate energy source for the cell?

Answer 19

The same feature that makes ATP a good energy donor is, due to the instability of its phosphate bonds

Question 20

Why is ATP not a good long term energy-term energy store?

Answer 20

The same feature that makes ATP a good energy donor is the instability of its phosphate bonds fats, and carbohydrates such as glycogen, serve this purpose far better. ATP is therefore the immediate energy source of a cell. As a result, cells do not store large quantities of ATP, but rather just maintain a few seconds’ supply. This is not a problem, as ATP is rapidly re-formed from ADP and inorganic phosphate (Pi) and so a little goes a long way. ATP is a better immediate energy source than glucose for the following reasons:

Question 21

ATP is used as a what source of energy in the cell?

Answer 21

An immediate energy source for the cell. As a result, cells do not store large quantities of ATP, but rather just maintain a few seconds’ supply. This is not a problem, as ATP is rapidly re-formed from ADP and inorganic phosphate (Pi) and so a little goes a long way. ATP is a better immediate energy source than glucose for the following reasons:

Question 22

ATP is a better immediate energy source than glucose for what reasons

Answer 22

ATP is a better immediate energy source than glucose for the following reasons:

• each ATP molecule releases less energy than each glucose molecule. The energy for reactions is therefore released in smaller, more manageable quantities rather than the much greater, and therefore less manageable, release of energy from a glucose molecule.
• 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 therefore the energy release takes longer.

Question 23

Can ATP be stored

Answer 23

ATP cannot be stored

Question 24

As ATP cannot be stored ATP it has to be continuously made in what organelle?

Answer 24

ATP cannot be stored and so has to be continuously made within the mitochondria of cells that need it.

Question 25

What cells in the body have many mitochondria

Answer 25

Cells, such as muscle fibres and the epithelium of the small intestine, which require energy for movement and active transport respectively, posses many large mitochondria.

Question 26

ATP is used in energy -requiring processes in cells including

Answer 26

1. metabolic processes. ATP provides the energy needed to build up macromolecules from their basic units. For example, making starch from glucose or polypeptides from amino acids
2. movement. ATP provides the energy for muscle contraction. In muscle contraction, ATP provides the energy for the filaments of muscle to slide past one another and therefore shorten the overall length of a muscle fibre.
3. active transport. ATP provides the energy to change the shape of the carrier proteins in plasma membranes. This allows molecules or ions to be moved against a concentration gradient.
4. secretion. ATP is needed to form the lysosomes necessary for the secretion of cell products.
5. activation of molecules. The inorganic phosphate released during the hydrolysis of ATP can be used to phosphorylate other compounds in order to make them more reactive, thus lowering the activation energy in enzyme-catalysed reactions. For example – the addition of phosphate to glucose molecules at the start of glycolysis.