Lesson 23 - ATP

Question 1

brief overview of how ATP is created

Answer 1

• All living organisms require energy to stay alive
• This energy comes initially from the sun
• Plants then use the sun’s energy to make organic molecules (sugars) through the process of photosynthesis(autotroph). - They use these molecules for growth and respiration.
• Heterotrophic organisms need to eat plants/animals that have eaten plants in order to gain the organic molecules needed for respiration.
• Sugars are respired to make molecules called ATP
  ATP is used by cells as the main energy source to carry out processes (e.g. the energy needed for anabolic reactions).

Question 2

what does ATP consist of?

Answer 2

3 phosphate molecules
1 ribose
1 adenine

Question 3

what does ATP stand for?

Answer 3

Adenosine Triphosphate

Question 4

what does ADP stand for?

Answer 4

Adenosine Diphosphate

Question 5

ATP hydrolase equation

Answer 5

ATP + H2O → ADP +Pi (+energy)

Question 6

is the hydrolase of ATP, exergonic or endergonic?

Answer 6

Hydrolysis of ATP to ADP + P is an Exergonic reaction fueling endergonic reactions

Question 7

is the synthase of ATP, exergonic or endergonic?

Answer 7

Formation of ATP from ADP + P is an Endergonic reaction fueled by exergonic reactions

Question 8

ATP synthase equation

Answer 8

ADP + Pi + 2H+ (energy out) ⇌ ATP + H2O + 2H

Question 9

what is the differnce between exergonic and endergonic reactions?

Answer 9

Exergonic: releases energy
Endergonic: absorbs energy

Question 10

The synthesis of ATP by the addition of a phosphate to ADP can occur in 3 ways:

Answer 10

• In the mitochondria of plant and animal cells during respiration (oxidative phosphorylation)
• In the chloroplasts of chlorophyll containing plant cells during Photosynthesis (photophosphorylation)
• In plant and animal cells when phosphate
  groups are transferred from donor molecules to ADP, requiring an enzyme (substrate-level phosphorylation)

Question 11

what are some properties of ATP?

Answer 11

• Releases energy in small manageable amounts & rapidly
• One single bond broken - therefore, immediate energy source NOT store
• Provides energy for reactions that require it (endergonic)
• Always readily available - because when hydrolysed for energy - rapidly reformed again
• Very water soluble - therefore transportable
• However - can NOT cross plasma membranes -
• So remains within cells - so that it is always available to act as an energy source for reactions in the cell
• Requires protein carriers to cross the membrane

Question 12

Roles of ATP?

Answer 12

It is used in many energy-requiring processes in cells including:
- Metabolic processes, anabolic reactions
- Movement, muscle contraction
- Active Transport, molecules travelling against their concentration gradient
- Secretion of products from cells
- Activation of molecules, The inorganic phosphate released when ATP is hydrolysed can be used to phosphorylate other things in order to make them more reactive (therefore lowering the activation energy in enzyme catalysed reactions).

Question 13

Compare ATP, glycogen and triglyceride in terms of their energy storage

Answer 13

ATP - immediate donor of energy
glycogen - mid term energy storage molecule
triglyceride - longer-term energy storage molecule