Energy and the role of ATP

Introduction to ATP and respiration

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Why do we need energy?

Cells require chemical energy for biological processes. Without it, we would die.

These processes include:

  • active transport
  • contraction of muscles
  • reproduction
  • growth
  • maintenance of body temperature

Plants require energy for:

  • uptake of minerals though roots
  • photosynthesis
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ATP (adenosine triphosphate) Intro

ATP is a small, water soluble molecule

It is made from adenine (a nucleotide base), a ribose sugar and 3 phosphate groups

It is a phosphorylated nucleotide (a nucleotide grp w. extra phosphate(s) attached)

Function: to carry energy from energy-releasing reactions to energy-consuming reactions

ATP is synthesised from ADP (adenosine diphosphate) + an inorganic phosphate (Pi), using energy from the breakdown of glucose. ATP synthase (an enzyme) catalyses the reaction.

It moves to the part of the cell that requires energy

ATP is then broken down to ADP + Pi and releases chemical energy. ATP-ase catalyses the reaction

ADP + Pi are recycled and the process repeats.

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Respiration Intro

Cells break down glucose to release energy by cellular respiration, producing CO2 + H2O + energy

The energy is used to produce ATP from ADP + Pi

Summary equation for aerobic respiration:

C6H12O6 + 6O2 -------> 6CO2 + 6H2O + energy

Respiration occurs in the mitochondria of eukaryotic organisms

cells that require lots of energy eg muscle/liver/sperm will have lots of mitochondria

ATP is produced in a stage called the electron transport chain, via the 'stalked particles' on the cristae of the inner membrane of the mitochondrion, and the Krebs cycle occurs in the matrix of the mitochondria

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Respiration terms/definitions

Catabolism: breaking down large molecules into smaller ones

Anabolism: combining smaller molecules to form larger ones

Both involve enzymes

Metabolic pathway: a series of small, enzyme-controlled reactions (eg respiration)

Phosphorylation: adding phosphate to a molecule (eg making ATP from ADP + Pi)

Photolysis: splitting a molecule using light energy (a photon)

(photo=light , lysis=splitting with)

Hydrolysis: splitting a molecule using water


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Redox reactions in respiration (and photosynthesis

Redox reactions involve both reduction and oxidation

Oxidation of one thing always means that something else is reduced

Reduction is:

gain of e- (electrons)

sometimes loss of oxygen, gain of hydrogen

Oxidation is:

loss of e-

sometimes loss of hydrogen, gain of oxygen

use 'OILRIG'

Oxidation Is Loss, Reduction Is Gain (of electrons and H)

The enzymes catalysing redox reactions are oxidoreductases

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