Show Menu
Cheatography
  1. Home >
  2. Education >

Importance of ATP Cheat Sheet (DRAFT) by

The importance of ATP in all living organisms

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Structure and roles of ATP

Adenine tripho­sphate belongs to a group of molecules called nucleo­tides.
It is made from ribose and adenine (ribulose) and 3 phosph­ates.
It is the universal energy carrier (used in all reactions in all organi­sms), and releases energy in small quantities (30.6kJ per mol) via a one-step reaction when the high energy bond between the second and third phosphate group is broken.
This hydrolysis reaction is hydrolysed by the enzyme ATPase.

Structure of ATP

Structure of ATP

When ATP is hydrolysed, it provides energy for a wide range of processes including: protein synthesis, active transport and mitosis.

Comparison of ATP synthesis in mito and chloro

Features
Mitoch­ondria
Chloro­plasts
Mechanism
Uses energy carried by electrons to pump protons across the membrane, they then flow back through stalked particles
Uses electron energy to pump protons across the membrane, which then flow back through stalked particles
Enzyme involved
ATP synthase
ATP synthase
Proton gradient
From inter-­mem­brane space to matrix
From thylakoid space to stroma
Site of electron transport chain
  
Thylakoid membrane
Co-enzyme involved
FAD, NAD
Terminal electron acceptor
  
NAPD and H+ (non-c­yclic photop­hos­pho­ryl­ation) and chloro­phyll+ (cyclic photop­hos­pho­ryl­ation)
 

Structure of mitoch­ondria and chloro­plasts

The mitoch­ondria and chloro­plast membranes

During photos­ynt­hesis and respir­ation, ATP is made when protons are pumped across membranes using energy from electrons to create an electr­och­emical or proton gradient.
When the protons flow back through the stalked particles down the concen­tration gradient, by a process known as chemio­smosis, ATP synthase phosph­ory­lates ADP into ATP.
In chloro­plasts this occurs on the thylakoid membranes, whereas in mitoch­ondria it occurs on the inner membrane or cristae.
The electrons pass from the proton pumps to a terminal electron acceptor: in mitoch­ondria this is oxygen, in chloro­plasts it is in the coenzyme NADP or chloro­phyll.

Types of phosph­ory­lation

Phosph­ory­lation is the addition of a phosphate group or ion to a molecule.
In respir­ation and photos­ynt­hesis ADP is the molecule most often phosph­ory­lated, but other molecules can be phosph­ory­lated, e.g. glucose in glycolysis forming glucose diphos­phate.
This makes the glucose more reactive and easier to split as it lowers the activation energy of the reaction involved.
1. Oxidative phosph­ory­lation. This occurs when a phosphate ion is added to ADP using energy from electron loss i.e. oxidation reactions.
2. Photop­hos­pho­ryl­ation. The energy that powers the proton pump and electron transport chain in chloro­plasts comes from light, hence ATP in chloro­plasts is synthe­sised by photop­hos­pho­ryl­ation.
3. Substrate level phosph­ory­lation. This occurs when phosphate groups are transf­erred from donor molecules, e.g. phosphate is transf­erred from glycer­ate­-3-­pho­sphate to ADP in glycolysis of respir­ation.

Key Terms

Chemio­smosis
The flow of protons down an electr­och­emical gradient, through ATP synthase, coupled with the synthesis of ATP from ADP and a phosphate ion.
Activation energy
The energy needed to start a chemical reaction.