Structure and Function of ATP (NICO) Flashcards
(22 cards)
Meaning of ATP
Adenosine Triphosphate
It is often referred to as the energy currency of a cell as it can pick up energy and transfer that energy to another chemical process
ATP
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Contains sugar ribose, N-base adenine, and a chain of three phosphate
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ATP
Structure of ATP
Sugar ribose, N-base adenine, chain of three phosphate
3 main kinds of work of a cell
chemical work, transport work, and mechanical work
possible through energy coupling, where the cells use an exergonic process to drive and endergonic reaction
3 main kinds of works
synthesis of polymers from monomers (pushing of endergonic reactions)
chemical work
pumping of substances across membranes (against the direction of spontaneous movement)
transport work
beating of cilia, contraction of muscles
mechanical work
used to make RNA
ATP (since ATP is used as one of the nucleoside triphosphate)
The bond between phosphate groups can be broken down by hydrolysis
TRUE
When the terminal phosphate is broken down by the addition of water molecule, a molecule of inorganic phosphate (HOPO3^-2) leaves the ATP
TRUE
The reaction is exergonic and releases ______ of energy per mole of ATP hydrolyzed
-7.3 kcal
Formula of ATP hydrolysis
ATP + H2O —> ADP + Pi
What happens during ATP Hydrolysis
- A lone pair of e- of oxygen in H2O will launch a nucleophilic attack on the phosphorus (of
phosphate). - However, it needs to overcome the negative charges to get close to the POSITIVE CHARGES. It
can be done with the help of ATPases. - ATPases surround the ATP molecule with positive ions and keep the negative ions busy.
- Eventually the electrons can bond with terminal P and cleave the bond.
- At the end of hydrolysis, ADP and inorganic phosphate (HOPO3^-2) are formed.
What is somewhat greater energy is released than the energy most other molecules could deliver
The energy released by ATP on losing a phosphate group is
somewhat greater
But why does this hydrolysis release so much energy?
we can see that all three
phosphate groups are negatively charged. These like charges are
crowded together, and their mutual repulsion contributes to the
instability of this region of the ATP molecule. The triphosphate tail of
ATP is the chemical equivalent of a compressed spring.
The adjacent negative charges repel each other.
ELECTROSTATIC REPULSION
The molecule that can achieve a lower energy state by hydrolysis, which allows the phosphate groups to separate from each other
ELECTROSTATIC REPULSION
When energy is released….
This comes from the chemical change of the system state of lower free energy and NOT from the phosphate
bonds.
How does the ATP Hydrolysis perform work?
Most of the time when an animal is exposed to a cold environment, the reaction of the body is through shivering. In this reaction of the organism, shivering uses ATP during muscle
contraction to warm the body. Since it will also be a disadvantage for organisms to generate heat during ATP hydrolysis, to maintain the living conditions inside the cell, the energy released during ATP hydrolysis is used by proteins to perform work: chemical, transport, and mechanical Hydrolysis of ATP leads to a change in the shape of the protein and in its ability to bind to another molecule. Phosphorylation (ADP to ATP) and dephosphorylation (ATP to ADP) promote crucial protein shape changes during important cellular process
Reaction coupling
> The use of an exergonic process to drive an endergonic one.
Two reactions are linked together with one providing the energy needed for the other to occur.
The linking often happens through a shared intermediate, meaning that a product of one reaction is “picked up” and used as a reactant in the second reaction.
The energy generated from one reaction is used to drive the second reaction. This is being done by phosphorylation.
