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Cell Energy

Biology 11

Energy and Metabolism

• Metabolism is all the chemical reactions required to support biological processes

• The reactions of metabolism are enzyme catalyzed and are all reversible.

• Adenosine Triphosphate (ATP) is the primary source of free energy in living cells

KWL CHART

What do I know about

ATP

What do I WANT to

know about ATP

What have I LEARNED about ATP

Where is Adenosine Triphosphate used in the cell?

Where is ATP produced in the cell? Connect to previous learning!

Fun Facts about ATP

• It is present in the cytoplasm and nucleoplasm of every cell, and essentially all the physiological mechanisms that require energy for operation obtain it directly from the stored ATP.

• 160kg of ATP is formed in the human body daily!

ATP • ATP contains the purine nitrogenous base

Adenine. This Adenine is attached to a five-carbon sugar, Ribose, which is bound to a chain of three phosphate groups

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ATP

• If you remove just one of these phosphate groups from the end, so that there are just two phosphate groups, the molecule is much happier.

• This conversion from ATP to ADP is an extremely crucial reaction for the supplying of energy for life processes.

• Just the cutting of one bond with the accompanying rearrangement is sufficient to liberate about 7.3 kilocalories per mole = 30.6 kJ/mol. This is about the same as the energy in a single peanut!

ATP Hydrolysis: Conversion from ATP to ADP

• Energy is released when ATP is converted to ADP

• Since the basic reaction involves a water molecule,

ATP + H2O → ADP + Pi

this reaction is commonly referred to as the hydrolysis of ATP.

ATP Hydrolysis

• Critical component to ATP is the phosphorous part.

• The three phosphorous groups are connected by oxygens to each other.

• Under the normal conditions in the body, each of these oxygens has a negative charge – electrons want to be with protons - the negative

charges repel each other.

• These bunched up negative charges want to escape - to get away from each other, so there is a lot of potential energy here.

ATP Hydrolysis

• When the cell requires free energy to drive a reaction, an enzyme called ATPase catalyzes the hydrolysis of the terminal phosphate of an ATP molecule, resulting in a molecule of adenosine diphosphate, ADP.

ATP Hydrolysis and Synthesis

• ATP + H2O ADP + Pi _ Energy

• The hydrolysis of a phosphate from ATP releases an amount of energy that is ideal for cellular metabolism

• The reverse process (phosphorylation) adds a phosphate and energy to ADP, resulting in ATP

• ATP + Pi + energy ATP + H2O

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REDOX REACTIONS

• Many chemical reactions involve the transfer of one or more electrons from one reactant to another.

• The process of losing electrons is called oxidation.

• The process of gaining electrons is called reduction

REDOX REACTIONS

• An electron transfer between two substances always involves an oxidation and a reduction, thus the name REDOX reaction.

REDOX REACTIONS

• The substance that gains the electron is reduced and the substance that provides the electron is called the reducing agent

• The substance that loses the electrons is oxidized and the substance that takes the electron is called the oxidizing agent

REDOX REACTIONS

• In some cases, a series of redox reactions occur in which the product of one redox reaction is the reactant of the next in the series.

• In this case, a substance that was reduced in the first reaction becomes oxidized in the next reaction.

• This can happen over a number of reactions, resulting in the transport of electrons through a

series of increasingly stronger electron carriers.