Energy and LifeEnergy and Life

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EnergyEnergy

• Energy is the ability to do work– Work can be playing a sport, thinking, or

building a protein in a cell– All living things obtain and use energy

Autotrophs and Autotrophs and HeterotrophsHeterotrophs

• Autotrophs: organisms that use light energy from the sun to make food– Organisms that do photosynthesis or

something similar to obtain energy– Examples: plants and algae

Autotrophs and Autotrophs and HeterotrophsHeterotrophs

• Heterotrophs: organisms that obtain energy from the food they consume– Organisms dependent on consuming other

organisms for food– Examples: animals (us ) and fungi

Chemical Energy and ATPChemical Energy and ATP

• Energy comes in many forms– Examples: light, heat, electricity, kinetic

energy, potential energy

• Most energy used in living systems comes from breaking chemical bonds

Chemical Energy and ATPChemical Energy and ATP

• ATP (Adenosine Triphosphate): chemical compound living things use to store and release energy

Chemical Energy and ATPChemical Energy and ATP

• ATP structure:

Adenine

Ribose

3 phosphategroups

Chemical Energy and ATPChemical Energy and ATP

• Energy is stored in the bonds between the phosphate groups

• Energy is released when the bonds between the second and third phosphate is broken

Energy!

Chemical Energy and ATPChemical Energy and ATP

• The resulting molecule is called ADP– Adenosine Diphosphate – It can have phosphate groups re-attached to

be used again

Energy!

Chemical Energy and ATPChemical Energy and ATP

• Cells keep a lot of ADP on hand

• When energy becomes available cells store it by adding a third phosphate to an ADP– Making ATP

• When a cell needs to do work the third phosphate is broken off, releasing energy

Using Biochemical Using Biochemical EnergyEnergy

• Most energy in a cell is used for active transport

• Also used for protein synthesis, contracting muscle cells, etc.– All life processes

Using Biochemical Using Biochemical EnergyEnergy

• Cells keep a small supply of ATP on hand– Cells regenerate ATP from ADP using energy

in food molecules like glucose– Done by mitochondria

Using Biochemical Using Biochemical EnergyEnergy

• A single glucose molecule contains 90 times more energy than an ATP molecule– Jobs done in a cell require tiny amounts of

energy– We couldn’t consume enough food to

maintain life if a glucose molecule were consumed for each cellular job

Using Biochemical Using Biochemical EnergyEnergy

• Making ATPs from glucose is like “making change”– Similar to having 100 $1 bills instead of a

$100 bill if all you need is a candy bar