Energy and Life 8-1

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

Chemical Energy and ATP ATP structure: Adenine 3 phosphate groups Ribose

Chemical 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 ATP The resulting molecule is called ADP Adenosine Diphosphate It can have phosphate groups re-attached to be used again Energy!

Chemical 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 Energy Most energy in a cell is used for active transport Also used for protein synthesis, contracting muscle cells, etc. All life processes

Using Biochemical Energy 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 Energy 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 Energy 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