The Need For Energy

9.1 The Need for Energy

Why do organisms need Energy? Energy is needed by organisms for activities such as: Muscle contraction Heart pumping

On a cellular level, energy is needed for: Active transport of ions across membrane (transmitting impulses in a nerve cell) Transport of hormones out of cell (exocytosis) Cell division (growth)

Need for energy continued Microorganisms need energy for: Movement of cilia or flagella Feeding (endocytosis)

Animals such as firelies or jellyfish need

energy to:

Produce light (bioluminescence)

How is Energy obtained? Plants and other green organisms trap energy

from sunlight and store it in sugar molecules for later use: Photosynthesis Animals eat plants or other animals to obtain the energy stored

ATP: The Energy Currency of The Cell ATP: Adenosine Triphosphate is composed of Adenosine (adenine + ribose sugar) 3 negatively charged phosphate groups

Energy between phosphate groups Adenosine plus a little bit of energy is required to add 1 phosphate group (AMP: adenosine monophosphate) A little more energy is required to add a second phosphate group to produce (ADP: adenosine diphosphate) A lot of energy is required to add the third phosphate group to produce (ATP: adenosine triphosphate) 

Formation & Breakdown of ATP http://student.ccbcmd.edu/biotutorials/energy /images/atp.gif

Breakdown of ATP Removing a phosphate (Pi) from ATP to

produce ADP is a hydrolysis reaction (water is added) This reaction is catalyzed by the enzyme ATPase

Formation of ATP ADP + Pi is catalyzed by the enzyme ATP

synthase