Energy and Photosynthesis Cell Energy All living organisms

Energy and Photosynthesis

Cell Energy • All living organisms must be able to obtain energy from the environment in which they live. • Plants and other green organisms are able to trap the light energy in sunlight and store it in the bonds of certain molecules for later use.

Obtaining energy • All organisms must have a way to obtain energy. They are classified in 2 ways: – Autotrophs – organisms that can make their own food – Heterotrophs – organisms that must obtain energy by consuming other organisms

Work and the need for energy • Active transport, cell division, movement of flagella or cilia, and the production, transport, and storage of proteins are some examples of cell processes that require energy. • There is a molecule in your cells that is a quick source of energy for any organelle in the cell that needs it.

Work and the need for energy • The name of this energy molecule is adenosine triphosphate or ATP for short. • ATP is composed of an adenosine molecule with three phosphate groups attached.

Comparing ATP & ADP = ½ charged battery ATP = fully charged battery 2 phosphate groups 3 phosphate groups

How cells tap into the energy stored in ATP • When ATP is broken down and the energy is released, the energy must be captured and used efficiently by cells. • Many proteins have a specific site where ATP can bind.

How does energy get to Earth? • • Energy from sun goes into plants Plants make sugars Animals eat the plants Other animals eat the first animals.

Trapping Energy from Sunlight • The process that uses the sun’s energy to make simple sugars is called photosynthesis.

The chloroplast and pigments • To trap the energy in the sun’s light, the chloroplasts contain pigments, molecules that absorb specific wavelengths of sunlight. • The most common pigment is chlorophyll. • Chlorophyll absorbs most wavelengths of light except green. Since green light is reflected, we see plants as green.

Photosynthesis Reactions • Uses energy storing compounds (ATP and NADPH) to produce high energy sugars • Provides the raw materials to produce everything the cells needs.

• The general equation for photosynthesis is written as 6 CO 2 + 6 H 2 O→C 6 H 12 O 6 + 6 O 2 Carbon Dioxide + Water → Sugar + Oxygen

What affects the rate of photosynthesis? • Temperature – most efficient between 0 – 35 o C • Water – insufficient water may slow or stop photosynthesis • Light intensity – ↑ light = ↑ photosynthesis – ↓light = ↓ photosynthesis – There is a maximum rate!