Download Energy and Life

PHOTOSYNTHESIS
Cellular Basis of Life
ENERGY AND LIFE
Energy – is the ablility to do work.
In our bodies we use energy for everyday activities but
even when your sleeping your body is using energy to
build new molecules, contract muscles and carry out
active transport.
Cells use adenosine triphosphate (ATP) to
store and release energy.
•
ATP can easily release and store energy by breaking and re-forming the bonds
between its phosphate groups – This makes it exceptionally useful as a basic
energy source for all cells.
•
Cells use ATP to carry out Active transport, synthesis of proteins and respond to
chemical signals at the cell surface.
Heterotrophs and Autotrophs
•
Heterotrophs – organisms that obtain food by consuming other living things.
•
Autotrophs- organisms that make their own food. Examples: plants, algae and
some bacteria.
•
The process by which autotrophs use the energy of sunlight to produce highenergy carbohydrates (sugars and starches) is known as photosynthesis.
•
In the process of photosynthesis, plants convert the energy of sunlight into
chemical energy stored in the bonds of carbohydrates.
Light
•
Light- “white light” is actually a mixture of different wavelengths.
•
Photosynthesis organisms capture energy from sunlight with pigments.
•
The plants main pigment is Chlorophyll. (chlorophyll a & chrolophyll b)
•
As temperature drops , chlorophyll molecules break down it leaves colors of red
and orange.
Chloroplasts
•
They contain saclike photosynthetic membranes called thylakoids.
Thylakoids are interconnected and arranged in stacks known as grana.
The fluid portion of the chloroplasts , outside the thylakoids is known as the
stroma.
Collecting energy from the Sun
•
Because light is the form of energy, any compound that absorbs light absorbs
energy.
•
When chlorophyll absorbs light a large fraction of the light energy is transferred
directly to electrons in the chlorophyll molecule itself.
•
By raising energy levels of these electrons, light energy can produce a steady
supply of high-energy electrons---this makes photosynthesis work.