8.1 Energy and Life
Biology
I. Autotrophs and Heterotrophs
• Energy is the ability to do
work
– Need to use and obtain
energy or living things will
die
• Energy comes from food
or sun
• Autotrophs
– Use light energy to make
their own food
– Plants, some bacteria
• Heterotrophs
– Organisms that cannot
make their own food
– Eat food to get energy
– Example: us, leopards,
etc
– Can also be
decomposers
• Ex: mushrooms, fungi
II. Chemical energy and ATP
• Energy has many forms
like heat, light, electricity
– Also in the form of
chemical compounds
• To release energy from
chemical compounds,
bonds are broken that hold
the elements together
• ATP (adenosine
triphosphate)
– Cellular energy
– Made of adenine (sugar),
ribose (sugar), and 3
phosphates
Storing energy
• ADP (adenosine diphosphate) only 2
phosphates attached
– When a cell has energy, it can store it by adding
a 3rd phosphate to make ATP
Releasing Energy
• To release energy in ATP, the last bond that
holds the 3rd phosphate is broken
– Energy is released
III. Using biochemical energy
• Uses of ATP
– Active transport
– Making proteins and nucleic acids
– Produce light (firefly)
• Cell only keeps a small amount of ATP on hand
– Its more efficient
– Make more energy by using the food we take in
• Cellular energy is created in the mitochondria
Photosynthesis Equation
• Carbon dioxide + water + light
glucose (C6H12O6) + oxygen
Light and Pigments
• Plants use sun’s
energy to go thru
photosynthesis
• Pigments in plants
help to absorb light
– Pigment-light
absorbing molecule
• Main pigment
– chlorophyll
Lights and Pigments
• The color you see is
reflected
• Chlorophyll reflects
green light and
absorbs reds and blues
very well
• Other pigments are
present
– Xanthophylls (reflect
yellow) and carotene
(orange)