Download Energy and Life 8-1

Energy and Life 8-1
Autotrophs and Heterotrophs
• Where does the energy that living things need
come from?
• Plants and some types of organisms are able
to use light energy from the sun to produce
food
• Organisms such as plants, which make their
own food are called autotrophs.
• Other organisms known as heterotrophs,
obtain energy from the foods they consume.
Chemical Energy and ATP
• Energy can be stored in chemical compounds.
• The activities of the cell are powered by
chemical fuels. One of the principal chemical
compounds that living things use to store
energy is adenosine triphosphate.
• ATP consists of a nitrogen-containing
compound called adenine, a 5-carbon sugar
called ribose, and a three phosphate groups.
• Adenosine diphosphate (ADP) has a structure
similar to ATP but with one important
difference.
• ADP has two phosphate groups instead of
three.
• This difference is the key to the way in which
cells store energy.
Releasing Energy from ATP
• Energy stored in ATP is released when ATP is
converted into ADP and a phosphate group.
• Because a cell can add and subtract a third
phosphate group, it has a way of storing and
releasing energy as needed.
• The characteristic of ATP make it an
exceptionally useful molecule that is used by
ALL types of cells as their basic energy source.
• Cells use the energy from ATP to allow active
transport to occur.
• ATP also powers movement within the cell.
Cell organelles are moved along microtubules
by proteins that use ATP to generate force.
ATP and Glucose
• Most cells have only a small amount of ATP,
just enough to last for a few seconds of
activity.
• ATP is not good for storing large amounts of
energy over the long term.
• Cells can regenerate ATP from ADP as needed
by using the energy in carbohydrates like
glucose (sugar).