Energy & ATP
Mrs. Stewart
Honors Biology
Central Magnet
Chemical Energy and ATP
• The main chemical compound that cells
use to store and release energy is called
ATP (adenosine triphosphate)
Adenosine Triphosphate
• All energy must eventually be in the form of
ATP in order for it to be used for cell
metabolism.
• ATP is the energy "currency" of the cell.
• Why?
• ATP is the only source of energy that the
body can use.
• Stored energy (e.g. fat, glycogen, creatine
phosphate) must first be converted to ATP
before the body can actually use it.
•You bring 50 loads of laundry to a
laundromat.
•It will only take quarters.
•It costs $5 in quarters per load
•There is a change machine at the
laundromat.
•Are you going to carry $250 in quarters?
Laundromat
Human Systems
Quarters
ATP
$1
Glycogen, Blood Glucose
$100
Stored Fat
Visa Checkcard
Protein
Storing Energy
• ATP holds energy in the bond between
the second and third phosphate group
• ATP is like a fully charged battery
• Stores enough energy for 8-12 seconds of
intense exercise.
Energy
Think – Pair – Share
Q: How is the energy in
ATP released?
A: Break bond between
the 2nd and 3rd
phosphates
ATP vs. ADP
• ATP – has all 3 phosphate groups
– Fully charged battery
– Brief energy storage
– Can remove a phosphate group to release energy
and form ADP
• ADP – has only 2 phosphate groups
– Partially charged battery
– Can add a phosphate group to make ATP
ATP Availability
• Most cells only have enough ATP for a few
seconds of activity
• Why?
– Not good at storing energy over the long term
– Glucose stores 90 times the chemical energy of
ATP
– Cells generate ATP from ADP as needed by using
the energy in foods (like glucose)
$1 = glycogen/glucose
• Glycogen/glucose is like having dollar bills that
can be broken down to quarters in a change
machine.
• Much greater capacity ($1) than carrying
quarters.
• The human body stores ~350 g of glycogen,
not enough to sustain long duration of exercise
or a period of time without food.
$100 = Stored Fat
• Fat stores are the energy sources for rest
and prolonged activity at lower levels of
exertion.
• Breaking down fat is a SLOW process. Just
like getting change for the $100 bill (in
quarters) would take a while, mobilizing
fat stores to be used to meet cellular
energy demands also takes longer than
using glucose or ATP.
VISA = Protein
• When either carbohydrate intake or overall
energy intake is low; proteolysis (the
breakdown of protein – mostly from lean
muscle) provides energy for biologic work.
• VISA: using protein as energy supplements
the ATP, glycogen and fatty acids that provide
the majority of the ATP.