Energy & ATP

Mrs. StewartHonors BiologyCentral 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 – ShareQ: 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.