THE POINT IS TO MAKE ATP! ENERGY

What Just Happened? What did the cracker taste like when you first put it in your mouth? Did you experience any change in taste over the time you held the saltine in your mouth? Explain. Discuss what you think was happening in your mouth while you held the saltine.

Cell Energy Energy is essential to life Organisms obtain energy from their environment:  Plants: trap energy from the sun and store it for later use  Animals: eat food; in some ways, they obtain energy from plants

Which of the following requires energy? (circle them) Processes the require energy  Active transport  Cell division  Production and transport of proteins  Exercising  Heart pumping  Brain controlling all of the functions in your body

What happens after you finish “work”? Body needs a quick source of energy  You may eat Cellular level: energy is stored in the bonds of adenosine triphosphate (ATP)

Why is fat the choice? Humans store their excess energy as fat rather than carbohydrates…WHY?  When broken down by the body, each fat molecule yields 51 ATP molecules; each carbohydrate yields 36 ATP molecules.  Carbohydrates bind and store water. The metabolism of water yields 0 ATP. Fat has no water bound to it.  An adult who weighs 70 kg (~150 lbs) can survive on energy derived from stored fat for 30 days without eating. The same person would have to weigh nearly 140 kg (~310 lbs) to survive 30 days on carbohydrates.

ATP Structure Adenosine molecule + 3 phosphate groups Recall:  Phosphate groups are charged particles  Particles with the same charges do not like to be too close together.

Forming & breaking down ATP

ATP is cyclic The addition and release of a phosphate group on ADP creates a cycle of ATP formation and breakdown

ATP is cyclic We cannot store ATP because  Too reactive  Transfers energy too easily  Only short term energy storage  Carbs and fats are long term As long as phosphate groups are available the cell can make more ATP  A working muscle recycles 10 million ATPs per second

How cells use the energy… ATP is broken down and energy is released Cells must capture the energy or it is wasted Uses in the cell: making proteins or transporting molecules across the membrane Just like batteries in a remote…batteries

Let’s Revisit the Cracker Amylase, an enzyme which degrades starch into sugars, is present in our saliva and changes cracker starch into sugar. Sugars taste sweet; starch doesn't. Breaking down starches to sugars is necessary for the body to use the starch for energy (MAKE ATP)! HOW IS THIS ENERGY STORED? WHY? WHY DO MARATHON RUNNERS “CARB LOAD”?