What is Energy? Essential Questions: What is energy? Where does it come from? How does our food hold energy and how do we get the energy out from our food? What is ATP and how is it used by the cell?

Where does all energy come from? The Source of all energy comes from the SUN! Energy - Is the capacity to do work which comes from the breaking of bonds and rearranging them to form new, and sometimes very different, products during a chemical reaction. –Exothermic : Combustion is an example of an exothermic process. It is an exothermic chemical reaction (give out heat to the surroundings). E.g., Burning of coal –Endothermic: Photosynthesis is an example of an endothermic chemical reaction. In this process, plants use the energy from the sun to convert carbon dioxide and water into glucose and oxygen.

Why do we need energy? LARGE SCALE: –So far we know all animals (heterotrophs) and plants (autotrophs) need energy to live. MOLECULAR SCALE: –So far we have learned that certain cell processes require energy to maintain homeostasis: Active Transport Facilitated Diffusion Cell Division Cilia & Flagella Enzymes Production and storage of proteins What organelle makes energy for the eukaryotic cell? Mitochondria!

How does our Food hold energy? The energy in our food is stored within the bonds between atoms. –Especially Glucose, the major energy storage molecule. –Glucose stores a good amount of energy. Similar to that of a $100 bill. Can you think of a case when 100 dollar bills are preferable to 1 dollar bills?

Two things can happen to glucose… 1.It can be burned through cellular respiration to make energy… OR 2.It can be strung together to make carbohydrates like starch for long term energy storage. (or cellulose in plants)

How is the energy from our food released? Bonds between the atoms are broken, releasing energy! –We call this Cell Respiration! If Glucose is like a 100 dollar bill, what is the smaller change used for small cellular reactions? –Like a 1 dollar bill? 50 cents?

Energy Currency of the Cell - ATP Called Adenosine Triphosphate Composed of… 1. an Adenine Molecule 2. a 5 Carbon Ribose Sugar 3. And 3 Phosphate groups attached The Phosphate groups are negatively charged and 3 charged groups will not like to be next to one another. –Like North & North poles on a magnet. –That repulsion stores a lot of energy! The covalent bonds that unite the phosphate units in ATP are high-energy bonds. This is where the energy is stored. When an ATP molecule is broken down by an enzyme, the third (terminal) phosphate unit is released as a phosphate group, or ion. When this happens, approximately 7.3 kilocalories of energy are released. (A kilocalorie equals 1,000 calories.) This energy is made available to do the work of the cell.

Energy conversions When the bond in a molecule of ATP (3 Phosphate) is broken, it converts from ATP to a lower energy form. (Like a 1 dollar bill!) –A 2 Phosphate molecule is called ADP, it has less energy because there are only 2 phosphate groups repelling one another. (50 cents) –A 1 Phosphate molecule is called AMP, it has the least energy because there is only 1 phosphate group. (25 cents!) nimat/metabolism/atpsyn1.swf Remember : ATP is not a good way of storing energy long term, glucose can store 90 times the chemical energy of ATP.

Energy Recycling makes happy proteins! An enzyme, ATP Synthase uses a proton (H+) gradient in the Mitochondria to add phosphorus back to ADP to create ATP. ages/anim/ATPmito.htmlhttp:// ages/anim/ATPmito.html This system of ATP/ADP is good because… –Relieves the cell of having to store all the ATP it needs. –ADP can be used as a resource for cell activities that do not require as much energy (as ATP would provide) so it is cost efficient. nts/Biology/Bio231/etc.html atpgradient/movie.htm

Real World Connection: Blood Sugar and Diabetes The blood glucose level is the amount of glucose in the blood. Glucose is a sugar that comes from the foods we eat, and it's also formed and stored inside the body.Glucose It's the main source of energy for the cells of our body, and it's carried to each cell through the bloodstream. Blood glucose levels are regulated by the pancreas and the liver to maintain the delicate balance in the body. –What happens when you are hypoglycemic? –What happens when you are hyperglycemic? –What is the balance of blood sugar called?