NOTES Cell Energy Part 1 Adenosine Triphosphate ATP

NOTES – Cell Energy Part 1 Adenosine Triphosphate (ATP)

Why do cells need energy?

In what ways are our cells like a tower? n n Are they organized? Do they have structure? There there forces in the environment that act to destroy the cell’s structure Randomly moving molecules n Physical forces n Chemical attack n n Disorder (entropy) is always on the increase

How can cells maintain their highly ordered structure? n n It takes energy, work, and information to maintain order Cells need energy just to stay the way they are and not break down

What do cells use energy for? n n n Repair themselves Growth Reproduction Movement Active transport Protein synthesis

ATP – The “energy currency” of the cell n n n ATP molecules are the basic energy source for cells ATP stands for adenosine triphosphate ATP molecules carry just enough energy to power a variety of cell activities

Structure of ATP n ATP molecules have three parts: 1. 2. 3. Adenine (a nitrogen-containing compound) Ribose (a 5 -carbon sugar) 3 Phosphate Groups

ATP Molecule

How does ATP store energy? n n n Chemical energy is stored in the bond between an ATP molecule’s second and third phosphate group Breaking the bond releases energy for cellular work ATP becomes ADP (adenosine diphosphate)

The ATP Cycle 1. Energy is used to bond ADP to a free phosphate creating a high-energy ATP molecule 2. ATP is broken down into ADP, releasing stored energy for cell work

The ATP Cycle Continued n n n ATP is a high-energy molecule ADP is a low-energy molecule When ATP is broken down, ADP and the extra phosphate can be recycled into more ATP

ATP Cycle Equations n Cell storing energy (endergonic): n n ADP + energy ATP Cell releasing energy (exergonic): n ATP ADP + energy

ATP is like a rechargeable battery n n Batteries are used, giving up their energy and can only be reused after the input of new energy ATP is the recharged battery while ADP is the used battery When the third phosphate is cut loose, ATP becomes ADP, and the stored energy is released. The input of additional energy (plus a phosphate group) "recharges" ADP into ATP

How fast is the ATP cycle? n n n A working muscle cell recycles all of its ATP about once each minute That’s about 10 million molecules of ATP consumed & regenerated per second, per cell! (600 million molecules per minute!) If ATP was not continuously regenerated, you would need to consume an amount roughly equal to your bodyweight every day to meet the energy needs of your cells!

How do cells make ATP? n n There a variety of processes that different types of cells use to produce ATP Eukaryotic cells produce ATP during 2 main processes: 1. Photosynthesis (plant cells only) – ATP is made using energy from the sun, then immediately used to help chloroplasts make larger food molecules 2. Respiration (plant and animal cells) – ATP is made using energy from food molecules

Cells use ATP molecules for their energy needs As ATP is used up, more is made by the cell Cells need a continuous input of energy in order to keep making ATP