Lesson 1

• cells - need chemical energy to carry out their life sustaining process
• What do the cells need chemical energy for?

  • to move
  • to reproduce
  • to grow
• ex. of actively transport materials across cell membrane

  • endocytosis
  • exocytosis
  • sodium-potassium pumps
• Example of activation energy - carrying out chemical reactions.

  • photosynthesis
  • respiration
  • metabolism
• Energy is stored in Food Molecules
• Chemical energy is stored in the organic molecules found in foods.
• Carbohydrates and Lipid molecules are the most important energy containing molecules in foods we eat.
• Organisms are classified by how they obtain their food
• Autotrophs make their own food from simple chemicals using light or other forms of energy as an input. They can be photosynthetic (plants) or chemosynthetic (some bacteria).
• 2 Groups of Autotrophs 

  • Photoautotrophs 
  • Chemoautotrophs 
• Photoautotrophs use Light Energy to make their food through Photosynthesis.

  • CyanoBacteria 
  • Protists (Algae) 
  • Plants
• Chemoautotrophs - use Chemical Energy to make their food through Chemosynthesis 

  Ex. Archaebacteria 
• Autotrophs make the organic compounds that serve as food for themselves and all other organisms on Earth. 
• 2. Heterotrophs are Organisms that eat other organisms (or their products) to obtain energy and carbon compounds. 

  • Animals 
  • Fungus 
  • Some Protists 
  • Most Bacteria
• Law of Conservation of Energy 

  “Energy cannot be created nor destroyed but it can be changed from one form to another”
• Energy Transformations that Support Life 

  Two processes are needed to convert the sun’s light energy into chemical energy the cell can use. 

  PHOTOSYNTHESIS & CELL RESPIRATION
• In photosynthesis, sunlight Energy is transformed into chemical Energy stored in food molecules. 
• In cell respiration, the chemical Energy stored in food molecules is released and repackaged into high energy molecules called ATP the cells can use.
• What happens to the Energy released from food in cellular respiration?

  • It is used to make high energy molecules called ATP
• ATP stands for the molecule Adenosine Triphosphate
• ATP is a high energy containing molecule used by all cells to carry out cellular functions.
• ADENOSINE TRIPHOSPHATE (ATP)

  • molecule in cell that allows for quick and easy access to energy when needed by the cell’s organelles
  • energy currency of the body
  • type of chemical energy
  • releases energy when chemical bonds are broken
• The ATP – ADP cycle

  ATP – High energy molecule

  ADP – Low energy molecule
• The process of making ATP from ADP + Pi is called phosphorylation
• Phosphorylation is the addition of a phosphate group to another molecule
• hydrolysis - water is used to break down chemical bonds
• When ATP loses a phosphate molecule it gives off Energy and becomes ADP.
• The Energy source to “recharge” ADP comes from the breakdown of food through respiration.
• ATP is linked to a process known as coupled reactions. It means two

  reactions occur at the same time and at the same place, usually utilizing the same enzyme complex.
• All chemical reactions either give off (exothermic) or take in

  (endothermic) energy.
• In a coupled reaction, an exothermic reaction supplies the energy needed to drive an endothermic reaction.
• The release of phosphate from ATP is exothermic and the reaction it is connected to is endothermic.
• Energy is stored from the breakdown of food molecules. The phosphate bonds in ATP are very helpful for storing energy.
• Energy that is released during breakdown of chemical bonds linking the phosphate groups in ATP is used by the cells to do their

  functions.
• The used-up energy, the ADP has a reduced amount of chemical energy than ATP.
• How do cells release energy?

  • Energy stored in food molecules is released in a series of enzyme-catalyzed chemical reactions.
  • When cells break own molecules, some of the energy released is in the form of heat.
  • The rest of the energy is stored as

  ATP
• • The chemical energy stored in food is changed in cells into forms needed to perform all the activities necessary for life.
  • The total of all chemical reactions in an organism is called METABOLISM.