Unit IV: Cell energy

Part I: energy in living

systems

List as many different forms of energy as you can

Give at least 2 examples of energy

being converted from one form to another

Energy•Definition: ability to do work•Sources of energy for biological organisms•Food we eat (chemical energy)•Energy from the sun (light energy)

Thermodynamics•Definition: Study of energy transformations in the universe•Two laws of Thermodynamics:•Energy is neither created nor destroyed; it is merely converted from one form to another•Energy cannot be converted without loss of useable energy•Energy is lost in the form of heat (thermal energy)

Food Chain!

Organisms Need Energy to Live

•Organisms get their energy in two different ways:•Autotrophs:•Organisms that make their own food (Ex. Plants)

•Heterotrophs:•Organisms that get food from external environment (Ex. Humans)

Auto or Hetero?

Auto or Hetero?

Auto or Hetero?

Auto or Hetero?

Metabolism•Definition: all the biochemical reactions in a cell•Biochemical pathway•Chemical reactions that are aligned in a sequence

Biochemical Pathways•Anabolic Pathway• Build large molecules from small molecules• Ex: Make proteins from individual amino acids

• Requires energy

•Catabolic Pathway• Break large molecules into small molecules

• Ex: Breakdown proteins into individual amino acids• Releases energy

In Ecosystems:•Photosynthesis• Performed by autotrophs• Anabolic pathway – makes organic compounds• Chemical Reaction: Light Energy + CO2 + H20 C6H12O6 + O2

•Cellular Respiration• Performed by almost all organisms• Catabolic pathway – organic compounds are broken down• Chemical Reaction: C6H12O6 + O2 CO2 + H20 + Energy

Compare the chemical reactions for

photosynthesis & CR. What do you notice about the 2

reactions?

Chemical Energy in Cells•ATP (Adenosine Triphosphate)•Most important biological

molecule that provides chemical energy to the cell

Structure of ATP•Made of:•Adenine base•Ribose sugar•3 phosphate groups

Function of ATP•Releases energy when the bond between the 2nd & 3rd phosphate is broken •(ATP->ADP)

Explain how the energy in ham and cheese sandwich ultimately came from the sun. In thinking about this problem, consider the energy

transformations that occur in the food chain.

Answer ?s in Unit Book