Energy in Living SystemsPre-AP Biology

Bellwork• List as many different forms of energy as you can• Give at least 2 examples of energy being converted from one form to

another

Learning Objectives• Define thermodynamics• Explain the first and second laws of thermodynamics• Distinguish between a catabolic and anabolic biochemical

pathway• Explain the structure and function of ATP

Key Terminology• Thermodynamics• Autotroph• Heterotroph• Metabolism• Anabolic• Catabolic• Photosynthesis• Cellular Respiration• ATP

Energy• Definition: ability to do work• Sources of energy for organisms

• Food we eat (chemical energy)• Energy from sun – ultimate energy source

• Energy from sun used to create organic compounds (chemical energy) that other living organisms can use

Food Chain

Thermodynamics• Definition: Study of energy transformations in the

universe• Two laws of Thermodynamics

• First law: Energy is neither created or destroyed merely converted from one form to another (example-blender)• Second law: Energy cannot be converted without loss of useable energy Energy lost in the form of heat thermal energy; considered unusable energy

Think-Pair-ShareExplain how the second law of

thermodynamics applies to the blender when making a fruit smoothie.

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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• (Example-humans)

Autotrophs or Heterotrophs?

Metabolism• Definition: all the biochemical reactions in a cell• Biochemical pathway

• chemical reactions that are aligned in sequence

A B C D

Two types of Biochemical Pathways• Anabolic Pathway

• Build large molecules from small molecules• requires energy

• Catabolic Pathway• Break large molecules into small molecules• releases energy

In an Ecosystem:

• Photosynthesis• performed by autotrophs• Anabolic pathway - makes organic compounds• Chemical reaction:

Light Energy + CO2 + H20 C6H12O6 + O2

• Cellular Respiration• Catabolic pathway - organic compounds are broken down• Chemical Reaction:

C6H12O6 + O2 CO2 + H20 + Energy (ATP)

Think-Pair-ShareCompare the reaction for

photosynthesis and cellular respiration. What do you notice about the two reactions?

3

Chemical Energy In Cells• ATP (adenosine triphosphate)

• Most important biological molecule that provides chemical energy to the cell

Structure and Function of ATP

• Structure: made of adenine base, ribose sugar, and three phosphate groups

• Function: Releases energy when the bond between second and third phosphate group is broken

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Minute Paper

Explain how the energy in a ham and cheese sandwich ultimately came from the sun. In thinking about this problem, consider the energy transformations that occur in the food chain.

Be prepared to share

IYOW answer the following questions