Biology
Unit 1 Notes:
Living
Requirements
(1) What does it mean to be “alive”?
• In science this means that an organism has certain characteristics / behaviors:
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Able to reproduce (or make offspring).
Able to grow and develop.
Able to respond, adapt, and evolve.
Able to metabolize food compounds (for energy) and excrete waste.
• “Organisms” (living things) must be able to complete all of these behaviors on
their own!
(2) Other Living Qualities
• Scientists also know that ALL organisms share the following as well…
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Made of at least one cell (the most basic unit of life).
Made of 6 specific biological elements.
Made of 4 specific biomolecules.
Composed mostly of water.
(3) The Biological Elements
• These are elements that make up ALL living things and biomolecules.
• The Elements are:
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C = carbon
H = hydrogen
O = oxygen
N = nitrogen
P = phosphorus
S = sulfur
• Carbon is the backbone for all biological molecules:
Because it can form up to 4 bonds, it can reposition into a variety of molecular
structures.
(4) The Biomolecules
• These are molecules that make
up ALL living things.
• The Molecules:
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Carbohydrates
Lipids
Proteins
Nucleic Acids
(5) Why Water?
• Water is a polar molecule:
• This means that the charge across the molecule is unevenly distributed.
• The Hydrogen-Ends of water are more POSITIVELY charged.
• The Oxygen-End of water is more NEGATIVELY charged.
• Many of the molecules that make up cells are also polar, allowing them to
easily interact with water.
• Water drives very important energy-exchange reactions.
(6) Energy & Matter
• To remain living requires a lot of
cellular and chemical work.
• Work requires energy.
• Energy transfer comes from the
breaking and forming of bonds.
• Therefore ALL living things must:
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Consume things made of matter and energy.
Be able to change the form the matter and energy comes in.
Release unusable matter and energy.
*As living things do this they cycle matter and energy through their environment for others to use.
(7) Types of Energy
• There are 2 types of energy:
• Potential
• Kinetic
• Kinetic Energy is…
• The energy being used by a cell right now, in some reaction.
• Potential Energy is…
• Stored energy which can be used later.
• In Biology we focus on CHEMICAL POTENTIAL energy:
• The energy stored in the bonds of molecules.