Transcript chemistry of living things

Chapter 2
CHEMISTRY OF LIVING
THINGS
CHEMISTRY
• Defined as the study of the
structure of matter and the
composition of substances, their
properties, and their chemical
reactions
• Biochemistry is the study of
chemical reactions of living things
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MATTER AND ENERGY
• Matter is anything that has weight
and occupies space; it is neither
created nor destroyed
• Energy is the ability to do work or
to put material into motion and
exists in the body as:
– Potential energy
– Kinetic energy
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ATOMS
• An atom is the smallest piece of an
element
• Atoms are made of subatomic
particles
– Protons have a positive charge
– Neutrons have no charge
– Electrons have a negative charge
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ATOMS
• Isotopes are atoms of a specific
element with the same number of
protons but a different amount of
neutrons
– Radioactive Isotopes are unstable and
may decay
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ELEMENTS
• Atoms that are alike combine to
form elements
• There are 92 elements found
naturally and each is represented
by a chemical symbol or
abbreviation
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COMPOUNDS
• Organic compounds are compounds
found in living things containing the
element carbon
• Molecules are the smallest units of
compounds that retain its
properties and remain stable
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IONS AND ELECTROLYTES
• Ions are atoms that have more
protons than electrons; creating a
positive charge
• Electrolytes are atoms that have
more electrons than protons;
creating a negative charge
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TYPES OF COMPOUNDS
• Inorganic Compounds
– Made of molecules that do not contain
carbon (C)
• Organic Compounds
– Always contain the element carbon (C)
– 4 Groups of organic compounds are:
• Carbohydrates
• Lipids
• Proteins
• Nucleic acids
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CARBOHYDRATES
• All carbohydrates are compounds of
carbon, hydrogen, and oxygen
• 3 Groups of carbohydrates:
– Monosaccharides
– Disaccharides
– Polysaccharides
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LIPIDS
• Lipids contain less oxygen than
hydrogen
• Examples of lipids:
– Fats
– Phospholipids
– Steroids
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PROTEINS
• Proteins are among the most
diverse and essential organic
compounds found in all living things
• Amino acids are the small units that
make up protein molecules
• Enzymes are specialized protein
molecules that help control
chemical reactions in a cell
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NUCLEIC ACIDS
• Nucleic acids are the largest known
organic molecules; made from
thousands of repeating subunits
called nucleotides
• There are two major types of
nucleic acids:
– DNA
– RNA
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ACIDS, BASES, AND SALTS
• Acids are substances that yield
hydrogen ions in solution
• Bases are substances that ionize
into negatively charged hydroxide
ions and positively charged ions of
metal when dissolved in water
• Salts are formed when acids and
bases are combined
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PH SCALE
• pH measures acidity or alkalinity of
a solution
• The pH scale ranges from 0 to 14
– A pH between 0 and 6.9 is acidic
– A pH between 7.1 and 14 is alkaline
– A pH of 7.0 is neutral as it contains
the same number of hydrogen and
hydroxide ions
© 2004 Delmar Learning, a Division of Thomson Learning, Inc.