Download Chapter 4: The Chemical Basis of Life

Chapter 4: The Chemical Basis of Life
4-3: Compounds of Life
Compounds of Life
 The number of possible organic compounds is almost
__________________________
 Fortunately, however, it is possible to classify many important organic
compounds found in living things into _____________________________
 The four groups of organic compounds found in living things are
carbohydrates, lipids, proteins, and nucleic acids
Carbohydrates
 ________________________________ are the molecules that we
often call sugars and starches
o Made up of carbon, hydrogen, and oxygen atoms
o Sugars are important because they contain a great deal of
____________________

Stored in the bonds that make up the carb molecules

When these bonds are ___________________,
energy is released
o Simplest carbohydrates are ___________________________,
meaning single sugars
o Glucose, fructose
o
C6H12O6
Dehydration Synthesis
 The chemical bond that links two simple sugars is formed between the –
OH groups present in each molecule
 One –OH from one molecule combines with the H of the –OH from the
other molecule
 When the bond is complete, a ___________________________________
is removed from the two monosaccharides
 Because of the loss of water, the joining of two sugars is known as
________________________________________
o The compound formed from the joining of two single sugars in
dehydration synthesis is called a ________________________
(double sugar)
Polysaccharides
 Very large molecules can be formed by joining together many
monosaccharide units
 Such compounds are known as _____________________________
o The form in which living things store excess sugar

____________________________________

____________________________________
Hydrolysis
 When polysaccharides are split apart to form monosaccharides, the
dehydration synthesis reaction is ____________________________
 This is known as ______________________________
o ___________________________________
o A molecule of water is consumed by the chemical reaction that
splits the bond between the monosaccharides
Lipids
 _____________________ are organic compounds that are waxy or
oily
o _____________________________________
o Generally fats and waxes are ___________________ at room
temperature; oils are ____________________
o Many important lipids are formed from combinations of fatty acids
and glycerol

Fatty acid = long chain of hydrogen and carbon atoms that
have a carboxyl group (-COOH) attached at one end
o Three major roles in living things

Can be used to ____________________________________

Used to form ______________________________________

Used as __________________________________________
Saturated and Unsaturated Lipids
 If every carbon atom in a fatty acid chain is joined to another carbon
atom by a single bond, the fatty acid is said to be
_________________________ because it contains the maximum
number of hydrogen atoms
o ____________________ at room temperature
 If a pair of carbon atoms is joined by a double bond, the fatty acid is said
to be ___________________________; because of the double
bond, it does not contain the maximum number of hydrogen atoms
o Liquid at room temperature
Sterols and Phospholipids
 Two other kinds of lipids are very important to living organisms
o __________________________

______________________________

Carry messages from one part of the body to another

Most common is __________________________
o ____________________________________

Consist of parts that dissolve well in water and parts that do
not dissolve well in water

Form _____________________________
o Forms by the attraction of the oily parts of lipid
molecules for each other and by the attraction
of the other parts of the lipid molecules for the
surrounding water
Proteins
 ________________________ are organic compounds that contain
nitrogen in addition to carbon, hydrogen, and oxygen
 Proteins are polymers of _____________________________
o Has an amino group on one end and a carboxyl group on the other
end
o These groups can form covalent bonds with each other
o All amino acids have a similar chemical structure, but they differ in
a region of the molecule known as an _______________________
o There are more than 20 different amino acids, each of which
contains a different R group
Peptides
 The covalent bond that joins two amino acids is known as a
____________________________
 Dipeptide contains ______________ amino acids
 Tripeptide contains ______________ amino acids
 Polypeptide contains _____________ amino acids
Protein Structure
 A complete protein contains one or more polypeptide chains and may
contain a few other chemical groups
 Proteins have numerous roles
o Carry out _________________________________________
o Pump molecules into and out of a cell
o Aid in ____________________________________
Enzymes
 Chemical reactions make life possible
 If they occurred too slowly, ordinary activities of life would come to a halt
 Some substances in the body must be responsible for speeding up the
process
o _______________________

Lowers the ___________________________________ of a
reaction

Living organisms contain their own special catalysts _____________________
 Speed up a reaction by binding to the reactants
 The reactants that are affected by an enzyme are known as
__________________________
o Substrates bind to enzymes at a region known as the
______________________________
Nucleic Acids
 __________________________________ are large complex
organic molecules composed of carbon, oxygen, hydrogen, nitrogen, and
phosphorus atoms
 Are polymers of individual monomers known as
__________________________
o Made of a __________________________________, a
____________________________________, and a
_____________________________________________
 Two basic kinds of nucleic acids
o ___________________________________________,
which contains the sugar ribose
o ___________________________________________,
which contains the sugar deoxyribose