Unit 2 Notes: Biochemistry
The Building Blocks of Life
6.4 Objectives:
1. Describe the role of carbon in living organisms
2. Summarize the four major families of biological macromolecules
3. Compare the functions of each group of macromolecules
Vocabulary:
Macromolecule- a large molecule formed by joining smaller organic molecules together (p.167)
Polymer- a large molecule formed from smaller repeating units of identical, or nearly identical,
compounds linked by covalent bonds (p. 167)
Carbohydrate- organic compound containing carbon, hydrogen, and oxygen in a ratio of one
oxygen and two hydrogen for each carbon atom (p. 168)
Lipid- hydrophobic biological molecule composed mostly of carbon and hydrogen; fats, oils, and
waxes are lipids (p. 169)
Protein- organic compound made of amino acids joined by peptide bonds; primary building
block of organisms (p. 170)
Amino acid- carbon compound joined by peptide bonds; building block of proteins (p. 170)
Nucleic acid- complex macromolecule that stores and communicates genetic information (p.
171)
Nucleotide- a subunit of nucleic acid formed from a simple sugar, a phosphate group, and a
nitrogenous base (p. 171)
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Main Idea: Organisms are made up of carbon-based molecules.
If something is organic, that means it contains carbon. Since all living things contain carbon,
they are considered to be organic and life on earth is considered to be carbon-based.
Four Major Categories of Biological Macromolecules
Group
Carbohydrates
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Example(s)
Glucose; Glycogen
Sucrose; Chitin
Fats; Wax
Oil; Steroid
Proteins
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Enzymes
hemoglobin
Nucleic Acids
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DNA
RNA
Lipids
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Function
Store energy
provide structural support
Store energy
Provide barriers
Cell membranes
Transport substances
Speed reactions
Provide structural support
Make hormones
Cellular processes
Store and communicate
genetic information
Types of carbohydrates:
Monosaccharide- simple sugars; carbohydrates that have values of n ranging from 3 to 7; an
example of this is glucose which plays a central role as an energy source for organisms
Disaccharide- two monosaccharides joined together; Examples are sucrose (table sugar) and
lactose (a component of milk
Polysaccharide- longer carbohydrate molecules; an example is glycogen (an energy storage
form of glucose that is found in the liver and skeletal muscle); chitin is a nitrogen-containing
polysaccharide that is the main component in the hard outer shell of shrimp, lobsters, and
some insects, as well as the c ell wall of some fungi
In plants, the carbohydrate cellulose provides structural support in cell walls.
Lipids:
The primary function of lipids is to store energy. They are composed of fatty acids, glycerol,
and other components. A lipid called a triglyceride is a fat if it is solid at room temperature and
oil if it is liquid at room temperature. . These are stored in the fat cells of the human body.
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In plants, lipids called wax coat plant leaves as a preventative to water loss. In a beehive, the
honeycomb is made of beeswax.
Saturated and Unsaturated Fats are lipids. Fatty acid tails with a single bond between carbon
atoms are saturated fats, and those with at least one double bond are unsaturated fats.
Lipids do not dissolve in water. (They are hydrophobic.)
Another group of lipids is the steroid group. These include cholesterol and hormones.
Proteins:
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Are organic molecules
Are made in cells
Enzymes are proteins
Amino acids are the building blocks of proteins
The number of amino acids in a chain and the order in which they are joined define the
protein’s primary structure.
Carbon and Oxygen are two elements always found in amino acids.
Peptide bonds join amino acids together.
Proteins make up about 15% of your total body mass and are involved in nearly every function
of your body: muscles, skin, hair, and cells
Nucleic Acids:
Store and transmit genetic information
Nucleic acids are made of smaller repeating subunits called nucleotides. There are 6 major
nucleotides that have three units: a phosphate, a nitrogenous base, and a ribose sugar.
Two types of nucleic acids in living organisms:
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DNA
RNA
ATP is a nucleotide with three phosphate groups; a storehouse of chemical energy that can be
used by cells in a variety of reactions. It releases energy when the bond between the second
and third phosphate group is broken.
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6-2 Objectives:
1. Identify the parts of a chemical reaction.
2. Relate energy changes to chemical reactions.
3. Summarize the importance of enzymes in living organisms.
Chapter 6, Section 2
“Chemical Reactions”
A. Chemical Reactions
a. Everything that happens in an organism is based on chemical reactions
b. Chemical reaction—process that changes one set of chemicals into another
c. Reactants—elements/compounds that enter into a reaction
d. Products—elements/compounds produced by a reaction
e. Chemical reactions change the chemical bonds that join atoms.
B. Energy in Reactions
a. Energy Changes
i. Energy is either released or absorbed during chemical reaction
ii. Chemical reactions that release energy often occur spontaneously
iii. Chemical reactions that absorb energy will not occur without a source of
energy
b. Activation Energy—the energy needed to start a reaction
C. Enzymes
a. Some chemical reactions are very slow
b. Catalyst—substance that speeds up the rate of a chemical reaction
c. Enzyme—speed up chemical reactions that occur in cells
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d. Enzyme’s name tells what it does (ex: amylase—found in saliva; digests food by
speeding up break of amylose)
e. Substrate—the reactants that bind to the enzyme; location of binding—active
site
D. Enzyme-Substrate Complex
a. Once substrate binds to active site, the site changes shape and forms the
enzyme-substrate complex
b. Enzyme-substrate complex helps chemical bonds in reactants to be broken and
new bonds form; substrates react to form products; enzyme releases product
c. Enzyme activity affected by pH, temperature, and other substances
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