The Molecules of Cells
I.
Life’s molecular diversity is based on the properties of carbon
a. Next to water, carbon compounds are the most abundant in
living organisms
b. ORGANIC COMPOUNDS – compounds synthesized by cells
and containing carbon
c. Carbon outer shell has 4 electrons and needs 8 total
d. HYDROCARBONS  compounds composed of only C and H
e. ISOMERS  same molecular formula but different structures
II.
Functional Groups help determine the properties of organic
compounds
a. FUNCTIONAL GROUPS  groups of atoms, in an organic
molecule, that usually participate in a chemical reaction
b. HYDROPHILIC  water soluble
i. As a result of polar covalent bonds
c. Compounds may have more than one functional group,
therefore have properties of both
III.
Cells make a huge number of large molecules from a small set of
molecules
a. MACROMOLECULES  gigantic molecules (ex. Carbs,
lipids, proteins, nucleic acids)
b. POLYMERS  “many parts”, a large molecule consisting of
many similar units strung together
c. MONOMERS  the units of polymers, the building blocks
d. DEHYDRATION SYNTHESIS  the removal of a water
molecule to link monomers
e. HYDROLYSIS  breaking apart a polymer by adding a water
molecule
IV.
Monosaccharides are the simplest carbohydrates
a. CARBOHYDRATE  refers to a class of molecules ranging
from small sugar to large polysaccharides (polymers of sugar
monomers)
b. MONOSACCHARIDES  sugar monomers (“single sugar”)
i. Examples  glucose, fructose
c. Generally have the formula C6H12O6
i. Isomers  different properties
d. Not usually shown in linear formation; form rings in solution
e. Monosaccharides are the main fuel for cells (especially glucose)
f. Carbon skeletons are used to form other compounds, like amino
acids
V.
Cells link single sugars to form disaccharides
a. Disaccharide  “double sugar”; joined monosaccharides
b. Accomplished by DEHYDRATION SYNTHESIS
c.
Disaccharide
Maltose
Sucrose
Lactose
VI.
Monosaccharide
Glucose + Glucose
Glucose + Fructose
Glucose + Galactose
How sweet is sweet?
a. Sweet receptors on our tongue
b. Sugar binds to these receptors, but not the only compound that
can do this
i. Aspartame (Equal or Nutrasweet) made of amino acids
c. All sweetness is relative to sucrose (table sugar)
i. Bitter aftertaste; compounds are also binding to bitter
receptors on tongue
VII. Polysaccharides are long chains of sugar units
a. POLYSACCHARIDES  polymers of a few hundred to a few
thousand monosaccharides linked by dehydration synthesis
b. STARCH  a storage polysaccharide found in plants
i. Composed of glucose (monomer)
ii. Broken down (hydrolyzed) when plant needs energy
iii. Humans and animals can also break it down when they
eat it (potatoes and grains)
c. GLYCOGEN  a storage polysaccharide in animals
i. Nearly identical to start except shape is slightly different
d. CELLULOSE  a building polysaccharide
i. Form tough walls that enclose plant cells and WOOD
ii. NOT able to be broken down by animals
iii. Need special micro-organisms in digestive tract to break
cellulose down
VIII. Lipids include fat, which are mostly energy storage molecules
a. LIPIDS  Diverse compounds of C and H linked by
NONPOLAR covalent bonds
b. HYDROPHOBIC  NOT water soluble
c. FAT  a large lipid made from two kinds of smaller
molecules; glycerol and fatty acids
d. TRIGLYCERIDE  a synonym for fat; glycerol + 3 (tri) fatty
acids
e. SATURATED vs UNSATURATED  maximum number of
H’s, versus having double bonds
IX.
Phospholipids, waxes, and steroids are lipids with a variety of
functions
a. Some lipids help build cell membranes, protect body surfaces
and regulate cellular and body function
b. PHOSPHOLIPIDS  a major component in cell membranes
i. Similar structure to fat but contains PHOSPHOROUS
and have only two fatty acids
c. WAXES  one fatty acid linked to an alcohol
i. More hydrophobic then fats, making them effective
coating on fruits, insects, etc…
d. STEROIDS  lipids whose carbon skeleton is bent to form
four fused rings
i. Cholesterol is a type of steroid
ii. ALL steroids have some structure of rings
iii. Used in cell membranes and hormone production
X.
Anabolic steroids and related substances pose health risks
a. ANABOLIC STEROIDS  synthetic variants of the male
hormone testosterone
i. Will help build up muscle mass
ii. Downside  liver damage, cholesterol problems, high
blood pressure, decreased output of sex hormones
XI.
Proteins are essential to the structures and activities of life
a. PROTEIN  “first place”; a polymer constructed from amino
acid monomers
i. Many types of proteins
1. Structural proteins
2. Contractile proteins
3. Storage proteins
4. Defensive proteins
5. Transport proteins
6. Signal proteins
b. ENZYMES  a protein that serves as a chemical catalyst
XII. Proteins are made from just 20 kinds of amino acids
a. AMINO ACIDS  have an amino group and a carboxyl group
b. The “R” is the variable group; what goes in that spot will
determine which of the 20 amino acids you have and the
resulting properties
XIII. Amino acids can be linked by peptide bonds
a. PEPTIDE BONDS  the resulting covalent linkage between
two amino acids
b. DIPEPTIDE  two attached amino acids
c. POLYPEPTIDE  a chain of amino acids
XIV. Overview: A protein’s specific shape determines its function
a. A protein consists of one or more polypeptide chains folded
into a unique shape
b. The SPECIFIC 3-D shape determines the specific function
c. DENATURATION  polypeptides unravel and lose their
specific shape and function
i. Temperature, pH, salt concentration ALL can denature
proteins
XV. Four MAJOR points about proteins
a. A protein’s primary structure is its amino acid sequence
b. Secondary structure is polypeptide coiling or folding produced
by hydrogen bonding
c. Tertiary structure is the overall shape of a polypeptide
d. Quaternary structure is the relationship among multiple
polypeptides of a protein
XVI. Nucleic acids are information-rich polymers of nucleotides
a. NUCLEIC ACIDS  polymers that serve as blueprints for
proteins
b. 2 types
i. DNA  Deoxyribonucleic Acid
ii. RNA  Ribonucleic Acid
c. DNA contain genes which control the amino acid sequence of
the proteins being produced
d. DNA doesn’t work directly, uses RNA as an intermediate
e. NUCLEOTIDES  monomers that make up nucleic acids
i. 5 carbon sugar (pentose)
ii. Phosphate group
iii. Nitrogenous base
f. RNA is a single strand of nucleotide units
g. DNA is a double strand (double helix) with the nitrogenous
bases fusing together to connect the two strands