Biology
101 Chapter 3
The Molecules of Life
Organic
compounds and organic chemistry:
Organic Compounds = any compound that
contains carbon and hydrogen
Organic Chemistry = the study of organic
compounds
Why
carbon?
1.
4
(max) covalent bonds
2.
hydrocarbons
(only contain C and H)
3.
carbon
skeletons
Functional
groups:
main parts designated with the letter R
Ex. Amine group of amino acids
Large
molecules from small molecules:
Monomer = individual small units
(like a link in a chain)
Polymer = many small units joined
together in a long line (like a whole chain)
Macromolecules = very large polymers
Dehydration Synthesis: chemical process whereby
monomers, smaller molecules, are linked to form polymers. Also called addition or condensation
reactions.
Hydrolysis: process whereby polymers
are broken down into individual monomers.
A lytic or tear down reaction.
Most
Organic Molecules are put into Four Major Classes
**
(1) Carbohydrates (the sugars)
Polymeric
**
(2) Lipids (fats, oils and waxes)
**
(3) Proteins
Polymeric
**
(4) Nucleic Acids (DNA + RNA)
Polymeric
The Carbohydrates
·
Ranges
from simple sugars to complex carbs
I.
The
Monosaccharides:
o
Simple
sugars, the monomers of carbs
o
3-7
carbon atom molecules
o
Example:
Glucose
§
Simplest
sugar
§
Most
important to us
§
C6H12O6
o
Another ex: Fructose
o
End in “ose”
Function: fuel for cells
II.
The
Disaccharides:
o
2
simple sugars joined together
o
Ex:
Sucrose, Lactose, and Maltose
Function:
fuel for cells
III.
The
Polysaccharides:
o
Very,
very large + complex, polymers
o
Multiple
units (5 – several thousand)
o
Maybe
branched
o
Ex:
Starch, Cellulose, Glycogen
Functions:
food storage; structural
Lipids
·
Widely
diverse group
·
Hydrocarbon
rings or chains
·
Nonpolar,
hydrophobic (water-fearing)
·
Types:
1) Fatty acids
2) Neutral fats
3) Phospholipids
4) Sterols
5) Waxes
I.
Fatty
Acids:
·
A
hydrocarbon chain with a carboxyl group end
·
Very
long (15-30 carbon atoms)
II.
Neutral
Fats: (fats and oils)
·
Consist
of 1, 2 or 3 fatty acid molecules attached to a glycerol molecule base
·
Includes
the Triglycerides
·
Structure:
III.
Phospholipids:
·
Structural
lipids
·
Main
component of cell membranes
·
Similar
to fats but contain phosphorus
·
Structure:
IV.
Sterols:
·
Carbon
skeleton of 4 fused rings
·
Regulate
cellular and body functions
·
Ex:
cholesterol and hormones
·
Structure:
V.
Waxes:
·
Fatty
acid linked to an alcohol
·
Extremely
hydrophobic
Special
Terms:
Saturated = animal fats, solid at room temp., unhealthy
Unsaturated = vegetable fats + oils, liquid, “healthy”
Proteins
·
Large
polymers, true macromolecules
·
Millions
of kinds, largest group of organics
·
Includes
the enzymes
·
All
proteins are encoded by DNA (proteins are the only thing coded for by DNA)
·
Made
up of smaller monomers called Amino
Acids
·
Only
20 different amino acids (a.a.) make up protein
·
Sequence
of a.a. determines structure of protein
·
Protein
structure determines function of protein
·
Peptide
bonds and polypeptides
·
4
levels of protein structure:
1) Primary: sequence of a.a.
2) Secondary: initial
coiling/folding of chain
3) Tertiary: subsequent
coiling, overall 3D shape
4) Quaternary: interaction
among several proteins and minerals in a larger complex. Ex. Hemoglobin
The Nucleic Acids
·
Polymers,
macromolecules
·
Serve
as “blueprints” for life, genetic code
·
Monomers
called nucleotides
·
2
types of nucleic acid
1. DNA = deoxyribonucleic acid
2. RNA = ribonucleic acid
Nucleotide
Structure:
3 parts
1) Five carbon sugar ribose
2) Phosphate group
3) Nitrogenous base
Nucleic
Acid Structure:
·
Sugar
phosphate backbone
·
Helical
shape
·
Double
stranded
·
Bases
face toward center, bases of opposite strands (if present) hydrogen bond together
·
Four
bases make up code (A, T, C and G)
·
DNA
structure and the base pairing rule
Characteristics
of DNA vs. RNA
DNA RNA
Sugar
deoxyribose sugar ribose
Double
stranded single
stranded
Four
bases uracil
in place of thymine