1.5 PROTEINS ( polypeptides) Nelson page 39–44, do que 1– 7 pg 47
- very important biological molecules making up about 50% of the dry
cell mass
- amino acid polymers in specific 3-D shape
- USES: structural, control metabolism (enzymes), membrane
transport, hormones, recognition and receptors on membranes
AMINO ACIDS: monomers made of carboxyl and amino groups
around a central carbon with a variable side group (R).
- 20 amino acid with 20 different “R” - groups
- 8 essential A.A. are not made by humans so must be in the diet
PEPTIDE BONDS: covalent bonds formed by dehydration between amino
acid (-NH2) of one amino acid and the carboxyl (-COOH) of a second amino
acid. Polypeptide 50 or more amino acids in length (can be 1000’s long).
A Protein is one or more polypeptides that are folded into a precise 3dimensional shape called its conformation which can be filamentous
(linear), sheet, or globular.
Genes on DNA directs ribosomes to join Amino Acids together in a
specific sequence in a process called Translation making specific proteins.
GLOBULAR PROTEINS (make your own notes)
- 4 levels of structure primary, secondary, tertiary, quaternary
- denaturing can destroy the function of proteins
1.5 NUCLEIC ACIDS Nelson page 45 – 47 do questions 8 – 11 page 47
 informational macromolecules that store hereditary information that
determine structural and functional characteristics
 Includes two types: Deoxyribonucleic Acid DNA (double stranded
helix) and ribonucleic acid RNA (single stranded helix)
both are polymers made of subunits called nucleotides
Nucleotides
General Structure of a Nucleotide
Nucleotides have five possible organic bases attached as
functional units :
 Adenine (A) and Guanine(G) are double ring Purines
 Thymine (T), Cytosine (C) and Uracil (U) are single ring
Pyrimidines
DNA only contain A, G, C, T while RNA has A, G, C, U
DNA has a carbon backbone of the sugar deoxyribose (lacks Oxygen
on carbon #2)
RNA has a carbon backbone of ribose
Nucleotides are connected together to form a polymer called a strand
The Nucleotides are covalently bonded (phosphodiester bond)
together between the phosphate of one group to the hydroxyl of the
next group
The two strands in DNA are held together by H-Bonds between
specific organic bases on the adjacent strand which runs the opposite
direction (antiparallel)
Adenine forms 2 H-bonds with only Thymine
Guanine forms 3 H-bonds with only Cytosine
Other types of Nucleotides:
 Adenosine triphosphate ATP
Contains three phosphates and used to drive almost all energy
requiring reactions in the cell
have three highly energetic phosphate bonds for short term
energy storage
 Nucleotide derivatives include:
o Nicotinamide adenine dinucleotide (NAD+) and
o Flavin adenine dinucleotide (FAD) used as electron
acceptors and short term energy transporters during cellular
respiration
o NADP+ is used in photosynthesis
o cyclic adenosine monophosphate (cAMP) is used as a
second messenger during hormone interactions and gene
control