DNA & RNA:
BACKGROUND LECTURE
October 1 st –
October 11 th ,
2012
TIMELINE
 Monday, October 1 st
 DNA & RNA Lecture, Read Lab 4A
 Tuesday, October 2 nd
 DNA & RNA Lecture, Pre-Lab Quiz, Lab 4A (approximately 50
minutes), read Lab 4B
 Thursday, October 4 th
 DNA & RNA Lecture, Lab 4B (50 minutes)
 Monday, October 8 th
 MAGIC MOUNTAIN!
 Tuesday, October 9 th
 Lab 4C, Lab 4A due
 Thursday, October 11 th
 Lab 4D, Lab 4B due, Post-Lab Quiz
DEOXYRIBOSE NUCLEIC ACID: REVIEW
 Composed of nucleic acids
 Antiparallel
 Structure:
 Sugar
 Phosphate Group
 Nitrogenous Base




Adenine
Guanine
Cytosine
Thymine
BASE PAIRING
 Adenine forms a base pair with thymine
 Cytosine forms a base pair with guanine
 Thymine and Cytosine
 Pyrimidine
 Composed of a single carbon ring
 Adenine and Guanine
 Purines
 Composed of a double carbon ring
NITROGENOUS BASES
RIBONUCLEIC ACID: REVIEW
 Composed of nucleotides
 mRNA
 Contains genetic information needed to produce proteins
 tRNA
 Used to deliver amino acids to the ribosome
 rRNA
 Used to link amino acids together to form proteins
 Structure
 Nitrogenous base
 Uracil instead of thymine
 Ribose sugar
 Phosphate groups
DIFFERENCES BETWEEN DNA AND RNA
DNA
 Double-stranded
 Contains a deoxyribose
sugar
 Complementary base
to adenine is thymine
RNA
 Single-stranded
 Contains a ribose
sugar
 Complementary base
to adenine is uracil
SIMILARITIES BETWEEN DNA AND RNA
 Composed of nucleotides
 Polar molecules
 Due to their negatively charged phosphate group
 Both have hydrogen bonds between the nitrogenous bases
 Phosphodiester bonds between adjacent sugar and phosphate
groups
 Make up the “backbone” of DNA and RNA
 Phosphodiester bonds are much stronger than hydrogen bonds
 Covalent bonds
 Hydrogen bonds are constantly broken to permit for DNA replication, while
phosphodiester bonds are hardly ever broken in natural processes
CENTRAL DOGMA OF BIOLOGY
DNA  RNA  Protein
CENTRAL DOGMA OF BIOLOGY
Transcription
Process by which the information contained in
a section of DNA is transferred to a newly
assembled piece of mRNA (messenger RNA)
DNA is “unzipped” by helicase enzyme
Read by RNA polymerase
CENTRAL DOGMA OF BIOLOGY
 Translation
Process by which mRNA is “read” by the
ribosomes and converted into amino acids, or
proteins
mRNA is read as triplet codons
Each codon codes for a specific amino acid
Begins with an initiator codon, for example, AUG
Ends with the stop codon, for example, UAA or
UAG
Introns vs. Exons
VIDEO: CENTRAL DOGMA OF BIOLOGY
http://www.youtube.com/watch?v=9kOGOY7vthk
CHARACTERISTICS OF DNA AND RNA
 Negatively charged phosphate backbones make them
polar molecules
 Hydrophilic
 Adding salt neutralizes the charge on the phosphate
backbone, and makes the DNA or RNA less
hydrophilic
 This causes the DNA or RNA to precipitate out of an
aqueous solution
 Ethanol makes it easier for the sodium (Na+) to
interact with the PO3- in the DNA/RNA backbone
 Foundation of 4A-4D lab series