DNA & rna : Background lecture

1. DNA & rna: Background lecture October 1st – October 11th , 2012

2. timeline • Monday, October 1st • DNA & RNA Lecture, Read Lab 4A • Tuesday, October 2nd • DNA & RNA Lecture, Pre-Lab Quiz, Lab 4A (approximately 50 minutes), read Lab 4B • Thursday, October 4th • DNA & RNA Lecture, Lab 4B (50 minutes) • Monday, October 8th • MAGIC MOUNTAIN! • Tuesday, October 9th • Lab 4C, Lab 4A due • Thursday, October 11th • Lab 4D, Lab 4B due, Post-Lab Quiz

3. Deoxyribose nucleic acid: REVIEW • Composed of nucleic acids • Antiparallel • Structure: • Sugar • Phosphate Group • Nitrogenous Base • Adenine • Guanine • Cytosine • Thymine

4. 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

5. Nitrogenous bases

6. 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

7. Differences between dna and rna • RNA • Single-stranded • Contains a ribose sugar • Complementary base to adenine is uracil • DNA • Double-stranded • Contains a deoxyribose sugar • Complementary base to adenine is thymine

8. 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

9. Central dogma of biology DNA  RNA  Protein

10. 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

11. 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

12. Video: central dogma of biology http://www.youtube.com/watch?v=9kOGOY7vthk

13. 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