October 1 st – October 11 th, 2012 DNA & RNA: BACKGROUND LECTURE

 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 TIMELINE

 Composed of nucleic acids  Antiparallel  Structure:  Sugar  Phosphate Group  Nitrogenous Base  Adenine  Guanine  Cytosine  Thymine DEOXYRIBOSE NUCLEIC ACID: REVIEW

 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 BASE PAIRING

NITROGENOUS BASES

 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 RIBONUCLEIC ACID: REVIEW

 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 DIFFERENCES 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 SIMILARITIES BETWEEN DNA AND RNA

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 CENTRAL DOGMA OF BIOLOGY

VIDEO: CENTRAL DOGMA OF BIOLOGY

 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 CHARACTERISTICS OF DNA AND RNA