DNA and RNA Structure and Function Honors Research in Molecular Genetics

DNA and RNA  DNA (deoxy-ribonucleic acid) is the genetic material  It is a type of super polymer. 1. Some act primarily to carry instructions. They are said to be "informational" or "instructional" 2. Some are best at performing operations. They are said to be "operational". They are molecular machines.

Nucleic Acids (P.C.F.NA.)  DNA (Deoxyribonucleic Acid)  Double helix  RNA (Ribonucleic Acid)  Single stranded  Monomers: Nucleotides  nitrogen base (C-N ring)  pentose sugar (5C)  ribose in RNA  deoxyribose in DNA  phosphate (PO 4 ) group Mono Nucleotide:

Deoxyribose vs. Ribose

The OH groups on the 5’ and 3’ carbons are the reactive groups through which nucleotides become joined a nucleotide includes one phosphate group joined at the 5’ position….. PO 4 © 2013 WSSP

PO 4 What to know about the phosphate: 1) linked at 5’ carbon 2) can have 1, 2, or 3 phosphate residues (nucleotide mono-phosphate, nucleotide di-phosphate, nucleotide tri-phosphate) 3) ***the oxygens of the phosphate group are negatively charged at physiological pH. Therefore DNA carries a large net negative charge! © 2013 WSSP

Classification of Nitrogen Bases  purines  double ring N base  adenine (A)  guanine (G)  pyrimidines  single ring N base  cytosine (C)  thymine (T)  uracil (U)

Nucleic Polymers  Sugar – Phosphate Backbone  phosphodiester bond in backbone  new base added to sugar of previous base  polymer grows in one direction  WHY?

The polynucleotide chain To form the polynucleotide chain, the oxygen of the 3' hydroxyl group on the chain “attacks” the phosphate of a nucleotide triphosphate eliminating H 2 O and releasing the two outermost phosphate residues. The phosphodiester bond © 2013 WSSP **Notice that the DNA chain is synthesized in a 5’ to 3’ direction.

Antiparallel Structure  Two strands of DNA run opposite each other  A-T contains 2 hydrogen bonds  C-G contains 3 hydrogen bonds

DNA is double-stranded--two polynucleotide chains Hydrogen bonds between bases hold these together G and C have 3 H-bondsA and T make 2 H-bonds  GuanineCytosineAdenineThymine Base Complementary © 2013 WSSP

DNA strands are arranged in an anti-parallel manner 5' 3' 5' 3' 5'-TCGTCA-3' 3'- -5' 5'-TGACGA-3' 3'- -5' "Flipped" © 2013 WSSP

Board Question: What is the complementary sequence of the sequence 5'-GGAATCG-3'? A) 5’-GCTAAGG-3’ B) 5’-CCTTAGC-3’ C) 5’-CGATTCC-3’ D) 5’-GGAATCG-3’ 3’-CCTTAGC-5’ © 2013 WSSP

Board Question: Which DNA would be harder to denature (separate the two strands)? A) ATTAD) GCGCGC TAAT CGCGCG B) GCGCE) AGCGCT CGCG TCGCGA C) AATATA TTATAT © 2013 WSSP

Critical Properties of DNA 1) Negative charge (will move toward a + electrode!) 2) DNA can be denatured and renatured (nucleic acid Hybridization). 3) DNA is soluble in water. 4) DNA absorbs UV light. 5) DNA can be stained and amounts of DNA can be Measured using ethidium bromide. © 2013 WSSP

Critical Properties of RNA 1. RNA is single stranded 2. RNA functions as both informational (ex. mRNA) and as operational (rRNA) polymers 3. RNA contains uracil instead of thymine 4. RNA contains ribose instead of deoxyribose 4. RNA is more unstable than DNA 5. RNA is typically shorter than DNA © 2013 WSSP

Conclusion Board Questions: With a partner, use the molecule below to answer the questions. 1.Name the molecule. 2.Which letter would the Phosphate be added? 3. Which letter would the base be attached to? 4. Which letter is important for DNA replication and transcription? © 2013 WSSP