Nucleotides & Nucleic Acids Roles: Energy currency (ATP, GTP) Chemical links in response of cells to hormones (cAMP) Involved in cofactors (NAD, FAD, CoA)

Nucleotides & Nucleic Acids

Roles:Energy currency (ATP, GTP)Chemical links in response of cells to hormones (cAMP)Involved in cofactors (NAD, FAD, CoA)Metabolic intermediates (acetyl CoA)Constituents of nucleic acids, DNA and RNA

Central Dogma of Biology

Storage and transmission of genetic infoContains genes

rRNA - structural components of ribosomesmRNA - carries genetic info from gene to

ribosome to make proteintRNA - adaptor that translates info in mRNA

into amino acid sequence

Nucleotides & Nucleic Acids

Nucleotides:1. Nitrogenous base2. Pentose sugar3. Phosphate

Nucleosides:1. Nitrogenous base2. Pentose sugar

Nitrogenous bases are either pyrimidines or purines

Nucleotides & Nucleic AcidsNitrogenous bases are either pyrimidines or purines

Nucleotides & Nucleic AcidsRibose sugars can be either 2’-deoxy (DNA) or have a 2’-OH (RNA)

Nucleotides & Nucleic Acids

Nucleotides & Nucleic AcidsHydrolysis of RNA

Nucleotides & Nucleic AcidsProperties of RNA and DNAForces involved in structure1.

Nucleotides & Nucleic AcidsProperties of RNA and DNAForces involved in structure1. Hydrophobic Bases hydrophobic at neutral pH, hydrophobic stacking interactions

Nucleotides & Nucleic Acids

Properties of RNA and DNANitrogenous rings are mostly planarResonance in cyclic rings allow nucleotide bases to absorb UV light

Nucleotides & Nucleic Acids

Properties of RNA and DNAForces involved in structure2. Hydrogen bonding patterns in RNA and DNAInvolve ring N, carbonyls, amino groupsPermits complementary association of 2 strands of nucleic acid (structure of DNA by Watson & Crick)

Uridine (RNA)

Nucleotides & Nucleic AcidsDiscovery of DNA structure and its role in housing genetic information

Miescher 1868Isolate phosphorus-containing substance which he termed “nuclein”Acidic (DNA) & basic portions (protein)Hypothesize that nuclein associated with genetic inheritance

Avery-MacLeod-McCarty 1944Direct evidence that DNA carries genetic info

Nucleotides & Nucleic AcidsDiscovery of DNA structure and its role in housing genetic informationAvery-MacLeod-McCarty 1944Direct evidence that DNA carries genetic info

Nucleotides & Nucleic AcidsDiscovery of DNA structure and its role in housing genetic informationAvery-MacLeod-McCarty 1944Direct evidence that DNA carries genetic info

Griffith

Avery-MacLeod-McCarty?? ResultsTreat DNA with protease - transformTreat DNA with deoxyribonucleases- destroy transforming activity

Nucleotides & Nucleic Acids

Hershey-Chase 1952More evidence that DNA carries genetic info

DNA radiolabeled Protein radiolabeled

Nucleotides & Nucleic Acids

Chargaff’s rules 1940s

1. Base composition of DNA varies from one species to another2. DNA from different tissues of same species have same base composition3. Base composition of DNA in given species does not change with age, nutritional state, environment4. In all cellular DNAs, regardless of species, the number of adenosine residues is equal to the number of thymidine residues (A=T), and the number of guanosines = cytidines (G=C)

A + G (purines) = C + T (pyrimidines)

Nucleotides & Nucleic Acids

Watson & Crick 1953 (Franklin & Wilkins too)

Franklin & WilkinsUsed x-ray crystallography to analyze fibers of DNA

X - indicates helical structure

Heavy bands - indicates recurring bases

Nucleotides & Nucleic Acids

Watson & Crick 1953 (Franklin & Wilkins too)

Watson & CrickUsed x-ray crystallography dataUsed Chargaff’s rules3D structure of DNA, strands antiparallel

Nucleotides & Nucleic Acids

DNA structureComplementarity (replicate by separating strands and synthesizing

complementary strand for each)Strands not identical in base sequence or composition

DNA replication

Nucleotides & Nucleic Acids

DNA structure - different 3D forms