nucleotides & nucleic acids roles: energy currency (atp, gtp) chemical links in response of...
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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