Molecular Biology - expanding on macromolecules, DNA, RNA

1. DNA and RNA Macromolecules Polymers of nucleotides Double stranded or single stranded Sugar-phosphate backbone …think back to Ch. 3 Molecular Biology - expanding on macromolecules, DNA, RNA

2. Polymers of 4 specific monomers = nucleotides Via dehydration synthesis between sugars Builds chain w/sugar-phosphate backbone Single stranded RNA Double stranded DNA Nucleic Acids

4. RNA is similar to DNA • Except for the sugar and one base • Uracil (U) in place of Thymine (T)

5. James Watson and Francis Crick, 1953 Rosalind Franklin Double helix Structure of DNA

6. Replicating DNA • Based on its structure, Watson & Crick predicted that cells copy genes by matching complimentary bases

7. Untwists and replicates both strands simultaneously Rapid process Efficient Builds in two directions Use of enzymes DNA polymerase Links nucleotides to growing daughter strand

8. Genotype = genetic makeup; contained in DNA Phenotype = traits; expressed from proteins Proteins are the link…genes build proteins How? DNA sends out instructions as RNA, which synthesizes proteins Link to genotype & phenotype

9. DNA is our blueprint The boss or engineer sends a carbon copy, transcribed RNA, for construction At the construction site, the foreman (ribosomes) translates the plan to the crew, who are not trained to read the plans, but know it in terms of amino acids; the building blocks of proteins … in other words

10. Nucleotides (A,T,C,G or A,U,C,G) are the alphabet Translation code Words made of 3 letters (triplets) = codons Polypeptide language Consists of 20 amino acids Translating nucleic acid language to polypeptides (chains of amino acids)

11. Cracking the genetic code • Rules of communicating • from RNA’s codons to amino acids in proteins

12. Transcribe the DNA strand: GGT-AAA-TGC ___ - ___ - ___ RNA Translate RNA into polypeptides

14. Transcribe the DNA strand: GGT-AAA-TGC CCA-UUU-ACG RNA Translate RNA into polypeptides Pro – Phe - Thr

15. Transcription Making the RNA Occurs in steps Initiation Enzyme with start point = promoter Elongation Adds nucleotides to RNA strand Termination Enzyme reaches stop point

16. DNA → RNA → protein • Flow of information begins in a gene • Nucleotide sequence = DNA • Serves as a template • Template transcribed into • Another nucleotide sequence = RNA • RNA is responsible (translation) for the next sequence • Amino acids = polypeptide • Proteins formed from polypeptide determines cell appearance and capabilities

17. Potential to look backward • From protein back to gene • E.g. Sickle cell disease caused by different amino acid in hemoglobin protein Caused by change of a single nucleotide = mutation

18. Types of gene mutations Base substitution No change Positive change Harmful change (sickle cell example) Base insertion or base deletion Alters the reading frame Very bad Mutations

19. Errors during DNA replication Mutagens Physical agent e.g. UV, X-rays, or gamma rays Chemical agent e.g. ethidium bromide, Causes of mutations