2. Protein Synthesis Transcription and Translation

3. RNA Structure Like DNA, RNA consists of a long chain of nucleotides 3 Differences between RNA and DNA: 1) Ribose sugar instead of deoxyribose 2) Single Stranded 3) Uracil replaces thymine

5. mRNA

7. Ribosomal RNA

8. Transcription During transcription, RNA polymerase binds to DNA and separates the DNA strands. RNA polymerase then uses one strand of DNA as a template from which nucleotides are assembled into a strand of RNA. ****Remember uracil in RNA and thymine in DNA

9. How does the RNA know which parts of the DNA to Copy??? Promoters are regions in the DNA strand where RNA Polymerase will bind to the DNA. This is where transcription begins. Similar signals in the DNA strand cause transcription to stop.

11. RNA Editing Introns: not involved in coding for proteins Exons: involved in protein coding Scientists are not sure what the purpose of the intron is. They do know that the RNA strand cuts introns before it leaves the nucleus.

12. Translation The Genetic Code Proteins are made by joining amino acids into long chains called polypeptides. Each polypeptide contains a combination of any or all of the 20 different amino acids. The properties of proteins are determined by the order in which different amino acids are joined together to produce polypeptides.

14. Practice The Genetic Code Codon: consists of three consecutive nucleotides that specify a single amino acid that is to be added to the the polypeptide. Example: RNA Sequence: UCGCACGGU Read sequence 3 bases at a time UCG-CAC-GGU The codons represent the different amino acids: UCG CAC GGU Serine Histidine Glycine

18. DNA Mutations Point Mutation: Subtitutions are considered point mutations because they occur at a single point in the DNA sequence. Frameshift Mutations: Insertions and Deletions are considered frameshift mutations because they “shift” the reading frame of the genetic message. Which do you think is more likely to have a greater affect to the organism, a point mutation or a frameshift mutation?

19. Mutations Point mutations – single base change – base-pair substitution silent mutation – no amino acid change – redundancy in code missense – change amino acid nonsense – change to stop codon

20. Point mutation leads to Sickle cell anemia What kind of mutation?

21. Point mutation leads to Sickle cell anemia What kind of mutation? Missense!

22. Sickle cell anemia Primarily Africans – recessive inheritance pattern – strikes 1 out of 400 African Americans hydrophilic amino acid hydrophobic amino acid

23. Mutations Frameshift – shift in the reading frame changes everything “downstream” – insertions adding base(s) – deletions losing base(s) Where would this mutation cause the most change: beginning or end of gene?

24. Cystic fibrosis Primarily whites of European descent – strikes 1 in 2500 births 1 in 25 whites is a carrier (Aa) – normal allele codes for a membrane protein that transports Cl - across cell membrane defective or absent channels limit transport of Cl - (& H 2 O) across cell membrane thicker & stickier mucus coats around cells mucus build-up in the pancreas, lungs, digestive tract & causes bacterial infections – without treatment children die before 5; with treatment can live past their late 20s

25. Effect on Lungs Chloride channel transports chloride through protein channel out of cell Osmotic effects: H 2 O follows Cl - airway Cl - H2OH2O H2OH2O mucus secreting glands bacteria & mucus build up thickened mucus hard to secrete normal lungs cystic fibrosis cells lining lungs Cl - channel

26. Deletion leads to Cystic fibrosis loss of one amino acid delta F508