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RNA

RNA. Ribonucleic Acid. Structure of RNA. Single stranded Ribose Sugar 5 carbon sugar Phosphate group Nitrogen Bases: Adenine , Uracil , Cytosine, Guanine. Types of RNA. Three main types Messenger RNA (mRNA) – carries DNA code to ribosomes for translation.

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RNA

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  1. RNA Ribonucleic Acid

  2. Structure of RNA • Single stranded • Ribose Sugar • 5 carbon sugar • Phosphate group • Nitrogen Bases: • Adenine, Uracil, Cytosine, Guanine

  3. Types of RNA • Three main types • Messenger RNA (mRNA) – carries DNA code to ribosomes for translation. • Transfer RNA (tRNA) – brings amino acids to ribosomes for protein synthesis. • Ribosomal RNA (rRNA) – Ribosomes are made of rRNA and protein.

  4. Transcription • RNA molecules are produced by copying part of the nucleotide sequence of DNA into complementary sequence in RNA, a process called 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 mRNA.

  5. mRNA

  6. How Does it Work? • RNA Polymerase looks for a region on the DNA known as a promoter, where it binds and begins transcription. • RNA strands are then edited. Some parts are removed (introns) - which are not expressed – and other that are left are called exons or expressed genes.

  7. The Genetic Code • This is the language of mRNA. • Based on the 4 bases of mRNA. • “Words” are 3 RNA sequences called codons. • The strand aaacguucgccc would be separated as aaa-cgu-ucg-ccc the amino acids would then be Lysine – Arginine – Serine - Proline

  8. Genetic Codes

  9. Translation • During translation, the cell uses information from messenger RNA to produce proteins. • Transcription occurs in nucleus. • mRNA moves to the cytoplasm then to the ribosomes. tRNA “read” the mRNA and obtain the amino acid coded for, starts with Methionine. • Ribosomesattach amino acids together forming a polypeptide chain. • Polypeptide chain keeps growing until a stop codon is reached.

  10. Translation to Protein

  11. Translation

  12. Mutations • Gene mutations result from changes in a single gene. Chromosomal mutations involve changes whole chromosomes.

  13. Gene Mutation • Point Mutation – Affect one nucleotide thus occurring at a single point on the gene. Usually one nucleotide is substituted for another nucleotide. • Frameshift Mutation – Inserting an extra nucleotide or deleting a nucleotide causes the entire code to “shift”.

  14. Gene Mutation

  15. Chromosomal Mutations • Deletion – Part of a chromosome is deleted • Duplication – part of a chromosome is duplicated • Inversion – chromosome twists and inverts the code. • Translocation – Genetic information is traded between nonhomologous chromosomes.

  16. Chromosomal Mutations

  17. Mutations

  18. More Mutations

  19. Gene Regulation • In simple cells (prokaryotic) lac genes which are controlled by stimuli, turn genes on and off. • In complex cells (eukaryotic) this process is not as simple. Promoter sequences regulate gene operation.

  20. Review

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