1 / 24

Nucleic Acids

Nucleic Acids. RNA. What are RNA?. Nucleic acid polymer of nucleotide monomers Plays role in translation of genetic information from DNA to protein products Acts as messenger between DNA and Protein synthesis complexes (ribosomes) Forms vital portions of ribosomes

jamal
Télécharger la présentation

Nucleic Acids

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Nucleic Acids RNA

  2. What are RNA? • Nucleic acid polymer of nucleotide monomers • Plays role in translation of genetic information from DNA to protein products • Acts as messenger between DNA and Protein synthesis complexes (ribosomes) • Forms vital portions of ribosomes • Carrier molecule for amino acids to be used in protein synthesis

  3. ..hot What does she look like? • Ribose and phosphate backbone bonded by phosphodiesters • 4 different bases-A, G, C and U • Uracil replaces Thymine • usually a single strand, not a helix • 5 carbon sugar-ribose **hydroxyl groups make the RNA less stable than DNA

  4. Mirror mirror on the wall……..

  5. Protein synthesis

  6. Protein synthesis

  7. What’s cooking? • The main copy of the genes is in the nucleus to protects it from damage. • During protein synthesis, the DNA code is transferred into a working copy made of messenger RNA (transcription) -DNA double helix is unwound • Genes are transcribed one at a time • The m-RNA leaves the nucleus and translation takes place in the cytoplasm, on the ribosome

  8. ….still cooking RNA • The enzymes progress along the template strand in the 3’-5’ direction synthesizing a complementary RNA molecule with elongation in the 5’-3’ direction • Some RNA-dependent RNA polymerases use RNA as their template for synthesis of the new RNA strand e.g. poliovirus (RNA virus)

  9. 3 Types of RNA are Involved in Protein Synthesis

  10. rRNA • Make up 80% of the RNA molecules • In the cytoplasm, rRNA and Protein combine to form a nucleoprotein-Ribosome • Ribosome binds mRNA and carries out protein synthesis. • Non-coding RNA are RNA genes that encode RNA not translated to proteins e.g. tRNA and rRNA both involved in translation

  11. The transcribed code is carried from the nucleus to the ribosomes by messenger RNA (m-RNA) • The ribosomes contain ribosomal RNA (r-RNA). This type is structural and also acts as an enzyme when the protein is lengthened • Transfer RNA (t-RNA) carries amino acids to the ribosomes: there must be at least 20 types of t-RNA

  12. Teach teacher…. Um no! TRANSLATE to amino acids • Decoding (translation) occurs on the ribosome • Ribosomes are constructed of a special RNA (r-RNA) and protein • They have 2 sub-units which come together to form a decoding machine • Some ribosomes attached to membranes (rough endoplasmic reticulum), others not attached (free ribosomes)

  13. m-RNA leaves the nucleus and looks for a Ribosome • RNA leaves the nucleus and carries the code into the cytoplasm, then attaches to a ribosome

  14. De-coding • The RNA Code is Translated into Protein • Ribosome finds start codon (AUG), then decodes the message, 3 bases at a time • When the ribosome reaches the stop codon the protein is released and the decoding can start over to make another protein

  15. In Translation Amino Acids are Carried to the Ribosomes by Transfer RNA • There are at least 20 kinds of t-RNA because there are 20 different amino acids • Each transfer RNA has a site that attaches to a specific amino acid, and a site with 3 nucleotide bases (anticodon) that must match up with the RNA code letter for that amino acid • Amino acids attach to the new protein only if the t-RNA anticodon matches (is complementary to) the m-RNA codon

  16. Proteins are Finished Off in the Endoplasmic Reticulum & Golgi Apparatus • Most new proteins are not immediately functional- they must be finished off • In the endoplasmic reticulum and Golgi apparatus they are folded into the proper shape and sometimes chemical groups are added or clipped off • Some are routed to the cytoplasm, others to the mitochondria, etc.

  17. …………..recap

  18. DNA synthesizes RNA which in turn makes Protein Many Hormones Act by Turning on Genes • certain hormones e.g. sex hormones, cortisone, aldosterone, thyroxine) pass through the cell membrane and enter the nucleus • In the nucleus they bind to receptors which turn on genes

  19. Reverse Transcription • RNA viruses • Some viruses use RNA instead of DNA as genetic material • One group of RNA viruses, termed retroviruses, convert RNA back to DNA. • RNA viruses make numerous mistakes in replicating genetic information. This means that some viruses like HIV (causes AIDS) changes very rapidly making it difficult to make a vaccine.

More Related