1 / 18

Protein Synthesis

Protein Synthesis. The whole point of all of this is to make proteins. DNA (gene)  RNA amino acid sequence Protein ***Why are proteins so important?***. Protein Synthesis. Proteins Synthesis: Transcription. What kind of RNA is DNA transcribed into?. mRNA Why?

gracie
Download Presentation

Protein Synthesis

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. Protein Synthesis • The whole point of all of this is to make proteins. • DNA (gene) RNA amino acid sequence Protein ***Why are proteins so important?***

  2. Protein Synthesis

  3. Proteins Synthesis: Transcription • What kind of RNA is DNA transcribed into? • mRNA • Why? • Because mRNA can leave the nucleus.

  4. A little more detail • Initiation: begins with Promoter DNA • Identifies which strand will be transcribed • Gives a spot for RNA polymerase to bind • Elongation : • RNA polymerase adds nucleotides 5’ to 3’ (about 40nts/sec) • Termination: • Terminator sequence on DNA codes for polymerase to detach and mRNA to leave nucleus and go to ribosome

  5. Fig. 17-3b-3 Nuclear envelope DNA TRANSCRIPTION Pre-mRNA RNA PROCESSING mRNA TRANSLATION Ribosome Polypeptide (b) Eukaryotic cell

  6. mRNA modification • mRNA receives a “cap” and a “tail” to protect it while in transit to the ribosome • The mRNA includes introns and exons . • Introns are removed before it leaves nucleus

  7. Protein Synthesis: Transcription

  8. Fig. 17-10 Exon Exon Intron 5 Exon Intron 3 Pre-mRNA Poly-A tail 5 Cap 146 31 104 1 105 30 Introns cut out and exons spliced together Coding segment mRNA 5 Cap Poly-A tail 1 146 5 UTR 3 UTR

  9. So what’s the purpose of exons and introns? • One gene can code for different proteins.. • Depending on which sections of the mRNA template are considered exons during processing. • This would explain our low number of genes for such a complex organism as a human

  10. Humans have only 1.5x as many genes as a fruit fly

  11. 0 DNA molecule Gene 1 Gene 2 Gene 3 DNA strand Transcription RNA Codon Translation Polypeptide Amino acid

  12. Proteins Synthesis: Transcription • Nucleotides are arranged into triplets called codons. • Example: AAC CG T TAC T TG GCA ATG • Each codon specifies (codes for) a particular amino acid. • The sequence of the codons in the DNA will be transferred to the RNA, which will then determine the sequence of amino acids.

  13. 0 DNA strand Transcription RNA Codon Translation Polypeptide Amino acid

  14. Protein Synthesis: Transcription • When RNA is being synthesized by enzymes, they pair the bases just like they would during DNA replication. • There is one BIG difference, though. • RNA does not have the base Thymine. • Instead, if the enzymes come across an Adenine base, they pair it with Uracil. • Can you transcribe the following DNA strand? DNA: ATC GGA TAC GGG CCA mRNA:

  15. Protein Synthesis: Transcription • But let’s remember the goal here… Proteins! Proteins! Proteins! • Now that we have our mRNA with the DNA code, the mRNA can leave the nucleus and head to the ribosome!

More Related