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DNA Transcription and Translation

DNA Transcription and Translation. Sections 12.3 and 12.4. Do Now. 1. What is RNA? 2. What are proteins used for in our bodies? 3. Fill in the chart below:. Gene. Segment of DNA that codes for a protein The Central Dogma of Biology:

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DNA Transcription and Translation

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  1. DNA Transcription and Translation Sections 12.3 and 12.4

  2. Do Now • 1. What is RNA? • 2. What are proteins used for in our bodies? • 3. Fill in the chart below:

  3. Gene • Segment of DNA that codes for a protein • The Central Dogma of Biology: • DNA codes for RNA and RNA makes protein (the synthesis of)

  4. One Gene – One Enzyme • The Beadle and Tatum experiment showed that one gene codes for one enzyme. • One gene codes for one polypeptide. • polypeptide - a chain of covalently bonded amino acids. • (proteins are made of one or more polypeptide)

  5. Let’s make some observations about RNA’s structure

  6. RNA • RNA stands for: • Ribonucleic acid • RNA is found: • Nucleus and Cytoplasm

  7. RNA Structure • Like DNA, RNA is made up of subunits called _____________, which are made of three parts: • Sugar (ribose) • Phosphate • Nitrogen Base

  8. RNA’s Nitrogen Bases • Adenine (A) • Cytosine (C) • Guanine (G) • Uracil (U)

  9. There are 3 types of RNA: • Messenger RNA (mRNA) – long strands of RNA nucleotides that are formed complementary to one strand of DNA. • Transfer RNA (tRNA) – smaller segments of RNA nucleotides that transport amino acids to the ribosomes. • Ribosomal RNA (rRNA) – associates with protein to form the ribosome.

  10. All RNA is … • Single stranded • Many different shapes • “Cheap copy” of DNA

  11. Do Now • 1. What is a protein made of? • 2. Explain the process between DNA and proteins.

  12. Transcription • First step in making proteins • Process of taking one gene (DNA) and converting into a mRNA strand • DNA -> RNA • Location: • Nucleus of the cell

  13. Steps to Transcription • 1. An enzyme attaches to the promoter (start signal region) of a gene and unwinds the DNA

  14. Steps to Transcription (Cont.) • 2. One strand acts as a template.

  15. Steps to Transcription (Cont.) • 3. A mRNA copy is made from the DNA template strand by RNA polymerase • 4. A mRNA copy is made until it reaches the termination (stop signal) sequence • 5. The two strands of DNA rejoin.

  16. Template vs. Non Template Strand

  17. Transcription animation • https://www.youtube.com/watch?v=ztPkv7wc3yU

  18. Transcribe this DNA to mRNA

  19. mRNA Processing • Pre-mRNA – the original sequence of RNA created during transcription • mRNA reaches the ribosomes

  20. RNA Processing

  21. What is RNA Processing? • After transcription the pre-mRNA molecule undergoes processing • 5’ cap is added • Poly A tail is added to the 3’ end • Introns are removed.

  22. Do Now • Label the Transcription diagram

  23. RNA Processing • In Eukaryotes only • Introns- non-coded sections • Exons- codes for a protein • Before RNA leaves the nucleus, introns are removed and exons are spliced together • A cap and poly A tail are added to ends of the sequence • mRNA leaves the nucleus through the nuclear pores

  24. Why is it necessary to add the poly A tail and 5’ cap?

  25. Let’s try an activity (11.5) • http://www2.pearsonsuccessnet.com/snpapp/iText/products/0-13-115075-8/index.html

  26. Pg. 339 • Pg. 339

  27. 3’ CAUGAUGUACGAUACGUA 5’ cap Let’s an example… • Original DNA Sequence (DNA): • 5’ GTACTACATGCTATGCAT 3’ • Translate it (RNA): • 3’ CAUGAUGUACGAUACGUA 5’ • Add the 5’ cap:

  28. Add a poly A tail onto the 3’ end Poly A tail 3’ CAUGAUGUACGAUACGUA 5’ 3’ CAUGACGGUA 5’ 3’ CAUGACGGUA 5’ cap cap cap Finish the job! • Remove the introns “UGUA” and “AUAC”:

  29. Get a new partner! • DNA Strand of non-template strand: • 5’ ATCGGTAGAGTATTTACAGATA 3’ • Remove introns: • CGGUA UUACAG

  30. Think, Pair, Share • Take a minute think on your own, then pair with your partner, and share your ideas! • Evolutionary, why do you think there are introns? • Where did they come from? • Why do we have them? • Remember there is NO wrong answer!

  31. PROTEINS!

  32. Proteins are made up of amino acids!!! • Proteins are polymers of amino acids • Only 20 different amino acids • BUT there are hundreds of thousands of different proteins How can this be?

  33. Let’s compare to it to the English language • How many letters are in the alphabet? A,b,c,d,… 26 • How many words are there? Miss, Ings, is, smart, .. Almost infinite! • Each word has a unique structure of letters. • Similar to proteins and amino acids

  34. Proteins- (PCFNa) -made of 20 different Amino Acids - Amino Acids bond to form polypeptide chains

  35. How do amino acids form these peptide chains? Peptide Bonds – Link each amino acids together to form proteins

  36. How many amino acids are in a dipeptide chain? How about a tripeptide chain? How many water molecules are formed from 2 amino acids? How many water molecules are formed from 100 amino acids?

  37. Do Now • Perform transcription on this DNA segment: GCTTCATACGA • Do RNA processing and remove the introns: GAA and UGC • How does this mRNA sequence leave the nucleus? • Where does it go?

  38. Protein Structure http://www3.interscience.wiley.com:8100/legacy/college/boyer/0471661791/structure/HbMb/hbmb.htm

  39. Translation • Production of proteins from mRNA • mRNA goes to the ribosomes in the cytoplasm or the RER and produces proteins

  40. Steps to Translation • 1. mRNA leaves the nucleus and binds to a ribosome • 2. the 5’ end of mRNA binds to ribosome

  41. Ribosome • Two subunits to the ribosome • 3 grooves on the ribosome (A, P, E) • A: tRNA binding site • P: polypeptite bonding site • E: exit site

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