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Understanding Gene Expression and Protein Synthesis

Explore how genetic code exits the nucleus, the processes of DNA replication and transcription, and the translation of DNA into proteins. Learn about gene expression, cell differentiation, and the role of mRNA, tRNA, and rRNA in protein synthesis.

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Understanding Gene Expression and Protein Synthesis

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  1. Tuesday 3/6/12 Aim: How does the genetic code get out of the nucleus? Do Now: Show the product after DNA replicates: Homework:page 315 questions 19 and 20

  2. Wednesday 3/7/12 pd 7 • AIM: how can we make an mRNA transcript from a DNA template? • DO NOW: Explain the difference between replication and transcription. • HOMEWORK: Internet project on the website due friday

  3. How does a DNA strand become a protein? Name the processes.

  4. Tuesday 4/5/11 • AIM: why is the primary transcript modified before leaving the nucleus? • DO NOW: Explain what makes a skin cell different from a cardiac (heart) cell. • Homework: Textbook Read page 306. reading check on page 306. analyze figure 13 on page 307. List the start codon and the 3 stop codons.

  5. Before becoming a protein, name the molecule synthesized during translation. polypeptide

  6. Gene Expression • DNA only provides instructions. • Gene expression is the process by which the information encoded in a gene is used to assemble protein . • In you body, do all cells have the same genetic information? • How come our cells in our stomach function differently than our skin? • Cells are differentiated meaning that different cells can have very different structure and function due to the genes they express. • Different cells listen to different instructions so that means they make different proteins

  7. How do skin cells make proteins? How do cardiac cells make proteins?

  8. How is the information in DNA turned into Protein?

  9. DNA template • On the double helix, the sequence being transcribed is called the sense strand • It holds the information to build the polypeptide • The noncoding DNA strand is called the anti-sense strand • The sense and anti-sense strands can switch and the cell makes a different polypeptide

  10. The primary transcript is complementary to the DNA template (sense strand)

  11. Thursday 3/8/12 • AIM:how does a mature mRNA molecule mirror its DNA template? • DO NOW: Transcribe the following ATTCGTAGCATG • Where does transcription take place? • Homework: project DUE TOMORROW!

  12. Primary transcript • Rough draft mRNA • First mRNA molecule made • It gets modified before it leaves the nucleus

  13. Transcription: DNA-RNA

  14. Transcription (nucleus) • DNA-RNA • Step 1: unzip the DNA double helix • Breaking the hydrogen bonds between Nitrogen bases • Step 2: Attract ribonucleotides to the DNA template • Base pair rules

  15. Types of RNA • mRNA: messenger RNA: carries the genetic code from the nucleus to the ribosome • rRNA: ribosomal RNA: builds ribosomes • tRNA: transfer RNA: carries amino acids to the synthesizing polypeptide • The Three RNAs (mRNA, tRNA, and rRNA) all work together to turn the information in DNA into a beautiful, 3-dimestional protein!!!

  16. Friday 3/9/12 • AIM: How is the primary transcript modified before it leaves the nucleus? • DO NOW:Explain the difference between a codon and an anticodon. • Transcribe the following: • Sense TACGGTACTGTAGGA • Antisense ATGCCATGACATCCT

  17. POP QUIZ! • Use the picture to answer questions 1-4 1-Name Enzyme A 2- What is the function Of Enzyme B 3- Name Strand 1 4- Why is strand 2 made In small fragments? Enzyme A Enzyme A Enzyme B Strand 2 Strand 1

  18. tRNA: Transfer RNA carries amino acids to the mRNA-ribosome complex

  19. Ribosomal RNA builds ribosomes

  20. How does tRNA know • The mRNA which amino acid to bring the ribosome • The mRNA holds the codons which tell which amino acid

  21. Transcription: DNA  RNA • DNA template used to create RNA • Step 1: RNA polymerase attaches to promoter region, unzips DNA strand Gene Complementary DNA

  22. A C G T A T C G C G T A U G C A U A G C G C A U Transcription: DNA  RNA • Step 2: As RNA polymerase unzips, it forms RNA strand with RNA nucleotides.  • Only one DNA strand is transcribed at a time. • Step 3: RNA polymerase continues until termination point.

  23. Tutorial 12.1 Transcription

  24. Transcription cont. • BUT BEFORE IT CAN LEAVE THE NUCLEUS, THE PRIMARY TRANSCRIPT (immature mRNA) MUST BE MODIFIED (changed) • WHY? • Make sure all the codons are in correct order • Get rid of junk DNA • Protect mRNA from degredation • Make sure mRNA recognizes and bonds to the ribosome • Start codon (AUG) must recognize and bond to the ribosome

  25. AIM: how do our cells make RNA from DNA templates • DO NOW: how do you think RNA polymerase unzips the DNA double helix and why does the DNA double helix have to get unzipped? • HOMEWORK: Quick Lab page 310 analysis questions 1-4 will be checked on Monday • EXAM WEDNESDAY

  26. Monday 3/12/12 • AIM: How does the primary transcript mirror the gene sequence? • DO NOW: Where are the instructions for all of your physical characteristics located? (BE SPECIFIC) • How do your physical characteristics develop? (from start to finish) • Homework: page 314 questions 12 Write out the question followed by the answer! • EXAM THIS THURSDAY DNA REPLICATION, TRANSCRIPTION and TRANSLATION Chapter 13 pages296-298,304-310

  27. Transcription • This animation shows the process of transcription

  28. Translation RNA-Polypeptide

  29. Transcription • Promoter sequence: sequence of nucleotides on the DNA molecule that tells RNA polymerase to begin transcription • Start of the genes codons • Terminator sequence: Tells RNA polymerase that transcription is over and to release the primary transcript

  30. Primary transcript • Immature Rough draft • Before it can leave the nucleus, must be modified • Prevents degrading (break down) • Helps ribosome to recognize

  31. Tuesday 3/13/12 pd 7 • AIM: How do genes develop into physical traits? • DO NOW: Transcribe A C G T A T C G C G T • HOMEWORK: Practice Test questions 1-10

  32. Modification of RNA The most important is RNA splicing (cutting out junk DNA gluing together important DNA) Addition of 5’cap and Poly-A tail

  33. Modification of RNA: splicing

  34. Tuesday 3/13/12 • AIM: How do genes develop into physical traits? • DO NOW: Transcribe the following gene sequence A C G T A T C G C G T • HOMEWORK: Textbook Page 310 Quick lab questions 1-4

  35. Transcription RNA polymerase continues until termination point. RNA molecule may become rRNA, tRNA, OR mRNA depending on what sequence was transcribed.

  36. Why do we have to modify the primary mRNA transcript?

  37. Modification of RNA •5’cap attached to the 5' end of the pre-mRNA • Poly(A) tailattached to the 3' end of the pre-mRNA • splicing is a modification of genetic information prior to translation • Introns get cut out, and Exons get together

  38. Splicesomes • Enzymes capable of cutting out introns and pasting together exons • Introns: noncoding sequences of nucleotides • Exons: coding sequences of nucleotides • Reading frame: sequence of coding nucleotides that code for an amino acid sequence • Codon: sequence of 3 nucleotides that specify one amino acid • The genetic word

  39. Monday 4/8/13 • AIM: How is the mature mRNA transcript read once it is at the ribosome? • DO NOW: transcribe and translate • Gene sequence: TACCCTCAACTCTCAACT • Homework: Textbook page 313 questions 8,9,10,12,13

  40. Lets build a protein Gene sequence: TACCCTCAACTCTCAACT mRNA: AUGGGAGUUGAGAGUUGA MET-GLY-VAL-GLU-SER tRNA: UACCCUCAACUCUCAACU

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