Presentation on theme: "Molecular Basis of Genetics and Biotechnology"— Presentation transcript:
1Molecular Basis of Genetics and Biotechnology The central dogma of molecular biology describes the flow of genetic information from DNARNAprotein. This flow happens through precise mechanisms, although mistake can happen during the process. Many technologies take advantage of the properties of DNA to generate novel products and tools.
2Each group will be given a different experiment or insight that led to the structure and function of DNA.Griffith experiment (2 groups) ( )Avery experiment (191, additional handout)Hershey-Chase experiment (2 groups) ( )Chargaff’s observation, structure of the 4 bases (195, 196)Wilkins and Franklin’s X-ray diffraction (196)Watson and Crick’s DNA model and pairing between bases ( )
4Avery experimentRepeated Griffith experiment to see which molecule actually transformed into the harmless strainTreated extract of heat killed smooth colonies with enzymes that broke down everything except for DNA. What happened?Did same with enzyme that broke down DNA. What happened?
6Watson and Crick ModelWhat did they know: DNA was a molecule involved in genetic informationWhat did they not know: The structure of the moleculeWhat evidence did they use?X-Ray diffraction: Scattered pattern of DNA X-rays on film produced by Rosalind Franklin (showed coiled strand and angle of stands)Chargaff’s ruleDNA sourceATGCStreptococcus29.831.620.518.0Yeast31.332.918.717.1Herring27.827.522.222.6Human30.929.419.919.8
7Reading quiz – Read through WB 34 Reading quiz – Read through WB 34. I will stamp SG 1 for full credit today only. I will also stamp SG 3 on Thursday for full credit (if not done)What is the basic unit (monomer) of a nucleic acid?What are the 3 subunits of a nucleotide. Draw them.Which of these subunits are the same in all nucleic acids?What are the 4 bases of DNA?What is the function of DNA, can it leave the nucleus?
8Analysis question 2Draw a labeled diagram of your DNA molecule. Keep the illustration in a straight “ladder” form as seen in figure 5. Do not attempt to draw the helical shape. Identify each nitrogen base.Do this on the back of WB 34
10Structure of DNA Double stranded helix Deoxyribose sugar Phosphate group4 nitrogen basesGuanine : CytosineAdenine : ThymineHydrogen bonds connect bases
11DNA replication Each strand is complementary Replication steps DNA Helicase (enzyme) “unzips” the DNA strand, breaking the hydrogen bondsDNA polymerase adds complementary bases to each strand (5’ to 3’)Sugar phosphate links extend the chain and DNA polymerase “proof reads” new strandDNA ligase seals fragements together
12Reading quiz Person closest to the molecular modeling kit Read through WB 35Rebuild your double helix exactly as it was on Monday/Tuesday. (You can use your instructions). Make sure you have the correct base sequence and base pairing. THIS IS YOUR READING QUIZ!Everyone else at the tableRead through WB 35 and define the following terms.1. Anticodon2. Codon3. Nucleotide4. Ribosome5. Transcription
13Reading quiz answers DNA model Check with model up front1. Anticodon: 3 nucleotides on a tRNA complementary to the codon2. Codon: 3 nucleotides of an mRNA that codes for an amino acid3. Nucleotide: Monomer of a nucleic acid consisting of a sugar, base, and phosphate4. Ribosome: Organelle which is the site of protein synthesis5. Transcription: Process of producing an mRNA molecule from a DNA strand
14Complete letters C-F using the DNA molecule just made Answer these questions on the back of WB 35 (yep, we’re conserving paper)3. A partial DNA stand has the following sequence: CACTTGCAC. What would be the complementary mRNA sequence4. How can protein be synthesized in the cytoplasm of a cell when DNA is contained in the nucleus?
15Structure of RNA Can leave the nucleus Single stranded Ribose sugar Phosphate group4 nitrogen basesGuanine : CytosineAdenine : Uracil
16TranscriptionThe process of copying part of a DNA strand into a complementary RNA strand, so the information can be taken outside of the nucleus without affecting the DNA molecule
17Complete the following chart Reading quiz. Use study guide and WB Staple exam to back of test corrections and turn in.Complete the following chartNucleic AcidActual NameShapeLocation in the cellFunction during protein synthesisDNAmRNAtRNA
18Complete letter GAnswer the following questions on the back of WB 365. You have the following mRNA sequence GUGAACGUG. What would be the anticodon base sequence on the corresponding tRNAs? Circle each codon and anticodon.6. Using a venn diagram, compare and contrast codons to anticodons (structure? Function? Location?)
24Reading quizLeft table of your group. Put together the mRNA molecule produced in letter F (hint, look at the diagram on WB 40 and think about which sugar to use)Right table of your group. Put together the tRNA molecules produced in letter G.Add appropriate amino acid (black) to each tRNA
25TranslationGoal of genetic code is to produce a protein. How does this happen?1) Transcription produces mRNA strand2) mRNA binds with ribosome3) tRNA anticodon binds with mRNA4) Amino acids attached to tRNA bond together
26Hookin’ up amino acidsmRNA and first tRNA bind to ribosome (but not each other yet). This is always the anti codon UAC (amino acid – methionine)Ribosome scans mRNA and keeps first codon sequence (AUG) at the P site. Anticodon hydrogen bonds with 1st codonAnticodon complementary to the 2nd codon hydrogen bonds to it at the A site.Amino acid of 1st tRNA detaches and forms peptide bonds with amino acid of 2nd tRNAmRNA and 2nd tRNA move to the left as the 1st tRNA leaves ribosomeWhen a “stop codon” is reached polypeptide chain leaves, other parts dissemblePolypeptide may be modified (where?) before it is a functional protein
27Write response in notebook Use the genetic code (on your desk) to find the amino acid sequence coded by the mRNA sequence AUGAAGUUUUse the genetic code (on your desk) to find the amino acid sequence coded by the DNA sequence TATCATGCC
28Mutations Point Frameshift THE CAT ATE THE RATTHC ATA TET HER ATMutations constantly happen (about 1 in every 1000 bases) and are important for variation Severity depends on location and number of mutations