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Molecular Basis of Genetics and Biotechnology The central dogma of molecular biology describes the flow of genetic information from DNA  RNA  protein.

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Presentation on theme: "Molecular Basis of Genetics and Biotechnology The central dogma of molecular biology describes the flow of genetic information from DNA  RNA  protein."— Presentation transcript:

1 Molecular Basis of Genetics and Biotechnology The central dogma of molecular biology describes the flow of genetic information from DNA  RNA  protein. 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.

2 Each group will be given a different experiment or insight that led to the structure and function of DNA. Griffith experiment (2 groups) (190-191) Griffith experiment (2 groups) (190-191) Avery experiment (191, additional handout) Avery experiment (191, additional handout) Hershey-Chase experiment (2 groups) (192-193) Hershey-Chase experiment (2 groups) (192-193) Chargaff’s observation, structure of the 4 bases (195, 196) Chargaff’s observation, structure of the 4 bases (195, 196) Wilkins and Franklin’s X-ray diffraction (196) Wilkins and Franklin’s X-ray diffraction (196) Watson and Crick’s DNA model and pairing between bases (196-197) Watson and Crick’s DNA model and pairing between bases (196-197)

3 Griffith experiment

4 Avery experiment Repeated Griffith experiment to see which molecule actually transformed into the harmless strain Repeated Griffith experiment to see which molecule actually transformed into the harmless strain Treated extract of heat killed smooth colonies with enzymes that broke down everything except for DNA. What happened? Treated 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? Did same with enzyme that broke down DNA. What happened?

5 Hershey-Chase experiment

6 Watson and Crick Model What did they know: DNA was a molecule involved in genetic information What did they know: DNA was a molecule involved in genetic information What did they not know: The structure of the molecule What did they not know: The structure of the molecule What evidence did they use? What 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) X-Ray diffraction: Scattered pattern of DNA X-rays on film produced by Rosalind Franklin (showed coiled strand and angle of stands) Chargaff’s rule Chargaff’s rule DNA source ATGC Streptoc occus 29.831.620.518.0 Yeast31.332.918.717.1 Herring27.827.522.222.6 Human30.929.419.919.8

7 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?

8 Analysis question 2 Draw 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. Draw 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 Do this on the back of WB 34

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10 Structure of DNA Double stranded helix Double stranded helix Deoxyribose sugar Deoxyribose sugar Phosphate group Phosphate group 4 nitrogen bases 4 nitrogen bases Guanine : Cytosine Guanine : Cytosine Adenine : Thymine Adenine : Thymine Hydrogen bonds connect bases Hydrogen bonds connect bases

11 DNA replication Each strand is complementary Each strand is complementary Replication steps Replication steps DNA Helicase (enzyme) “unzips” the DNA strand, breaking the hydrogen bonds DNA Helicase (enzyme) “unzips” the DNA strand, breaking the hydrogen bonds DNA polymerase adds complementary bases to each strand (5’ to 3’) DNA polymerase adds complementary bases to each strand (5’ to 3’) Sugar phosphate links extend the chain and DNA polymerase “proof reads” new strand Sugar phosphate links extend the chain and DNA polymerase “proof reads” new strand DNA ligase seals fragements together DNA ligase seals fragements together

12 Reading quiz Person closest to the molecular modeling kit Person closest to the molecular modeling kit Read through WB 35 Read through WB 35 Rebuild 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! Rebuild 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 table Read through WB 35 and define the following terms. 1. Anticodon 2. Codon 3. Nucleotide 4. Ribosome 5. Transcription

13 Reading quiz answers DNA model DNA model Check with model up front Check with model up front 1. Anticodon: 3 nucleotides on a tRNA complementary to the codon 2. Codon: 3 nucleotides of an mRNA that codes for an amino acid 3. Nucleotide: Monomer of a nucleic acid consisting of a sugar, base, and phosphate 4. Ribosome: Organelle which is the site of protein synthesis 5. Transcription: Process of producing an mRNA molecule from a DNA strand

14 Complete letters C-F using the DNA molecule just made Complete letters C-F using the DNA molecule just made Answer these questions on the back of WB 35 (yep, we’re conserving paper) 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 sequence 3. A partial DNA stand has the following sequence: CACTTGCAC. What would be the complementary mRNA sequence 4. How can protein be synthesized in the cytoplasm of a cell when DNA is contained in the nucleus? 4. How can protein be synthesized in the cytoplasm of a cell when DNA is contained in the nucleus?

15 Structure of RNA Can leave the nucleus Can leave the nucleus Single stranded Single stranded Ribose sugar Ribose sugar Phosphate group Phosphate group 4 nitrogen bases 4 nitrogen bases Guanine : Cytosine Guanine : Cytosine Adenine : Uracil Adenine : Uracil

16 Transcription The 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 The 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

17 Reading quiz. Use study guide and WB 34-35. Staple exam to back of test corrections and turn in. Complete the following chart Complete the following chart Nucleic Acid Actual Name Shape Location in the cell Function during protein synthesis DNA mRNA tRNA

18 Complete letter G Complete letter G Answer the following questions on the back of WB 36 Answer the following questions on the back of WB 36 5. You have the following mRNA sequence GUGAACGUG. What would be the anticodon base sequence on the corresponding tRNAs? Circle each codon and anticodon. 5. 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?) 6. Using a venn diagram, compare and contrast codons to anticodons (structure? Function? Location?)

19 Genetic code

20 Has a four letter alphabet Has a four letter alphabet There are 20 different amino acids (protein building blocks) There are 20 different amino acids (protein building blocks) How many letters codes for each amino acid? How many letters codes for each amino acid? Codon: 3 letter combination of mRNA strand Codon: 3 letter combination of mRNA strand English code

21 tRNA Anticodon (complementary to mRNA) Anticodon (complementary to mRNA) Attached amino acid Attached amino acid Codon: AAA, then anticodon is ____ Codon: AAA, then anticodon is ____

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24 Reading quiz Left 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) Left 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

25 Translation Goal of genetic code is to produce a protein. How does this happen? Goal of genetic code is to produce a protein. How does this happen? 1) Transcription produces mRNA strand 1) Transcription produces mRNA strand 2) mRNA binds with ribosome 2) mRNA binds with ribosome 3) tRNA anticodon binds with mRNA 3) tRNA anticodon binds with mRNA 4) Amino acids attached to tRNA bond together 4) Amino acids attached to tRNA bond together

26 Hookin’ up amino acids mRNA and first tRNA bind to ribosome (but not each other yet). This is always the anti codon UAC (amino acid – methionine) mRNA 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 1 st codon Ribosome scans mRNA and keeps first codon sequence (AUG) at the P site. Anticodon hydrogen bonds with 1 st codon Anticodon complementary to the 2 nd codon hydrogen bonds to it at the A site. Anticodon complementary to the 2 nd codon hydrogen bonds to it at the A site. Amino acid of 1 st tRNA detaches and forms peptide bonds with amino acid of 2 nd tRNA Amino acid of 1 st tRNA detaches and forms peptide bonds with amino acid of 2 nd tRNA mRNA and 2 nd tRNA move to the left as the 1 st tRNA leaves ribosome mRNA and 2 nd tRNA move to the left as the 1 st tRNA leaves ribosome When a “stop codon” is reached polypeptide chain leaves, other parts dissemble When a “stop codon” is reached polypeptide chain leaves, other parts dissemble Polypeptide may be modified (where?) before it is a functional protein Polypeptide may be modified (where?) before it is a functional protein

27 Write response in notebook Use the genetic code (on your desk) to find the amino acid sequence coded by the mRNA sequence AUGAAGUUU Use the genetic code (on your desk) to find the amino acid sequence coded by the mRNA sequence AUGAAGUUU Use the genetic code (on your desk) to find the amino acid sequence coded by the DNA sequence TATCATGCC Use the genetic code (on your desk) to find the amino acid sequence coded by the DNA sequence TATCATGCC

28 Mutations Point Point Frameshift Frameshift THE CAT ATE THE RAT THE CAT ATE THE RAT THC ATA TET HER AT THC ATA TET HER AT Mutations constantly happen (about 1 in every 1000 bases) and are important for variation Severity depends on location and number of mutations Mutations constantly happen (about 1 in every 1000 bases) and are important for variation Severity depends on location and number of mutations

29 Chromosomal mutations

30 Gene regulation All cells in an organism have the same genes All cells in an organism have the same genes Do all cells look the same and do the same job? Why? Do all cells look the same and do the same job? Why? How is this possible? How is this possible?


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