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Biology Chapter 12 DNA and RNA Unit 12.3Unit 12.2Unit 12.1Unit 12.4Unit 12.5.

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Presentation on theme: "Biology Chapter 12 DNA and RNA Unit 12.3Unit 12.2Unit 12.1Unit 12.4Unit 12.5."— Presentation transcript:

1 Biology Chapter 12 DNA and RNA Unit 12.3Unit 12.2Unit 12.1Unit 12.4Unit 12.5

2 DNA In class assignment. 1. Draw four different symbols (i.e. Ω ∆ π ). 2. Write down any five letter word. 3. Develop a code for the five letters of that word using only your four symbols. How can you code for five different letters with only four different symbols? 4.How many different letters can you code for using only two of your symbols to stand for each letter. 5. How many different letters could you code for using a string of three symbols for each letter?

3 DNA Essential Questions of mid 1900’s How do genes work? What are they made of? Are genes single molecules or longer structures made up of many molecules? WHAT IS THE CHEMICAL NATURE OF THE GENE?

4 DNA 1928 Frederick Griffith - How do pneumonia make people sick? Two strains of bacteria smooth strain - caused disease rough edges - no disease

5 DNA 1928 Frederick Griffith - How do pneumonia make people sick? Two strains of bacteria smooth strain - caused disease rough edges - no disease Griffith’s Experiment Thought that poison killed mice But heat-killed smooth bacteria didn’t kill mice Transformation Griffith mixed dead smooth cell bacteria with live rough bacteria Mice died Somehow the rough bacteria had been transformed

6 DNA Disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Heat-killed, disease- causing bacteria (smooth colonies) Control (no growth) Heat-killed, disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies)

7 DNA Disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Heat-killed, disease- causing bacteria (smooth colonies) Control (no growth) Heat-killed, disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Dies of pneumoniaLives Live, disease-causing bacteria (smooth colonies) Dies of pneumonia

8 DNA Avery and DNA Repeated Griffith’s experiment Treated extract with enzymes to destroy proteins, lipids, carbohydrates, RNA Transformation still occurred Finally broke down DNA No transformation occurred Griffith’s Experiment Thought that poison killed mice But heat-killed smooth bacteria didn’t kill mice Transformation Griffith mixed dead smooth cell bacteria with live rough bacteria; Mice died Somehow the rough bacteria had been transformed

9 DNA Avery and DNA Repeated Griffith’s experiment Treated extract with enzymes to destroy proteins, lipids, carbohydrates, RNA Transformation still occurred Finally broke down DNA; no transformation occurred AVERY AND OTHERS DISCOVERED THAT DNA STORES AND TRANSMITS GENETIC INFORMATION HERSHEY-CHASE EXPERIMENT 1952 Alfred Hershey & Martha Chase Bacteriophages (bacteria eaters) Used radioactive markers phosphorus-32 and sulfur- 35 Phosphorus only in DNA, Sulfur only in protein Showed DNA, not protein was genetic material

10 DNA

11 Structure of DNA Must carry genetic information to new generations Must be easily copied Polymer DNA Monomer - nucleotide deoxyribose (sugar) phosphate group nitrogenous base adenine & guanine are purines cytosine & thymine are pyrimidines By early 1950’s scientists wondered how DNA, just a string of nucleotides could be the genetic code

12 DNA Structure of nucleotides PurinesPyrimidines Adenine Guanine CytosineThymine Phosphate group Deoxyribose

13 DNA Chargaff’s Rule Erwin Chargaff discovered percentages of G and C are almost equal percentages of A and T are almost equal Source of DNAATGC Streptococcus Yeast Herring Human Streptococcus Yeast Herring Human

14 DNA Chargaff’s Rule Erwin Chargaff discovered percentages of G and C are almost equal percentages of A and T are almost equal X-Ray Evidence Early 1950’s Rosalind Franklin X-ray diffraction X-shaped pattern showed twisted or helix shape

15 DNA The Double Helix Francis Crick and James Watson Made cardboard and wire models When they say Franklin’s X-ray pattern the light came on: Credited with the double-helix model Two strands wound around each other BASE PAIRING - explained Chargaff’s rule A bonds to T G bonds to C

16 DNA Base Pairing Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Sugar-phosphate backbone Nucleotide

17 DNA Base Pairing Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Page 294 Nucleotide

18 DNA The Double Helix Francis Crick and James Watson, 1953

19 DNA The Double Helix Hydrogen bonds Nucleotide Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Page 294

20 12.2Chromosomes and RNA Replication Goals Summarize the events of DNA replication Relate the DNA molecule to chromosome structure

21 12.2Chromosomes and RNA Replication Prokaryotes: One circular DNA molecule DNA and Chromosomes

22 12.2Chromosomes and RNA Replication Prokaryotes: One circular DNA molecule Eukaryotes: 1,000 times as much DNA DNA and Chromosomes DNA found in nucleus Organized into chromosomes 46 in human beings 8 in drosophila 22 in redwood trees

23 12.2Chromosomes and RNA Replication E. Coli 4,639,221 base pairs 1.6 millimeters inside a 1.6µm (1/1,000 of a mm) imagine 1m yarn inside 1mm ball DNA length

24 12.2Chromosomes and RNA Replication Eukaryote DNA packed more tightly Human chromosome > 30 million base pairs A human cell has more than 1METER of DNA! How does it all fit? Chromosome Structure

25 12.2Chromosomes and RNA Replication A human cell has more than 1METER of DNA! How does it all fit? Chromosome Structure DNA and protein(histones) pack together into bead-like nucleosomes which coil into tight loops and coils chromatin Chromatin is dispersed until cell division when chromosomes form

26 12.2Chromosomes and RNA Replication Chromosome Structure A human cell has more than 1METER of DNA! How does it all fit? DNA and protein(histones) pack together into bead-like nucleosomes which coil into tight loops and coils chromatin Chromatin is dispersed until cell division when chromosomes form

27 12.2Chromosomes and RNA Replication Two strands are, “complimentary” You could construct one strand from the other (remember base-pairing) DNA Replication DNA separates into two strands Each strand is a model for a duplicate complimentary strand

28 12.2Chromosomes and RNA Replication Enzymes unzip the molecule DNA polymerase Nucleotides are arranged on the template strand. DNA Replication DNA separates into two strands Each strand is a model for a duplicate complimentary strand

29 12.2Chromosomes and RNA Replication DNA Replication Page 298

30 Quiz 1 15 points 3 questions 5 points for each question You will need a piece of paper and a pen or pencil. Get those out now. You may use your notes; please put books neatly away This paper must have a standard heading at the top of the page, full name, date, and period Yes, neatness does count. Drawings must be clearly labeled

31 1. Make a drawing or several drawings of DNA that demonstrate your understanding of its basic structure. Be sure to include and label the sugar- phosphate backbone, base pairing and double helix. Correctly show the relationship between the Adenine, Thymine, Guanine, and Cytosine 2. Make a labeled drawing and explain how DNA is replicated 3. Describe one of the experiments that demonstrated that DNA is the substance that carries genetic information.

32 12.RNA and Protein Synthesis How does RNA differ from DNA? What are the different types of RNA? What is transcription of RNA? What is the genetic code? Explain translation What is the relationship between genes and protein? Click for a great animation Essential Questions

33 12.RNA and Protein Synthesis 1.A part of the genetic code is copied from DNA to mRNA 2.RNA carries out process of making proteins

34 12.RNA and Protein Synthesis The information encoded with the DNA nucleotide sequence of a double helix is transferred to a mRNA molecule. The mRNA molecule travels out of the nucleus and attaches to a ribosome Using the RNA nucleotide sequence and the genetic code, the ribosome assembles a protein “The Central Dogma”

35 12.RNA and Protein Synthesis DNA stays in the nucleus mRNA is copied from DNA and sent out into the cytoplasm Animations: Transcription showing full complex Transcription – cool sounds TRANSCRIPTION

36 12.RNA and Protein Synthesis The Central Dogma (brief) DNA is copied to mRNA mRNA is used as blueprint to make protein

37 12.RNA and Protein Synthesis RNA’s sugar backbone contains ribose instead of deoxyribose RNA is like one strand of the DNA double-helix RNA uses uracil instead of Thymine Structure of RNA

38 12.RNA and Protein Synthesis RNA’s sugar backbone contains ribose instead of deoxyribose RNA is like one strand of the DNA double-helix RNA uses uracil instead of Thymine Types of RNA PROTEIN SYNTHESIS Messenger RNA brings a copy of gene code from nucleus to cytoplasm Ribosomal RNA Transfer RNA transfers code to protein

39 12.RNA and Protein Synthesis PROTEIN SYNTHESIS Messenger RNA brings a copy of gene code from nucleus to cytoplasm Ribosomal RNA Transfer RNA transfers code to protein Transcription RNA polymerase separates strands makes a transcript of one strand on mRNA Promoters tell RNA polymerase where to start transcribing

40 tRNA tRNA - transfer Specified amino acids are attached to tRNA each anti-codon corresponds to the amino acid specified by the genetic code Each tRNA has an anti-codon (3 nucleotides) Anti-codon region base pairs with mRNA trascript

41 RNA DNA RNA polymerase Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) 12.RNA and Protein Synthesis RNA polymerase separates strands makes a transcript of one strand on mRNA Promoters tell RNA plymerase where to start transcribing

42 12.RNA and Protein Synthesis RNA polymerase separates strands makes a transcript of one strand on mRNA Promoters tell RNA plymerase where to start transcribing RNA Editing Some editing takes place once RNA is transcribed Introns - sections of mRNA to are cut out Exons - spliced back together to form final mRNA

43 12.RNA and Protein Synthesis Introns - sections of mRNA to are cut out Exons - spliced back together to form final mRNA Genetic Code Polymer - protein Monomer - amino acid (there are 20 possibilities) codon - 3 nucleotides codes for each amino acid

44 12.RNA and Protein Synthesis Polymer - protein Monomer - amino acid (there are 20 possibilities) 3 nucleotides = 1 codon - codes for each amino acid Translation Assembly happens in ribosome Transfer RNA anticodon matches to mRNA codon and brings attached amino acid Polypeptide chain grows until STOP codon is reached

45 12.RNA and Protein Synthesis Assembly happens in ribosome Transfer RNA anticodon matches to mRNA codon and brings attached amino acid Polypeptide chain grows until STOP codon is reached

46 12.RNA and Protein Synthesis Assembly happens in ribosome Transfer RNA anticodon matches to mRNA codon and brings attached amino acid Polypeptide chain grows until STOP codon is reached

47 12.RNA and Protein Synthesis Assembly happens in ribosome Transfer RNA anticodon matches to mRNA codon and brings attached amino acid Polypeptide chain grows until STOP codon is reached Roles of DNA / RNA DNA - master plan kept safe in nucleus RNA - working blueprints brought out to cytoplasm

48 12.RNA and Protein Synthesis DNA - master plan kept safe in nucleus RNA - working blueprints brought out to cytoplasm Genes and Proteins Genes code proteins Proteins are enzymes catalyze chemical reactions Color, antigens, blood type Proteins are the key

49 12.RNA and Protein Synthesis

50 12.RNA and Protein Synthesis animations Translation Translation – no sound, basicTranslation

51 CODE Breaker Activity Four Roles DNA - Agent DiNA Provides code to be broken mRNA - Agent miRNA Translates code for Agent tuRNA tRNA - Agent tuRNA picks up code delivers it to rRNA - Agent R.B.Some compiles information

52 CODE Breaker Activity Step 1 DNA - Agent DiNA counts 3 numbers starting from left cuts 1 group passes it off to Agent miRNA only 1 group of 3 may be cut at a time

53 CODE Breaker Activity Step 2 mRNA - Agent miRNA Using secret table code, Agent miRNA decodes and translates to a letter Relays letter information to Agent tuRNA

54 CODE Breaker Activity Step 3 tRNA - Agent tuRNA Gets letter information from Agent miRNA Turns letter over to R.B.Some

55 CODE Breaker Activity Step 3 R.B.Some Assembles letters After step four is completed, REPEAT Until code is broken

56 12.4 Mutations Cells make mistakes 1.Copy the following information about Protein X: Methionine— Phenylalanine—Tryptophan—Asparagine—Isoleucine—STOP. 2.Use Figure 12–17 on page 303 in your textbook to determine one possible sequence of RNA to code for this information. Write this code below the description of Protein X. Below this, write the DNA code that would produce this RNA sequence. 3.Now, cause a mutation in the gene sequence that you just determined by deleting the fourth base in the DNA sequence. Write this new sequence. 4.Write the new RNA sequence that would be produced. Below that, write the amino acid sequence that would result from this mutation in your gene. Call this Protein Y. 5.Did this single deletion cause much change in your protein? Explain your answer.

57 12.4 Mutations Cells make mistakes Mutate - to change Gene mutations are changes in a single gene Chromosomal mutations involve changes in whole chromosomes

58 12.4 Mutations Gene Mutations Point mutations change in one nucleotide Substitution changes 1 amino acid Frameshift mutation insertion or deletion of one nucleotide throws off subsequent codons can prevent functioning of gene

59 12.4 Mutations Gene Mutations

60 12.4 Mutations Gene Mutations

61 12.4 Mutations Chromosomal Mutations Change in number or structure of chromosomes deletion duplication inversion translocation

62 Every cell in your body, with the exception of gametes, or sex cells, contains a complete copy of your DNA. Why, then, are some cells nerve cells with dendrites and axons, while others are red blood cells that have lost their nuclei and are packed with hemoglobin? Why are cells so different in structure and function? If the characteristics of a cell depend upon the proteins that are synthesized, what does this tell you about protein synthesis? Answer the questions that follow: 1.Do you think that cells produce all the proteins for which the DNA (genes) code? Why or why not? How do the proteins made affect the type and function of cells? 2.Consider what you now know about genes and protein synthesis. What might be some ways that a cell has control over the proteins it produces? 3.What type(s) of organic compounds are most likely the ones that help to regulate protein synthesis? Justify your answer Gene Regulation

63 Every cell in your body, with the exception of gametes, or sex cells, contains a complete copy of your DNA. Why, then, are some cells nerve cells with dendrites and axons, while others are red blood cells that have lost their nuclei and are packed with hemoglobin? Why are cells so different in structure and function? If the characteristics of a cell depend upon the proteins that are synthesized, what does this tell you about protein synthesis? Answer the questions that follow: 1.Do you think that cells produce all the proteins for which the DNA (genes) code? Why or why not? How do the proteins made affect the type and function of cells? 2.Consider what you now know about genes and protein synthesis. What might be some ways that a cell has control over the proteins it produces? 3.What type(s) of organic compounds are most likely the ones that help to regulate protein synthesis? Justify your answer Gene Regulation

64 Goals Describe a typical gene Describe how the lac genes are turned on and off Explain how most eukaryotic genes are controlled Relate gene regulation to development

65 12.5 Gene Regulation Gene Expression Not every gene is expressed in every cell Cells in your finger don’t produce amylase Promoters tell RNA to start transcription What are the regulatory sites next to the promoter ?

66 12.5 Gene Regulation Gene Regulation: An Example the lac operon In E. coli 3 genes are turned on and off together Operon - genes that operate together These 3 genes help E. coli use lactose - lac operon Gene Expression Not every gene is expressed in every cell Cells in your finger don’t produce amylase Promoters tell RNA to start transcription What are the regulatory sites next to the promoter ?

67 12.5 Gene Regulation Lac operon codes for proteins that take lactose across the cell membrane break lactose up into galactose and glucose The lac operon genes are turned on by the presence of lactose Beside the 3 lac operon genes are two other regions Promoter Operator Gene Regulation: An Example the lac operon In E. coli 3 genes are turned on and off together Operon - genes that operate together These 3 genes help E. coli use lactose - lac operon

68 12.5 Gene Regulation When RNA polymerase gets to the promoter, it transcriptions begins The operator blocks it by binding to a protein called the lac repressor BUT if lactose binds to the repressor, it falls off allowing RNA polymerase to begin transcription Lac operon codes for proteins that take lactose across the cell membrane break lactose up into galactose and glucose The lac operon genes are turned on by the presence of lactose Beside the 3 lac operon genes are two other regions Promoter Operator

69 12.5 Gene Regulation Eukaryotic Gene Regulation Operons are not used Genes are controlled individually Regulatory sequences more complex than lac TATATA or TATAAA region “TATA Box” helps position RNA polymerase Found just before eukaryotic promoters When RNA polymerase gets to the promoter, it transcriptions begins The operator blocks it by binding to a protein called the lac repressor BUT if lactose binds to the repressor, it falls off allowing RNA polymerase to begin transcription

70 12.5 Gene Regulation Many, “enhancer,” sequences found in eukaryotes unwind tightly twisted chromatin attract RNA polymerase block access (like prokaryote repressor proteins ) Eukaryotic Gene Regulation Operons are not used Genes are controlled individually Regulatory sequences more complex than lac TATATA or TATAAA region “TATA Box” helps position RNA polymerase Found just before eukaryotic promoters

71 12.5 Gene Regulation Many, “enhancer,” sequences found in eukaryotes unwind tightly twisted chromatin attract RNA polymerase block access (like prokaryote repressor proteins ) Regulatory sites Promoter (RNA polymerase binding site) Start transcription DNA strand Stop transcription

72 12.5 Gene Regulation WHY IS THE SYSTEM SO COMPLEX IN EUKARYOTES Complex multicellular organisms All cells carry the code Each cell uses only a tiny fraction of the code Many, “enhancer,” sequences found in eukaryotes unwind tightly twisted chromatin attract RNA polymerase block access (like prokaryote repressor proteins )

73 12.5 Gene Regulation Regulation and Development “hox genes” control embryo development Which cells develop into what Master control genes Fruit fly legs growing in the place of antennae Copy of mouse eye growth gene inserted into drosophila leg caused fruit fly to grow an eye on its knee! Onward to Genetic Engineering next week WHY IS THE SYSTEM SO COMPLEX IN EUKARYOTES Complex multicellular organisms All cells carry the code Each cell uses only a tiny fraction of the code


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