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DNA, RNA and Protein Synthesis= CH 10. Griffith’s Experiments Showed that hereditary material can pass from one bacterial cell to anotherShowed that hereditary.

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Presentation on theme: "DNA, RNA and Protein Synthesis= CH 10. Griffith’s Experiments Showed that hereditary material can pass from one bacterial cell to anotherShowed that hereditary."— Presentation transcript:

1 DNA, RNA and Protein Synthesis= CH 10

2 Griffith’s Experiments Showed that hereditary material can pass from one bacterial cell to anotherShowed that hereditary material can pass from one bacterial cell to another The transfer of genetic material from one cell to another or organism to organism is called transformationThe transfer of genetic material from one cell to another or organism to organism is called transformation Heat killed virulent bacteria can transfer their disease causing ability to harmless bacteriaHeat killed virulent bacteria can transfer their disease causing ability to harmless bacteria

3 Griffith’s Experiments

4 Avery’s Experiments Showed that: DNA is the hereditary material that transfers info btwn bacterial cellsShowed that: DNA is the hereditary material that transfers info btwn bacterial cells Cells missing RNA and Protein could transform R into S cellsCells missing RNA and Protein could transform R into S cells Cells missing DNA could not transform cellsCells missing DNA could not transform cells

5 Hershey-Chase Experiment DNA not protein is the genetic materialDNA not protein is the genetic material DNA of viruses enters bacterial cells and this causes the bacterial cell to produce more viruses containing DNADNA of viruses enters bacterial cells and this causes the bacterial cell to produce more viruses containing DNA Protein doesn’t enter cellsProtein doesn’t enter cells

6 Discovery Of Structure 1953:Watson and Crick put together a model of DNA using Franklin’s and Wilkins’s DNA diffraction X-rays1953:Watson and Crick put together a model of DNA using Franklin’s and Wilkins’s DNA diffraction X-rays

7 DNA is composed of 2 strands made of 4 kinds of nucleotidesDNA is composed of 2 strands made of 4 kinds of nucleotides Each nucleotide consists of 3 parts:Each nucleotide consists of 3 parts: – one 5-carbon sugar (deoxyribose) – one phosphate group, and – one of 4 bases adenine (A), guanine (G), thymine (T), cytosine (C).adenine (A), guanine (G), thymine (T), cytosine (C). Molecular Structure of DNA

8 Sugar & Phosphate are “sides” of ladder and Bases are the “rungs” & attach to sugarsSugar & Phosphate are “sides” of ladder and Bases are the “rungs” & attach to sugars Structure of a nucleotide

9 2 categories of DNA bases: Purines vs Pyrimidines 2 categories of DNA bases: Purines vs Pyrimidines PURINES = A, G = SMALL WORD, BIG BASES = 2 RINGS = PuAG PYRIMIDINES = T, C = BIG WORD, SMALL BASES= 1 RING = PyTC

10 Purines vs Pyrimidines Chargaff showed thatChargaff showed that – % of A always = % of T – % of G always = % of C Purines always with pyrimidinesPurines always with pyrimidines –BIG BASE ALWAYS WITH SMALL

11 DNA Structure

12 Complementary base pairing rules Base pairs are formed by hydrogen bonding of A with T (2 H bonds), andBase pairs are formed by hydrogen bonding of A with T (2 H bonds), and G with C (3 H bonds)

13 DNA Replication

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15 DNA Replication = in S phase of cell cycle An enzyme (helicase) breaks the H bonds between base pairs and unZIPS the strands = replication forkAn enzyme (helicase) breaks the H bonds between base pairs and unZIPS the strands = replication fork

16 Another enzyme (DNA polymerase) attaches the complementary base to the original DNA strandAnother enzyme (DNA polymerase) attaches the complementary base to the original DNA strand DNA Replication

17 Results in DNA molecules that consist of one "old" strand and one "new" strandResults in DNA molecules that consist of one "old" strand and one "new" strand Known as semi- conservative replication b/c it conserves the original strand).Known as semi- conservative replication b/c it conserves the original strand). DNA Replication

18 Changes = mutationChanges = mutation Proofreading & repair prevent many errorsProofreading & repair prevent many errors Unrepaired mutation can cause cancerUnrepaired mutation can cause cancer DNA Errors in Replication

19 Flow of Genetic Material: DNA → RNA → Proteins

20 RNA Structure RNA differs from DNARNA differs from DNA – RNA uses ribose as the sugar not deoxyribose. not deoxyribose. – RNA bases are A, G, C, and uracil (U). G-CG-C A-UA-U –Single Stranded –Shorter than DNA –Can Leave the nucleus

21 3 Types of RNA rRNA - ribosomalrRNA - ribosomal mRNA - messengermRNA - messenger tRNA - transfertRNA - transfer

22 Messenger RNA (mRNA) Made from DNA in nucleus using RNA Polymerase Is the “Blueprint" for a proteinIs the “Blueprint" for a protein –Carried to ribosomes in cytoplasm after “stop” is reached Carries message from nucleus to cytosolCarries message from nucleus to cytosol

23 Ribosomal RNA (rRNA) rRNA + protein makes a ribosomerRNA + protein makes a ribosome Site where proteins are assembled in cytoplasmSite where proteins are assembled in cytoplasm

24 Transfer RNA (tRNA) Carries correct AA to ribosome/ mRNA complexCarries correct AA to ribosome/ mRNA complex

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26 Transcription DNA → RNADNA → RNA –uses RNA Polymerase (binds at “promoter” region) –Process similar to DNA replication –Begins with a START codon and ends with a STOP codon Makes rRNA, tRNA or mRNAMakes rRNA, tRNA or mRNA Message is “transcribed” from DNA code to RNA codeMessage is “transcribed” from DNA code to RNA code

27 Transcription

28 Protein Synthesis: Translation Making of protein at the rRNA using mRNA and tRNAMaking of protein at the rRNA using mRNA and tRNA Each base triplet in mRNA is called a codonEach base triplet in mRNA is called a codon -specifies an amino acid to be included into a polypeptide chain -specifies an amino acid to be included into a polypeptide chain –Uses genetic code to determine amino acid

29 Genetic Code Universal for all forms of lifeUniversal for all forms of life – 61 triplets specifying amino acids – 3 “stop” codes Stop codes = UAA, UAG, UGAStop codes = UAA, UAG, UGA Start Codon = AUG = methionineStart Codon = AUG = methionine

30 From DNA to Proteins

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33 Translation RNA → PROTEINRNA → PROTEIN mRNA leaves nucleus goes to ribosomemRNA leaves nucleus goes to ribosome Begins when ribosome attaches to start codonBegins when ribosome attaches to start codon tRNA gets specific amino acid (floating free in cytosol), anticodon matches codon of mRNA and A.A.tRNA gets specific amino acid (floating free in cytosol), anticodon matches codon of mRNA and A.A. tRNA brings its AA to ribosome and attaches it to growing chain of AA (protein)tRNA brings its AA to ribosome and attaches it to growing chain of AA (protein) stops at “stop” codonstops at “stop” codon

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36 Chapter 11 Gene Expression TURN “ON” GENES to REGULATE PROTEIN AND GENE EXPRESSION

37 Role of Gene Expression Activation of a gene that results in transcription and production of mRNAActivation of a gene that results in transcription and production of mRNA Only a fraction of a cell’s genes are expressed at any one timeOnly a fraction of a cell’s genes are expressed at any one time –You only express genes or make proteins when NEEDED!

38 Gene Expression in Prokaryotes -Studies in 1960’s by French scientists -Started with simple intestinal prokaryotic cell= Escherichia coli = E. coli

39 Bacteria adapt to changes in their surroundings by using proteins to turn groups of genes on and off in response to various environmental signals The DNA of Escherichia coli is sufficient to encode about 4000 proteins, but only a fraction of these are made at any one time. E. coli regulates the expression of many of its genes according to the food sources that are available to it

40 - Scientists discovered how genes in this bacteria metabolize lactose when present- Scientists discovered how genes in this bacteria metabolize lactose when present -lactose = disaccharide…needs to be broken down into galactose and glucose-lactose = disaccharide…needs to be broken down into galactose and glucose

41 Gene Expression in Prokaryotes When lactose is absent, E. coli will not produce the protein…is repressedWhen lactose is absent, E. coli will not produce the protein…is repressed When lactose is present, E. coli will produces the 3 structural enzymesWhen lactose is present, E. coli will produces the 3 structural enzymes –Meaning this will make the “protein” or go through induction…..so it can break down lactose!

42 Gene Expression in Prokaryotes http://www.phschool.com/science/biology_place/biocoach/lacoperon/genereg.htmlhttp://www.phschool.com/science/biology_place/biocoach/lacoperon/genereg.htmlhttp://www.phschool.com/science/biology_place/biocoach/lacoperon/genereg.html GREAT ANIMATION TO REVIEW AT HOME!GREAT ANIMATION TO REVIEW AT HOME!

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44 Gene Expression in Prokaryotes Operon: series of genes coding for specific products = “lac” operonOperon: series of genes coding for specific products = “lac” operon Operon = structural genes + promoter + operatorOperon = structural genes + promoter + operator

45 Gene Expression in Prokaryotes Promoter: segment of DNA recognized by RNA polymerase which then starts transcriptionPromoter: segment of DNA recognized by RNA polymerase which then starts transcription Operator: segment of DNA that acts as “switch” by controlling the access of RNA polymerase to promoterOperator: segment of DNA that acts as “switch” by controlling the access of RNA polymerase to promoter

46 Prokaryotic On & Off switches Transcription can be turned “on or off” depending on what the cell needsTranscription can be turned “on or off” depending on what the cell needs When turned “off” a repressor protein is bound to DNA in front of the geneWhen turned “off” a repressor protein is bound to DNA in front of the gene To turn a gene “on” an inducer (lactose) binds to the repressor, causing it to fall off….then gene is expressedTo turn a gene “on” an inducer (lactose) binds to the repressor, causing it to fall off….then gene is expressed

47 Repression Activation

48 Gene Expression in Eukaryotes Have not found “operons” in eukaryotesHave not found “operons” in eukaryotes Genomes are larger & more complexGenomes are larger & more complex Organized into introns and exonsOrganized into introns and exons –Through removal of introns from pre- mRNA

49 Controlling Transcription in Eukaryotes

50 Removal of Introns After Transcription

51 Eukaryotic Genes are made of introns and exons Introns noncoding portions of the gene, removed by enzymes before mRNA leaves the nucleus (pre-mRNA)Introns noncoding portions of the gene, removed by enzymes before mRNA leaves the nucleus (pre-mRNA) Exons portions that will eventually be translated remain in the finished mRNA that leaves the nucleus.Exons portions that will eventually be translated remain in the finished mRNA that leaves the nucleus.

52 Gene Expression in Development Expressed Genes: have been transcribed & translatedExpressed Genes: have been transcribed & translated Cell Differentiation: Development of cells w/ different functionsCell Differentiation: Development of cells w/ different functions Morphogenesis: development of form in an organismMorphogenesis: development of form in an organism Homeotic genes (hox): determine where anatomical structuresHomeotic genes (hox): determine where anatomical structures (appendages) will develop (appendages) will develop & controls differentiation & controls differentiation in early development in early development

53 Gene Expression in Development Homeobox Sequence:Homeobox Sequence: – w/in homeotic genes –Sequence of DNA that regulates patterns of development –Homeoboxes of many diff eukaryotic many diff eukaryotic organisms appear organisms appear to be very similar to be very similar

54 Gene Expression & Cancer Oncogene: Gene that causes cancerOncogene: Gene that causes cancer Proto-oncogene = normal gene, regulates cell growth. May mutate into oncogene that may lead to cancerProto-oncogene = normal gene, regulates cell growth. May mutate into oncogene that may lead to cancer Tumor-supressor gene (3 types): for protein that prevents uncontrolled cell division, mutation may stop this protein productionTumor-supressor gene (3 types): for protein that prevents uncontrolled cell division, mutation may stop this protein production Viruses may have oncogenes or trigger them in another cellViruses may have oncogenes or trigger them in another cell

55 Cancer Continue to divide indefinitely, even if too tightly packed or detach from other cellsContinue to divide indefinitely, even if too tightly packed or detach from other cells Tumor: uncontrolled, abnormal cell divisionTumor: uncontrolled, abnormal cell division benign tumor: does not migrate to other areas, usually harmlessbenign tumor: does not migrate to other areas, usually harmless malignant tumor: invade other healthy tissues = cancermalignant tumor: invade other healthy tissues = cancer metastasis: breaking away and spreading to other body parts to form new tumorsmetastasis: breaking away and spreading to other body parts to form new tumors

56 Causes of Cancer CarcinogenCarcinogen –Chemicals in tobacco smoke, asbestos, UV light from the sun –Mutagen: causes a mutation

57 Kinds of Malignant Tumors Carcinoma: in skin & tissue lining organsCarcinoma: in skin & tissue lining organs Sarcoma: in bone & muscle tissueSarcoma: in bone & muscle tissue Lymphoma: in tissues that form bloodLymphoma: in tissues that form blood Leukemia: uncontrolled production of white blood cellsLeukemia: uncontrolled production of white blood cells

58 Causes of Cancer Mutations that change expression of genes coding for growth factor proteinsMutations that change expression of genes coding for growth factor proteins Usually comes after exposure to carcinogen (tobacco, UV light etc.)Usually comes after exposure to carcinogen (tobacco, UV light etc.) usually need more than 1 mutation to get cancerusually need more than 1 mutation to get cancer

59 Genetic Engineering and Biotechnology = Ch 13

60 DNA Identification/fingerprinting Gene = segment of DNA bases that code for traits and proteinsGene = segment of DNA bases that code for traits and proteins Genetic engineering= use of genes to create or modify the genomeGenetic engineering= use of genes to create or modify the genome DNA fingerprinting = The repeating sequences in noncoding DNA (introns) vary between individuals & thus be used to identify an individualDNA fingerprinting = The repeating sequences in noncoding DNA (introns) vary between individuals & thus be used to identify an individual

61 Steps in DNA identification (fingerprinting) Gel electrophoresis: pieces are separated by size on a gel creating “bands” = fingerprintGel electrophoresis: pieces are separated by size on a gel creating “bands” = fingerprint Everybody has different number and size of pieces because their DNA sequences are differentEverybody has different number and size of pieces because their DNA sequences are different PCR = polymerase chain reaction = duplicate DNAPCR = polymerase chain reaction = duplicate DNA –cut “digest” DNA with restriction enzyme to get a bunch of pieces

62 Gel Electrophoresis DNA fragments placed into “wells” in gel agaroseDNA fragments placed into “wells” in gel agarose Electricity pulls on DNA fragments, DNA is “-” and thus goes toward “+” sideElectricity pulls on DNA fragments, DNA is “-” and thus goes toward “+” side Fragments travel at different rates based on size and ability to squeeze through swiss-cheese-like agaroseFragments travel at different rates based on size and ability to squeeze through swiss-cheese-like agarose

63 DNA Fingerprinting

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65 Polymerase Chain Reaction (PCR) Useful if you only have a little bit of DNA and need to make copies of itUseful if you only have a little bit of DNA and need to make copies of it Crime scenes, genetic disorders in embryonic cells, study ancient DNA fragmentsCrime scenes, genetic disorders in embryonic cells, study ancient DNA fragments

66 Restriction Enzymes Cuts DNA at specific base sequenceCuts DNA at specific base sequence Produces sticky endsProduces sticky ends Recombinant DNA = Complementary sticky ends can be fused together…is recombinedRecombinant DNA = Complementary sticky ends can be fused together…is recombined

67 Restriction Enzymes

68 Producing Restriction Fragments DNA ligase enzyme used to splice together cut plasmids and chromosome fragmentsDNA ligase enzyme used to splice together cut plasmids and chromosome fragments

69 Producing & combining restriction fragments

70 Making identical copies of cellsMaking identical copies of cells Can clone genes or organismsCan clone genes or organisms Cloning a Gene= making large quantities of a desired DNA piece …usually insert into a vector (bacteria)Cloning a Gene= making large quantities of a desired DNA piece …usually insert into a vector (bacteria) Transfers gene between organismsTransfers gene between organisms Plasmids: circle of DNA in bacterium replicates independently of the single main chromosomePlasmids: circle of DNA in bacterium replicates independently of the single main chromosomeCloning

71 Gene may be used to make bacteria produce specific protein - insulin productionGene may be used to make bacteria produce specific protein - insulin production Transplanting Genes

72 Stem Cells Stem cells have the ability toStem cells have the ability to 1.divide and renew themselves 2.remain undifferentiated in form 3. develop into a variety of specialized cell types

73 Genomic Library Includes all pieces of genome that come from cutting with a particular restriction enzymeIncludes all pieces of genome that come from cutting with a particular restriction enzyme Can have multiple libraries for the same organism - all cut with different R.E.’sCan have multiple libraries for the same organism - all cut with different R.E.’s

74 Transgenic Organism The host that has received the recombinant DNAThe host that has received the recombinant DNA Organism produces the new protein unless the gene gets “turned off”Organism produces the new protein unless the gene gets “turned off” Keep gene “turned on” by splicing it in near a gene that is frequently expressedKeep gene “turned on” by splicing it in near a gene that is frequently expressed

75 Human Genome Project Sequence entire human genomeSequence entire human genome Began in 1990 - expected completion was 2005, but it was completed in 2000Began in 1990 - expected completion was 2005, but it was completed in 2000 Thought humans had 100,000 genes, but its fewer than 30,000Thought humans had 100,000 genes, but its fewer than 30,000 We have the sequence of genes, but don’t know what they all do yetWe have the sequence of genes, but don’t know what they all do yet Use info for diagnosis, treatment, prevention of genetic disordersUse info for diagnosis, treatment, prevention of genetic disorders

76 Future of Genomics Bioinformatics: Uses computers to catalog & analyze genomesBioinformatics: Uses computers to catalog & analyze genomes Proteomics: studies the identities, interactions, and abundances of an organisms proteinsProteomics: studies the identities, interactions, and abundances of an organisms proteins Microarrays: two-dimensional arrangement of cloned genes, useful to compare specific proteins such as those that cause cancerMicroarrays: two-dimensional arrangement of cloned genes, useful to compare specific proteins such as those that cause cancer

77 Medical Applications Gene Therapy: Used on individuals to insert normal genes (or repair damaged DNA) into body cells to cure diseaseGene Therapy: Used on individuals to insert normal genes (or repair damaged DNA) into body cells to cure disease – Abnormal gene can still be inherited Used on fertilized zygotes or embryos to insert normal genes for both developing body AND sex cellsUsed on fertilized zygotes or embryos to insert normal genes for both developing body AND sex cells – Genome changed permanently

78 Uses of DNA Technology CloningCloning Stem Cell ResearchStem Cell Research Pharmaceutical ProductsPharmaceutical Products –insulin VaccinesVaccines –work because body recognizes proteins, can produce protein without introducing pathogen

79 Uses of DNA Technology Agricultural CropsAgricultural Crops –disease resistance –herbicide resistance –Improve nutrition –require less fertilizer (incorporate nitrogen fixing gene)

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83 Concerns of DNA Technology Plants might produce toxins that could cause allergies in people who consume themPlants might produce toxins that could cause allergies in people who consume them

84 Concerns of DNA Technology What if the plants get into the “wild” - forming “superweeds”What if the plants get into the “wild” - forming “superweeds” Do we really know what we are doing when we mix genes?Do we really know what we are doing when we mix genes?


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