Presentation on theme: "DNA and RNA Chapter 12-1 http://faculty.uca.edu/~johnc/mbi1440.htm http://www.wappingersschools.org/RCK/staff/teacherhp/johnson/visualvocab/mRNA.gif."— Presentation transcript:
1DNA and RNA Chapter 12-1 http://faculty.uca.edu/~johnc/mbi1440.htm
2Objectives: Summarize the relationship between genes and DNA Summarize the experiments of Frederick Griffith, Oswald Avery, and Hershey-Chase.Describe the overall structure of the DNA molecule
3GENETIC MATERIALIn the middle of the 1900’s scientists were asking questions about genes.What is a gene made of?How do genes work?How do genes determine characteristics of organisms?
4DO PROTEINS CARRY THE GENETIC CODE? At the time most scientists believed that _________ had to be the molecules that made up genes.There were so many different kinds proteins and DNA seemed to be too monotonous repeating the same ___ subunits.proteins4
5SEE GRIFFITH’s EXPERIMENT 1928 – Frederick Griffith looked atpneumonia bacteria trying tofigure out what made people dieR (Rough) strain-mice livedS (SMOOTH) strain- killed miceImages from:
6If he heated the LETHAL strain first _______________mice lived.The heat killed bacteria were no longerLETHAL.Images from:
7Images from: http://microvet. arizona BUT. . .If he mixed heat-killed LETHAL bacteria with live harmless bacteria________________mice DIED !When he looked inside dead mice, he found______________ bacteria!Somehow the heat killed LETHAL bacteria passed their characteristics to the harmless bacteria.LIVE LETHAL
8See a video clip about GRIFFITH’S EXPERIMENTS (12A)
9But what was the factor that caused the transformation? Griffith called this process __________________ because one strain of bacteria had been changed permanently into another.But what was the factor that caused thetransformation?A protein ? A lipid ? A carbohydrate ?A nucleic acid ?TRANSFORMATION
101944- Oswald Avery’s team of scientists repeat Griffith’s experiments 1944-Oswald Avery’s team of scientistsrepeat Griffith’s experimentslooking for the transforming molecule.After heat killing the LETHALPneumonia bacteria, he treated them with digestive enzymes that destroy specific kinds of molecules.If proteins, polysaccharides, lipids, or RNA’s were destroyed .. .______________________________Transformation still occurred!
11DNA But when they treated the heat-killed LETHAL bacteria with enzymes todestroy _____ there was NOtransformation!. . . the mice lived!DNA was the moleculethat caused the geneticchange.DNA
12GRIFFITH EXPERIMENT (PNEUMONIA-RAT) Showed ____________ could bepassed between bacteria & cause achange.AVERY EXPERIMENT (Digestive enzymes)showed that the genetic materialwas _____genetic materialDNA
13bacteriophages proteins Scientists are skeptical… it takes more than one experiment to convince them.1952-Alfred Hershey and Martha Chaseexperimented with viruses that infect bacteria = _________________Knew bacteriophageswere made of________ and _______bacteriophagesproteinsDNAHear about theircool experiment
23CHARGAFF’S RULES A = T G = C _________ _________ _________ _________At time no one knew why…now we know its becauseAdenine always bonds across with____________Guanine always bonds across with ____________THYMINECYTOSINEImage from:
24DOUBLE HELIX Hydrogen _____________ bonds between nitrogen bases hold the two strands together.Image from:
25Interest Grabber Answers 1. On a sheet of paper, draw a curving or zig-zagging line that divides the paper into two halves. Vary the bends in the line as you draw it. Without tracing, copy the line on a second sheet of paper.Hold the papers side by side, and compare the lines. Do they look the same?3. Now, stack the papers, one on top of the other, and hold the papers up to the light. Are the lines the same?4. How could you use the original paper to draw exact copies of the line without tracing it?5. Why is it important that the copies of DNA that are given to new daughter cells be exact copies of the original?Lines will likely look similar.Overlaying the papers will show variations in the lines.Use 1st line as a template to draw the line on another sheet of paper.Each cell must have the correct DNA, or the cell will not have the correct characteristics.
29DNA in EUKARYOTES is packaged into chromosomes Humans have approximately 3 billion base pairs (1 m long)60,000 to 100,000 genesIf the diameter of the DNA (2 nanometers) was as wide as a fishing line (0.5 millimeters) it might stretch as far as 21.2 km (or 13.6 miles) in length which would all have to be packed into a nucleus, the equivalent size of 25 cm in diameter. That is some packaging!
30THINK ABOUT IT How could you get this piece of string into the container?
35HOW IS DNA COPIED? The structure of DNA explains how it can be copied. Image from:HOW IS DNA COPIED?The structure of DNA explains how it can be copied.Each strand has all the info needed to constructthe __________other half.If strands are separated,_____________ rules allowyou to fill in the complementary bases.matchingbase-pairing
36Figure 12–11 DNA Replication Section 12-2Original strandDNA polymeraseNew strandGrowthDNA polymeraseGrowthReplication forkReplication forkNitrogenous basesNew strandOriginal strandSites where strand separation andreplication occur are called _____________replication forks
37REPLICATION STEPS Enzymes “unzip” molecule by breaking _______________ that hold the strandstogether and unwind it.2. _______________ joins nucleotidesusing original strand as template and______________for errors.3. Copying happens in ________ directionsalong the two strands & in __________places at once.Hydrogen bondsDNA polymerasespell checksoppositemultiple
38REPLICATIONANIMATIONSee a video clip about DNA REPLICATION (12B)
41Objectives Describe how RNA differs from DNA Name the three types of RNADescribe transcription and the editing of RNAIdentify the genetic codeSummarize translationExplain the relationship between genes and proteins
42RNA- the Other Nucleic Acid NUCLEOTIDESAlso made of ___________Sugar is _______ insteadof deoxyribose.RNA is _________ strandedContains _________ insteadof thymine.RIBOSESINGLEURACIL
44Figure 12–14 Transcription Section 12-3Adenine (DNA and RNA)Cystosine (DNA and RNA)Guanine(DNA and RNA)Thymine (DNA only)Uracil (RNA only)RNA polymeraseDNARNAEnzyme called _____________________separates strands, then uses one strandas a template to assemble an RNA copy.RNA POLYMERASE
45How does RNA POLYMERASE know where a gene starts and stops? Enzyme binds to places with specific DNA sequences called _______________.PROMOTERS tell _________________where to start.Signals at the end of the gene code cause transcription to _____ .PROMOTERSRNA POLYMERASEstop
46See a video clip about TRANSCRIPTION (12C) Transcription animationSee anothertranscription animationSee a video clip about TRANSCRIPTION (12C)
48RNA’s require EDITING before use Image by Riedell
49WHY WASTE IT? Why spend energy making a large RNA and then throw parts away?May allow same gene to be used indifferent ways in different kinds of cells.May have a role in evolution… allows smallchanges in genes to have a big effect.
56SEE ANOTHER Translation Animation Video 4SEE ANOTHER Translation AnimationSee a video clip aboutPROTEIN SYNTHESIS (12D)TRANSLATION VIDEO (Choose Large video)
57GENES & PROTEINS Proteins are the connection between Mendel/flower images from: Blood cell by RiedellGENES & PROTEINSProteins are the connection betweenthe gene code in the DNA and how thatgene is expressed.A gene that codes for an enzyme (protein)to make a pigment can controlthe color of a flower.A gene that codes for an enzyme (protein)adds carbohydrates to glycoproteins to produce your blood type.Enzymes catalyze and regulate chemical reactions so proteins build and operate all cell components.
58REPLICATIONDNA → DNA ____________DNA → RNA ____________RNA→ Protein ___________TRANSCRIPTIONTRANSLATION
59Concept Map Section 12-3 can be also called which functions to fromtoto make up
60Bring amino acids to ribosome Concept MapSection 12-3RNAcan beMessenger RNARibosomal RNATransfer RNAalso calledwhich functions toalso calledwhich functions toalso calledwhich functions tomRNACarry instructionsrRNACombinewith proteinstRNABring amino acids to ribosomefromtoto make upDNARibosomeRibosomes
62Objectives:Contrast gene mutations and chromosomal mutations
63_______________ are changes in the genetic material. MUTATIONS REMEMBER!_______________ are changes in the genetic material.MUTATIONSMutations can happen when cells make_____________ in copying their own DNA or be caused by _______________ or___________ in the enviroment.mistakesradiationchemicals
64KINDS OF MUTATIONSMutations that produce changes in a single gene = ______________________Mutations that produce changes in whole chromosomes = _____________________GENE MUTATIONSCHROMOSOMAL MUTATIONS
65GENE MUTATIONS Mutations involving ________________ ____________ = __________________ because they occur at a single point in the DNA sequence.TYPES OF POINT MUTATIONS:_____________________One or a fewnucleotidesPoint mutationsubstitutionsdeletionsinsertions
66SUBSTITUTION A T T C T A G C T Changes one base for another A T T C G A G C TA T T C T A G C T
67SICKLE CELL ANEMIA CAUSE: (autosomal recessive) A changed to T (glu to val)gene on chromosome #11that codes for part ofhemoglobin protein(carries oxygen in blood)
68DELETION Piece of DNA code for one gene is lost ________________________________________Image from:
69Duchenne Muscular Dystrophy CAUSE:(X linked recessive)DELETION in gene that codes for a muscle protein
70INSERTION Piece of DNA is copied too many times Image from:
72FRAME SHIFT MUTATIONS Change multiple bases in code thefatcatatetherat____________________INSERTIONthefatcatateateateatetheratDELETIONthe fat cat ate the ratthe fat cat ate ate ate ate the ratthe fat ata tet her at
73FRAME SHIFTSFrame shift mutations change every ___________ in the ___________ that follows the shift.Frame shifts can alter a protein so much it is unable to _____________Amino acidproteinfunction
74CHROMOSOMAL MUTATIONS Mutations involving changes in the _____________ or ______________of whole chromosomesTYPES OF CHROMOSOMAL MUTATIONS:_____________________NumberstructuredeletionsSee a Video (deletions & duplicationsduplicationsSee a Video (inversions & translocationsinversionstranslocations
75DELETION Piece of chromosome is lost ________________________________________Image from:
76DUPLICATION Piece of DNA is copied too many times ________________________________________________Image from:
77HUNTINGTON’S Degenerative brain disorder Symptoms appear age 30-40 Lose ability to walk, think, talk, reasonCause = ADDITION of extra CAG repeats
78INVERSION Segment flips and reads backwards Image from:
79TRANSLOCATIONSegment breaks off and joins a different non-homologous chromosomeImage from:
80MUTATIONSMost mutations are ____________ meaning they have little or no effect on gene ____________.Mutations that cause ________________ are usually ____________Harmful mutations are associated with many________________ and can cause____________neutralfunctiondefective proteinsHARMFULgenetic disorderscancer
81MUTATIONS Mutations are also a source of _________________ and can be Genetic variabilitybeneficialCan help an organism_________________Provide _________in populationfor ____________to act uponSurvive and reproducevariationnatural selection
82POLYPLOIDYCondition in which an organism has extra sets of chromosomes= _________________________ in humans, but beneficialin some ___________.Triploid (___) or tetraploid (___) plants are often ________________than diploid plants.POLYPLOIDYLETHALplants3N4Nlarger and stronger
84Objectives: Describe a typical gene Describe how the lac genes are turned on and offExplain how most eukaryotic genes are controlledRelate gene regulation to development
85PROMOTER REGULATORY SITES Only a fraction of genes in a cell are expressed (made into RNA) at any given time.How does the cell decide which will be turned on and which will stay “silent”?You already know about _____________ regions that show RNA polymerase where to start.There are other ______________________ thatcontrol whether a gene is ON or OFF.PROMOTERREGULATORY SITES
87E. Coli lac operonSee a MOVIE choose animation/narratedGroup of genes that operate together are called an ________________OPERONGenes code for enzymes neededto digest lactose sugar.Only needed if glucose is not available
88Most of time glucose is available so lac operon is turned _____ by a____________ molecule that sits on aregulatory site next to the promotercalled the ___________OFFREPRESSOROPERATOR
89What if there’s NO GLUCOSE? Cells need to get rid of the repressorand turn _____the lac genes to digestlactose instead.The presence of lactosecauses a change in the____________ molecule soso it can’t bind theoperator site.ONREPRESSORImage modified from:
90Cells turn genes ON & OFF as needed Many genes are regulated by_____________ proteins that keep them turned off until needed.Others use proteins that speed up_______________ or affect___________________REPRESSORtranscriptionprotein synthesis
91EUKARYOTES are more COMPLEX Additional regulatory sequences:1. ___________ regionsupstream from promotersbind many different regulatory proteins2. __________ (TATATA or TATAAA)helps position RNA POLYMERASEENHANCERTATA boxImage by Riedell
92DEVELOPMENT & DIFFERENTIATION Gene regulation is also important in shaping way organisms developHow does a zygote become a multi-cellular organism?How does it know what kind of cell to be?
93DEVELOPMENT & DIFFERENTIATION DIFFERENTIATECells ________________ by turning different genes on and off.BUT… How does a cell know where it is in the body?and what genes it should turn on?and when?
94In the 1980s, researchers discovered a series of genes in fruit flies called ___________ These genes control the organization of the developing embryo and tell parts where to grow and when. Mutations to Hox genes can cause a leg to grow where an antenna should sprout.Hox genes
96HOX GENESSimilar genes controlling the eyes of insects and our own eyes have also been discovered.Our version of the gene can be inserted in a fly and still trigger the building of an insect eye!
97SO WHAT? The similarities between HOX gene sequences in very different organismsand the ability of these genes to tradeplaces and still function in differentspecies suggests that these organisms__________________________share a common ancestor
99Core High School Nature of Science Performance Descriptors High school students performing at the ADVANCED level:given a scientific discovery, evaluate how different societal, cultural, and personal beliefs influenced the investigation and its interpretation;High school students performing at thePROFICIENT level:given a scientific discovery narrative, determine and describe how societal, cultural, and personal beliefs influenced the investigation and its interpretation;High school students performing at the BASIC level:describe the role of observation in the development of hypotheses, theories, and laws and conduct student investigations;given a scientific discovery narrative, identify the cultural and personal beliefs that influenced the investigation.
100Core High School LIFE Science Performance Descriptors High school students performing at the ADVANCED level:predict the function of a given structure;explain how protein production is regulated;High school students performing at thePROFICIENT level:describe and give examples of chemical reactions required to sustain life (hydrolysis, dehydration synthesis, role of enzymes. . .);describe the relationship between structure and functiontell how DNA determines protein formation;High school students performing at the BASIC level:name chemical reactions required to sustain life (hydrolysis, dehydration synthesis, role of enzymes . . .);recognize that different structures perform different functions;