Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Whodunit?Whodunit?Historical: Just who Historical: Just who isis the genetic material the genetic materialHint: you already know the answerHint: you already know the answerHence, that Hence, that cannotcannot be the purpose in be the purpose in discussing this with you!!!discussing this with you!!!1DNA, RNA, Protein❖We know one well: made of amino acidsWe know one well: made of amino acids❖We’re meeting the other: made of ‘bases’We’re meeting the other: made of ‘bases’23Who is the genetic material?Advice: never jump to the answer. Wrap your head around the QUESTION first, then consider the TOOLS. Then try applying them to the hypotheses & predictions❖Nucleic acid? This repetitive, structurally boring stuff Nucleic acid? This repetitive, structurally boring stuff made from made from onlyonly 4 chemical blocks (‘nucleotides’) 4 chemical blocks (‘nucleotides’)❖Protein? Diverse in terms of length, 3D structure, made Protein? Diverse in terms of length, 3D structure, made up 20 different blocks (‘amino acids’). Exciting!up 20 different blocks (‘amino acids’). Exciting!Lunar lander, anyone?4http://www.asm.org/division/m/foto/T4Mic.htmlhttp://www.nsf.gov/od/lpa/news/02/pr0207images.htmhttp://extremethinkover.files.wordpress.com/2009/12/eagle-lunar-lunar-lander-separates-from-ap111.jpgThese viruses of bacteria literally ‘bore a hole’ through the cell wall using an enzyme in their tailsFoundational logic❖Viral strategy: you are a traveling set of Viral strategy: you are a traveling set of instructions instructions in a protective in a protective casecase❖Inject the Inject the instructionsinstructions, these are what’s required to , these are what’s required to ‘drive’ a cell’s machinery to execute your will‘drive’ a cell’s machinery to execute your will❖The The casingcasing can be left behind, but the can be left behind, but the instructions instructions mustmust mingle with the cell’s machinery mingle with the cell’s machinery5Write your own exam... and mine!❖You may submit one question, You may submit one question, with answerwith answer to me or staff (a to me or staff (a name would be good, too). Due by Friday pre-examname would be good, too). Due by Friday pre-exam❖If the answer is sound & the question unique & conceptual & If the answer is sound & the question unique & conceptual & non-trivial & I use it, you get 1 point on said exam (and you’ll non-trivial & I use it, you get 1 point on said exam (and you’ll know the answer to one question) [max 1 point/exam]know the answer to one question) [max 1 point/exam]❖All decisions final, no appeal, cannot even be whined about in All decisions final, no appeal, cannot even be whined about in my presencemy presence❖this is anthis is an incrediblyincredibly effectiveeffective way to prepare for a test way to prepare for a test❖You think about You think about what was importantwhat was important❖You think about You think about how key concepts could be question-izedhow key concepts could be question-ized6Where now/where Next❖We’re watching & learning how DNA was We’re watching & learning how DNA was implicated in the crime of being the ‘instructions’ implicated in the crime of being the ‘instructions’ for all lifefor all life❖In lab, and soon in lecture, we’re looking at how In lab, and soon in lecture, we’re looking at how those instructions are copied, read out, those instructions are copied, read out, implementedimplemented78Chemically speaking, what’s the diff?A unit of DNASome units of proteinFig. 4-3What differences can you identify?You’re looking for physical aspects that distinguish the 2Hint: Knowing the alphabet letters is enoughRadioactivity in 60 seconds9❖Atomic Atomic identityidentity is determined by proton # (thus is determined by proton # (thus electron outer shell occupancy), electron outer shell occupancy), neutronsneutrons are a wild are a wild card/freebiecard/freebie❖Extra neutrons can make the nucleus unstable. Stuff Extra neutrons can make the nucleus unstable. Stuff sometimes gets kicked outsometimes gets kicked out❖It comes It comes zingingzinging out of there & can be detected out of there & can be detected❖Carbon has 6 protons & Carbon has 6 protons & usually usually 6 neutrons; can have 6 neutrons; can have 7 or 8 (weight = protons + neutrons, thus 12, 13, 14)7 or 8 (weight = protons + neutrons, thus 12, 13, 14)❖3535S instead of S instead of 3232S; S; 3232P instead of P instead of 3030PPNote colors; figure will use green, orange for radioactivityRound 1: ‘hot’ protein*10Campbell Concepts & Connections*‘hot’ = radioactive = detectablecoitus interruptus via blender 11Campbell Concepts & ConnectionsOption 1: hot protein12Campbell Concepts & ConnectionsResult: radioactivity floating, not with (infected) cellsTherefore sulfur NOT in the instructions!!Bacteria big; ‘sink’ to bottom (‘pellet’)So we know somethingOr do we?Or do we?If we get the result “no radioactive sulfur If we get the result “no radioactive sulfur observed in the bacteria after infection observed in the bacteria after infection protocol”…protocol”…Is the conclusion “DNA must go in” Is the conclusion “DNA must go in” inescapableinescapable??13Option II: label DNA14Campbell Concepts & ConnectionsResult:radioactivity sinks because it is ‘captured’ within cells!Therefore, phosphate travels with instructions15Fig. 14-5-hereditary materialAlt view16171819What you need to know20❖How knowledge is accumulated in science is more How knowledge is accumulated in science is more important than what has been accumulatedimportant than what has been accumulated❖This experiment is a grand example of This experiment is a grand example of goodgood sciencescience. . UnderstandUnderstand::❖the two the two contradictorycontradictory hypotheseshypotheses❖the ‘lever’--a critical point of difference that creates the ‘lever’--a critical point of difference that creates distinctiondistinction❖enough to briefly explain the enough to briefly explain the