DNA The Genetic Material Think Back Gregor Mendel and inheritance Factors that determine traits are passed down from generation to generation they come from both mom and dad But where did this information come from and where was it stored ID: 1045588
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1. Chapter 12DNA
2. The Secret of LifeDNA: The Genetic Material
3. Think Back…Gregor Mendel and inheritance… Factors that determine traits are passed down from generation to generation, they come from both mom and dad But where did this information come from, and where was it stored?Scientists knew there were both proteins and nucleic acids (DNA) in the nucleus of cellsLeft scientists wondering what molecule was involved in inheritance – DNA or proteins?
4. DiscoveryGriffith: found that one strain of bacteria could be transformed into another Created the search for the transforming substance.Avery: identified the transforming moleculeScientists were still skepticalHershey & Chase: experiments provided definitive evidence that DNA was the transforming factorAfter these discoveries, scientists were more confident that DNA was the transforming factor
5. The ScandalRosalind FranklinX-Ray Diffraction: Rosalind Franklin used this method to discover the double helix structureOther scientists stole this work, and used it to take credit for themselves, this later won them a Nobel Prize
6. WAIT!Remaining questions –How do nucleotides come together to form DNA?How does DNA communicate information?How does DNA store information?How does DNA duplicate itself?
7. So we found it, but…WHAT IS IT!?Genetic material!Blueprint for living organisms!Passed from generation to generation!DNA: Deoxyribonucleic AcidClassified as a nucleic acid, made up of millions of tiny subunits called nucleotides
8. NucleotidesNUCLEOTIDESMade of a sugar (deoxyribose)a phosphatea nitrogenous base
9. REMEMBER!A nucleotide is made ofSugarPhosphateBase
10. Double HelixThe phosphate of one group bonds to the sugar of anotherThe phosphate and sugar form the backbone of the DNA moleculeLike the “sides” of a ladderThe bases form the “rungs”4 types of bases
11. BasesGuanine (G)Adenine (A)Cytosine (C)Thymine (T)Each base will only bond with 1 other specific baseA – TC – G Complementary base pairingthe order of the bases in one strand determines the order of the bases in the other strand
12. Hydrogen BondsEach pair is held together with a hydrogen bondA – T: two hydrogen bondsC – G: three hydrogen bonds
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14. 2) Four Bases (Attached in Pairs)1) A Sugar Phosphate Backbone
15. DNAIn prokaryotic cells, DNA is a loop in the cytoplasmEukaryotic DNA is organized into individual chromosomes in the nucleusThe length of a chromosome can be 51 million to 245 million base pairs!And remember, each of your cells has a copy of ALL that DNA!!!!DNA makes up GENES which make up CHROMOSOMES found in the NUCLEUS of the CELL
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17. K’NEXFollowing the directions on your handout, build your modelComplete labeling sheet and crossword if not doneDUE tomorrowSUGARDOUBLE HYDROGENTRIPLE HYDROGENADENINECYTOSINEGUANINETHYMINEPHOSPHATENUCLEOTIDE
18. 12.2DNA Replication
19. DNA ReplicationRemember – every cell in your body has a copy of your DNABut, that DNA in the cell must be copied first so that the new cells (remember you get 2 new daughter cells from one parent in mitosis) get a copy of the old DNA.How does it get there?DNA replicates during interphase of mitosis and meiosis
20. DNA ReplicationThe double helix structure helps explain how DNA copies itselfDNA replicates by making a strand that is complementary to the original strandThe double helix separates, acts as a template, and creates a new strand UnwindingBase pairingJoining
21. DNA ReplicationThe “parent strand” has two complementary strandsBecause of this complementary base pairing, the order of the bases in one strand determines the order of the bases in the other strand.
22. UnzipThe first step is to “unwind” the parent strandDNA helicase: enzyme responsible for unwinding and unzipping the double helix. Hydrogen bonds are broken and there are two single strands
23. TemplateFree Floating nucleotides (in the nucleus) match up to the parent strands of DNADNA polymerase adds new nucleotides to the single strands and proofreads before creating two new identical strands
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25. DNA, RNA & Proteins
26. DNADNA is a codeThe nitrogen bases spell out a message that creates proteinsProteins then make up the organism!
27. The CodeIt’s like A, T, C, and G are the only letters in the alphabet - You can use them as many times as you’d like and in any order to make “words” These combine to make “sentences”The “sentences” combine to make “paragraphs” The paragraphs give instructions to the nucleus to make a living organism and all its unique traits
28. The Central DogmaHow does DNA act as a code for protein synthesis?Amino acids make up proteins and proteins act as building blocks for cells and enzymesCentral Dogma: DNA is TRANSCRIBED into RNARNA is TRANSLATED into proteins
29. Ribonucleic AcidNucleic acid, single strandContains sugar riboseHas Uracil instead of ThymineA – U C – G Messenger protein (mRNA), carries the DNA to ribosomesTranslates DNAThink of DNA as written in French, the RNA must translate it into English so the body can use it
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31. The CodeDNA is a 3 base (nitrogen) code3 nitrogen bases in a strand of DNA code for 1 amino acidFor example, UCU codes for serineThis unique 3 base sequence is called a CODONA start codon is where a specific gene starts, and a stop codon is where the gene endsA codon of DNA is transcribed into RNA 1st step of central dogma!
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33. The CodeOnce the RNA is synthesized and processed, it moves to the ribosomeRemember, ribosomes are the cell organelle that make proteinsThe ribosome reads and translates the RNA in order to make a protein2nd step of central dogma
34. Mutation
35. MutationsSometimes errors occur when chromosomes are copiedSometimes, there is little to no effect because the cell has some repair mechanismsMutation: a permanent change in a cell’s DNA
36. MutationsIf a trait that hasn’t been present in either family suddenly appears, we can guess a mutation took place A mutation causes a change in a child’s trait only when it takes place in the parents’ sex cellsMutations in the autosomal cells do not get passed onMutations that occur in sex cells are passed on to the organism’s offspring and will be present in every cell of the offspring.
37. Types of MutationsPoint Mutation: chemical change in just 1 base pairSubstitution: one base is exchanged for anotherMissense: DNA will code for wrong amino acidNonsense: change codon to stop codon, causes translation to stop earlyFrameshift Mutation: the gain or loss of a nucleotideInsertion: addition of a nucleotide to the DNA sequenceDeletion: removal of a nucleotide to the DNA sequenceThese all disrupt normal protein production and can sometimes cause genetic disorders
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40. Causes of MutationsSome are spontaneousSome are caused from things outside of the cellRadiationMutagensVarious chemicals - nicotine, pesticides
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42. Genetic EngineeringGenetic Engineering: manipulating the DNA of one organism in order to insert the DNA of another organismJellyfish fluorescence added to mosquito DNAHas applications in human health and agricultureCan be used to increase or decrease the expression of specific traitsBiotechnology: The use of genetic engineering to solve problems
43. Genetic EngineeringGlow in the dark cats - researchers took skin cells from Turkish Angora female cats and used a virus to insert genetic instructions for making red fluorescent proteinVenomous cabbage - Scientists have recently taken the gene that programs poison in scorpion tails and looked for ways to combine it with cabbage
44. Genetic EngineeringMedicinal eggs - scientists have created a breed of genetically modified hens that produce cancer-fighting medicines in their eggs. The animals have had human genes added to their DNA so that human proteins are secreted into the whites of their eggs, along with complex medicinal proteins similar to drugs used to treat skin cancer and other diseases.Web spinning goats - Researchers inserted a spiders’ dragline silk gene into the goats’ DNA in such a way that the goats would make the silk protein only in their milk. This “silk milk” could then be used to manufacture a web-like material called Biosteel.
45. CloningClones: Using the DNA of one organism to create another exact copy of the organism
46. Plant and Animal BreedingCloning is a way of producing living things with identical desirable traits.Breeding: the bringing together of two living things to produce offspringSelective breeding: can bring out the desired traits of living thingsexamples: dog breeding, agricultureKnowing what to expect tells us which living things to breed for certain traits.
47. Designer BabiesUsing genetic engineering to choose the traits of your offspringSavior Siblings - children conceived with the initial purpose of acting as donors for a sick brother or sister.
48. Gene TherapyTechnique aimed at correcting mutated genes that cause diseasesScientists insert a normal gene into a chromosome to replace a dysfunctional gene
49. The Human Genome Project The genetic blueprint for a human beingThe mapping of the genome was finished in 2003, and scientists are continuing to discover what each gene does and how it functions.