Presentation on theme: "IDENTIFYING DNA AS THE GENETIC MATERIAL"— Presentation transcript:
1 IDENTIFYING DNA AS THE GENETIC MATERIAL CH. 8IDENTIFYING DNA AS THE GENETIC MATERIAL
2 CH. 5 & 6 REVIEW ANSWER THE FOLLOWING QUESTIONS: 1. What macromolecule group does DNA & RNA belong in?2. What monomer do we use to assemble the macromolecule group from question #1.
3 CH. 5 & 6 REVIEW ANSWER THE FOLLOWING QUESTIONS: 3. What is a nucleotide?4. What would a nucleotide for DNA contain?5. What would a nucleotide for RNA contain?
4 Ch. 8.1 – Identifying DNA as the Genetic Material Griffith finds a “transforming principle.” - NOTES
5 Ch. 8.1 – Identifying DNA as the Genetic Material Griffith finds a “transforming principle.”- QUESTION & ANSWER:1. What was “transformed” in Griffith’s experiment?That the R bacteria in the presence of the dead S bacteria became pathogenic.2. Explain how the results support the experimenters conclusion.The mice dying when they shouldn’t have means that the S bacteria must have contained some information that was able to change the harmless bacteria t deadly bacteria.
6 Ch. 8.1 – Identifying DNA as the Genetic Material Avery Identifies DNA as the transforming principle - NOTES
7 Ch. 8.1 – Identifying DNA as the Genetic Material Avery Identifies DNA as the transforming principle – QUESTION & ANSWERS:1. How did Avery and his group identify the transforming principle?1st identifying the 2 components: proteins & DNAUsed enzymes to break down the protein & the R-bacteria were still transformed to S bacteria killing the mice.Only when an enzyme to break down DNA did the transformation failed to occur.2. Explain how the results support their conclusions for the transforming principle.By using the enzyme to break down DNA and not having the transformation occur.
8 Ch. 8.1 – Identifying DNA as the Genetic Material Hershey & Chase confirm that DNA is the genetic material – NOTES
9 Ch. 8.1 – Identifying DNA as the Genetic Material Hershey & Chase confirm that DNA is the genetic material – QUESTIONS & ANSWERS:1. Summarize how Hershey & Chase confirmed that DNA is the genetic material.A: They labeled the protein of bacteriophages with radioactive sulfur and their DNA with radioactive phosphorus. The bacteriophages were allowed to infect bacteria.2. Summarize why the bacteriophage was an excellent choice for research to determine whether genes are made of DNA or proteins?A: A bacteriophage consists of little more than a protein coat surrounding DNA. The protein coat is left behind when the viral DNA enters a bacterium.3. Explain how the results support their conclusions.A: That the phage’s DNA had entered the bacteria, but the protein had not, convincing scientists that the genetic material is DNA & not protein.
10 Review1. What did Hersey & Chase know about bacteriophages that led them to use these viruses in their DNA experiments?
11 ANSWER:That bacteriophages are made up of a protein coat surrounding DNA.
12 DNA is composed of 4 types of nucleotides (monomer): 8.2 – Structure of DNADNA is composed of 4 types of nucleotides (monomer):Nucleotide composed of:Phosphate group5 carbon sugarNitrogen base
13 DNA is composed of 4 types of nucleotides con’t. Nucleotide in DNA is composed of:Phosphate groupDeoxyribose sugarNitrogen baseCytosine = CThymine = TAdenine = AGuanine = GNucleotide in RNA is composed of:Ribose sugarUracel = U (replaces thymine)Letter abbreviations refer both to the base & to the nucleotides that contain that base
14 DNA is composed of 4 types of nucleotides con’t. CHARGAFF’S RULE:A = TG = CQUESTION:What is the only difference among the 4 DNA nucleotides?Which part of a DNA molecule carries the genetic instructions that are unique for each individual; the sugar-phosphate backbone or the nitrogen-containing bases? Explain.
15 ANSWER TO QUESTIONS 1. THE 4 NITROGEN BASES. 2. THE NITROGEN BASES, BECAUSE THE REMAINING PARTS OF THE NUCLEOTIDE ARE IDENTICAL.
16 Watson & Crick Developed an accurate model of DNA - NOTES
17 Watson & Crick Developed an accurate model of DNA – QUESTION & ANSWER: What bases are considered pyrimidines & purines?Pyrimidines = T & CPurines = A & GHow did the Watson & Crick Model explain Chargaff’s rules?The pyrimidine – thymine a single ringed base pairs with a purine – adenine a double ringed base so that the double helix will be able to maintain the correct shape.
18 Nucleotides always pair in the same way. DNA nucleotides of a single strand are joined together by covalent bonds connecting the sugar of one nucleotide to the phosphate of the next nucleotide.Alternating sugars & phosphates form the sides of a double helix sort of like a twisted ladder.DNA double helix is held together by hydrogen bonds between the bases in the middle.
19 Nucleotides always pair in the same way – QUESTIONS & ANSWERS: What sequence of bases would pair with the following sequence: T T A C G C G A CA A T G C G C T G
20 8.3 – DNA ReplicationReplication copies the genetic informationWatson & Crick’s experiments showed that one strand of DNA is used as a template to build the other strandGuarantees that each strand of DNA is identical.
21 Proteins carry out the process of replication How :DNA is unzipped at numerous places (H bonds broken)Free floating nucleotides pair with the exposed bases (template strands)DNA polymerase bonds the nucleotides together to form the new strands that are complementary to the template strand (original strand).Creates 2 identical molecules of DNA.Each DNA molecule has an original & a new strand.Why DNA replication is called semiconservative replication.
23 Replication is fast & accurate Replication is fast because the DNA strand is opened at hundreds of different points & allowing nucleotides to be added at many spots at the same time.Proofreading is carried out at the same time that nucleotides are added.DNA polymerase can detect errors & make corrections.Pg. 238, fig. 8.9 shows this process
24 8.4 TRANSCRIPTIONRNA carries DNA’s instructionsCentral DogmaInformation flows from DNA to RNA to proteinsTranscription converts a DNA message into an intermediate molecule, called RNA.Translation interprets an RNA message into a string of amino acids, called a polypeptide.Either a single polypeptide or many polypeptides working together make up a protein.
25 RNA carries DNA’S instructions con’t. Prokaryotic cells:Replication, transcription, and translation all occur in the cytoplasm at approximately the same time.Eukaryotic cells:Replication, transcription, and translation occur in different locations.Replication & transcription – nucleusTranslation – occurs in the cytoplasm
26 RNA carries DNA’s instructions con’t. RNA acts as an intermediate link between DNA in the nucleus & protein synthesis in the cytoplasm.Gets used then destroyed.RNA is single stranded, contains ribose sugar & has uracil instead of thymineA (DNA) = U (RNA)T (DNA) = A (RNA)G (DNA) = C (RNA)C (DNA) = G (RNA)
27 Transcription makes 3 types of RNA Transcription is the process of copying a sequence of DNA to produce a complementary strand of RNA.Part of the chromosome, called a gene, is transferred into an RNA message.Transcription is catalyzed by RNA polymerase.
28 Transcription produces 3 major types of RNA molecules mRNA (messenger RNA) – an intermediate message that is translated to form a proteinrRNA (ribosomal RNA) – forms part of ribosomes, a cell’s protein factoriestRNA (transfer RNA) – brings amino acids from the cytoplasm to a ribosome to help make the growing protein.Pg. 241, Fig visualizes transcription
29 Transcription vs. replication SimilaritiesHappen in nucleus of eukaryotic cellsNeed enzymes to begin the processUnwind the DNA double helixComplementary base pairing to the DNA strandRegulated by the cellDifferencesReplication makes sure each new cell will have one complete set of genetic instructions & occurs only once during each round of the cell cycle.Transcription could make hundreds or thousands of copies of certain proteins or the rRNA or tRNA molecules needed to make proteins based on the demands of the cell, using a single stranded complementary mRNA strand.
30 8.5 TRANSLATIONAmino acids are coded by mRNA base sequencesTranslation is the process that converts, or translates, an mRNA message into a polypeptide.Could be 1 or more polypeptides to make up a proteinLanguage of nucleic acids:DNA – uses 4 nucleotides = A, G, C, & TRNA – uses r nucleotides = A, G, C, & ULanguage of proteins uses 20 amino acids
31 Triplet CodeGenetic code uses codons, which is read in groups of 3 nucleotide basesCodon is a 3 nucleotide sequence that codes for a particular amino acid, referred to as the reading frame.First 2 nucleotides are usually the most important in coding for an amino acidStart codon – signals the start of translation and the amino acid is methionine3 stop codons – signal the end of the amino acid chain.If reading frame is changed, changes protein or even can prevent a protein from being made.Almost all organisms, including viruses, follows the genetic code.This allows scientists to insert a gene from 1 organism into another organism to make a functional protein.
34 A) methionine(start), threonine, asparagine, serine DETERMINE WHAT AMINO ACID SEQUENCES ARE CREATED FROM THE FOLLOWING STRINGS OF NUCLEOTIDES1) A U G A C C A A C A G CA) methionine(start), threonine, asparagine, serine2) A U G C C C C A A U G AA) methionine(start), proline, glutamine, stop
35 Amino acids are linked to become a protein Review:mRNA is a short lived molecule that carries instructions from DNA in the nucleus to the cytoplasmmRNA message is read in groups of 3 nucleotides called codonsHow it translates the codon into an amino acid requires the use of rRNA & tRNA molecules
36 PG. 246, Fig. 8.16 Translation Read pg. 247 Amino acids are linked to become a proteinRibosomes are made of a combination of rRNA & proteins & they catalyze the reaction that forms the bonds between amino acids.Ribosomes have a large & small subunit that fit together & pull the mRNA strand through.Small unit holds the mRNA strand & the large subunit holds onto the growing proteintRNA carries amino acids from the cytoplasm to the ribosomeHas an L shape to the tRNA molecule, one end of the L is attached to the specific amino acid & the other end of the L, is called the anticodon, which recognizes a specific codon.Anticodon is a set of 3 nucleotides that is complementary to an mRNA codon.PG. 246, Fig TranslationRead pg. 247
37 8.6 – GENE EXPRESSION & REGULATION mRNA processingImportant part of gene regulation in eukaryotic cells is RNA processing.mRNA that is produced by transcription needs to be editedExons are nucleotide segments that code for parts of the protein.Introns are nucleotide segments that are located between the exonsIntrons are removed from mRNA before it leaves the nucleus.Exons are joined back together
39 8.7 MUTATIONSSome mutations affect a single gene & others affect the entire chromosomeMutation is a change in an organism’s DNATypes of gene mutations:Point mutation – a mutation in which one nucleotide is substituted for another.DNA polymerase could find & correct mistake, if not may permanently change an organism’s DNAFrameshift mutation – involves the insertion or deletion of a nucleotide in the DNA sequenceAffects the polypeptide more than a point mutation (substitution)Causes the reading frame from point of insertion or deletion to change the remaining amino acids
40 MUTATIONSORIGINAL NUCLEOTIDE SEQUENCE:A U G C C G U U A A C G C G A U C C G GREADS:MUTATED NUCLEOTIDE SEQUENCE:A U G C A C G U U A A C G C G A U C C G G
41 Types of chromosomal mutations: Gene duplication:During crossing over chromosomes do not align & the chromosomal segments are different sizes. The chromosome receiving the larger segment would have part of the chromosome that is duplicated.Gene deletion:During crossing over chromosomes do not align & the chromosomal segments are different sizes. The chromosome receiving the smaller segment would have part of the chromosome that is deleted.Translocation:A piece of one chromosome moves to a non-homologous chromosome.
42 Mutations may or may not affect phenotype. Phenotype – Collection of all of an organism’s physical characteristics.Ex: black hair, blue eyes, attached ear lobes.Chromosomal mutationsUsually have big affect on organismsEx: may break a gene causing it not to functionEx: may create a new hybrid gene with a new functionEx: may cause a gene to be more or less activeGene mutations – could have a bad affect, no affect, or create a beneficial mutationCould change the active site for an enzyme & now it cannot accept the substrateCould affect how protein folds & possibly destroying the protein’s functionCould create a premature stop, making protein nonfunctional
43 Mutations can happen in body cells & in germ cells. Impact on offspringMutations can happen in body cells & in germ cells.Body cell mutations only affect that individualGerm cell mutations may be passed to offspringCan be source of genetic variations, which is the basis of natural selection.Will affect the phenotype of offspringCould be harmful & the offspring do not develop properly or could die before reproducingCould be mutations not well suited to environment & the alleles will be removed from the populationCould be a mutation that is well suited to environment & the alleles will be increased in the population
44 Mutations can be caused by several factors Mutagens – agents in the environment that can change DNA.Speed up the rate of replication errorsBreak DNA strandsCause cancerTypes of mutagens:UV lightIndustrial chemicals