DNA, RNA, Protein DNA, RNA, Protein SynthesisSynthesis

Chapter 12Chapter 12

Discovery of DNADiscovery of DNAProtein or Nucleic acid Question (1928)Protein or Nucleic acid Question (1928)– Which stored the genetic information?Which stored the genetic information?

Frederick GriffithFrederick Griffith– Used mice and Streptococcus pneumoniaeUsed mice and Streptococcus pneumoniae– Summary of his findingsSummary of his findings

TreatmentTreatment Affect on mouseAffect on mouse

S strainS strain dieddied

R strainR strain livedlived

Heated S strainHeated S strain livedlived

R stain w/ Heated S StrainR stain w/ Heated S Strain dieddied

Disease-causing bacteria (smooth

colonies)

Harmless bacteria (rough colonies)

Heat-killed, disease-causing bacteria (smooth colonies)

Control(no growth)

Heat-killed, disease-causing bacteria (smooth colonies)

Harmless bacteria (rough colonies)

Dies of pneumonia Lives Lives Live, disease-causingbacteria (smooth colonies)

Dies of pneumonia

Section 12-1Griffith’s Experiment

Cont…Cont…

Griffith concluded that information or factor Griffith concluded that information or factor was transferred from heated S strain to the was transferred from heated S strain to the live R stain. This process he called live R stain. This process he called transformation.transformation.Oswald Avery- did the same experiment Oswald Avery- did the same experiment but also used an enzyme that destroyed but also used an enzyme that destroyed carbohydrates, protein and lipids.carbohydrates, protein and lipids.Avery was able to show that it was nucleic Avery was able to show that it was nucleic acid not proteins that store genetic acid not proteins that store genetic informationinformation

Structure of Nucleic AcidStructure of Nucleic Acid Edwin Chargaff- tested amounts of Edwin Chargaff- tested amounts of nitrogen bases in organismnitrogen bases in organism–Four types of basesFour types of bases

Adenine, thymine, cytosine, guanineAdenine, thymine, cytosine, guanine–Chargaff found that the amount of Chargaff found that the amount of

adenine was always the same as adenine was always the same as thymine, and guanine the same as thymine, and guanine the same as cytosinecytosine

DNA is made up of NucleotidesDNA is made up of Nucleotides

NucleotidesNucleotides– Five carbon sugar (deoxyribose)Five carbon sugar (deoxyribose)– A phosphate groupA phosphate group– One Nitrogenous Bases One Nitrogenous Bases

AdeneineAdeneine

GuanineGuanine

CytosineCytosine

ThymineThymine

Purine

Pyrimidines

Purines Pyrimidines

Adenine Guanine Cytosine Thymine

Phosphate group

Deoxyribose

DNA NucleotidesSection 12-1

Watson & CrickWatson & Crick

Used knowledge of Chargaff experiments Used knowledge of Chargaff experiments and X-ray imaging to discover some very and X-ray imaging to discover some very important characteristics of DNAimportant characteristics of DNA– Double strandedDouble stranded– Double helixDouble helix– Sugar and phosphate make up backboneSugar and phosphate make up backbone– Bases bind together (base pairing)Bases bind together (base pairing)

Adenine to thymineAdenine to thymine

Cytosine to GuanineCytosine to Guanine

Hydrogen bonds

Nucleotide

Sugar-phosphate backbone

Key

Adenine (A)

Thymine (T)

Cytosine (C)

Guanine (G)

 Structure of DNASection 12-1

DNA ReplicationDNA Replication

Remember this is done during the S phase Remember this is done during the S phase of interphase in cell life cycleof interphase in cell life cycleHow it does it?How it does it?– DNA unwinds (enzymes break the hydrogen DNA unwinds (enzymes break the hydrogen

bonds)bonds)– DNA polymerase enzyme attaches to each DNA polymerase enzyme attaches to each

strand and uses free floating nucleotides to strand and uses free floating nucleotides to assemble complementary strandassemble complementary strand

– This process continues until two complete This process continues until two complete copies of the DNA are madecopies of the DNA are made

 DNA ReplicationSection 12-2

Growth

Growth

Replication fork

DNA polymerase

New strand

Original strand DNA

polymerase

Nitrogenous bases

Replication fork

Original strandNew strand

Chromosome StructuresChromosome Structures

Strands of DNA are wrapped around Strands of DNA are wrapped around proteins called histonesproteins called histones– This is what makes up chromatinThis is what makes up chromatin– During cell division this chromatin is packed During cell division this chromatin is packed

tightly into chromosomestightly into chromosomesThis is done to assist the genetic information in This is done to assist the genetic information in separating properlyseparating properly

Also there is evidence to show the compact DNA Also there is evidence to show the compact DNA can influence the expression of the genescan influence the expression of the genes

Chromosome Structure of Eukaryotes

Chromosome

Supercoils

Coils

Nucleosome

Histones

DNA

double

helix

Section 12-2

Nondisjunction in MeiosisNondisjunction in MeiosisDuring anaphase a chromosome fails to During anaphase a chromosome fails to separate thus one gamete will have two separate thus one gamete will have two many of one chromosome and on will be many of one chromosome and on will be short a chromosome.short a chromosome.– Monsomy- zygote has one copy of Monsomy- zygote has one copy of

chromosomechromosome– Trisomy-zygote has three copies of same Trisomy-zygote has three copies of same

chromosomechromosomeEx. Down syndrome is a trisomy on the 21 Ex. Down syndrome is a trisomy on the 21 chromosomechromosome

– Genotype may look like the following: (AAa, Genotype may look like the following: (AAa, XXX, XXY, or XO)XXX, XXY, or XO)

Review of DNA Review of DNA

Double strandedDouble stranded

Double helixDouble helix

Base pairingBase pairing

– Adenine to ThymineAdenine to Thymine

– Cytosine to GuanineCytosine to Guanine

Replication prior to cell divisionReplication prior to cell division

DNA and RNADNA and RNA

Deoxyribose Nucleic Deoxyribose Nucleic AcidAcid

Double strandedDouble stranded

Thymine BaseThymine Base

Genetic information Genetic information storagestorage

Ribonucleic AcidRibonucleic Acid

Single strandedSingle stranded

Uracil BaseUracil Base

instruct the making of instruct the making of proteins (protein proteins (protein synthesis)synthesis)

Three typesThree types– messengerRNA (mRNA)messengerRNA (mRNA)– transferRNA (tRNA)transferRNA (tRNA)– ribosomalRNA (rRNA)ribosomalRNA (rRNA)

mRNAmRNA

Makes a complimentary template of DNA Makes a complimentary template of DNA sequencesequence

Codon-three-nucleotide sequence on Codon-three-nucleotide sequence on mRNA that codes for an amino acidsmRNA that codes for an amino acids

Amino Acids are the building blocks of Amino Acids are the building blocks of proteinsproteins

Transcription: RNA SynthesisTranscription: RNA Synthesis

Process by which DNA is copied into a Process by which DNA is copied into a complementary strand of RNAcomplementary strand of RNA

Why must DNA do this?Why must DNA do this?

This process is a lot like replication but only This process is a lot like replication but only short single stranded RNA is producedshort single stranded RNA is produced

This process takes place in the nucleus of This process takes place in the nucleus of the cellthe cell

RNADNA

RNApolymerase

 TranscriptionSection 12-3Adenine (DNA and RNA)Cystosine (DNA and RNA)Guanine(DNA and RNA)Thymine (DNA only)Uracil (RNA only)

RNA splicingRNA splicing

Introns – noncoding regions of DNA or Introns – noncoding regions of DNA or RNARNA

Exons- regions of DNA or RNA that do Exons- regions of DNA or RNA that do code for proteinscode for proteins

Before mRNA leave the nucleus it splices Before mRNA leave the nucleus it splices or remove the introns and splices the or remove the introns and splices the exons togetherexons together

TranslationTranslation

Decoding of mRNA into polypeptide Decoding of mRNA into polypeptide chains (proteins)chains (proteins)Ribosome attach to mRNA in the Ribosome attach to mRNA in the cytoplasmcytoplasmtRNA is now ready to attach amino acid to tRNA is now ready to attach amino acid to the ribosomethe ribosometRNA anticodon matches up with mRNA tRNA anticodon matches up with mRNA codon to assemble the amino acids in codon to assemble the amino acids in correct ordercorrect order

 TranslationSection 12-3

 Translation (continued)Section 12-3

ProteinsProteins

Long chains of amino acids form what is Long chains of amino acids form what is called polypeptides called polypeptides

Polypeptides combine to form protein Polypeptides combine to form protein moleculesmolecules

Proteins are what we see in our phenotypeProteins are what we see in our phenotype

Changes to DNAChanges to DNA

Mutations- random changes in nucleotide Mutations- random changes in nucleotide sequence of DNAsequence of DNA– Chromosomal Mutations-involve entire Chromosomal Mutations-involve entire

chromosome (cancer)chromosome (cancer)

– Gene mutations- involve single individual Gene mutations- involve single individual genesgenes

Chromosomal MutationsChromosomal Mutations

Deletion-occurs when chromosomes brake Deletion-occurs when chromosomes brake and a piece is lost and a piece is lost

Duplication- occurs when chromosome Duplication- occurs when chromosome breaks off and is incorporated back into breaks off and is incorporated back into the chromosome, resulting is an extra the chromosome, resulting is an extra copycopy

Translocation- chromosome breaks off Translocation- chromosome breaks off and attaches to different chromosomeand attaches to different chromosome

Chromosomal Mutation cont…Chromosomal Mutation cont…

Inversion- chromosome break off, turns Inversion- chromosome break off, turns around, and reattaches in reverse orderaround, and reattaches in reverse order

Deletion

Duplication

Inversion

Translocation

 Chromosomal MutationsSection 12-4

Gene MutationGene Mutation

Frameshift- deletion or addition that Frameshift- deletion or addition that disrupts codons sequencedisrupts codons sequence

See fig. 8.14 pg. 194See fig. 8.14 pg. 194

Point Mutation- occurs because of a Point Mutation- occurs because of a substitution of a base pairsubstitution of a base pair– Only effect one codonOnly effect one codon