Chapter #10Chapter #10

10.1 Discovery of DNA10.1 Discovery of DNA10.2 DNA Structure10.2 DNA Structure10.3 DNA Replication10.3 DNA Replication10.4 Protein Synthesis10.4 Protein Synthesis

Griffith’s ExperimentsGriffith’s Experiments

Griffith’s Experiments (2)Griffith’s Experiments (2)

19281928 A mouse injected w/ both heat killed S A mouse injected w/ both heat killed S

(virulent) and R types can cause (virulent) and R types can cause pneumoniapneumonia A HEREDITARY FACTOR must be released A HEREDITARY FACTOR must be released

and taken into the R typeand taken into the R type Is this factor protein? DNA? RNA?Is this factor protein? DNA? RNA?

Avery’s ExperimentsAvery’s Experiments 1940’s1940’s Wanted to determine if the material that was Wanted to determine if the material that was

transforming was protein, DNA or RNAtransforming was protein, DNA or RNA Protease to destroy proteinProtease to destroy protein

Injected w/heat killed S cells and R cellsInjected w/heat killed S cells and R cells Able to transform R to SAble to transform R to S

RNase to destroy RNARNase to destroy RNA Injected w/heat killed S cells and R cellsInjected w/heat killed S cells and R cells Able to transform R to SAble to transform R to S

DNase to destroy DNADNase to destroy DNA Injected w/heat killed S cells and R cellsInjected w/heat killed S cells and R cells Not able to transform R to SNot able to transform R to S

Hershey-ChaseHershey-Chase Experiment Experiment

19521952 Protein or DNA?Protein or DNA?

Little protein found Little protein found

in viruses; all the in viruses; all the

DNA was presentDNA was present

DNA!!!!!DNA!!!!!

The Structure of DNAThe Structure of DNA

Sugar-Phosphate BackboneSugar-Phosphate Backbone Deoxyribose (sugar found in DNA)Deoxyribose (sugar found in DNA)

Nitrogen BasesNitrogen Bases AdenineAdenine ThymineThymine GuanineGuanine CytosineCytosine

The Structure of DNA (2)The Structure of DNA (2)

PurinePurine Double ringed baseDouble ringed base Guanine and ThymineGuanine and Thymine

PyrimidinePyrimidine Single ringed baseSingle ringed base Cytosine and AdenineCytosine and Adenine

Purines must pair with pyrimidines so the Purines must pair with pyrimidines so the helix can be made (it can twist)helix can be made (it can twist)

DNA DNA

Deoxyribonucleic acidDeoxyribonucleic acid

Contains genes that code for proteinsContains genes that code for proteins

Involved in heredityInvolved in heredity

AdenineAdenine

Nitrogen base in both DNA and Nitrogen base in both DNA and RNARNA

Purine that pairs with thymine in Purine that pairs with thymine in DNA and uracil in RNADNA and uracil in RNA

GuanineGuanine

Nitrogen base in both DNA and Nitrogen base in both DNA and RNARNA

Purine that pairs with cytosine in Purine that pairs with cytosine in both DNA and RNAboth DNA and RNA

ThymineThymine

Nitrogen base in DNA onlyNitrogen base in DNA only Pyrimidine that pairs with adeninePyrimidine that pairs with adenine

CytosineCytosine

Nitrogen base found in both DNA Nitrogen base found in both DNA and RNAand RNA

DeoxyriboseDeoxyribose

5 carbon sugar found in DNA5 carbon sugar found in DNA

Makes up the backbone of DNA Makes up the backbone of DNA (sides of the ladder)(sides of the ladder)

Phosphate GroupPhosphate Group

Backbone of DNABackbone of DNA Alternates with deoxyriboseAlternates with deoxyribose

Hydrogen BondsHydrogen Bonds

Bond that joins the nitrogen bases Bond that joins the nitrogen bases togethertogether

NucleotideNucleotide

Building block of nucleic acidsBuilding block of nucleic acids Contains…Contains…

5 carbon sugar5 carbon sugarNitrogen baseNitrogen basePhosphate groupPhosphate group

DNA Carries the Genetic CodeDNA Carries the Genetic Code

ReplicationReplication

Process of duplicating DNA Process of duplicating DNA Results in 2 DNA molecules (old Results in 2 DNA molecules (old

and new strands mixed)and new strands mixed) Replication is said to be semi-Replication is said to be semi-

conservativeconservative

DNA HelicaseDNA Helicase

Enzyme responsible for the untwisting of Enzyme responsible for the untwisting of DNADNA

Starts the replication processStarts the replication process

DNA PolymeraseDNA Polymerase

Enzyme responsible for attaching the Enzyme responsible for attaching the nucleotides in the correct order during nucleotides in the correct order during replication.replication.

DNA RNADNA RNA

DeoxyriboseDeoxyribose Double strandedDouble stranded ThymineThymine One versionOne version

RiboseRibose Single strandedSingle stranded UracilUracil 3 versions3 versions

Sugar-Phosphate backboneNucleic Acids Adenine, Guanine, Cytosine

Steps in replicationSteps in replication

DNA helicase unwinds the DNA molecule at DNA helicase unwinds the DNA molecule at several spotsseveral spots Breaks the hydrogen bonds between the basesBreaks the hydrogen bonds between the bases

DNA polymerase adds new nucleotidesDNA polymerase adds new nucleotides 2 new strands2 new strands

Original strand + new strand = semiconservative Original strand + new strand = semiconservative modelmodel

Structure of RNAStructure of RNA

Uracil – nitrogen base found only in Uracil – nitrogen base found only in RNA (pyrimidine)RNA (pyrimidine)

Ribose – 5 carbon sugar found only in Ribose – 5 carbon sugar found only in RNARNA

Types of RNATypes of RNA

tRNA - transfertRNA - transfer mRNA - messengermRNA - messenger rRNA - ribosomalrRNA - ribosomal

tRNAtRNA

Used to carry amino acids to codons on Used to carry amino acids to codons on mRNAmRNA

Contains the anticodons on one end and Contains the anticodons on one end and an amino acid on the other endan amino acid on the other end

mRNAmRNA

Contain codonsContain codons Made through transcription in the Made through transcription in the

nucleusnucleus Read by the tRNA during translation in Read by the tRNA during translation in

the ctyoplasmthe ctyoplasm

Transcription Vs. TranslationTranscription Vs. Translation

Transcription – process of making RNA Transcription – process of making RNA from DNA in the nucleus of the cellfrom DNA in the nucleus of the cell

Translation – process of making proteins Translation – process of making proteins tRNA recognizes codons of the mRNA and tRNA recognizes codons of the mRNA and

attaches the amino acids in the correct attaches the amino acids in the correct sequence for the protein that DNA coded sequence for the protein that DNA coded for. for.

CodonCodon

Set of 3 bases found on mRNASet of 3 bases found on mRNA Complementary to the anticodon on the Complementary to the anticodon on the

tRNAtRNA

AnticodonAnticodon

Set of 3 bases found on a tRNA Set of 3 bases found on a tRNA moleculemolecule

Recognizes the codon on mRNA during Recognizes the codon on mRNA during translationtranslation

Amino AcidAmino Acid

Building block of a proteinBuilding block of a protein 20 different kinds (essential and 20 different kinds (essential and

nonessential)nonessential)

Peptide BondPeptide Bond

Bond that joins amino acids together in Bond that joins amino acids together in the growing polypeptide chainthe growing polypeptide chain

PolypeptidePolypeptide

Made through translationMade through translation Growing chain of amino acids that Growing chain of amino acids that

transforms into a proteintransforms into a protein

RNA PolymeraseRNA Polymerase

Enzyme responsible for attaching RNA Enzyme responsible for attaching RNA nucleotides in the correct order. nucleotides in the correct order.

Steps of Transcription (in Steps of Transcription (in the nucleus)the nucleus)

DNA is the templateDNA is the template

RNA polymerase adds the RNA nucleotidesRNA polymerase adds the RNA nucleotides Uracil replaces ThymineUracil replaces Thymine

Once transcribed, mRNA leaves the nucleus and Once transcribed, mRNA leaves the nucleus and enters the cytoplasmenters the cytoplasm

Hooks up with a ribosome to begin translationHooks up with a ribosome to begin translation

Steps of TranslationSteps of Translation

Ribosome, mRNA and tRNA needed to beginRibosome, mRNA and tRNA needed to begin

Anticodon on tRNA matches with the codon on Anticodon on tRNA matches with the codon on mRNAmRNA Always begins w/ start codon (AUG)Always begins w/ start codon (AUG)

Adjacent amino acids form peptide bondsAdjacent amino acids form peptide bonds

tRNA keeps adding amino acids until the stop tRNA keeps adding amino acids until the stop codon is readcodon is read

Steps of TranslationSteps of Translation

tRNA releases the polypeptide chain (it tRNA releases the polypeptide chain (it will fold and become a functional will fold and become a functional protein)protein)

““naked” tRNA molecules find more naked” tRNA molecules find more amino acids and the process starts all amino acids and the process starts all over (as certain proteins are needed)over (as certain proteins are needed)