DNA, RNA And Protein Synthesis. Structure of DNA must allow the storage and transmission of genetic information. Function of DNA Modern Biology Pages

DNA, RNA And DNA, RNA And Protein Protein

SynthesisSynthesis

Structure Structure of DNA of DNA must allow must allow the the storage storage and and transmissitransmission of on of genetic genetic informatioinformation.n.

Function of DNAFunction of DNAModern BiologyModern Biology

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DNA spills from E. coli cell.

Genetic Genetic informatioinformation must n must tell tell cell(s) cell(s) how to how to make make proteins.proteins.

Function of DNAFunction of DNA

Proteins are made in the Proteins are made in the cytoplasm but DNA remains in cytoplasm but DNA remains in nucleusnucleus

Modern BiologyModern Biology

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http://www.youtube.com/watch?v=4PKjF7OumYo

Proteins Proteins form form structurestructures and s and control control chemistry chemistry of cell.of cell.

Functions of DNAFunctions of DNA

Ribosomes embedded in the Ribosomes embedded in the E.R. construct proteinsE.R. construct proteins


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Structure Structure of DNA of DNA must must allow allow exact exact replicatireplication to on to occur.occur.

Functions of DNAFunctions of DNAModern BiologyModern Biology

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Why Why Understanding Understanding

DNA is Important DNA is Important to You.to You.

Griffith’s Experiment

DISCOVERY OF DNA DISCOVERY OF DNA – GRIFFITH’S – GRIFFITH’S EXPERIMENTEXPERIMENT

• Called Called transformation.transformation.

• Used mice and Used mice and pneumonia.pneumonia.– Rough (non-Rough (non-virulent)virulent)

– Smooth (virulent)Smooth (virulent)


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Avery Determines DNA Avery Determines DNA To Be Hereditary To Be Hereditary

MoleculeMolecule• Avery, Avery, McCloud, McCloud, and and McCartyMcCarty– Used process Used process of of elimination.elimination.

– Determined Determined DNA was DNA was heredity heredity material.material.


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Important People Important People in DNA Sciencein DNA Science

• Rosalind Rosalind Franklin of Franklin of Cal Tech in Cal Tech in Los Angeles Los Angeles took took pictures pictures using X-Rays using X-Rays in the in the 1930’s1930’s Was never given due credit for her Was never given due credit for her

contribution to DNA Sciencecontribution to DNA Science


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Important People Important People in DNA Sciencein DNA Science

• James Watson & James Watson & Francis Crick Francis Crick discovered discovered structure of structure of DNA in 1953.DNA in 1953.

James Watson Left & Francis Crick right: James Watson Left & Francis Crick right: Nobel prize for DNA structureNobel prize for DNA structure


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DNA DNA StructureStructure

–DNA is a DNA is a polymer.polymer.

–The The monomer of monomer of DNA is DNA is called a called a nucleotidenucleotide..

deoxyribonucleic deoxyribonucleic acidacid


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Nucleotide Nucleotide StructureStructure

• One 5 carbon One 5 carbon sugar called sugar called deoxyribose.deoxyribose.– ““Deoxy” = one Deoxy” = one less oxygen.less oxygen.

– ““ribo” = than ribo” = than ribose.ribose.

• DeoxyribonucleiDeoxyribonucleic acidc acid– ““nucleic” = nucleic” = found in found in nucleus.nucleus.

– ““acid” = acidicacid” = acidic

Deoxyribose, a pentose Deoxyribose, a pentose sugar, has each carbon sugar, has each carbon

numbered.numbered.


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Nucleotide Nucleotide Structure Structure

Phosphate group Phosphate group attached to attached to the #5 carbon the #5 carbon of the sugar. of the sugar.

The phosphoric The phosphoric acid is acid is negative and negative and so makes the so makes the DNA molecule DNA molecule negative.negative.

The deoxyribose has a nitorgenous base The deoxyribose has a nitorgenous base and a phoshate attached to it.and a phoshate attached to it.


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Nucleotide Nucleotide StructureStructure

One nitrogenous One nitrogenous base attached to base attached to the #1 carbon in the #1 carbon in the sugar..the sugar..

–Adenine (Purine)Adenine (Purine)–Guanine (Purine)Guanine (Purine)–Cytosine Cytosine (Pyrimidine)(Pyrimidine)–Thymine Thymine (Pyrimidine)(Pyrimidine)

Four bases of DNAFour bases of DNA


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DNA StructureDNA Structure

• DNA DNA molecule molecule has shape has shape of a of a double double helix.helix.

• The sides The sides are anti-are anti-parallel.parallel.

Modern Modern BiologyBiology

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DNA Structure• Nucleotides Nucleotides linked linked together form together form the sides of the sides of the DNA the DNA molecule.molecule.

• PhosphodiestePhosphodiester bond links r bond links phosphates phosphates and and deoxyribosedeoxyribose Each phosphate is Each phosphate is

linked to two sugar linked to two sugar molecules.molecules.


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DNA StructureDNA Structure

Complementary base Complementary base pairing rulespairing rules–Nitrogenous bases form Nitrogenous bases form “steps” or rungs of the “steps” or rungs of the helix.helix.•Adenine (2 rings) is bonded Adenine (2 rings) is bonded with Thymine (1 ring) using 2 with Thymine (1 ring) using 2 hydrogen bonds.hydrogen bonds.

•Guanine (2 rings) is bonded Guanine (2 rings) is bonded with Cytosine (1 ring) using 3 with Cytosine (1 ring) using 3 hydrogen bonds.hydrogen bonds.


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CENTRAL DOGMA CENTRAL DOGMA OF DNAOF DNA

DNA mRNADNA mRNAProteinProtein

1)1) DNA must send a message to ribosomes as DNA must send a message to ribosomes as to how a protein is to be produced.to how a protein is to be produced.

2)2) DNA must replicate itself exactly prior DNA must replicate itself exactly prior to each cell division.to each cell division.


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Replication Replication of DNAof DNA

• Replication Replication must:must:– Occur prior to Occur prior to every cell every cell division.division.

– Occur during Occur during “S” phase of “S” phase of interphase.interphase.

– Result in two Result in two identical identical copies of the copies of the DNA molecule.DNA molecule.


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Replication Replication of DNAof DNA

• DNA DNA replication replication is semi-is semi-conservativeconservative– Each new Each new molecule is molecule is composed of composed of one old and one old and one new one new strand.strand.


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ReplicatioReplication Processn Process• Replication fork Replication fork is where double is where double helix is split helix is split apart.apart.

• Double helix is Double helix is split apart by split apart by enzyme called enzyme called DNA Helicase.DNA Helicase.


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Replication Replication ProcessProcess

• Role of DNA Role of DNA polymerase.polymerase.– Constructs a new Constructs a new strand of DNAstrand of DNA• One side is One side is continuouscontinuous

• One side is One side is discontinuousdiscontinuous

• Complementary Complementary nature of bases nature of bases allows allows replication to replication to occur properly.occur properly.

• Replication Replication occurs at many occurs at many sites at same sites at same time.time.


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Replication Replication ProcessProcess

•Mistakes and repair Mistakes and repair processes.processes.

–Xeroderma PigmentosaXeroderma Pigmentosa–Lacks proper enzyme to repair Lacks proper enzyme to repair DNA damage due to sunlight.DNA damage due to sunlight.


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•Multiple Multiple carcinomas develop carcinomas develop due to exposure to due to exposure to uV lightuV light

RNARNA•Structure of RNA.Structure of RNA.

–Ribose instead of Ribose instead of deoxyribose.deoxyribose.–Uracil instead of Uracil instead of thymine.thymine.–Single helix instead Single helix instead of double.of double.

•Three types of Three types of RNA.RNA.

–mRNAmRNA–tRNAtRNA–rRNArRNA


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RNA is made from RNA is made from DNADNA

TRANSCRIPTIONTRANSCRIPTION• Making mRNA Making mRNA as a as a messenger.messenger.– Process Process referred to referred to as as transcriptiotranscription.n.

– Purpose is Purpose is to copy the to copy the message for message for a protein a protein from the DNA from the DNA molecule.molecule.

Making mRNAMaking mRNA


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TRANSCRIPTIONTRANSCRIPTION

Making mRNAMaking mRNA

• TranscriptionTranscription– DNA untwists and DNA untwists and unzips in area of unzips in area of molecule where molecule where the message for a the message for a certain protein certain protein is held.is held.

– Role of RNA Role of RNA polymerase.polymerase.

– Role of promoter.Role of promoter.– Role of Role of termination termination signal.signal.


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TRANSCRIPTIONTRANSCRIPTION

– The product The product of of transcriptiotranscription is mRNA, n is mRNA, tRNA,and tRNA,and rRNA.rRNA.

– TranscriptioTranscription occurs in n occurs in the nucleus the nucleus of the cell.of the cell.


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TranslatioTranslationn

• Translation occurs Translation occurs in the cytoplasm.in the cytoplasm.

• Amino acids are Amino acids are assembled assembled polypeptides. polypeptides. (Proteins)(Proteins)

• Ribosomes assemble Ribosomes assemble polypeptides based polypeptides based on instructions held on instructions held in the DNA molecule.in the DNA molecule.

mRNA leaving the mRNA leaving the nucleusnucleus


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• Protein Protein structurestructure– Composed of Composed of building blocks building blocks called amino acids.called amino acids.• 20 different 20 different types of amino types of amino acids.acids.

• Sequence and Sequence and length of amino length of amino acid chain acid chain determines the determines the characteristics characteristics of the protein.of the protein.

Wednesday 1/8/03Wednesday 1/8/03

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Ribosomes attach to the Ribosomes attach to the mRNA molecule in the mRNA molecule in the cytoplasm.cytoplasm.

Genetic Genetic codecode

• The Genetic CodeThe Genetic Code• Each 3 nucleotides Each 3 nucleotides

on mRNA is a codon.on mRNA is a codon.– Each codon codes Each codon codes for a specific for a specific amino acid.amino acid.

– 64 possible 64 possible codons.codons.

– 1 start codons1 start codons– 3 stop codons3 stop codons– 60 different 60 different codons code for codons code for 20 different 20 different types of amino types of amino acids.acids. mRNA codon listmRNA codon list


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• The ribosome binds to The ribosome binds to the mRNA.the mRNA.

• tRNA (with anticodon) tRNA (with anticodon) brings proper amino acid brings proper amino acid to ribosome. (met tRNA)to ribosome. (met tRNA)

• Ribosome moves to next Ribosome moves to next three bases (codon).three bases (codon).

• Another tRNA brings Another tRNA brings proper AA to ribosome.proper AA to ribosome.

• Protein is assembled.Protein is assembled.• Stop codon signals end Stop codon signals end

of protein.of protein.

tRNA brings an amino acid tRNA brings an amino acid to the ribosome.to the ribosome.


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DNA, RNA And Protein Synthesis. Structure of DNA must allow the storage and transmission of genetic information. Function of DNA Modern Biology Pages