DNADNA

Replication Replication

and and

Protein SynthesisProtein Synthesis

Central Dogma of Gene Central Dogma of Gene ExpressionExpression

DNADNA

• Deoxyribonucleic AcidDeoxyribonucleic Acid– Controls cells activitiesControls cells activities– Contains organism’s traitsContains organism’s traits– Contains messages to produce Contains messages to produce

proteinsproteins

DNADNA

• Monomer- Nucleic AcidMonomer- Nucleic Acid

DNADNA

DNA – 4 basesDNA – 4 bases

Purines Pyrimidines

Adenine bonds with Thymine

Guanine bonds with Cytosine

DNA- Base PairsDNA- Base Pairs

• Just remember:Just remember:

AT Central GwinnettAT Central Gwinnett

A bonds with T

C bonds with G

DNA structureDNA structure

• James Watson James Watson and Francis Crick and Francis Crick 19531953Shaped like a ladderShaped like a ladder

SidesSides- alternating - alternating sugars and sugars and phosphatesphosphatesStepsSteps-base pairs -base pairs joined by hydrogen joined by hydrogen bondsbonds

DNA StructureDNA Structure

• Then ladder Then ladder

is twisted is twisted

forming a forming a

double helixdouble helix

DNA ReplicationDNA Replication

• During mitosis- chromosomes During mitosis- chromosomes (DNA) are copied (replicated)(DNA) are copied (replicated)

• Every cell gets a complete set of Every cell gets a complete set of chromosomeschromosomes

• Replication- Replication- process in which DNA process in which DNA is copiedis copied

DNA ReplicationDNA Replication

• Steps to DNA replicationSteps to DNA replication– 1. Chemical bonds split between base pairs, 1. Chemical bonds split between base pairs,

DNA is unzippedDNA is unzipped– 2. Free nucleotide bases pair up with 2. Free nucleotide bases pair up with

complementary base on DNA strands. Each complementary base on DNA strands. Each original strand is called a original strand is called a templatetemplate..

– 3. Sugars and phosphates bond between 3. Sugars and phosphates bond between free nucleotidesfree nucleotides

– 4. Result is 2 identical molecules of DNA. 4. Result is 2 identical molecules of DNA. Each new molecule consists of one old Each new molecule consists of one old strand and one new strandstrand and one new strand

DNA ReplicationDNA Replication

DNA DNA ReplicationReplication

Note: Each new DNA molecule is made of one old strand

and one new strand

DNA Replication LinksDNA Replication Links

• http://www.lewport.wnyric.org/jwanhttp://www.lewport.wnyric.org/jwanamaker/animations/DNA%20Replicamaker/animations/DNA%20Replication.htmlation.html

DNA and RNADNA and RNA

DNADNA RNARNA

StrandsStrands Double strandDouble strand Single strandSingle strand

SugarSugar DeoxyriboseDeoxyribose riboseribose

Base Base pairspairs

A-TA-T

C-GC-GA-UA-U

C-GC-GUracilUracil is substituted for is substituted for thyminethymine

DNA and RNADNA and RNA

Types of RNATypes of RNA

• mRNAmRNA- messenger RNA- single strand - messenger RNA- single strand copied from one side of the DNA copied from one side of the DNA molecule in the nucleus. Moves to the molecule in the nucleus. Moves to the cytoplasm. “Carries the message”cytoplasm. “Carries the message”

• tRNAtRNA- transfer RNA- carries the amino - transfer RNA- carries the amino acids to make a protein. Carries them to acids to make a protein. Carries them to the ribosome and mRNA.the ribosome and mRNA.

• rRNArRNA- ribosomal RNA- bonds with mRNA, - ribosomal RNA- bonds with mRNA, site where tRNA brings amino acids to site where tRNA brings amino acids to form a proteinform a protein

Types of RNATypes of RNA

mRNA

rRNA

tRNA

Protein SynthesisProtein SynthesisTranscription and TranslationTranscription and Translation

• TranscriptionTranscription- one side of a DNA - one side of a DNA molecule is copied forming a mRNA molecule is copied forming a mRNA moleculemolecule

• TranslationTranslation- protein is formed by - protein is formed by joining Amino Acidsjoining Amino Acids-sequence of mRNA bases is converted -sequence of mRNA bases is converted

into an amino acid sequenceinto an amino acid sequence

Protein SynthesisProtein SynthesisTranscriptionTranscription

• 1. DNA unzips1. DNA unzips• 2. Free floating 2. Free floating

nucleotides bond to nucleotides bond to one side of DNA (Uracil one side of DNA (Uracil bonds with Adenine)bonds with Adenine)

• 3. Bases are joined 3. Bases are joined togethertogether

• 4. mRNA leaves the 4. mRNA leaves the nucleus and enters the nucleus and enters the cytoplasmcytoplasm

Protein SynthesisProtein SynthesisTranslationTranslation

• CodonCodon- set of - set of three bases, three bases, each one codes each one codes for one amino for one amino acidacid

Protein SynthesisProtein SynthesisTranslationTranslation

Determine the chain of Amino Acids for the following codonsDetermine the chain of Amino Acids for the following codons

AUG CAG UAU GAU GUU UUA CCU UAGAUG CAG UAU GAU GUU UUA CCU UAGMethionine Glutamine Tyrosine Aspartate Valine Leucine Proline Stop

Protein SynthesisProtein SynthesisSteps of TranslationSteps of Translation

• 1. Ribosome attaches to mRNA1. Ribosome attaches to mRNA• 2. tRNA with 2. tRNA with anti-codon anti-codon that is the complement that is the complement

of the codon attaches to mRNA carrying a of the codon attaches to mRNA carrying a specific amino acidspecific amino acid

• 3. Ribosome slides to second codon3. Ribosome slides to second codon• 4. Second tRNA with complementary anti-codon 4. Second tRNA with complementary anti-codon

bonds with second codonbonds with second codon• 5. Amino acid from 15. Amino acid from 1stst tRNA bonds with amino tRNA bonds with amino

acid attached to 2acid attached to 2ndnd tRNA tRNA• 6. Ribosome continues down mRNA creating a 6. Ribosome continues down mRNA creating a

chain of amino acids until a stop codon is chain of amino acids until a stop codon is reachedreached

Protein SynthesisProtein SynthesisSteps of TranslationSteps of Translation

Protein Synthesis linksProtein Synthesis links

• http://www.lewport.wnyric.org/jwanhttp://www.lewport.wnyric.org/jwanamaker/animations/Protein%20Synamaker/animations/Protein%20Synthesis.htmlthesis.html

• http://www.wisc-online.com/objectshttp://www.wisc-online.com/objects/index_tj.asp?objid/index_tj.asp?objid=AP1302=AP1302

U C G UU C A A AmRNA

A

GC TTCA AAT

GC AAT

TG Ttemplate Strand

U C G UU C A A AmRNA

A

GC TTCA AAT

GC AAT

TG Ttemplate Strand

Nucleus

Cytoplasm

Ribosome

A

GC TTCA AAT

GC AAT

TG TTemplate Strand

Nucleus

Cytoplasm

U C G UU C A A A

U C G UU C A A AmRNA

U C G UU C A A A

A

GC TTCA AAT

GC AAT

TG TTemplate Strand

Nucleus

CytoplasmAA1

AGC

tRNA’s

U C G UU C A A A

A

GC TTCA AAT

GC AAT

TG Ttemplate Strand

Nucleus

CytoplasmAA1

AGCtRNA’s

U C G UU C A A A

A

GC TTCA AAT

GC AAT

TG Ttemplate Strand

•AA2

AAG

AA1

AGCtRNA’s

Nucleus

Cytoplasm

ATP

U C G UU C A A A

A

GC TTCA AAT

GC AAT

TG TTemplate Strand

AA3

U U U

•AA2

AAG

AA1

Nucleus

CytoplasmAGC

AA1

ATP

U C G UU C A A A

A

GC TTCA AAT

GC AAT

TG TtemplateStrand

AA3

U U U

•AA2

AAG

AA1

Nucleus

Cytoplasm

AGC

AA1

U C G UU C A A A

A

GC TTCA AAT

GC AAT

TG TTemplate Strand

AA3

U U U

•AA2

AAG

AA1

Nucleus

Cytoplasm

AGC

AA1

U C G UU C A A A

A

GC TTCA AAT

GC AAT

TG TTemplate Strand

AA3

U U U

•AA2

AAG

AA1

Nucleus

Cytoplasm

AGC

AA1

Mistakes in the Mistakes in the Genetic CodeGenetic Code

• MutationMutation- a change in the genetic code- a change in the genetic code• MutagenMutagen- any substance that causes a - any substance that causes a

mutation to occurmutation to occur– Examples:Examples: chemicals, radiation, high chemicals, radiation, high

tempstemps

Types of MutationsTypes of Mutations

• 1. Point mutation1. Point mutation- change in one - change in one base pair, often has no effect on base pair, often has no effect on phenotypephenotype

• Example GGU = glycineExample GGU = glycine

GGC = glycineGGC = glycine

Types of MutationsTypes of Mutations

• 2. Frame shift mutation2. Frame shift mutation- deletion or - deletion or addition of a baseaddition of a base– Codons get shiftedCodons get shifted

Example:Example:

GGG CUU CCU ACUGGG CUU CCU ACU

Gly Leu Pro ThrGly Leu Pro Thr

Suppose third G in first codon is lost, then:Suppose third G in first codon is lost, then:

GGC UUC CUA CUGGC UUC CUA CU

Gly Phe LeuGly Phe Leu

Types of MutationsTypes of Mutations

• 3. Chromosomal mutation3. Chromosomal mutation- whole - whole chromosome is added or deletedchromosome is added or deleted– Caused by Caused by non-disjunctionnon-disjunction

Genetic TechnologyGenetic Technology• Selective breedingSelective breeding- farmers choose organisms with - farmers choose organisms with

desirable traits to breeddesirable traits to breed– Increases frequency of desired allele in populationIncreases frequency of desired allele in population

• Genetic EngineeringGenetic Engineering- faster method of increasing - faster method of increasing desired allele in populationdesired allele in population– Small fragment of DNA is cut or cleaved from one Small fragment of DNA is cut or cleaved from one

organism and fragment is inserted into a host organism and fragment is inserted into a host organismorganism

– Also called Also called recombinant DNArecombinant DNA- connecting - connecting fragments of DNA from different sourcesfragments of DNA from different sources

Transgenic organismTransgenic organism- organism containing - organism containing fragments of foreign DNAfragments of foreign DNA

Genetic TechnologyGenetic TechnologyGel ElectrophoresisGel Electrophoresis

• Fragments of DNA are separated Fragments of DNA are separated by weightby weight

• Matching bands can be used to Matching bands can be used to identify the source of the DNAidentify the source of the DNA

• Link: Link: http://www.lewport.wnyric.org/jwanhttp://www.lewport.wnyric.org/jwanamaker/animations/Chrom%26Elphamaker/animations/Chrom%26Elpho.htmlo.html