molecular biology of the gene part 2
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Molecular Biology of the Gene PART 2. Debbi Ann Morrissette Graduate Student Researcher Laboratory of Molecular Neuropathogenesis University of California, Irvine. PART 1. Structure of DNA DNA Replication DNA vs. RNA. PART 2. Flow of Genetic Info Mutations Cloning Differentiation - PowerPoint PPT PresentationTRANSCRIPT
Molecular Biology Molecular Biology of the Geneof the Gene
PART 2PART 2Debbi Ann MorrissetteDebbi Ann Morrissette
Graduate Student ResearcherGraduate Student ResearcherLaboratory of Molecular Laboratory of Molecular
NeuropathogenesisNeuropathogenesisUniversity of California, IrvineUniversity of California, Irvine
PART 1PART 1
Structure of DNAStructure of DNA DNA ReplicationDNA Replication DNA vs. RNADNA vs. RNA
PART 2PART 2 Flow of Genetic InfoFlow of Genetic Info MutationsMutations CloningCloning DifferentiationDifferentiation X Chromosome InactivationX Chromosome Inactivation
The 2 Main Functions of The 2 Main Functions of DNADNA
Passing genetic information to Passing genetic information to daughter cellsdaughter cells Through DNA replicationThrough DNA replication
Directing the synthesis of proteinsDirecting the synthesis of proteins Through Through transcriptiontranscription of the DNA code of the DNA code
and and translationtranslation of the nucleotide code of the nucleotide code into an amino acid sequenceinto an amino acid sequence
Basic Nucleotide Basic Nucleotide StuctureStucture
Sugar
Phosphate
Nitrogenous Base
HDeoxyribose
Sugar
Phosphate
Nitrogenous Base
Sugar
Phosphate
Nitrogenous Base
DNA vs. RNADNA vs. RNA
Deoxyribonucleic Acid Ribonucleic Acid
Nitrogenous Bases
T C A GNitrogenous Bases
U C A G
OH
Uracil
Thymine HCH3
Ribose
Base Pairing Base Pairing
DNA:DNA (replication)DNA:DNA (replication) A:TA:T C:GC:G
T
C G
A
G C
A
A
T
T
DNA:RNA (transcription)DNA:RNA (transcription) A:UA:U C:GC:G T:AT:A
T A AC CA
C
T
C C AA
U
TT
GG
G T T A ACUAC
GG
T A
From DNA to ProteinsFrom DNA to Proteins
DNA
RNA
Protein
Translation
Transcription
Genotype
Phenotype
DNA molecule
Gene 1
Gene 2
Gene 3
AAAAA C C GG C
CCGG G U U U UUUU
AADNA strand
Transcription
RNA
Translation
Polypeptide
Amino acid
Codon
OvervieOvervieww
Genotype
Phenotype
Note:
U pairs with A
A still pairs with T
The RNA “Players”The RNA “Players” mRNA = messenger mRNA = messenger
RNA RNA ““The Mailman”The Mailman”
rRNA = ribosomal rRNA = ribosomal RNARNA ““The Recruiter”The Recruiter”
tRNA = transfer RNA tRNA = transfer RNA ““The Translator”The Translator”
G A A U UG U U A G
TranscriptioTranscriptionn
TerminationTermination RNA reaches the RNA reaches the terminatorterminator sequence sequence on the DNA strand on the DNA strand and releases from and releases from the DNAthe DNA
ElongationElongation RNA polymerase moves RNA polymerase moves
along the DNA strand along the DNA strand adding complementary adding complementary RNA nucleotides to make RNA nucleotides to make the mRNA strandthe mRNA strand
InitiationInitiation RNA polymerase attaches RNA polymerase attaches
to the to the promoterpromoter sequence sequence on DNA strand on DNA strand
RNA polymerase
Initiation
PromoterDNA
TerminatorDNA
Initiation
Elongation
TerminationGrowingRNA
Completed RNA RNApolymerase
DNA of gene
Elongation –A Closer Elongation –A Closer LookLook
RNApolymerase
RNA nucleotides
Templatestrand of DNA
Direction oftranscription
Newly made RNA
T A AC CA
CT
C C AA
U
TT
GG
U
G T T AA
CCUAC
GG
T A
mRNAmRNA
Following Following transcription, the transcription, the “message” is “message” is brought from the brought from the nucleus to the nucleus to the cytoplasm.cytoplasm.
_______________
_______________
_______________
The RNA “Players”The RNA “Players” mRNA = messenger mRNA = messenger
RNA RNA ““The Mailman”The Mailman”
rRNA = ribosomal rRNA = ribosomal RNARNA ““The Recruiter”The Recruiter”
tRNA = transfer RNA tRNA = transfer RNA ““The Translator”The Translator”
G A A U UG U U A G
TranslationTranslation
rRNA recruits both mRNA and tRNArRNA recruits both mRNA and tRNA
rRNA
G A A U UG U U A G
mRNA
tRNA
Met
Small ribosomalsubunit
CAUA GU
Large ribosomalsubunit
tRNAtRNA tRNA must tRNA must
translate the RNA translate the RNA message carried message carried by mRNAby mRNA
Translation of RNA Translation of RNA nucleotides to nucleotides to amino acidsamino acids
tRNA has to be tRNA has to be “bilingual”“bilingual”
Anticodon
Amino acidattachment site
Translation of the Translation of the Genetic CodeGenetic Code
3 nucleotide bases = 1 amino acid3 nucleotide bases = 1 amino acid Every group of 3 mRNA nucleotides = Every group of 3 mRNA nucleotides =
CodonCodon Corresponding triplet of bases on the Corresponding triplet of bases on the
tRNA = AnticodontRNA = AnticodonCCGG G U U U UUUU
Amino acid
Codon
Anticodon
Amino acidattachment site
The mRNA to Amino Acid The mRNA to Amino Acid DictionaryDictionary
AUG =StartAUG =Start UAA and UAG = StopUAA and UAG = Stop The code is The code is
redundant:redundant: Just as “drink” and Just as “drink” and
“beverage” both “beverage” both representrepresent
GCU and GCG both GCU and GCG both code for alaninecode for alanine
Second base
Fir
st
bas
e
Th
ird
bas
e
UUU
U C A G
G
AA
C
U
U
U
C
A
C
A
G
G
U
C
A
G
U
C
A
G
UUC
UUA
UUG
CUU
CUC
CUA
CUG
AUU
AUC
AUA
Leu
lle
AUG Met orstart
GUU
GUC
GUA
GUG
Val Ala
Thr
GCG
GCA
GCC
GCU
ACG
ACA
ACC
ACU
Pro
CCG
CCA
CCC
CCU
UCG
UCA
UCC
UCU
Ser
Tyr CysUAU
UAC
UAA
UAG
CAU
CAC
CAA
CAG
His
Gln
Stop
Stop
UGU
UGC
UGA
UGG Trp
Stop
Arg
CGU
CGU
CGA
CGG
Asn
Lys
Asp
Glu
Gly
Arg
SerAAU AGU
AAC
AAA
AAG
GAU
GAG
AGC
AGA
AGG
GGU
GGC
GGG
Phe
Leu
GAC
GAA
GAG
GGA
Translation OverviewTranslation Overview
IntitiationIntitiation
ElongationElongation
TerminationTermination
TranslationTranslation
IntitiationIntitiation
Initiator tRNA binds to START codonInitiator tRNA binds to START codon
Met
CAU
A GU
Amino acid
tRNA rRNA
mRNAAnticodon
Codon
TranslationTranslationPolypeptide
mRNA Codons
Anticodon
Aminoacid
Condon recognition
Peptide bondformation
Newpeptidebond
Translocation
Stop codon
mRNAmovement
ElongationElongation Codon recognitionCodon recognition
TranslocationTranslocation
Peptide bond formationPeptide bond formation rRNA also functions as an enzymerRNA also functions as an enzyme
TranslationTranslation
Stop codon
Growingpolypeptide
New peptidebond forming
mRNA
Polypeptide
Codons
Elongation
Termination
The ribosome recognizesa stop codon. The poly-peptide is terminatedand released.
TerminationTermination
STOP codon on mRNASTOP codon on mRNA Polypeptide (protein) is Polypeptide (protein) is
releasedreleased
SummarySummary The DNA code that The DNA code that
makes up a gene makes up a gene is is transcribedtranscribed into into mRNAmRNA
rRNA brings rRNA brings mRNA and tRNA mRNA and tRNA togethertogether
tRNA tRNA translatestranslates the code from the code from nucleotides to nucleotides to amino acidsamino acids
Newly made Newly made protein is releasedprotein is released
Genotype
Phenotype