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Biological Sciences 210 Genetics and Molecular Biology
Fall, 2006
Sequence of the CF Gene
The 4 Nucleotides in DNA
DNA Structure
The DNA Double Helix
E.M. of Prokaryotic Genome
Electron Micrograph of Plasmids
Genes and Intergenic Regions
Chromatin Structure
Chromatin Structure
Chromatin Structure
Human Karyotype
Comparative Genomes
Gene Structure
One Strand of a Gene is the
Transcribed (Template) Strand
Figure 3-4, p. 60
Protein Structure
The Genetic Code
Missense Point Mutation
Wild-Type
•
DNA
3'-TACTTTGTCGGTCCA…-5'
•
mRNA 5'-AUGAAACAGCCAGGU…-3'
•
Protein
fMet--Lys-Gln--Pro-Gly…
Missense Mutant
3’-TACTTTGTAGGTCCA…-5'
5’-AUGAAACAUCCAGGU…-3'
fMet--Lys-His--Pro-Gly…
Nonsense Point Mutation
Wild-Type
Nonsense Mutant
•
DNA
3'-TACTTTGTCGGTCCA…-5'
3'-TACATTGTAGGTCCA…-5'
•
mRNA
5'-AUGAAACAGCCAGGU…-3’
5'-AUGUAACAUCCAGGU…-3'
•
Protein
fMet--Lys-Gln--Pro-Gly…
fMet
Silent Point Mutation
Wild-Type
Silent Mutant
•
DNA
3'-TACTTTGTCGGTCCA…-5'
3'-TACTTTGTTGGTCCA…-5'
•
mRNA
5'-AUGAAACAGCCAGGU…-3’
5'-AUGAAACAACCAGGU…-3'
•
Protein
fMet--Lys-Gln--Pro-Gly…
fMet--Lys-Gln--Pro-Gly…
Frameshift Mutations
•
READING FRAME - Translation of an mRNA must start at the appropriate AUG of the
mRNA and work along the mRNA in a 5' ----> 3' direction, reading the mRNA in units
of 3. It must read in the exactly correct sequence of 3-base codons.
•
Demonstration:
•
THE FAT CAT ATE THE BIG RAT
•
HEF ATC ATA TET HEB IGR AT
Frameshift Mutation
•
Frameshift mutations change the reading frame of the messenger RNA.
•
For example: Template strand of DNA
•
3'-TACAGAGTGCTGCAT…-5'
•
5'-AUGUCUCACGACGUA…-3' mRNA
•
AUG UCU CAC GAC GUA… codons
•
fMet -- Ser -- His -- Asp -- Val…
•
Through a deletion, the DNA strand loses the fifth base in the sequence above:
•
3'-TACAAGTGCTGCAT…-5'
•
5'-AUGUUCACGACGUA…-3' mRNA
•
AUG UUC ACG ACG UA…
•
fMet-- Phe -- Thr -- Thr…
Structure of the CFTR Protein
Automated DNA Sequencing
Data
GGCTTACGGTTACTCGAAT TCTACCGCAAGAAT TCTGCTATTT
*Cuts at 1st EcoR I sit e, but not at 2nd EcoR I sit e (Partial dig est):
GGCTTACGGTTACTCG + AAT TCTACCGCAAGAAT TCTGCTATTT
GGCTTACGGTTACTCGAAT TCTACCGCAAGAAT TCTGCTATTT
*Does no t Cut at 1 st EcoR I sit e, but cuts at 2nd EcoR I sit e (Partial dig est):
GGCTTACGGTTACTCGAAT TCTACCGCAAG + AATTC TGCTATTT
Now, you can a li gn into Contigs!
GGCTTACGGTTACTCGAAT TCTACCGCAAG
AATT CTACCGCAAGAAT TCTGCTATTT
GGCTTACGGTTACTCGAAT TCTACCGCAAGAAT TCTGCTATTT
Constructing cDNA