Download Human Molecular Genetics

Genome Sequencing & App. of DNA
Technologies
• Genomics is a branch of science that focuses
on the interactions of sets of genes with the
environment.
– Identification of Genes
• computer software scans for the existence of certain
known features associated with genes
– start and stop sequences
– intron splicing sites
– ESTs - expressed sequence tags
» known gene sequences expressed in functioning genes
Non-Coding Areas & Mutations
• Within the human genome the majority of the
DNA (~75%) is made up of sequences not
involved in coding for proteins, RNA, or
regulatory sequences… “Junk DNA".
– exon regions - 1.5%
• much exists as multi-gene families
• Ribosomal RNA will have hundreds of gene copies in the
same gene transcript
– regulatory regions - 24%
DNA Fingerprinting
• Segments can then be compared to
find the differences by gel
electrophoresis - southern blotting
– Looks at non-coding sections of DNA
called RFLPs (repeat fragment length
polymorphisms)
• RFLPs common to all of a species but
differ in length within family lines
– fluorescent or radioactive markers
are then added to the gel to
elucidate the bands present
DNA Sequencing:
• The human Genome Project that spanned from 1993 to
2003 pushed the development of faster more efficient
methods of DNA sequencing.
– Dideoxy Chain-Termination Method
– DNA to be sequenced is digested and amplified (phage
vectors, YACs & BACs)
– Cloned fragments are then sequenced using the dideoxy
method
• The project continues to identify the genomes of
additional organisms
• Identification of Genes
– computer software scans for the existence of certain
known features associated with genes
• start and stop sequences
• intron splicing sites
• ESTs - expressed sequence tags
– known gene sequences expressed in functioning genes
Genomic Patterns
• As the complexity of the organism increases so does the amount of non-coding
DNA, the amount of genes per Mb decreases
• may be due to the role of non-coding regions in the regulation of gene
expression
• larger intron regions lead to alternative splicing and increased complexity
of protein products
organism
haploid genome
size (Mb)
# of genes
genes per Mb
E. coli
4.6
4,400
940
nematode
97
19,000
200
drosophila
180
13,700
76
zebra fish
1,700
22,000
13
human
2,900
25,000
10
Determining Gene Function
• Interactions of groups of genes
– accomplished through the use of micro arrays (DNA chips)
• all known genes are attached to a class slide
• mRNA are harvested and copies made using cDNA, reverse transcriptase, and
fluorescent labeled nucleotides
• cDNA mixture is added to the slide displaying the genes active at that
particular time
Applications of DNA technology
• Medicine
– diagnosis of disease
– gene therapy
– development of pharmaceuticals
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Forensics
Environmental cleanup
Agriculture Applications
Safety & ethical questions
– GM organisms & food
– privacy issues
– cloning