Genetics & genomics
Sequencing of the genetic code
Chromosome nucleosomes chromatin (DNA is condensed with the aid
of histones) DNA double helix
Histones: 2H2A, 2 H2B, 2 H3 and 2 H4
To make transcripts DNA should be accessible:
Histone modification: DNA become less tightly bound to histone
proteins
o Histone acetylation: addition of acetyl groups to histones
– DNA become more accessible to transcription factors –
euchromatin: loosely pakced form and generally active
o Histone deacetylation: removal of acetyl groups from
histones – DNA become less accessible to transcription
factors – heterochromatin: firmly packed form and
genetically inactive
o Nucleosome remodelling (change in structure)
DNA modification/methylation
DNA sequencing:
Method invested in 1976 by Fred sanger;
Chain-termination method: making many DNA product with
the use of enzymes and terminate the reaction – size of
product determines the next base in line
In 2003; the code is published
Later; advances went much quicker than expected because increase in computer-
storage
Measuring gene expression:
1. PCR methods
a. Relative expression
b. Work well for small number of genes
c. Real quantitative version is the best
2. Hybridization-based methods
a. Relative expression
b. Very popular between 2000-now because
of price
3. Sequencing-based methods (Tag-based)
a. Serial analysis of gene expression (SAGE)
– gene expression
b. Cap analysis of gene expression (CAGE) –
gene expression and promotor use (newest
one!)
Make cDNA and use CAP at 5’ end and add a linker to the CAP
sequence this and count number (=presence of transcripts)
Sequencing of the genetic code
Chromosome nucleosomes chromatin (DNA is condensed with the aid
of histones) DNA double helix
Histones: 2H2A, 2 H2B, 2 H3 and 2 H4
To make transcripts DNA should be accessible:
Histone modification: DNA become less tightly bound to histone
proteins
o Histone acetylation: addition of acetyl groups to histones
– DNA become more accessible to transcription factors –
euchromatin: loosely pakced form and generally active
o Histone deacetylation: removal of acetyl groups from
histones – DNA become less accessible to transcription
factors – heterochromatin: firmly packed form and
genetically inactive
o Nucleosome remodelling (change in structure)
DNA modification/methylation
DNA sequencing:
Method invested in 1976 by Fred sanger;
Chain-termination method: making many DNA product with
the use of enzymes and terminate the reaction – size of
product determines the next base in line
In 2003; the code is published
Later; advances went much quicker than expected because increase in computer-
storage
Measuring gene expression:
1. PCR methods
a. Relative expression
b. Work well for small number of genes
c. Real quantitative version is the best
2. Hybridization-based methods
a. Relative expression
b. Very popular between 2000-now because
of price
3. Sequencing-based methods (Tag-based)
a. Serial analysis of gene expression (SAGE)
– gene expression
b. Cap analysis of gene expression (CAGE) –
gene expression and promotor use (newest
one!)
Make cDNA and use CAP at 5’ end and add a linker to the CAP
sequence this and count number (=presence of transcripts)
