● Alternative RNA splicing: code for different but related
proteins
● Transcription initiation can be regulated by the
methylation of DNA
● DNA methylation - methyl group is added to cytosine
base in 5’ CpG 3’ dinucleotide by enzyme DNA
methyltransferases
● CPG islands is where the DNA methyltransferases can
add the methyl groups
● DNA methylation at these islands silences gene
expression and inhibits the initiation of transcription
● Cytosine methylation pattern is maintained when
somatic cells divide
○ DNA methylation is epigenetic: heritably alter gene
expression without changing DNA sequence
● Genomic imprinting of Igf2 gene affects fetal growth
○ Maternal allele is silent
○ Paternal allele is active
● Patterns of DNA methylation are reset in germ cells during
meiosis before being passed on to the next generation
● Paternal imprinting: methylated and silenced
● Maternal imprinting: methylated and silenced
● Genomic imprinting and human disease
○ Prader willi syndrome is a result of the paternal
deletion inheritance
○ Angelman syndrome: deletion is inherited from the
mother
proteins
● Transcription initiation can be regulated by the
methylation of DNA
● DNA methylation - methyl group is added to cytosine
base in 5’ CpG 3’ dinucleotide by enzyme DNA
methyltransferases
● CPG islands is where the DNA methyltransferases can
add the methyl groups
● DNA methylation at these islands silences gene
expression and inhibits the initiation of transcription
● Cytosine methylation pattern is maintained when
somatic cells divide
○ DNA methylation is epigenetic: heritably alter gene
expression without changing DNA sequence
● Genomic imprinting of Igf2 gene affects fetal growth
○ Maternal allele is silent
○ Paternal allele is active
● Patterns of DNA methylation are reset in germ cells during
meiosis before being passed on to the next generation
● Paternal imprinting: methylated and silenced
● Maternal imprinting: methylated and silenced
● Genomic imprinting and human disease
○ Prader willi syndrome is a result of the paternal
deletion inheritance
○ Angelman syndrome: deletion is inherited from the
mother
