Chapter 11- Gene Expression and Regulation Flashcards
Isoforms
Different proteins encoded by the same gene
Spliceopathy
Abnormal splicing of genes
Spinal Muscular Atrophy (SMA)
Mutation in survival motor genes (SMN1 and SMN2)
Autosomal recessive
Following mutation, gene is spliced to make non-functional protein
Muscle atrophy, weakness, and diaphragm paralysis
Non-coding DNA
RNA product, not protein products of gene
Function to regulate host genes
tRNA, rRNA, microRNA, long ncRNA
MicroRNA
~20 bases long
Base pairs to mRNA to block ribosome binding and prevent translation
Double-stranded RNA is marked for degradation
Act as dimmer switch
Can be used as drug for RNA interference (RNAi)
Epigenetics
Molecular mechanisms that alter DNA expression without changing sequence
Methylation
DNA Methyltransferases (DNMTs) add methyl groups to CpG sites, often in promoter sequences
Blocks transcription factor binding, downregulation expression
Histone Modification
Acetylation of histones removes positive charge, weakening DNA association and promoting transcription
Common in locus control regions of genes
Euchromatin
Highly expressed
High acetylation and low methylation
Heterochromatin
Low expression
Low acetylation and high methylation
Viral DNA
8% of genome
Virus inserts viral DNA and uses reverse transcriptase to incorporate into genome
Infection in germ cells passes viral DNA to offspring
Repetitive DNA
50% of genome
Mostly outside genes and transcriptionally inactive
Dispersed repeats- Transposons, LINEs, SINEs
Tandem repeats
DNA Transposons
Cut and paste process
Transposase enzyme cuts DNA and adds to new position
Retrotransposons
RNA copy created through transcription
Reverse transcriptase creates another copy and adds to new positon
Actively expands genome
Long Interspersed Nuclear Elements (LINEs)
Several thousand base pair dispersed repeats
