Epigenetics: Exam 2 Flashcards
Epigenetics
study of variations in gene expression not caused by differences in nucleotide sequence (internal vs. external)
Regulation of gene expression/protein function
Access to DNA, Transcription factors, alternative splicing, access to/persistence of mRNA, persistence/activity of protein
DNA packaging
DNA is packed/coiled around histones (type of protein): DNA is wound around histones/nucleosomes : preventing access to transcriptional machinery
Histone Acetylation
addition of acetyl group to histone protein: lowers affinity b/ histones and DNA (loosens packaging): catalyzed by (HATs)
DNA methylation
affects transcriptional access: addition of methyl group (CH3) to cytosine, interferes with binding of RNA polymerase
Transcription factors
proteins that prevent transcription: control gene expression: alternative splicing
Alternative Splicing
Removing different introns to create slightly different proteins: introns interrupt, exons express; type of protein made controlled, performed by spliceosomes
Dscam
gene that produces 38,000 different proteins: proteins that rest on surface of neuron cells: prompts cellular self-awareness necessary to ensure correct wiring of neurons in the brain ~ exons are used
Later stage of gene expression subject to regulation
lifetime of mRNA molecule helps determine how much protein is made, protein may bind to mRNA interfering with function, mRNA broken down by enzymes
MicroRNA (miRNA)
repression of translation/destruction of mRNA (complementary): regulates 1/3 of genes
Final protein is regulated
function is blocked by other proteins, misfolded, transported to wrong location, rate of protein degradation by enzymes affect amount of final, need to be activated
Post-translational modification
Folding; chemically altering protein structure; cutting certain regions
