Regulation of Gene Expression in Prokaryotes and Mutations

Gene expression

process of DNA being transcribed + translated into a functional protein

transcription

DNA to RNA

translation

RNA to protein

regulatory sequences

stretches of DNA that can promote or inhibit protein synthesis

regulatory proteins

interaction of regulatory sequences with ? controls transcription

histones

proteins that DNA wraps around

epigenetic changes

the character of histone packing (tight or loose) that regulates gene expression

• loose = polymerase access

• tight = restricted access, no transcription

phenotype

an organism’s ? is determined by gene expression

transcription factors

proteins that promote or inhibit transcription of a gene

• all of these are regulatory proteins, but not all regulatory proteins are these

operons

closely linked genes that produce a single mRNA during transcription

• genes, regulatory sequence, operator (components)

lac operon

a type of operon that is inducible because it can turn on

• it’s usually in the off position

inducers

induce operons hence releasing regulatory proteins

• releasing these proteins allow RNA polymerase to start transcribing genes

trp operon

example of operon that is repressible (able to turn off)

• it’s usually on, but it can turn off under the right circumstances

co-repressor

on a repressible operon like trp operon, the binding of a ? to a repressor protein activates the repression

point mutation

when one nucleotide has been substituted for a different nucleotide

frameshift mutation

when one or more nucleotides are inserted / deleted, causing reading frame to shift

Nonsense mutation

when a point mutation causes a premature stop

silent mutation

when change in nucleotide sequence has no effect on amino acid sequence