Unit 6, Topic 5: Regulation of Gene Expression Flashcards
a group of genes that can be turned on or off
operons
where RNA polymerase can attach
promoter
the on/off switch
operator
operon that can be activated or repressed depending on cellular needs and the surrounding environment
inducible
these affect cell differentiation by determining which regions of an embryo will form what structures.
cytoplasmic determinants
substrate binds to allosteric site and stabilizes the enzyme shape so that the active sites are closed (inactive form)
allosteric inhibitor
produces a repressor protein that binds to operator to block RNA polymerase from transcribing the gene (reversible)
regulatory gene
substrate binds to allosteric site and stabilizes the shape of the enzyme so that the active sites remain open
allosteric activator
sections of noncoding DNA that serve as binding sites
Control elements
adds acetyl groups to histones, which loosen the DNA
Histone acetylation
epigenetic modification that leads to gene silencing; commonly found in cancer cells
DNA methylation
chromatin modifications do not alter the nucleotide sequence of the DNA, but they can be heritable to future generations
Epigenetic inheritance
code for related enzymes in pathway
Gene
cells become specialized in their structure and function
Differentiation
the physical process that gives an organism its shape
Morphogenesis
cell to cell signals that can cause a change in gene expression
induction
map out the body structures
Homeotic genes
programmed cell death in cases of harmful mutations
Apoptosis
Pattern Formation
What are the three parts of an operon?
Promoter, operator, and the genes
Differentiate between a repressible and inducible operon.
Repressible operon: transcription is usually turned on, but can be repressed or stopped.
Inducible operon: transcription is usually off, but can be induces or started.
The trp operon is repressible/inducible.
repressible
trp is series of genes necessary to synthesize tryptophan
in prokaryotic cells
If a bacterial cell uses up its tryptophan storage, what would happen to the trp operon?
The repressor would leave the operator and transcription can continue. The operon would turn on again and more tryptophan would be produced.
If a bacterial cell does not need tryptophan and it builds up inside of the cell, what would happen to the trp operon?
The trp operon would be switched off. This means that tryptophan will bind to the repressor and temporarily shut off transcription of that gene.
If a bacterial cell has a mutation to the trp repressor that changes the shape of the active site, how would this affect the production of tryptophan?
The production of tryptophan would be constant. Since the trp repressor has a differentially shaped active site, tryptophan would be unable to it and could not shut off transcription.
The lac operon is repressible/inducible.
inducible
lac operon encodes genes required for processing and intake of lactose
found in prokaryotes
If a bacterial cell is grown in a nutrient rich, lactose free medium, what would you expect to see at the lac operon?
Is is expected that the lac repressor is bound to the operator, making it allosterically active. Transcription is OFF.
on to off operon
repressible
