Topic 6.5 - Regulation of Gene Expression 𖦹⋆｡°✩ Flashcards
what do the differences in gene expression account for
account for phenotypic differences between organisms
what is gene expression
the process by which instructions in the DNA are transcribed and translated into a functional protein
what regulates gene expression
different types of chemical reactions
what are regulatory sequences
stretches of DNA that promote/inhibit protein synthesis
what are regulatory proteins used for
used to assist with the promotion/inhibition of protein synthesis
how is transcription controlled
the interaction of regulatory sequences with regulatory proteins
what do epigenetic changes involve
involve reversible modifications of DNA or histones
what are histones
proteins used to wrap around DNA. slight chemical modifications of DNA and histones cause tight/loose packing of DNA
what regulates gene expression
packing/unpacking DNA
do all cells within an organism have the same DNA sequences
yes, but they do not have the same function
how is the phenotype of a cell determined
by the combination of genes that are expressed
what is cell differentiation
cells within the same organism having different phenotypes
what are transcription factors
proteins that promote/inhibit gene transcription
what determines how a cell differentiates
the presence of various transcription factors
what is a result of sequential gene expression
the process of development from an undifferentiated cell to a differentiated cell
what is the difference between differentiated vs undifferentiated cells
differentiated cells are specialized for certain jobs, undifferentiated cells are not yet specialized (ex. stem cells)
what are operons
closely linked genes that produce a single mRNA molecule during transcription
what do operons do and what do they include
operons are under the control of the same regulatory sequence and they include the genes to be transcribed, the regulatory sequence, and the operator
what is an operator
a sequence that either inhibits/promotes transcription by binding with regulatory proteins
what happens in the genome
structural proteins with related functions are encoded together. they are controlled by a single regulatory sequence
what are the two operons we discussed
lac and tryptophan operons
how is lactose inducible
when the regulatory protein is bound to the operator, RNA polymerase cannot bind to the regulatory sequence (needs something to induce it)
what happens when lactose is absent
transcription of genes is inhibited
what are inducers
molecules that can bind to the regulatory protein and cause it to change shape
what happens when the inducer binds to the regulatory protein
the protein changes shape and cannot bind to the operator, allowing transcription to occur
