5a slides Flashcards
what do prokaryotes and eukaryotes do in response to cellular and environmental cues
regulate gene expression
in multicellular eukaryotes what does gene expression regulate
development and is responsible for differentiation of cell types
promoter
specific nucleotide sequence of a gene that binds RNA polymerase
what binds to a specific DNA sequence called a promoter
RNA polymerase
where does the promoter position the RNA polymerase and in what direction does it point the enzyme
at the start of the gene and points the enzyme in the right direction to transcribe a given gene
what do proteins recognize and bind to
discrete sites
what is the most likely consequence of the DNA binding site for a particular protein is mutated
mutations can enhance and decrease binding affinity between proteins and DNA
downregulation
less protein made
upregulation
more protein made
domains of proteins that bind DNA in a nucleotide fit in where
in the groove of the doubke standard helix where it can form non covalent bonds with the correct base pairs
how does bacteria respond to environmental changes
by regulating gene expression
Natural selection has favored bacteria that produce only the gene products needed to live in a particular environment. Why?
a cell can regulate the production of enzymes by gene regulation
what is the operon a mechanism for
the coordinate control of multiple genes that affect a single bacterial trait
operon
the entire stretch of DNA that incldues the oeprator, the promoter, and all the genes they control
what does it mean when you see a word before operon in italic
that it is a gene
what does the trp operon code for
all the enzymes required to synthesize the amino acid, tryptophan
what is the switch in a segment of DNA called, what does it often overlap with
an operator and often overlaps the promoter region
what are encoded within a single mRNA
multiple polypeptides
what can the trp operon be switched off by
a protein repressor
what does the repressor prevent
gene transcription by binding to the operator and blocking out the RNA polyermase
what is the repressor the product of, where is it located
a seperate regulatory gene, located some distance away from the operon itself
qualites of trp present in the environment
-bacterium does not need to make tryptophan
-repsenting trp operon saves energy required to synthesize the enzymes of the pathway to make trp
qualities of tryptophan absent in the environment
-bacterium needs tryptophan for synthesis of proteins
-removing repression of trp operon allows synthesis of the enzymes of the pathway to synthesize trp
what form can you find the repressor
in active or inactive form depending on the presence of other molecules
what does a corepressor cooperate with
a repressor protein to switch an operon off by affectin protein conformation
corepressor
a small molecule that binds to a bacterial repressor protein and changes the proteins shape allowing it to bind to the operator and switch an operon off
what are operators blocked by
repressor binding
default trp operon are….
on and the genes for tryptophan synthesis are transcribed
in what way is trp operon expression self regulating
The tryptophan (trp) operon in bacteria is an example of a self-regulating pathway. It is self-regulating because the concentration of tryptophan itself acts as a corepressor, directly influencing the operon’s activity.
what type of pathway is trp synthesis
anabolic pathway
anabolic pathway
metabolic pathway that consumes energy to synthesize a complex molecule from simpler molecules
what are anabolic pathways controlled by
repressible operon
what are ctabolic pathways controlled by
inducible operson
catabolic pathway
a metabolic pathway that releases energy by breaking down complex molecules to simpler molecules
transcription with recessible operon
transcription is usually on but can be inhibited when a specific molecule binds to a repressor
transcription for inducible operon
transcription is ually off by can be stimulated when a specific molecule binds to a repressot
example of inducible operon
lac operon
lac operon is part of what pathwat
catabolci pathway to metabolize lactose
example of repressible operon
trp
effect of repressible operon type
repressor attaches to operator ->transcription off (repressed)
what is repressible operon in presence of
corepressor
effect of inducible operon type
repressor does not attach to operator -> transcription on (inducded)
inducer
a specific small molecule that binds to a bacterial repressor protein and changes the repressor’s shape so that it cannot bind to an operator, thus switching an operon on
examples of upregulation include
immune response (increase antibodies)
-tissue repair (growth factors)
-increased fertility (increase in genes associated with gamete production and fertilization)
examples of downregulation
-developmental defects
-cognitive impairment (synaptic proteins)
what does anabolic consume
consumes energy (ATP) to synthesize large molecules from simple ones
catabolic releases what
releases energy by breaking down molecules
