UW BIOL 200 EXAM 3
Describe several ways a bacterial cell can control the rate of transcription at a specific
operon or the amount of specific protein that's active - answer-transcriptional control:
regulation of genes by changing the rate at which genes are transcribed to produce
mRNA
-both negative and positive control
*negative: binding of regulatory protein to DNA represses transcription
*positive: binding of regulatory protein to DNA promotes transcription
*both impact RNA polymerase's ability to bind to promoter
-translational control: regulation of gene expression by various mechanisms that alter
the lifespan of mRNA or the efficiency of translation
-post-translational control: regulation of gene expression by modification of proteins
(addition of phosphate group or sugar residues)
constitutively active - answerGenes that are always being expressed
inducible genes - answerGenes that can be turned on and off
Operon - answera region of bacterial DNA that codes for a series of functionally related
genes and is transcribed from a single promoter into one mRNA
Predict which genes are on/off in lac operon under various conditions and explain how
this state relates to bacterial fitness - answer-Global gene regulation occurs when a
group of genes is turned into a regulon which allows for a group of genes to be
regulated by the same regulatory molecule
-these regulons can be regulated with positive or negative control and allows bacterial
cells to respond to changes in their environment such as temperature, a loss of
nutrients, shift to new environment, or extensive DNA damage
Compare contrast bacterial vs eukaryotic gene regulation - answer-both can be
regulated at transcriptional, translational, and post-translational levels
-eukaryotes also have chromatin remodeling and RNA processing
-chromatin remodeling: the process by which the structure of chromatin is changed to
inhibit or activate transcription
*interaction between DNA and histones must be altered for RNA polymerase to be able
to bind
*DNase works to cut DNA and can only do so when it's not tightly wrapped by proteins
*chromatin is altered through DNA methylation
-RNA processing: the changes that a primary RNA transcript undergoes to become a
mature RNA molecule (Ex: 5' cap and 3' Poly A tail, remove introns, etc)
, Compare contrast location of bacterial and eukaryotic DNA regulatory sequences -
answer-transcription and translation are separated by the nucleus in eukaryotes
whereas in prokaryotes simultaneous transcription and translation can occur in the
cytosol
Explain how chromatin structure can impact eukaryotic gene expression - answer-
chromatin is made up of DNA, Histone proteins, and non Histone proteins in repeating
units called nucleosomes
-in order for DNA to be transcribed, chromatin must uncoil or be open for RNA
polymerase to bind and transcribe
-acetylation at Histone proteins occurs with HAT enzyme causing uncoiling of
chromatin, creating euchre matin and an increase in transcription
-HDAC enzyme can reverse this and condense chromatin creating heterochromatin and
decreasing transcription
-this is a form of transcriptional gene regulation in eukaryotes
Explain how one gene can code for more than one mRNA - answerOne gene can code
for more than one mRNA through alternative splicing. Alternative splicing is when a pre-
mRNA is spliced one out of two or many ways. If it is spliced differently it will produce a
different mature mRNA and a different protein. It depends on which exons are kept and
which aren't. These different combinations lead to different phenotypes from the same
gene.
Given a gene, predict possible alternatively spliced forms of mRNA - answer
Given a scenario, propose a hypothesis for how a cell's environment could lead to
expression of a subset of genes - answer-our environment impacts how our genes are
expressed
-certain genes are optimally active under certain conditions such as temperature, pH,
etc.
-if our environment is altered in a way that causes a subset of genes to be optimally
active, those genes will now be expressed even though there was no change in DNA
Explain what GFP is and why we study it - answer
Interpret data from reporter gene assay - answer
Transcription repressor - answerA protein that binds to a specific regulatory region of
DNA to prevent transcription of an adjacent gene.
Transcription activator - answerA protein that binds to a specific regulatory region of
DNA to permit transcription of an adjacent gene.
Transcription factor - answerA regulatory protein that binds to DNA and affects
transcription of specific genes.
Describe several ways a bacterial cell can control the rate of transcription at a specific
operon or the amount of specific protein that's active - answer-transcriptional control:
regulation of genes by changing the rate at which genes are transcribed to produce
mRNA
-both negative and positive control
*negative: binding of regulatory protein to DNA represses transcription
*positive: binding of regulatory protein to DNA promotes transcription
*both impact RNA polymerase's ability to bind to promoter
-translational control: regulation of gene expression by various mechanisms that alter
the lifespan of mRNA or the efficiency of translation
-post-translational control: regulation of gene expression by modification of proteins
(addition of phosphate group or sugar residues)
constitutively active - answerGenes that are always being expressed
inducible genes - answerGenes that can be turned on and off
Operon - answera region of bacterial DNA that codes for a series of functionally related
genes and is transcribed from a single promoter into one mRNA
Predict which genes are on/off in lac operon under various conditions and explain how
this state relates to bacterial fitness - answer-Global gene regulation occurs when a
group of genes is turned into a regulon which allows for a group of genes to be
regulated by the same regulatory molecule
-these regulons can be regulated with positive or negative control and allows bacterial
cells to respond to changes in their environment such as temperature, a loss of
nutrients, shift to new environment, or extensive DNA damage
Compare contrast bacterial vs eukaryotic gene regulation - answer-both can be
regulated at transcriptional, translational, and post-translational levels
-eukaryotes also have chromatin remodeling and RNA processing
-chromatin remodeling: the process by which the structure of chromatin is changed to
inhibit or activate transcription
*interaction between DNA and histones must be altered for RNA polymerase to be able
to bind
*DNase works to cut DNA and can only do so when it's not tightly wrapped by proteins
*chromatin is altered through DNA methylation
-RNA processing: the changes that a primary RNA transcript undergoes to become a
mature RNA molecule (Ex: 5' cap and 3' Poly A tail, remove introns, etc)
, Compare contrast location of bacterial and eukaryotic DNA regulatory sequences -
answer-transcription and translation are separated by the nucleus in eukaryotes
whereas in prokaryotes simultaneous transcription and translation can occur in the
cytosol
Explain how chromatin structure can impact eukaryotic gene expression - answer-
chromatin is made up of DNA, Histone proteins, and non Histone proteins in repeating
units called nucleosomes
-in order for DNA to be transcribed, chromatin must uncoil or be open for RNA
polymerase to bind and transcribe
-acetylation at Histone proteins occurs with HAT enzyme causing uncoiling of
chromatin, creating euchre matin and an increase in transcription
-HDAC enzyme can reverse this and condense chromatin creating heterochromatin and
decreasing transcription
-this is a form of transcriptional gene regulation in eukaryotes
Explain how one gene can code for more than one mRNA - answerOne gene can code
for more than one mRNA through alternative splicing. Alternative splicing is when a pre-
mRNA is spliced one out of two or many ways. If it is spliced differently it will produce a
different mature mRNA and a different protein. It depends on which exons are kept and
which aren't. These different combinations lead to different phenotypes from the same
gene.
Given a gene, predict possible alternatively spliced forms of mRNA - answer
Given a scenario, propose a hypothesis for how a cell's environment could lead to
expression of a subset of genes - answer-our environment impacts how our genes are
expressed
-certain genes are optimally active under certain conditions such as temperature, pH,
etc.
-if our environment is altered in a way that causes a subset of genes to be optimally
active, those genes will now be expressed even though there was no change in DNA
Explain what GFP is and why we study it - answer
Interpret data from reporter gene assay - answer
Transcription repressor - answerA protein that binds to a specific regulatory region of
DNA to prevent transcription of an adjacent gene.
Transcription activator - answerA protein that binds to a specific regulatory region of
DNA to permit transcription of an adjacent gene.
Transcription factor - answerA regulatory protein that binds to DNA and affects
transcription of specific genes.
