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WorksheetsAP Bio Chp 18 Epigenetics
Total questions: 72
Worksheet time: 50mins
ATG CCA AAT
Operons are found in the cells of which of the following types of organisms?
prokaryotes
eukaryotes
animals only
viruses
A key advantage of grouping genes with related functions is that a single "on-off" switch can control the whole cluster.
True
False
The tryptophan operon is
permanently turned on.
turned on when tryptophan is present in the growth medium.
turned off only when glucose is present in the growth medium.
turned off when tryptophan is added to the growth medium.
The repressor is the protein product of a(n)
operator
regulatory gene
lac gene
corepressor
The binding of repressors to operators are not reversible.
True
False
The lac operon is referred to as a(n) __________ operon.
inducible
repressible
audible
inaudible
All the genes in both a prokaryotic cell and a eukaryotic cell are expressed at the same time.
True
False
Prokaryotes regulate gene expression primarily
in order to maintain homeostasis
in response to changing environmental conditions
during development as cells specialize
Prokaryotes do not regulate gene expression. All genes are always on.
One way to regulate the expression of a gene is to control the formation of mRNA. This is called ___ control.
transcriptional
translational
post-transcriptional
post-translational
In order for a gene to be expressed, ___ must bind to the gene's ___, a specific sequence of nucleotides at one end of the gene, thus initiating transcription.
DNA polymerase, promotor
DNA polymerase, operator
RNA polymerase, promotor
RNA polymerase, operator
An operon is
a genetic on/off switch in prokaryotes
a genetic on/off switch in eukaryotes
a group of related genes and the associated gene switches in prokaryotes
a group of related genes and the associated gene switches in eukaryotes
Genes can be shut off (not expressed) when a ___ binds to the ____.
activator, operator
repressor, operator
corepressor, operator
repressor, promotor
What molecule can remove a repressor protein from the operator?
a corepressor
an inducer
Genes can be turned on (expressed) when a(n) ____ such as CRP or cAMP receptor protein binds to the CRP binding site.
repressor
corepressor
inducer
activator
In the lac operon system, __ must first bind to CRP so that it is capable of binding to the DNA. This occurs when glucose levels are __.
cAMP, high
cAMP, low
inducer, high
inducer, low
Negative control of gene expression is mediated by __ and results in a(n) __ in the frequency of transcription.
activators, increase
activators, decrease
repressors, increase
repressors, decrease
In the trp operon, __ acts as a __ and helps the repressor bind to the operator.
tryptophan, corepressor
tryptophan, inducer
lactose, corepressor
lactose, inducer
The trp operon has only ___ control which is common for the genes needed for ___ processes.
positive, catabolic
positive, anabolic
negative, catabolic
negative, anabolic
Which of the following is/are similarities between prokaryotic and eukaryotic gene expression?
both use proteins to interact with the DNA to control gene expression
both have histones complexed with their DNA
both separate the processes of transcription and translation spatially
all of the above
___ are DNA sequences which are often located far from the genes they regulate in eukaryotes where transcription activators can bind.
histones
promotors
enhancers
Which of the following help to turn genes on so that they are expressed (transcribed and translated)?
a high level of condensation (coiling around histones)
histone acetylation
DNA methylation
histone methylation
Inheritance NOT involving the nucleotide sequence of the DNA but involving chromatin modifications such as methylation is called
epigenetic inheritance
antigenetic inheritance
Which of the following are types of post-transcriptional control of genes in eukaryotes?
alternative RNA splicing or processing
gene silencing through RNA interference
destruction of ubiquitin tagged proteins
all of the above
Alternative RNA splicing involves
removing introns and splicing the same exons together
removing exons and splicing the same introns together
removing introns and splicing different exons together
removing exons and splicing different introns together
Two types of gene control are
repressible & inducible
repressible & active
active & inactive
repressible & corepressible
How does active CAP induce expression of the genes of the lactose operon?
It terminates production of repressor molecules.
It degrades the substrate allolactose.
It stimulates splicing of the encoded genes.
It stimulates the binding of RNA polymerase to the promoter.
What is occurring in this diagram?
This is an mRNA which is being replicated. Two exonucleases can now chop the ends of the sequences and degrade the mRNA strands.
This is mRNA degradation. Endonuclease enzyme cuts the mRNA into two fragments. Two exonucleases can now hydrolyse at 3’ end or 5’ end.
After the mRNA strand is cleaved into two different fragments by endonuclease, two enzymes attach to the ends, ligating the enzymes. This is so that they can attach to the surface of the cell which inactivates them.
The mRNA eventually degrades naturally into two pieces. The sequences now become nonfunctional as they are disconnected
What is occurring in this diagram?
Once the original mRNA sequence has been shortened in length by cutting enzymes, it can extend through the cell membrane, leaving the cytoplasm and rendering the sequence nonfunctional.
Firstly, an enzyme removes the 3’ poly-A tail (deadenylation). Then, an enzyme removes the 5’ cap (decapping). The sequence is now nonfunctional without these important end parts on the sequence.
Firstly, an enzyme removes the 3’ poly-A tail (deadenylation). Then, an enzyme removes the 5’ cap (decapping). Now, both the 3’ and 5’ ends are exposed, allowing exonucleases to cut the strand into small pieces.
An enzyme starts chopping 5’ end, before another enzyme starts chopping at the 3’ end of the strand. Eventually, these enzymes will stop when near each other, at which point the sequence is nonfunctional.
Cell Regulation relies on many factors -intrinsic or extrinsic. Which of the following are cell extrinsic regulation factors? Environmental cues mean from outside of the cell.
Select all that Apply:
Modified DNA
Small Molecules and Temperature
Secreted Proteins and Oxygen
Modified Chromatin
Cell cues from other cells in organism or organisms environment
How do the transcription factors (TATA binding proteins and TATA associated factors), binding to the TATA box in the promoter sequence allow gene expression?
The conformation of this allows RNA polymerase II to bind, which can then move downstream to express gene of interest.
Transcription factors binding to the promoter, provides a bridge that attaches to the rest of sequence. This enables RNA polymerase to move downstream and express gene of interest.
Transcription factors provide a force to allow RNA polymerase, enabling it to motion towards gene so that it can be expressed.
When transcription factors bind to the promoter sequence, repressor proteins are blocked from accessing the sequence. This stops repressors from silencing gene expression and allows expression of the gene.
What are the three different molecules in the promoter sequence, in order from the most upstream to downstream?
TATA box, GC box and CAAT box.
TATA box, MOOUSE box, and GC box.
TATA box, CAAT box and GC box.
CAAT box, TATA box, and GC box.
DNA methylation is known as epigenetic modification that is found in silent regions of the genome. Cytosines that are found in this region are methylated, producing 5’-methylcytosine which can promote chromatin condensation and silence transcription and gene expression.
True
False
