BSC 315 Lecture Notes - Lecture 15: Repressor, Cyclic Adenosine Monophosphate, Conformational Change
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1. What is the term when the product of a biochemical pathway inhibits the activity of the first enzyme of a pathway?
feedback inhibition. | ||
activator inhibition. | ||
diffusional regulation. | ||
enzyme activation. |
2. Through control of gene expression, prokaryotes respond to changing __________ conditions.
internal | ||
protein | ||
environmental | ||
genetic |
3. A protein that negatively regulates transcription by binding to the operator is known as the
operon | ||
repressor | ||
activator | ||
inducer |
4. During attenutation, when tryptophan levels are high, the ________ stem-loop forms and transcription ________ the trpL gene.
1-2, ends just past | ||
3-4, ends just past | ||
1-2, continues beyond | ||
3-4, continues beyond |
5. The process of turning on the expression of a gene in response to a substance in the environment is called:
constituation. | ||
repression. | ||
induction. | ||
catabolism. |
6. What is a function of some specific transcription factors?
to bind to the promoter region of the gene to facilitate the proper alignment of the RNA polymerase | ||
to bind to the centromere to induce meiosis | ||
to bind to enhancer regions to help regulate gene transcription | ||
to bind to the operator to recruit sigma factor |
7. How does exposing an E.coli cell to glucose affect the regulation of the lac operon via CAP?
cAMP binds to CAP and transcription is increased. | ||
cAMP binds to CAP and transcription is decreased. | ||
cAMP does not bind to CAP and transcription is increased. | ||
cAMP does not bind to CAP and transcription is decreased. |
8. The lac repressor protein works when mutations in the repressor gene and structural genes are:
in cis or in trans. | ||
in trans only. | ||
in cis only. | ||
in both prokaryotes and eukaryotes. |
QUESTION 10
If you can drink milk as an adult, it means that you have inherited a mutation in the promoter of your lactase gene (the gene that encodes the enzyme you need to break down lactose). Predict the effect of this mutation:
The mutation changes the number of domains in the enzyme, which makes it work more efficiently | ||
The mutation changes the amino acid sequence of the lactase protein | ||
The mutation increases the number of copies of the lactase gene that will be found in your genome | ||
The mutation changes whether the lactase sequence is found in an intron or exon | ||
The mutation affects the expression of the lactase gene |
1.2 points
QUESTION 11
A competitive inhibitor is decreasing the activity of an enzyme. Predict the effect of adding more substrate to the reaction.
The substrate will increase the reaction rate by binding to the allosteric site | ||
The substrate will increase the reaction rate by competing with the inhibitor for the active site | ||
The reaction rate will not change unless the inhibitor can be removed | ||
The enzyme adjusts its shape so that the substrate, but NOT the competitive inhibitor, can bind | ||
The substrate will bind to the competitive inhibitor and block its ability to bind to the enzyme |
1.2 points
QUESTION 12
What determines where in the genome a transcription regulator will bind?
Transcription regulators bind to the 5' UTR region of a gene | ||
Regulators bind via complementary base-pairing to certain DNA molecules | ||
Covalent bonds form between the transcription regulator and the atoms of the DNA backbone | ||
Every eukaryotic gene has a different transcription regulator that will bind to the 5' end of the gene | ||
Transcription regulators bind to specific DNA sequences via multiple weak non-covalent interactions |
1.2 points
QUESTION 13
What is the basic premise of cell theory?
DNA -> RNA -> protein | ||
All cells arise from pre-existing cells | ||
DNA provides the complete instructions to create a cell | ||
The identity of a cell is determined through gene expression patterns | ||
All cells contain the same four basic macromolecules |
1.2 points
QUESTION 14
What is the benefit of using BOTH the lac activator and the lac repressor to control gene expression?
Using both an activator and repressor enables cells to more accurately determine the amount of lactose available in the environment | ||
Enzymes to digest lactose are only made when energy is low and lactose is available | ||
The activator can override the inhibition of the lac operon by the repressor | ||
The repressor can control the enhancer, while the activator can control the promoter | ||
When neither the lac activator or repressor is present, expression of the lac operon is too high |
1.2 points
QUESTION 15
What is the histone code used for?
Phosphorylation and acetylation of DNA affect its ability to be compacted | ||
Changes to the sequence of DNA change whether DNA will wrap around histone proteins | ||
Covalent modifications of histones affect the ability of the transcription initiation complex to form | ||
Histones provide the codon sequences needed for translation to occur | ||
The histone code affects which amino acids will get added to a polypeptide |