BIL 250 Chapter 9: Control of Gene Expression
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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 |
