Semester 1 Final Exam Flashcards
The tryptophan operon is a repressive operon that is
E. turned off whenever tryptophan is added to the growth medium
The lactose operon is likely to be transcribed when
D. The cyclic AMP and lactose levels are both high within the cell
For a repressive operon to be transcribed, which of the following must occur?
C. RNA polymerase must bind to the promoter, and the repressor must be inactive
The Trp operon is a coordinated regulated group of genes (trpA-trpE) that are required for tryptophan biosynthesis in E. Coeli. Based on the figure above, which of the following correctly describes the regulation of the Trp operon?
B. In the presence of tryptophan, the repressor is active and binds to the Trp operator, preventing RNA polymerase from transcribing the operon
Gene expression might be altered at the level of post-transcriptional processing in eukaryotes rather than prokaryotes because of which of the following?
Eukaryotic exodus may be spliced in alternative patterns
[Image] A fish inherits a mutation in the Pitx 1 coding region.This is a nonsense mutation that introduces a premature stop codon, resulting in a nonfunctional truncated protein. You isolate DNA from jaw, pelvic, eye and pituitary tissues.
In which tissues would you expect to see this Pitx1 coding region mutation?
Jaw, Eye, Pelvis, Pituitary (all)
[Image] If a different, independent mutation occurred that caused activator 4 to be nonfunctional, in which tissues would there be a change in the Pitx1 expression
Pituitary
[Image] The figure above depicts the DNA-protein complex that is assembled at the transcriptional start site of gene X when the expression of gene X is activated in liver cells. Previous studies have shown that gene X is never expressed in nerve cells. Based on the diagram, which of the following most likely contributes to the spesific expression pattern of gene X?
The activator is a sequence-specific DNA-binding protein that is a present in some tissues but not in other tissues.
Which of the following characteristics of the lytic cycle?
A large number of phages are released at a time
Which of the following statements describes the lysogenic cycle of lambada phage?
The Phan he genome replicates along with the host genome.
Most molecular biologists think that viruses originated from fragments of cellular nuclei acid (DNA or RNA). Which of the following observations supports this theory?
Viral genomes are usually similar to the genome of the host cell.
Which viruses have single-stranded RNA that acts as a template fro DNA synthesis?
Retroviruses
During the infection cycle for a typical retrovirus, such as HIV, which uses. RNA as genetic material, the genetic variation in the resulting population of new viruses particles is very high because of:
Errors introduced in the DNA molecule through reverse transcription
A researcher is using adult stem cells and comparing them to other adult cells from the same tissue. Which of the following is a likely finding?
The cells from the two sources exhibit different patterns of DNA methylation
Proto-oncogenes can change into oncogenes that cause cancer. Which of the following best explains the presence of these potential time bombs in eukaryotic cells?
Proto-oncogenes normally regulate cell division
A new mutation that arose in one copy of gene X is a somatic cell resulting in the formation of a tumor. Which of the following pieces of evidence best describes how the new mutation directly caused the tumor?
Protein X normally stimulates cell division, and the mutation created an overactive version of protein X.
What is bioinformatics?
A method that uses very large national and international databases to access and work with sequence information
If the bacterium Staphylococcus aureus experiences a cost for maintaining one or more antibiotic-resistance genes, then what should happen in environments from which antibiotics are missing?
These bacteria should be outcompeted and replaced by bacteria that have lost these genes.
