Nucleotides can be radiolabeled before they are incorporated into newly forming DNA and can therefore be assayed to track their incorporation. In a set of experiments, a student—faculty research team used labeled T nucleotides and introduced these into the culture of dividing human cells at specific times.
Which of the following questions might be answered by such a method?
A) How many cells are produced by the culture per hour?
B) What is the length of the S phase of the cell cycle?
C) When is the S chromosome synthesized?
D) How many picograms of DNA are made per cell cycle?
E) When do spindle fibers attach to chromosomes?
Answer: B
The research team used the setup to study the incorporation of labeled nucleotides into a culture of lymphocytes and found that the lymphocytes incorporated the labeled nucleotide at a significantly higher level after a pathogen was introduced into the culture. They concluded that
A) the presence of the pathogen made the experiment too contaminated to trust the results.B) their tissue culture methods needed to be relearned.
C) infection causes lymphocytes to divide more rapidly.
D) infection causes cell cultures in general to reproduce more rapidly.
E) infection causes lymphocyte cultures to skip some parts of the cell cycle.
Answer: C
Once they had determined which cells were dividing, the team wanted to use a non-radioactive method to track whether various physiological factors (such as food or body temperature) affect the action of the pathogen. Which of the following would be effective, simple, and safe?
B) measuring numbers of chromosomes
C) measuring numbers of chromatids
D) counting the frequency of cells in mitosis
E) counting newly formed plasma membranes
Answer: D
If the answers is incorrect or not given, you can answer the above question in the comment box. If the answers is incorrect or not given, you can answer the above question in the comment box.