If Cells Are Provided with Nucleotides Labeled with a Radioactive

question 49

Multiple Choice

If cells are provided with nucleotides labeled with a radioactive isotope of hydrogen (³H) ,newly synthesized DNA will be radioactively labeled.In a set of experiments,a student-faculty research team introduced labeled T nucleotides into a culture of dividing human cells at specific times.Following a 30-minute incubation with the radiolabeled nucleotides,cells were lysed,and the DNA was isolated and tested for presence of radioactivity.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 duration of the S phase of the cell cycle?
• C)What is the duration of mitosis?
• D)How many picograms of DNA are contained in each nucleus?

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Definitions:

Fugue

A psychiatric disorder characterized by reversible amnesia for personal identity, including the memories, personality, and other identifying characteristics of individuality.

Shameful Thought

An uncomfortable feeling of embarrassment or guilt that arises from actions, thoughts, or circumstances perceived as dishonorable or improper.

Obsessions

Persistent, unwanted thoughts, images, or urges that cause distress or anxiety.

Compulsions

Repetitive behaviors or mental acts that an individual feels driven to perform in response to an obsession or according to rules that must be applied rigidly.