Bacteria Are Grown in a Medium Containing [¹⁵N]H₄Cl for a Number

question 38

Multiple Choice

Bacteria are grown in a medium containing [¹⁵N]H₄Cl for a number of generations so that all of the DNA is made of fully 'heavy' DNA. The bacteria are moved to a new medium and grown in [¹⁴N]H₄Cl so that all subsequent new DNA will be 'light.' If replication were dispersive, what would the DNA look like after two generation times?

• A)All of the DNA is made of two 'light' strands.
• B)Half of the DNA is made of two 'light' strands and half of the DNA is made of one 'light' strand and one 'heavy' strand.
• C)All of the DNA is made of one 'heavy' strand and one 'light' strand.
• D)Each strand is made of a mixture of 'heavy' and 'light' DNA, with each strand being between 75% and 100% 'light.'
• E)Three quarters of the DNA is made of two 'light' strands and one quarter is made of two 'heavy' strands.

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Definitions:

Analysis of Variance

A collection of statistical models and their associated procedures which compare means by partitioning variance into components attributable to various sources of variability.

Group Means

The average values obtained from different groups in a study, often used in research to compare and contrast groups.

Procedure

A set procedure or method followed in a scientific study or test to achieve certain objectives or results.

More Than Two Groups

A situation in statistical analysis where comparisons are made among three or more distinct groups or categories.