Multiple Choice
A non-autonomous element is a chromosomal element that can what?
16. Transposable Elements
Discovery of Transposable Elements
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In Barbara McClintock's study of corn, which of the following kernel phenotypes did she find was due to transposable elements?
A
Purple kernel
B
Blue kernel
C
White kernel with purple spots
D
Blue kernel with purple spots
Verified step by step guidance1
Understand the concept of transposable elements: Transposable elements, also known as 'jumping genes', are DNA sequences that can change their position within the genome. This can cause mutations and changes in the cell's genome size, and they are often associated with certain phenotypic changes.
Review Barbara McClintock's research: McClintock's work on maize (corn) was pioneering in demonstrating the existence of transposable elements. She discovered that these elements could cause changes in kernel color by disrupting or activating pigment-producing genes.
Identify the phenotypic effect of transposable elements: In McClintock's study, the presence of transposable elements was linked to the appearance of spots or variegation in the corn kernels. This is because the transposable elements can insert themselves into genes responsible for pigment production, leading to a spotted phenotype.
Analyze the given phenotypes: Among the options provided, 'White kernel with purple spots' is indicative of a transposable element's activity. The white background suggests a lack of pigment production, while the purple spots indicate areas where the transposable element has been excised, allowing pigment production to resume.
Conclude the analysis: Based on the understanding of transposable elements and their effects on kernel color, the phenotype 'White kernel with purple spots' is the result of transposable elements, as it reflects the characteristic variegation caused by these genetic elements.
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