Question

why do scientists load a molecular weight marker on the agarose gel along with the samples?

○ a. it makes it possible to determine the size of your samples

○ b. it helps your samples sink to the bottom of the wells when loading.

○ c. it ensures that no empty slots are left on your agarose gel.

○ d. it helps you practice loading a sample of dna before you have to load your actual samples.

Explanation:

Molecular weight markers (also known as DNA ladders) have DNA fragments of known sizes. During agarose gel electrophoresis, as DNA fragments move through the gel based on size (smaller fragments move faster), by comparing the position of sample DNA fragments with those of the marker fragments, the size of the sample DNA can be estimated. Option b is incorrect as a loading dye (not the molecular weight marker) helps samples sink. Option c is wrong as the purpose is not about filling slots. Option d is incorrect as it's not for practice - it's a functional component in size determination.

Answer:

A. It makes it possible to determine the size of your samples