To create a cDNA library, cDNA can be inserted into vectors and cloned. In the analysis of cDNA clones, it is often difficult to find clones that are full length—that is, many clones are shorter than the mature mRNA molecules from which they are derived. Why is this so?

Video transcript

Hi, everybody. Let's take a look at this practice problem together which of the following statements about C DNA libraries is not true. Now, recall what C D N A is and the C stands for complementary. Therefore, a C D N A library is a collection of all the C D N A from a particular organism or tissue, which of our statements therefore is not true. A it provides D N A s from RNA transcripts. So recall through reverse transcription, you get production of C D N A from A M RNA strand. So this is a true statement and cannot be the correct answer. Option B it only represents the genes that were expressed in sales when the library was created. This is also true. It only contains the genes expressed during the time the sample was extracted. So B is also not the correct answer. Then option D it is useful for studying genes expressed in certain cells or tissues under certain conditions. This is also true. It is useful in lab research since it's a collection of coding sequences in the form of C D N A. So D is not the correct answer that means the correct answers options. See it contains codeine as well as non coding segments of D N A such as introns. So the reason why this is the false statement is because it contains only coding regions. So only Exxon's it does not include entrance. So C is the correct answer. Alright, everyone. I hope you found this helpful and I'll see you soon for the next practice problem.