Question

Regarding transposable elements: Question 8 Not yet answered Points out of 2.00 P Flag question Select one: a. non autonomous elements require other elements for transposition b. autonomous elements encode the function needed for movement O c. mobile genetic elements are thought to be present in all forms of life d. transposable elements are common in most genomes e. all of these answers are correct o In prokaryotic cells: Question 9 Not yet answered Points out of 2.00 P Flag question Select one: O a. transposase is an enzyme present in IS elements that is required for transposition b.insertion sequence elements move from one place to another 0 c. R factors are plasmids that encode resistance to several different antibiotics 0 d. two of these answers are correct 0 e. all of these answers are correct Question 10 Not yet answered Points out of 2.00 P Flag question During tautomerization, guanine (G) changes from the keto form that pairs with cytosine (C. to the rare enol form that pairs with thymine (T). If the mispairing is not corrected before DNA synthesis, the mutational event would be Select one: o a. AT to TA O b. GC to CG c. TA to AT d. GC to AT 0 0 0 e. none of these

Answer 1

Q8. Transposable elements: Also called as jumping genes are the DNA sequences that change their position in genomes. They make up a large fraction of the genomes and are responsible for much of the mass of DNA in a eukaryotic cell. Though they are identified first in maize, they are present in almost all the organisms. There arw two types in transposons, autonomous and non-autonomous.

Non autonomous are those that require presence of another transposable elements to move. eg., dissociation elements

Autonomous elements are those that can move on themselves. eg., Activator element.

Hence all the above options are correct(e).

Q9. Insertion elements

Short DNA sequences that act as a simple transposable elements, they are relatively small and only code for proteins implicated in the transposition activity. These proteins are transposases that catalyse the enzymatic reaction allowing the IS to move.

R factors also called as resistance transfer factors that encodes antibiotic resistance. Genes related to different antibiotic resistance as high as 8 can be tranferred through a single R factor transfer.

Hence all the answers are right (e)

Q10. Keto-enol tautomerism refers to a chemical equilibruim between the keto form and an enol forms. These two forms are said to be tautomers of each other. The interconversion involves movement of alpha-hydrogen atom and reorganisation of bonding electrons. These are among the primary cause for the spontaneous mutations during DNA replication and repair.

Given that G is in its enol form and hence pairs with T rather than with C. Hence further DNA replication would lead to mutational event that would result in AT rather than normal GC.

Hence d) GC to AT.