Question

just anserer no need for explaination

A transversion mutation from an G in the DNA template would result in it being replaced with:

	T
	C
	T or U
	T or C
	T, U, or C

The separation of DNA fragments by gel electrophoresis is based upon

	their positive charge and size, with smaller fragments migrating more quickly.
	their negative charge and size, with smaller fragments migrating more slowly.
	their negative charge and size, with smaller fragments migrating more quickly.
	their positive charge and size, with larger fragments migrating more quickly.

Primase is required for DNA replication because

	DNA polymerases require a free 3'-OH for the addition of nucleotides
	DNA polymerases require a free 5'-OH for the addition of nucleotides
	primers must be removed and replaced with deoxyribonucleotides
	DNA polymerase I cannot remove primers on its own

Answer 1

1. The correct answer is d. T or C

Basically, transversion mutation is a point mutation occurring in DNA where a single purine which is two-ring structures is replaced with pyrimidine which is a single ring structure. This occurs because of some ionizing radiation or some alkylating agents. In this mutations, 8 patterns of replacement are seen, where A replaced with T, T replaced with A, A replaced with C, C replaced with A, G replaced with T, T replaced with G, G replaced with C, C replaced with G. Since here DNA template is asked, uracil does not take part. G (Guanine) can be replaced either with T(Thymine) or with C (cytosine)

2. The correct answer is C. their negative charge and size, with smaller fragments migrating more quickly

Basically, gel electrophoresis separates macromolecules like DNA, RNA molecules, and proteins. DNA is negatively charged molecule because of its presence of a negatively charged phosphate group in its structure. There is always an attraction between oppositely charged molecules so since DNA is negatively charged it moves towards the positively charged electrode under the influence of electric field. Now, separation or the speed of the movement of molecules depends on their size. DNA molecules or fragments that are large in size move slowly and the smaller fragments are able to move faster which means the smaller fragments reach the electrode first and then the larger ones accordingly depending on their size.

3. The correct answer is a. DNA polymerases require a free 3'-OH for the addition of nucleotides

Basically, DNA polymerase enzyme can make another strand only if it has 3-OH end of the existing nucleotide strand. It can add nucleotides only at this end and extension of the strand occurs from thus end. Primase is an enzyme that consists of short RNA sequences called a primers that are extended by DNA polymerase to make another strand. This sequences are complementary to ssDNA i.e single stranded DNA. SO, in simpler terms, primers gives the start for the DNA replication to occur from the existing strand, it gives the complementary sequences to DNA polymerase so that it can add nucleotides at 3-OH end and start replication process.