Question

1. For each question about the region of chromosome pictured below, choose the best answer and explain your choice. (3 points each) A. T or F: During replication, the top strand of DNA in region B would be a template for a leading strand. B. T or F: During transcription, the top strand of Region B would be the template strand. C. T or F: To copy this region of chromosome using PCR, you could use the primer 5’ CTACCACGGG 3’. D. T or F: To copy this region of chromosome using PCR, you could use the primer 5’ TAGGTAAATGA 3’.

Answer 1

ANSWER 1.A :-

1. In case of replication, both the above and the lower strands may act as templates for the synthesis of a complementary new strand due to which the first statement becomes TRUE.

ANSWER 1.B :-

1. The template strand is the strand which is used for the synthesis of mRNA mocecule. This strand runs in the 3'-5' direction whereas the leading strand is the one which is complementary to the template strand.
2. In the above mentioned diagram, the direction of the strand is in the 5'-3' direction and hence the region B cannot be considered as a template strand in terms of transcription process due to which the statement becomes FALSE.

ANSWER 1.C :-

1. The 5'-3' region of the DNA strand has the sequence 5'-CCCGTGGTAG-3' and thus the complementary sequence which should be used as a primer for extension or synthesis of a new strand is 3'-GGGCACCATC-5' which is the same as stated in the statement and hence the answer is TRUE.

ANSWER 1.D :-

1. As the region B is being highlighted in the top strand, using a primer which has been stated in the question is not complementary to the sequence due to which it will not ligate and initiate replication process. Hence, the statement is FALSE.

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