The DNA replication by the action of DNA polymerase takes place in the 3' to 5' direction on the leading strand. The lagging strand which has the opposite orientation or polarity as that of the leading strand requires a more time to get synthesised. The DNA replication of the lagging strand happens in short segments where a RNA primer forms a compliment with a part of the DNA segment on its 3' end. This RNA primer helps initiate the replication of the Okazaki fragments. When the replication on the lagging strand reaches its end, the RNA primer forms a compliment with the last bit of the strand. This small segment gets missed in the end as no more DNA is left to form a RNA primer-DNA compliment. Such shortening of the lagging strand in the replication process is the end-replication problem.
Telomeres are protective ends of the DNA strands. These ends contain a poly-A tail. When the lagging strand replication reaches its end, the RNA primer forms a compliment with the telomere and initiates the replication. This leads to the shortening of the telomere and not the coding segments on the lagging strand of DNA. The telomerase repairs the shortened telomere by re-synthesising it.
Answer:
25000 fragments
Explanation:
A restriction enzyme can cut a random DNA sequence once per every 4^n where n = number of bases in the recognition site of enzyme.
There are 6 bases in Xbal's recognition site (TCTAGA) so it will cut once per every 4^6 = 4096 bases (4kb).
Total genomic size = 100000kb
So expected number of fragments = Total genomic size/Size of one fragment
= 100000/4
= 25000 fragments
Resistance stage of the general
adaptation syndrome (gas)
Resistance stage is the second
stage in which the body goes through series of changes while trying to resist
or adapt to the stressor. For the question given above, according to Hans Selye,
Katie is currently in the resistance stage of the general adaptation syndrome
(gas).
Answer:
In John Watson's Little Albert experiment, the white rat was stimulus associated specific entity and the loud noise was the associated stimulus.