3.3 DNA replication rates Assuming that Figure 3.35 is a representative sample o
ID: 150792 • Letter: 3
Question
3.3 DNA replication rates Assuming that Figure 3.35 is a representative sample of the replication process: (a) Estimate the fraction of the total fly genome shown in the micrograph. Note that the fly genome is about 1.8 x 10 nucleotide pairs in size. 8 (b) Estimate the number of DNA polymerase molecules in a eukaryotic cell like this one from the fly D. melanogaster (c) There are eight forks in the micrograph. Estimate the lengths of the DNA strands between replication forks 4 and 5, counting up from the bottom of the figure. If a replication fork moves at a speed of roughly 40 bp/s, how long will it take for forks 4 and 5 to collide? (d) Given the mean spacing of the bubbles, estimate how long it will take to replicate the entire fly genome.Explanation / Answer
Answer
a).
measure the length of the picture and this genome is roughly 1.4µm.
convert it into nm
1 µm=1000
1.4x1000=1400
No. of base pair=1400nm/0.34nm per bp
=4000base pairs
fraction of the total fly genome is roughly=4000/2x108bp
=2x10-5
B). all the DNA polymerase molecules are found in the bounded form with the DNA at the time of replication.
The figure shows 8 DNA polymerase molecules (one in each fork)
No. of DNA polymerase molecules= 8x2x108bp/4000
=4x105
C). There are eight forks in the micrograph.
Here the approximate distance between forks 4 & 5 is 200nm or 0.2 µm (600bp).
If the DNA polymerase is move at a speed of approx 100bp/s,
it means it takes 3 seconds for each fork to collide.
d) The given image, the stage of replication is in its development, and each cycle of cellular time takes ten minutes, that is why all the cells replicate and divide very quickly. The density of the replication bifurcations is constant and the replication speed is 100 nt / s, so the replication time has a time scale of approximately five seconds.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.