Homologous chromosomes pair up and exchange segments of DNA.
Option A
<h3><u>Explanation:</u></h3>
Crossing over is an event of Prophase 1 of meiosis 1. It occurs in the zygotene phase of prophase 1. Here the homologous chromosome pairs get very close together and gets packed within protein coat. The enzymes randomly cut the DNA segments from both chromosomes at same loci and exchange them with each other. This results in the exchange of genes between the two chromosomes. This is how the variation comes to place between offsprings of the same individuals. The crossing over results to form X shaped intersections between homologous pair of chromosomes which is called as chaismata. This phase occurs in pachytene phase and is visible in diplotene phase when the protein coat dissolves.
One wouldn’t allow for passive transport. And the other would allow to much. The membrane serves as a gate. Non-permeable would be a solid wall were nothing and no one can get through or get out . Including things like water. And fully permeable would represent no gate at all and would allow to much in and out of the cell.
Answer:
Given:
Number of colonies on plate = 40
Amount of DNA used for transformation = 100ng
Volume of competent cells used = 100ul
Total volume = 1ml (1000ul)
Volume plated for growth = 200ul
The amount of cells transformed per 1 µg of DNA is called the transformation efficiency
(CFU is colony forming units) => (number of colonies on plate/ng of DNA plated) X 1000 ng/µg = CFU/µg of DNA
Amount of DNA used for plating = 100ng * (200/1000)
= 100ng * (1/5)
= 100/5 = 20ng
Efficiency calculation = 40 colonies / 20ng = 2 colonies/ng
(2 colonies/ng) * (1000 ng/µg) = 2000 CFU/ug DNA
Transformation efficiency = 2000 Transformants / ug DNA
= 2 x 10³ Transformants / ug DNA
Explanation:
Efficiency of transformation is highest in the 100 pg-1 ng range, so Low transformation efficiency could be because of high amount of DNA used for transformation.
The Farallon plate was forced under north America by slow geological movement, this process is called subduction.
