If the cross described in Problem 18 were made, and if Sb and cu are 8.2 map units apart on chromosome III, and if 1000 offspring were recovered, what would be the outcome of the cross, assuming that equal numbers of males and females were observed?

Video transcript

Hi everyone. Welcome back. Let's look at our next problem. It says the genes for purple I. P. And vestigial wing V. G. R. 10.7 M. U. Apart. The following cross was done in Drosophila. P. Plus B. G. Plus um Hetero sickos. With P. V. G. Crossed with homesickness, excessive P. V. G. P. V. G. And 1000 offspring were obtained, calculate the total number of recombinant offspring. Well in order to do this we need to think about what is the meaning of that um distance apart and how does that affect the number of recombinant offspring? Well the distance apart is a number that comes from the recombination frequency. So in this case uh 10.7 M. You apart means that 10.7 of the gametes produced RB continent in this case. So 10.7 out of offspring would be recumbent. In this case we've got 1000 offspring. And so that will mean that 107 offspring out of 1000 would be expected to be recumbent. So when we look at our answer choices, we see that indeed Choice B. Is 107. So again the total number of competent offspring in this particular cross, When the gene for purple, I invested two wing are 10.7 M. U. Apart is choice B. 107. See you in the next video