Can u please answer this question A cross is made between an Hfr that is met+ thr + str-r and an f- strain that is met- thr- str-s. Interrupted mating studies show that met+ enters the recipient last so met+ recombinants are selected on a medium containing threonine and streptomycin. These recombinants are tested for the presence of the thr+ nd str-r alleles. Based on the recombinants obtained as shown below what would be the order of genes in this strain and the distance between the markers. Met+ thr+ str-r. 280 Met+ thr+ str-s. 1 Met+ thr- str-r 7 Met+ thr- str-s 60 Anss order is met str the and the distances are respectively 17.2my and 2 mu
Given that met+ recombinants are selected on a medium containing threonine and streptomycin, and met+ enters the recipient last, we have the following insights: Met+ is the last gene to be transferred. The large number of Met+ thr+ str-r recombinants (280) suggests that thr+ and str-r are transferred before met+, and they are close to each other because they often co-occur. The rarity of Met+ thr+ str-s recombinants (1) suggests that the str-s allele is far from thr+ and met+, or it is negatively selected against in the presence of met+. The presence of Met+ thr- str-r (7) and Met+ thr- str-s (60) recombinants suggests that str is closer to met than thr is, as we see a gradient of recombinants based on str resistance or sensitivity. From the information, the order of genes on the chromosome appears to be: thr - str - met
To calculate the map distances, we'd typically look at the frequency of recombinants as a representation of crossover events between these genes. Since the order is being questioned, and based on the recombinant frequencies, let's deduce: If str is closer to met, then the higher frequency of Met+ thr- (both str-r and str-s) suggests str and met are closely linked. Given the setup, we'll assume a total number of selected Met+ recombinants as the sum of all categories, although this approach simplifies the calculation and might not fully reflect the actual crossover percentages. Total recombinants = 280 + 1 + 7 + 60 = 348 Distance between thr and met: Considering thr+ is selected against in some, but we are selecting for met+, the distance is harder to calculate directly without assuming which gene is in the middle. However, we can hint at distances using the least frequent recombinant types as indicative of the longest crossovers. Without clear delineation of middle markers in the original question or typical crossover calculation methods (like using half the sum of single and double crossovers), the precise calculation you're asking for (especially given a specific answer format you mentioned) isn't directly applicable here. The approach to calculating distances typically relies on having a clearer picture of total offspring counts, the selection criteria, and a confirmed gene order.
Can u please answer this question
A cross is made between an Hfr that is met+ thr + str-r and an f- strain that is met- thr- str-s. Interrupted mating studies show that met+ enters the recipient last so met+ recombinants are selected on a medium containing threonine and streptomycin. These recombinants are tested for the presence of the thr+ nd str-r alleles. Based on the recombinants obtained as shown below what would be the order of genes in this strain and the distance between the markers.
Met+ thr+ str-r. 280
Met+ thr+ str-s. 1
Met+ thr- str-r 7
Met+ thr- str-s 60
Anss order is met str the and the distances are respectively 17.2my and 2 mu
Given that met+ recombinants are selected on a medium containing threonine and streptomycin, and met+ enters the recipient last, we have the following insights:
Met+ is the last gene to be transferred.
The large number of Met+ thr+ str-r recombinants (280) suggests that thr+ and str-r are transferred before met+, and they are close to each other because they often co-occur.
The rarity of Met+ thr+ str-s recombinants (1) suggests that the str-s allele is far from thr+ and met+, or it is negatively selected against in the presence of met+.
The presence of Met+ thr- str-r (7) and Met+ thr- str-s (60) recombinants suggests that str is closer to met than thr is, as we see a gradient of recombinants based on str resistance or sensitivity.
From the information, the order of genes on the chromosome appears to be: thr - str - met
Thank you sir please tell how to calculate distance between genes. I am not getting the answer
To calculate the map distances, we'd typically look at the frequency of recombinants as a representation of crossover events between these genes.
Since the order is being questioned, and based on the recombinant frequencies, let's deduce:
If str is closer to met, then the higher frequency of Met+ thr- (both str-r and str-s) suggests str and met are closely linked.
Given the setup, we'll assume a total number of selected Met+ recombinants as the sum of all categories, although this approach simplifies the calculation and might not fully reflect the actual crossover percentages.
Total recombinants = 280 + 1 + 7 + 60 = 348
Distance between thr and met:
Considering thr+ is selected against in some, but we are selecting for met+, the distance is harder to calculate directly without assuming which gene is in the middle. However, we can hint at distances using the least frequent recombinant types as indicative of the longest crossovers.
Without clear delineation of middle markers in the original question or typical crossover calculation methods (like using half the sum of single and double crossovers), the precise calculation you're asking for (especially given a specific answer format you mentioned) isn't directly applicable here. The approach to calculating distances typically relies on having a clearer picture of total offspring counts, the selection criteria, and a confirmed gene order.
Thank you sir for the reply
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Thank you so much♥️. Awesome explanation. Clearly understood.
Glad it was helpful!
Clearly understood the concept.
Why you have taken 0 ? 2ndly why u added extra Pur,Pro,His on the upper sequence . plz explain
You just overlap them and fill in the gaps.
How we know the direction of the replication?!
DNA replication go in both directions simultaneously.
where does the point of origin go?
In different directions until whole chromosome will be replicated.
Why b will be the ans ...replication can start from 0 only ...then first gene to come is met ...can u justify it
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The reason for taking zero.?why u took zero
For convenience - I could leave the original time also - it would not change calculations.
Thank you sir.🙏
Most welcome
I could not listen to u properly
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