If gene freuency between genes a and c 2%, b and c 13%, b and d 4%, a and b 15%, c and d 19%. What will be the sequence of these genes in a chromosome?

Options

A. a,b,c,d
B. a,c,b,d
C. d,b,a,c
D. a,d,b,c

Answer

To determine the sequence of genes A, B, C, and D in a chromosome based on the given gene frequencies, we will analyze the recombination percentages and arrange the genes accordingly. Here’s how we can approach the problem step by step:

### Step 1: List the Gene Frequencies
We start by listing the gene frequencies provided:
- A and C: 2%
- B and C: 13%
- B and D: 4%
- A and B: 15%
- C and D: 19%

### Step 2: Identify the Farthest Genes
The highest recombination percentage indicates the farthest distance between two genes. Here, C and D have the highest recombination frequency of 19%. This means C and D are the farthest apart on the chromosome.

### Step 3: Identify the Closest Genes
Next, we look for the smallest recombination percentage, which indicates the closest genes. A and C have the smallest recombination frequency of 2%, meaning they are the closest genes on the chromosome.

### Step 4: Arrange the Genes Based on Distances
Now, we will arrange the genes based on the distances:
1. Start with C and D as they are the farthest apart (19%).
2. Next, we have A and C as the closest (2%). Since A is closest to C, we place A next to C.
3. Now, we need to place B. The distances we have are:
- A and B: 15%
- B and C: 13%
- B and D: 4%

Since A is already linked closely to C, we can place B next to A. The distance between A and B is 15%, which is higher than the distance between B and C (13%) and B and D (4%). Therefore, B should be placed next to A.

### Step 5: Final Arrangement
From the analysis, we can summarize the arrangement:
- A is closest to C (2%).
- B is next to A (15%).
- C is next to B (13%).
- D is next to B (4%).

Thus, the sequence of genes on the chromosome is A, C, B, D.

### Conclusion
The correct sequence of genes in the chromosome is **A, C, B, D**.