In a linear chromosome, map distance between four loci are ab = 12, bc = 4, ad = 2, ac = 8. The distance between c and d will be -

Options

A. 0.1
B. 0.06
C. 10% or 6%
D. 3% or 6%

Answer

To find the distance between loci C and D on a linear chromosome, we can use the given map distances between the other loci. Here's how to approach the problem step by step:

### Step-by-Step Solution:

1. **Identify the given map distances:**
- Distance between A and B (ab) = 12
- Distance between B and C (bc) = 4
- Distance between A and D (ad) = 2
- Distance between A and C (ac) = 8

2. **Understand the relationship between the loci:**
- We can visualize the arrangement of the loci based on the distances provided.
- Since A and B are the farthest apart (12 units), we can place them at the ends of our linear model.

3. **Place the loci on a linear model:**
- Place A at position 0 and B at position 12.
- Now, we need to place C and D based on the distances from A and B.

4. **Calculate the position of C:**
- The distance from A to C is 8 units. Therefore, C will be placed at position 8.

5. **Calculate the position of D:**
- The distance from A to D is 2 units. Therefore, D will be placed at position 2.

6. **Determine the distance between C and D:**
- Now that we have the positions:
- Position of C = 8
- Position of D = 2
- The distance between C and D is calculated as:
\[ \text{Distance (c to d)} = |8 - 2| = 6 \]

7. **Convert the distance to map units:**
- Since 1 map unit corresponds to 1% recombination, the distance between C and D in map units is 6.

### Final Answer:
The distance between loci C and D is **6 map units**.

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