A probe which is a molecule used to locate specific sequence in a mixture of DNA or RNA molecules could be

Options

A. a single stranded RNA
B. a single stranded DNA
C. either RNA or DNA
D. can be single stranded DNA but not single stranded RNA

Answer

To solve the question regarding the type of probe used to locate specific sequences in a mixture of DNA or RNA molecules, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of a Probe**:
A probe is a molecule that can bind to a specific sequence of nucleotides in DNA or RNA. It is used in various applications, including genetic engineering, to identify and locate specific genes or sequences.

**Hint**: Remember that a probe must be able to bind to its target sequence through complementary base pairing.

2. **Identify the Types of Probes**:
Probes can be made from either DNA or RNA. They are typically single-stranded and can be designed to match a specific sequence of nucleotides.

**Hint**: Consider the structure of DNA and RNA and how they can be complementary to target sequences.

3. **Evaluate the Options**:
- **Single-stranded RNA**: This can be a probe since it can bind to complementary RNA sequences.
- **Single-stranded DNA**: This can also serve as a probe for complementary DNA sequences.
- **Either RNA or DNA**: This option suggests that probes can be made from either type of nucleic acid, which aligns with the definition of probes.
- **Can be single-stranded DNA but not single-stranded RNA**: This option is incorrect because RNA can also function as a probe.

**Hint**: Think about the versatility of probes and their ability to be made from different types of nucleic acids.

4. **Select the Correct Answer**:
Based on the understanding that probes can be either single-stranded DNA or RNA, the correct answer is **either RNA or DNA**.

**Hint**: Look for the option that encompasses both possibilities.

### Final Answer:
The correct answer is **either RNA or DNA** (Option 3).