Question

According to Figure \(2,\) if 2 genes are separated by 70 mu, the \(\mathrm{RF}\) of those 2 genes is most likely closest to which of the following? A. 0.377 B. 0.477 C. 0.577 D. 0.677

Short answer

Answer: D. 0.677

Step-by-step solution

Write down the given distance between the two genes

We are given that the distance between the genes is 70 mu.

Use the formula to calculate the RF value

Now, we apply the formula RF = (mu) / 100. So, we have: RF = (70) / 100

Calculate the result

Now, we can simplify the equation to find the RF value. RF = 70 / 100 = 0.7

Compare the result with the given options

We have calculated the RF value to be 0.7. Now, let's compare it with the given options: A. 0.377 B. 0.477 C. 0.577 D. 0.677 We can see that option D (0.677) is the closest value to our calculated RF value of 0.7. Therefore, the recombination frequency (RF) is most likely closest to 0.677. The correct answer is option D.

Key concepts

Genetic Linkage

Genetic linkage is a fundamental concept that helps us understand how different genes are inherited together. It's based on the notion that genes that are physically close to each other on a chromosome are less likely to be separated during meiosis. This is because during the process of crossing over, close genes tend to be inherited as a unit rather than being shuffled independently. Imagine two close friends who usually travel together; similarly, 'linked' genes are like friends on a chromosome that often stay together.

However, the closer two genes are, the lower the probability of them being separated, which means a lower recombination frequency (RF). Recombination frequency is a quantifiable representation of this likelihood, and in genetic studies, it's crucial for determining the presence and strength of linkage between genes. Through examining offspring traits and calculating the RF, researchers can conclude whether genes are linked and, if so, how closely.

Gene Mapping

Gene mapping, also known as linkage mapping, is like solving a puzzle of heredity. It involves the determination of the sequence of genes, and their relative distances from each other, on a chromosome. Each gene occupies a specific location, called a locus. By studying recombination frequencies, scientists can estimate the distance between these loci and create a genetic map. This map is instrumental in understanding the genetic terrain that influences traits and diseases.

While physical maps measure actual DNA sequences, genetic maps are more about probability, measuring how often parental genes are separated during the formation of gametes. This is particularly helpful for identifying genetic markers associated with diseases. It's important to note that this map doesn’t show exact distances but rather offers an overview of gene order and relative distances based on recombination frequencies.

Morgan Units (mu)

Morgan units (mu), often simply termed as 'map units', are the standard units used to express genetic distances on chromosomes. Named after geneticist Thomas Hunt Morgan, one mu represents a 1% chance that a gene at one locus will be separated from a gene at a second locus due to crossing over during meiosis. In other words, genetic distances in mu are a direct reflection of the recombination frequencies between genes.

For example, if we say two genes are 10 mu apart, this means that on average, there's a 10% chance that a single crossover will occur between these genes in a single generation. It's a way to quantify the likelihood of genes being inherited separately, and thus, mu serves as a practical unit for constructing genetic maps and studying heredity patterns.