Assume you are performing a cross between a plant that is heterozygous for the dominant traits red flowers and wrinkled seeds, with a plant that is homozygous for the recessive traits white flowers and smooth seeds. Assume the alleles are R for red flowers, r for white flowers, W for wrinkled seeds, and w for smooth seeds. The offspring of this cross show the following phenotypes:

43 red flowers and wrinkled seeds

7 red flowers and smooth seeds

9 white flowers and wrinkled seeds

41 white flowers and smooth seeds

What are the traits of the recombinant offspring in terms of flower color and seed shape? Explain how you know that these offspring are recombinant. What alleles would you expect to see in the individual chromosomes of each parent before and after crossing-over takes place? What is the recombination frequency? What is the distance between the genes in map units?

The traits of the recombinant offspring in terms of flower color and seed shape:

Red, smooth
White, wrinckled
These are recombinants because they are different with their parents. The genes are the same but they don't share the same alleles as parents.
The number of recombinants is always less than the number of parental types.

Genotype of parents: RrWw (red , wrinckled)
rrww (white , smooth)
after crossing over : Rrww
rrWw
(these two are the genotypes of recombinants)

recombination frequency = # recombinants / # total progeny
= 7+9 / 43+41+7+9 = 0.16
the genes are 16 m.u apart

Well, well, well, looks like we've got ourselves some genetic shenanigans going on here! Let's break it down, shall we?

First, we need to figure out the traits of the recombinant offspring. In this case, we have two phenotypes that don't match either parent: 7 red flowers and smooth seeds, and 9 white flowers and wrinkled seeds. These unique combinations of traits clue us in that recombination has occurred.

So, how does recombination happen? It's a magical process called crossing-over, where genetic information gets shuffled and swapped between homologous chromosomes during meiosis. As a result, new combinations of alleles are formed, giving rise to different traits in the offspring.

Now, let's talk alleles! Before crossing-over takes place, the heterozygous parent has one chromosome with the alleles R and W, and the other chromosome with r and w. On the other hand, the homozygous parent has both chromosomes with the alleles r and w. But once crossing-over happens, things get mixed up!

After crossing-over, the chromosomes in the heterozygous parent could have different combinations of alleles. For example, one chromosome might end up with R and w, while the other could have r and W. This results in the recombinant offspring having different traits than the parents.

Now, to calculate the recombination frequency and map distance. The recombination frequency is the percentage of recombinant offspring among the total number of offspring. In this case, we have a total of 100 offspring, and 7 + 9 = 16 recombinant offspring. So, the recombination frequency is (16/100) x 100 = 16%.

The map distance, also known as the genetic distance, gives us an estimate of the physical distance between two genes on a chromosome. It is measured in map units or centimorgans (cM). In this case, since the recombination frequency is 16%, the map distance is 16 cM.

Remember, these values might not be 100% accurate since we're assuming the genes are independent and there are no intervening genes affecting the recombination. But hey, genetics is a funny business, so we roll with it!

Hope this helps, and may the genes be ever in your favor!

From the given phenotypic ratios, it is clear that there are two types of recombinant offspring present:

1. Red flowers and smooth seeds
2. White flowers and wrinkled seeds

These recombinant offspring are the result of recombination events during crossing-over between the homologous chromosomes during meiosis. Since the parent plants have different alleles for flower color and seed shape, recombination occurred, leading to the production of offspring with new combinations of traits.

To determine the alleles present in the individual chromosomes before and after crossing-over, we need to analyze the phenotypic ratios and the principles of Mendelian genetics.

From the given data, we can deduce the following:

- The parent plant that is heterozygous for red flowers (Rr) and wrinkled seeds (Ww) can produce gametes with the alleles R and W or r and w.
- The parent plant that is homozygous for white flowers (rr) and smooth seeds (ww) can only produce gametes with the alleles r and w.

After crossing-over, the chromosomes exchanged corresponding sections containing the alleles for flower color and seed shape. This led to the production of recombinant offspring with new combinations of traits, namely red flowers and smooth seeds, and white flowers and wrinkled seeds.

The recombination frequency can be determined by summing the number of recombinant offspring (red flowers and smooth seeds, and white flowers and wrinkled seeds) and dividing it by the total number of offspring. In this case, the recombination frequency is (7 + 9) / 100 = 0.16 or 16%.

To determine the distance between the genes in map units, we can use the recombination frequency as an estimate. In this case, since the recombination frequency is 16%, we can approximate the distance between the genes to be 16 map units.

To determine the traits of the recombinant offspring, we need to analyze the combinations of flower color and seed shape that are different from both parents.

From the given data, we can see that the two parental combinations are red flowers with wrinkled seeds (43 offspring) and white flowers with smooth seeds (41 offspring). These combinations match the phenotypes of the homozygous parents.

Now, let's focus on the offspring that display different combinations of traits. In this case, we have 7 offspring with red flowers and smooth seeds and 9 offspring with white flowers and wrinkled seeds. These combinations are different from both parents' traits, indicating that they are the recombinant offspring.

To understand why these offspring are recombinant, we need to consider the process of crossing-over during meiosis. Crossing-over occurs between homologous chromosomes, where DNA segments are exchanged. In this scenario, the genes for flower color (R/r) and seed shape (W/w) are located on the same chromosome. Thus, crossing-over can lead to the exchange of alleles between the two traits.

Before crossing-over, the heterozygous parent's chromosomes would be represented as follows:

Parent 1: RrWw
Parent 2: rrww

During crossing-over, the chromatids of these homologous chromosomes can exchange corresponding segments, resulting in different combinations of alleles in the recombinant offspring.

Recombination frequency is a measure of the likelihood of crossing-over occurring between two specific genes. To calculate recombination frequency, we use the formula:

Recombination frequency (%) = (Number of recombinant offspring / Total number of offspring) x 100

In this case, the recombination frequency can be calculated as follows:

Recombination frequency (%) = [(7 + 9) / (43 + 7 + 9 + 41)] x 100

The distance between genes in map units can be calculated using the formula:

Map distance (in %) = Recombination frequency (%) x 100

In this scenario, map distance = Recombination frequency (%)

Therefore, the map distance between the flower color (R/r) gene and seed shape (W/w) gene is equal to the recombination frequency.

To obtain the precise values, we can substitute the values from the data into the formulas mentioned above.