In tomatoes, dwarf (d) is recessive to tall (D) and opaque...

In tomatoes, dwarf $(d)$ is recessive to tall $(D)$ and opaque (light-green) leaves $(o p)$ are recessive to green leaves $(O p) .$ The loci that determine height and leaf color are linked and separated by a distance of 7 m.u. For each of the following crosses, determine the phenotypes and proportions of progeny produced. a. $\frac{D}{d} \frac{O p}{o p} \times \frac{d}{d} o p$ b. $\frac{D}{d} \frac{o p}{O p} \times \frac{d}{d} \quad o p$ c. $\frac{D}{d} \frac{O p}{o p} \times \frac{D}{d} \frac{O p}{o p}$ d. $\frac{D}{d} \frac{o p}{O p} \times \frac{D}{d} \quad o p$

In tomatoes, dwarf $(d)$ is recessive to tall $(D)$ and opaque (light-green) leaves $(o p)$ are recessive to green leaves $(O p) .$ The loci that determine height and leaf color are linked and separated by a distance of 7 m.u. For each of the following crosses, determine the phenotypes and proportions of progeny produced.
a. $\frac{D}{d} \frac{O p}{o p} \times \frac{d}{d} o p$
b. $\frac{D}{d} \frac{o p}{O p} \times \frac{d}{d} \quad o p$
c. $\frac{D}{d} \frac{O p}{o p} \times \frac{D}{d} \frac{O p}{o p}$
d. $\frac{D}{d} \frac{o p}{O p} \times \frac{D}{d} \quad o p$

Key Concepts

Mendelian Inheritance

Mendelian inheritance is the principle that traits are determined by discrete genes that come in pairs, with each parent contributing one allele. This foundational concept explains how dominant and recessive traits are transmitted from parents to offspring and predicts the ratios of different phenotypes in progeny.

Dominant and Recessive Alleles

Dominant alleles mask the expression of recessive alleles when present in a heterozygous condition. Recessive traits are only observable when an individual possesses two copies of the recessive allele, which is key to predicting the outcomes of genetic crosses.

Linked Genes

Linked genes are those that are located close together on the same chromosome and therefore tend to be inherited together during meiosis. This non-independent assortment of alleles modifies the expected phenotypic ratios from those predicted by Mendel's law of independent assortment.

Recombination and Genetic Mapping

Recombination is the process by which homologous chromosomes exchange segments during meiosis, resulting in new allele combinations. The frequency of recombination between two loci is used to determine their distance on a genetic map, measured in map units (centiMorgans), which is crucial for understanding linked inheritance.

Test Crosses in Linkage Analysis

Test crosses involve mating an individual of unknown genotype with a homozygous recessive individual. In linkage analysis, test crosses help to reveal the phase of alleles on chromosomes and the degree of recombination between linked genes, allowing for the determination of gene order and map distances.

Transcript

Please give Ace some feedback