Introduction to Genetic Principles
David R. Hyde
Format: PDF / Kindle (mobi) / ePub
Hyde’s Introduction to Genetics teaches the principles of genetics with an innovative approach that emphasizes the basic concepts involved in solving problems as well as teaching students how to manipulate genetic data.
While most genetics textbooks provide some examples and several problems for the student to work, the texts primarily stress facts and historical information. It is often left to the student to make the connection from what is in the text to elucidating the approaches to solve problems. Dr. David Hyde presents these skills to the students throughout the narrative in a stepped-out fashion, making an explicit tie between the facts and their application.
This text maintains the rigor that faculty require in a genetics book, while incorporating a student-friendly presentation style that helps the reader comprehend the material.
genetically determined phenotype D. 9:3:4 ratio in offspring E. 13:3 ratio in offspring F. 9:7 ratio in offspring G. Individual composed of two different genotypes, producing two different phenotypes H. 15:1 ratio in offspring I. Gene that is masked by the effects of another J. Differential gene expression based on parent of origin 2. How do codominance and incomplete dominance differ? 3. Compare and contrast dominance and epistasis? 4. What is the difference between incomplete penetrance and
6.5. Third, these standard 1:1:1:1 phenotypic ratio. crosses do not identify which chromosome contains the loci. well as the great majority of the testcross offspring. To summarize, the testcross in figure 6.4 shows We call these phenotypic categories in the F2 progeny that 99.5% of the gametes produced by the dihybrid the nonrecombinants, or parentals, because they posfemale are nonrecombinant, whereas only 0.5% are sess the same phenotypes as the individuals in the recombinant. This very small
infection of tobacco plants corresponded to the RNA type, not the protein. Therefore, the nucleic acid (RNA in this case) was the genetic material. Subsequently, scientists rubbed purified tobacco mosaic virus RNA into plant leaves. Normal infection and a new generation of typical, protein-coated tobacco mosaic virus resulted, confirming RNA as the genetic material for this virus. From these and other landmark experiments, geneticists have concluded that DNA (and in some cases RNA) is the genetic
the double dominant phenotypic and wg from the homozygous recessive parclass, with round, yellow seeds, represents ent. The resulting F1 plants are heterozygous four genotypes: WWGG, WWGg, WwGG, for both genes (dihybrid). Self-fertilizing figure 2.13 and WwGg. When we group all the genothe dihybrid (WwGg) produces the F2 Reginald C. Punnett types by phenotype, we obtain the ratio generation. (1875–1967). shown in figure 2.14. WG WWGg WwGG WwGg Ovules WWGG hyd8760x_ch02.indd 28 10/18/07
based on their parents’ genotypes. Individuals II-1, II-5, and II-6 must be heterozygotes to produce the affected daughters III-2 and III-5. If this trait is rare, then individual II-4 would likely be homozygous dominant (RR). The genotypes of these individuals can be conclusively deduced, but two individuals have ambiguous genotypes. There is a 50% chance that the female III-3 is a heterozygote, based on her parents’ genotypes (Rr × RR). Individual III-4 is phenotypically normal and the son of