In rabbits, coloration of the fur depends on alleles of the...

In rabbits, coloration of the fur depends on alleles of the gene $c .$ From information given in the chapter, what phenotypes and proportions would be expected from the following crosses: (a) $c^{+} c^{+} \times c c ;$ (b) $c^{+} c \times c^{+} c ;$ (c) $c^{+} c^{b} \times c^{+} c^{c b}$ (d) $c c^{c b} \times c c ;$ (e) $c^{+} c^{b} \times c^{+} c ;$ (f) $c^{b} c \times c c$ ?

Key Concepts

Punnett Square Analysis

A Punnett square is a diagrammatic tool used to predict the genetic outcomes of a cross by listing all possible gametes from each parent. By systematically combining these gametes, it allows for the calculation of expected proportions of genotypes and the resulting phenotypes.

Genotype vs Phenotype

The genotype refers to the genetic makeup of an organism, while the phenotype is the observable physical or biochemical characteristics. The relationship between the two is determined by the interaction of alleles, particularly under the influence of dominant, recessive, or codominant patterns.

Probability and Ratio Calculations

Probability theory is applied in genetics to predict the likelihood of certain alleles or combinations being passed onto offspring. By using techniques such as Punnett square analysis, expected phenotypic ratios can be computed, which is crucial for understanding the distribution of traits in a population.

Mendelian Inheritance

This concept deals with the transmission of genetic traits from parents to offspring following the patterns first described by Gregor Mendel. It focuses on the segregation of alleles during gamete formation and their random combination at fertilization, which thereby determines the genotype and, ultimately, the phenotype of the progeny.

Allelic Dominance Hierarchy

In many genetic systems, multiple alleles are present at a single gene locus and show a specific order of dominance, meaning that some alleles will mask the expression of others when paired. Understanding this hierarchy is essential for predicting the phenotypic outcomes in crosses, as it dictates which traits are expressed in heterozygous conditions.

Transcript

00:01 Asking this about rabbits and their fur colors and how different crosses would work.

00:07 It's kind of a long question, and i'm just going to run through this using a series of punnet squares.

00:13 So the first one, a has c plus, c plus, cross to c, c, c, since the c plus can only give a c plus rabbit, and the little c, the albino rabbit can only give an albino.

00:34 All of the outcomes are going to be c plus c, and so they're all going to be wild type.

00:44 Every single rabbit will be c plus and c, so they'll all be wild types.

00:50 For b, we have c plus, so c plus and c, and c, and, another c plus and c.

01:13 Now remember the pluses of the wild type and the c's are albinos.

01:19 So this would be c plus c plus, which you can just abbreviate as plus plus.

01:23 This would be c plus c.

01:26 This would be c plus c.

01:29 And then the last one would just be two little c's.

01:32 In terms of their appearance, right, we're gonna have three, because they have at least one c plus will be wild type.

01:43 And one will be albino.

01:52 Our third cross is going to be c plus and then c himalaya cross to two, c plus c chinchilla.

02:11 And if we do the planet square for this, that's plus and then himalaya and plus chinchilla, we would have a wild type, a plus, and then a himalaya, a plus, and then a chinchilla, and then himalaya, and then himalaya and a chinchilla.

02:51 Since three of these have pluses, right, anything that's plus is going to be wild type...

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