Genetics Unit 2: Extensions to Mendelian Analysis

Multiple alleles play a crucial role in genetic stability and diversity within a population.

The different allelic forms of a gene exhibit variations in their nucleotide sequences, leading to distinct levels of activity in their respective gene products.

The four alleles are C (wild-type), cch (chinchilla), ch (Himalayan), and c (albino).

<p>The order of dominance is C &gt; cch &gt; ch &gt; c.</p> Signup and view all the answers

<p>The wild-type allele in rabbits refers to the C allele, which is dominant and results in the full color phenotype.</p> Signup and view all the answers

<p>The homozygous dominant genotype (CC) expresses the full color phenotype.</p> Signup and view all the answers

<p>Mutant alleles, such as cch, ch, and c, contribute to genetic diversity and variability among individuals in a population.</p> Signup and view all the answers

<p>Multiple alleles lead to varied phenotypic expressions, which affects the ratios of different genotypes in the offspring.</p> Signup and view all the answers

<p>Mendel's work laid the foundation for the principles of heredity, demonstrating how traits are inherited from parents to offspring.</p> Signup and view all the answers

<p>Codominance occurs when both alleles in a heterozygote are fully expressed, resulting in offspring with a phenotype that is neither dominant nor recessive. An example is the AB blood type in humans.</p> Signup and view all the answers

<p>Epistasis is when one gene's expression is affected by another gene, influencing the phenotypic outcome. It can mask or modify the effects of other genes.</p> Signup and view all the answers

<p>Incomplete dominance occurs when the phenotype of a heterozygote is an intermediate between the phenotypes of the two homozygotes. This contrasts with complete dominance, where one allele completely masks the other.</p> Signup and view all the answers

<p>Lethal alleles are alleles that can cause the death of an organism when present in a certain genotype, often leading to modified Mendelian ratios in offspring. For example, certain alleles in mice can lead to death if homozygous.</p> Signup and view all the answers

<p>Pleiotropy refers to a single gene influencing multiple phenotypic traits. An example is the gene responsible for sickle cell disease, which affects red blood cell shape and can lead to various health complications.</p> Signup and view all the answers

<p>Multiple alleles refer to the existence of more than two alleles for a genetic locus. An example in humans is the ABO blood type system, which includes A, B, and O alleles.</p> Signup and view all the answers

<p>Gene interactions can modify the expected Mendelian ratios by altering the expression and dominance relationships between genes, leading to phenotypic ratios that are different from those predicted by simple Mendelian inheritance.</p> Signup and view all the answers

<p>The phenotypic ratio is 9:7.</p> Signup and view all the answers

<p>Dominant alleles from both gene pairs are required to synthesize anthocyanin pigment, resulting in a purple flower phenotype.</p> Signup and view all the answers

<p>The epistatic gene is the one that masks the expression of another gene, while the hypostatic gene is the one whose expression is masked.</p> Signup and view all the answers

<p>The phenotypic ratio in dominant epistasis is 12:3:1.</p> Signup and view all the answers

<p>The 'W' gene for white fruit color is dominant and suppresses the expression of the 'Y' gene for yellow fruit color.</p> Signup and view all the answers

<p>When both the W and Y genes are absent, the phenotype expressed is green.</p> Signup and view all the answers

<p>Complementary gene interaction refers to a situation where two different genes must have dominant alleles to express a particular phenotype.</p> Signup and view all the answers

<p>A recessive pair of either gene C or P will prevent the formation of the anthocyanin pathway, resulting in white flowers.</p> Signup and view all the answers

<p>A dominant allele expresses its phenotype while a recessive allele's expression is suppressed in the heterozygous condition.</p> Signup and view all the answers

<p>Incomplete dominance results in an intermediate phenotype due to blending, while co-dominance expresses both phenotypes equally.</p> Signup and view all the answers

<p>The F2 phenotypic ratio in complementary gene interaction is 9:7.</p> Signup and view all the answers

<p>Epistasis occurs when one gene masks the expression of another non-allelic gene, affecting the observed phenotype.</p> Signup and view all the answers

<p>The phenotypic ratio associated with dominant epistasis is 12:3:1.</p> Signup and view all the answers

<p>Multiple alleles refer to the presence of more than two alleles controlling a trait, such as the ABO blood groups in humans.</p> Signup and view all the answers

<p>The phenotypic ratio for recessive epistasis is 9:3:4.</p> Signup and view all the answers

<p>Supplementary gene interaction involves one dominant gene requiring another for expression, with a phenotypic ratio of 12:3:1.</p> Signup and view all the answers

<p>Complete dominance occurs when one allele completely masks the expression of another allele.</p> Signup and view all the answers

<p>A heterozygous organism displays the dominant phenotype, while a homozygous recessive organism displays the recessive phenotype.</p> Signup and view all the answers

<p>The dominant allele masks the expression of the recessive allele, which is only expressed in the homozygous condition.</p> Signup and view all the answers

<p>An example is allele 'A' being dominant and allele 'a' being recessive.</p> Signup and view all the answers

<p>Mendel's studies indicate that traits can be traced through generations and are controlled by dominant and recessive alleles.</p> Signup and view all the answers

<p>Dominant traits can be recognized in an organism with just one dominant allele, while recessive traits require two recessive alleles for expression.</p> Signup and view all the answers

<p>The homozygous condition for recessive alleles is significant because it is the only way these alleles can be fully expressed.</p> Signup and view all the answers

<p>Heterozygosity refers to having two different alleles for a trait, such as 'Aa', where the dominant allele is expressed.</p> Signup and view all the answers

<p>Rh factor is crucial for blood compatibility and can cause Rh incompatibility in pregnancies.</p> Signup and view all the answers

<p>Rh factor was discovered by Karl Landsteiner and Alexander Wiener in 1937.</p> Signup and view all the answers

<p>It can be tested by reacting a blood sample with anti-Rh serum to observe if agglutination occurs.</p> Signup and view all the answers

<p>The D antigen is encoded by the RHD gene.</p> Signup and view all the answers

<p>Rh+ indicates the presence of the D antigen, while Rh- indicates its absence.</p> Signup and view all the answers

<p>Weiner's theory posits that there is one Rh gene with multiple alleles producing various Rh antigens.</p> Signup and view all the answers

<p>Fisher-Race nomenclature identifies five antigens: D, C, c, E, and e.</p> Signup and view all the answers

<p>The antigens C and c, as well as E and e, are considered antithetical.</p> Signup and view all the answers