Which of the following is not correct for an autosomal...

Which of the following is not correct for an autosomal recessive pedigree? a. Males inherit the trait 50$\%$ of the time. b. Heterozygous individuals are carriers. c. Only homozygous recessive individuals express the trait. d. Homozygous dominant individuals and heterozygotes have the same phenotype.

Which of the following is not correct for an autosomal recessive pedigree?
a. Males inherit the trait 50$\%$ of the time.
b. Heterozygous individuals are carriers.
c. Only homozygous recessive individuals express the trait.
d. Homozygous dominant individuals and heterozygotes have the same phenotype.

Key Concepts

Autosomal Inheritance

This concept refers to the pattern of inheritance where the gene in question is located on one of the non-sex chromosomes. As a result, both males and females are equally affected by the allele, and there is no bias in terms of sex-specific transmission of the trait.

Recessive Inheritance

In recessive inheritance, an individual must inherit two copies of the recessive allele to express the trait. If only one copy is present, the dominant allele masks the effect of the recessive allele, and the trait is not expressed.

Carrier Status

Carriers are individuals who have one dominant allele and one recessive allele for a trait. They do not express the trait themselves due to the presence of the dominant allele, but can pass the recessive allele on to their offspring.

Genotype-Phenotype Relationship

This concept encompasses the relationship between an individual's genetic makeup (genotype) and the physical or physiological expression of traits (phenotype). In autosomal recessive traits, only those with a homozygous recessive genotype show the phenotype, while heterozygotes and homozygous dominants display the dominant phenotype.

Pedigree Analysis

Pedigree analysis is a tool used to study patterns of inheritance over several generations. It helps in determining how traits, such as autosomal recessive traits, are passed down in families, by tracking the occurrence of traits in relation to family relationships.

Transcript

00:01 This question comes from biology 2015, chapter 11, and this is problem 7.

00:06 The question asks, which of the following is not correct for an autosomal recessive pedigree? now, you may think that you need to draw a complicated pedigree in order to solve this question, but that's not really the case.

00:18 The question and some of the answer choices actually give you some helpful hints for solving the problem and some of the key terms used here.

00:26 So because the question is asking you what's not correct for this particular question, for this particular set of answers, you can solve this problem by simple process of elimination.

00:37 So first let's start by defining some of these key terms.

00:42 So the problem asks for an autosomal recessive pedigree or what passing down of an autosomal recessive trait means.

00:51 And so first let's define what those terms are.

00:54 So autosomal simply talks about a trait that's linked to some gene on a non -sexism.

01:01 Chromosome.

01:12 And then recessive talks about how the phenotype or a trait of interest is actually visible relative to the genetic makeup of the individual.

01:27 So recessive requires that two recessive alleles actually be present or homozygous in the organism to observe a phenotype.

01:40 So when we're talking about alleles here, you may be familiar with two different kinds of alleles, just looking at sort of general genetic notation here, where a dominant allele is usually a capital letter, recessive allele is usually a lowercase letter, and so someone who is homozygous or has two copies of the recessive allele, if it's a diploid, looks like that...

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