Skip to main content
Pearson+ LogoPearson+ Logo
Ch. 3 - Mendelian Genetics
Klug - Essentials of Genetics 10th Edition
Klug10th EditionEssentials of GeneticsISBN: 9780135588789Not the one you use?Change textbook
Chapter 3, Problem 22c

Draw all possible conclusions concerning the mode of inheritance of the trait portrayed in the following limited pedigree.
Pedigree chart showing two generations with one affected female indicated by a filled circle among unaffected family members.

Verified step by step guidance
1
Step 1: Identify the affected individuals and their sex in the pedigree. Here, only one female (represented by a filled circle) is affected, while all other individuals are unaffected.
Step 2: Consider the pattern of inheritance by analyzing the distribution of the trait across generations and between sexes. Since only one female is affected and no males are affected, this suggests the trait might not be Y-linked.
Step 3: Evaluate whether the trait could be autosomal dominant or recessive. If it were autosomal dominant, typically one affected parent would pass the trait to offspring, but here neither parent is affected, which argues against autosomal dominant inheritance.
Step 4: Consider X-linked inheritance. Since only a female is affected and no males, and the trait appears in only one generation, it could be consistent with X-linked recessive or dominant inheritance, but the absence of affected males makes X-linked recessive less likely.
Step 5: Summarize conclusions: The trait is likely inherited in an autosomal recessive or possibly X-linked dominant manner, but more data would be needed to confirm. The single affected female with unaffected parents suggests recessive inheritance.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
2m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Pedigree Analysis

Pedigree analysis is a tool used to study the inheritance patterns of traits through generations in a family. It uses standardized symbols to represent individuals and their traits, helping to identify whether a trait is dominant, recessive, autosomal, or sex-linked. Understanding how to interpret these symbols and relationships is essential for drawing conclusions about inheritance.
Recommended video:
Guided course
01:59
Pedigree Flowchart

Modes of Inheritance

Modes of inheritance describe how genetic traits are transmitted from parents to offspring. Common modes include autosomal dominant, autosomal recessive, X-linked dominant, and X-linked recessive. Each mode has characteristic patterns in pedigrees, such as affected individuals in every generation for dominant traits or skipping generations for recessive traits.
Recommended video:
Guided course
05:13
Organelle Inheritance

Sex-Linked vs. Autosomal Traits

Sex-linked traits are associated with genes located on sex chromosomes, often showing different patterns in males and females, while autosomal traits are linked to non-sex chromosomes and typically affect both sexes equally. Recognizing whether a trait affects males and females differently or equally helps determine if the trait is sex-linked or autosomal.
Recommended video:
Guided course
07:56
Sex-Linked Genes