Inheritance of simple and complex traits Flashcards
(28 cards)
What does transmission genetics study?
How genetic differences are passed from one generation to the next
What principle describes the independent segregation of different gene pairs?
Independent assortment
What genetic process allows exchange of genetic material between homologous chromosomes?
Crossing over
Name some complications in simple Mendelian inheritance
Incomplete dominance, epistasis, incomplete penetrance, and variable expression
What is incomplete penetrance?
When a trait is not always expressed despite having the genotype
What is variable expression?
When a trait is always expressed but varies in severity
What is an example of an X-linked genetic disorder mentioned?
Haemophilia in the European royal family
What are quantitative traits?
Traits controlled by many genes and influenced by environment, measured along a continuum (e.g., blood pressure, obesity)
What rule explains why offspring traits tend to regress toward the population mean?
Galton’s rule of regression toward the mean
Why does regression toward the mean occur in quantitative traits?
Because recombination breaks up gene combinations and environmental effects vary
What is heritability?
The proportion of variation in a trait due to genetic differences among individuals in a population
Name three ways to estimate heritability
- Comparing parents and offspring
- Twin studies
- Pedigree analysis.
Why do twin studies help estimate heritability?
Because differences between identical twins must be due to the environment
What is concordance in twin studies?
The proportion of twin pairs where both show the same trait
Does high heritability mean a trait is largely genetically determined in an individual?
No, heritability refers to variation in a population, not individual determination
Can low heritability mean a trait has no genetic component?
No, low heritability does not rule out genetic influence
What does heritability help us understand in populations?
How traits might respond to natural selection
What is cultural inheritance?
Traits or behaviors learned from others in a group, forming a second inheritance system
Give an example of cultural inheritance in animals
Banded mongoose offspring inherit foraging skills from role models, not parents
What is epigenetic inheritance?
Heritable changes in gene expression without changes in DNA sequence
How does royal jelly affect honeybee caste development?
It suppresses Dnmt3, reducing DNA methylation and allowing queen traits to develop
What is paramutation?
When one allele heritably alters the expression of another allele without changing DNA sequence
What is genomic imprinting?
When gene expression depends on whether the gene is inherited from the mother or father
How does DNA methylation regulate gene expression?
Adding methyl groups (usually at CpG sites) blocks transcription factor binding, reducing transcription
