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Uniformity in Genetics
What is the basic structure and function of a gene in all organisms?
Genes are made up of base sequences in DNA molecules, and they code for proteins through processes like DNA replication, transcription, and translation.
Characteristics of Model Organisms
List three characteristics of model organisms that make them useful for genetic studies
Model organisms have short lifespans, can be easily genetically engineered, and often share evolutionary origins with humans, allowing for generalisation of findings
Heritability
What is broad-sense heritability (BSH)?
BSH is the amount of phenotypic variance in a population that can be attributed to genetic variance, including all genetic contributions
Heritability
How does narrow-sense heritability (NSH) differ from broad-sense heritability?
NSH refers to the proportion of phenotypic variance due only to additive genetic variance, excluding dominance, epistasis, and genetic interactions
Sex Chromosomes and Sex Determination
How does the Y chromosome influence sex determination in humans?
The Y chromosome contains the testis-determining factor (TDF) gene, which directs the development of testes in embryos, leading to male differentiation.
Sex Chromosomes and Sex Determination
In a Punnet square involving a sex-linked recessive trait, what result would indicate the trait is likely on the X chromosome?
If reciprocal crosses show different results depending on the sex of the parent with the trait, it suggests the trait is X-linked.
Pedigree Analysis
What is complete penetrance in pedigree analysis?
Complete penetrance means that every individual with a dominant allele for a trait will exhibit that trait, assuming no environmental modifiers
Pedigree Analysis
How can one infer autosomal recessive inheritance from a pedigree?
If an affected individual has two unaffected parents, the trial is likely autosomal recessive, as each parent would need to contribute one recessive allele
Explain dominant epistasis with an example
In dominant epistasis, one gene (e.g. A) will mask the effect of another gene (e.g., B), as long as there is at least one dominant allele of A. An example ratio for F2 would 12:3:1.
Epistasis and Gene interactions
What is epistasis?
Epistasis is when one gene masks or modifies the expression of another gene, affecting the phenotype
Genetic Mapping and Recombination
How does recombination frequency relate to the genetic distance between genes?
Higher recombination frequencies indicate that genes are farther apart on a chromosome, while a frequency below 50% suggest they are linked and closer together
Genetic Mapping and Recombination
What is a map unit, and how is it used?
A map unit, or centimorgan, represents the genetic distance in which 1% recombination occurs between two genes
Quantitive Genetics
What is a quantitive trait locus (QTL)?
A QTL is a DNA segment associated with a quantitive trait, often identified by its influence on continuous traits through variation at multiple loci
Quantitive Genetics
What is a quantitive trait locus (QTL)?
A QTL is a DNA segment associated with a quantitive trait, often identified by its influence on continuous traits through variation at multiple loci
Quantitive Genetics
Describe the process of QTL mapping
Mapping involves crossing genetically distinct parents, screening for marker loci, generating recombinant offspring, and analysing trait distribution to locate regions associated with trait variation
