achilles - genetic linkage Flashcards
(30 cards)
What is Mendel’s principle of segregation?
Individuals have two copies of each trait, and each parent transmits one of its two copies to its offspring.
What does the principle of dominance state?
In a heterozygous, only the dominant phenotype will be expressed.
What is the principle of independent assortment?
Genes do not influence each other with regard to the sorting of alleles into gametes, and every possible combination of alleles for every gene is equally likely to occur.
Define complete dominance.
A situation where the dominant allele completely masks the effect of the recessive allele in a heterozygous individual.
What is negative dominance?
The product of one mutated allele results in a product that interferes with the wild-type allele.
What is incomplete dominance?
Expression of two alleles displaying an intermediate phenotype.
Define codominance.
Expression of two equally dominant alleles, resulting in both phenotypes being detectable.
How can environmental effects impact phenotypes?
Environmental conditions such as temperature can affect the phenotypic relationship between alleles.
What are multiple alleles?
Multiple alleles may be present in the population, although only 2 are found per diploid individual.
Provide an example of multiple alleles.
Blood types, where 1 gene has 3 possible alleles.
Who proposed a biochemical pathway to explain the behavior of arginine auxotrophs?
George Beadle and Edward Tatum.
What are the different types of molecular pathways?
- Synthetic pathways
- Metabolic pathways
- Signal transduction pathways
- Developmental pathways
What can mutations in different genes of the same pathway lead to?
Similar phenotypes.
What is the first step in inferring gene interactions?
Obtain many single-gene mutations and test for dominance.
What is a complementation test?
A test performed to assess whether 2 mutations belong to the same gene.
What does it mean if two mutations are on different chromosomes?
The F1 will show a wild-type phenotype if the two mutations are on different chromosomes.
What is the expected phenotypic ratio in a dihybrid cross with no gene interaction?
9:3:3:1.
What is a synthetic lethal?
Two variable single mutants intercrossed resulting in a lethal double mutant.
Define penetrance.
The percentage of individuals with a given allele who exhibit the phenotype associated with that allele.
What is expressivity?
The range of phenotypic expression.
What did William Bateson and his team study in 1905?
Crossed homozygous pea plants with different flower colors and pollen grain shapes.
What did Thomas Morgan identify in his studies?
X-linked genes after observing unexpected F2 results in fruit flies.
What are linked genes?
The loci of those genes on the same chromosome, where the alleles are physically joined by the DNA between them.
What is crossing over?
The process by which paired homologous chromosomes at meiosis occasionally break and exchange parts.
