LInkage Mapping Flashcards
What are nonrecombinant offspring?
Offspring that inherit parental combinations of alleles without any crossover.
How is map distance calculated?
Map distance = (number of recombinant offspring / total offspring) × 100
Why is linkage important in genetics?
Linkage affects inheritance patterns, leading to correlated patterns of inheritance.
What is genetic mapping also known as?
Gene mapping or chromosome mapping
What does genetic mapping determine?
The linear order and distance of linked genes along the same chromosome.
What is a locus in genetics?
The specific site where a gene is found within a chromosome.
What is the significance of double crossover events?
They are very uncommon and affect the proportion of recombinant offspring.
What are the three hypotheses proposed by Morgan regarding gene inheritance?
- Genes for body color, eye color, and wing length are on the X chromosome
- Crossing over can result in new combinations of alleles
- The likelihood of crossing over increases with distance between genes
What are the uses of genetic maps?
- Understanding genetic organization
- Cloning genes
- Understanding evolutionary relationships
- Diagnosing inherited diseases
- Predicting inherited disease likelihood
- Improving agricultural strains
What are map units also referred to as?
CentiMorgans (cM)
What does one map unit (mu) represent?
1% recombination frequency.
What phenotype combination is observed most frequently in offspring of linked genes?
Nonrecombinant phenotypes.
What is the purpose of a testcross?
To determine the extent of linkage between genes.
What does a high recombination frequency suggest about two genes?
They are farther apart on the chromosome.
Linkage leads to a deviation from which principle?
Mendelian expectation in inheritance patterns.
What does recovery of only nonrecombinants indicate about gene linkage?
Extensive linkage, suggesting genes are on the same chromosome and close together.
Fill in the blank: The likelihood of crossing over is more likely to occur between two genes that are ______.
[far apart from each other]
True or False: Genetic mapping can be used to diagnose inherited human diseases.
True
What is the purpose of linkage analyses in genetics?
To identify genes underlying a phenotype of interest
What is a testcross used for?
To assess the extent of linkage
What does recovery of only nonrecombinants indicate?
Extensive linkage; genes for the two traits are on the same chromosome and physically close
What does recovery of 50% nonrecombinant and recombinant progeny indicate?
Independent assortment and a lack of linkage
What does the term synteny mean?
Two or more genes are located on the same chromosome and are physically linked
What is genetic linkage?
The phenomenon that genes close together on a chromosome tend to be transmitted as a unit
