PEDIGREE ANALYSIS Flashcards
What is a propositus?
member of the family that firsts comes to geneticist’s attention
Tell tale signs that a trait is X linked recessive from a pedigree?
- all affected daughters MUST have a heterozygous mother and a hemizygous father
- many more males show phenotype than females
- NONE of an affected male’s offspring are affected but all of his daughters are carriers
Tell tale signs that a trait is X linked dominant?
- affected males pass condition on to ALL daughters but none of their sons
- affected heterozygous females married to unaffected males pass condition to half sons and half daughters
What is a sex influenced/ limited trait?
phenotypes differ between sexes but the gene inheritance pattern is autosomal
Restriction site and cleavage site are two ____ properties
separate
What is an RFLP?
restriction fragment length polymorphism
- differ in the presence of absence of a restriction recognition site
what is a dominant negative mutation?
mutant gene phenotype product interferes with the wild type product and prevents function
What is haploinsufficiency?
gene product is insufficient because of normal allele and prevents wild type phenotype being expressed
Haemophilia is an _ - ___ recessive gene that is caused by a loss of restriction site in the middle of a factor ___ gene.
x- linked
VIII
What is co-dominance?
- when the products of both alleles are expressed in phenotype
eg. blood type AB has a contribution from A and B
What is incomplete dominance?
When the phenotype produced is an intermediate of both phenotypes
what is penetrance?
probability the genotype will yield the phenotype at all
What is expressivity?
the extent to which the phenotype is expressed
Multifactorial traits depend on the interaction between multiple genes and the ____.
environment
What is GWAS? Used for?
genome wide association studies
- find single nucleotide polymorphisms, and aim to identify genes/ differences in DNA sequences between affected individuals and normal individuals for a trait
Huntingdon’s disease is an autosomal __(a)__ disease that shows __(b)__ expressivity. This can prove genetic __(c)___ due to varieties in the size of the unstable allele. Poly-__(d)___ chains increase through generations and the gene gets __(e)___.
a) dominant
b) variable
c) anticipation
d) glutamine
e) larger
How does PCR work?
1) pairs of primers on opposite strands are extended towards eachother
2) strands are heated to denature to generate single stranded templates (95 degrees)
3) temp lowered to 55 degrees for annealing of the primers
4) raised to 72 degrees for DNA polymerase action
What does consanguineous mean?
descend from shared ancestor
