L12-13 Inheritance Flashcards
Polygenic traits show…
Continuous variation
Mendel’s laws state that…
- Each gene is segregated (Law of Segregation)
2. Copies of each gene segregate independently of each other (Law of Independent Assortment)
Linked genes cannot…
Assort independently
A monohybrid cross is a…
1 trait cross
The ratio of genotypes for offspring of a monohybrid cross is…
1 : 2 : 1
AA : Aa / aA : aa
The ratio of phenotypes for offspring of a monohybrid cross is…
3 : 1
AA, Aa and aA all express dominant allele ‘A’
aa expresses recessive allele ‘a’
There are ( few / many ) single gene traits
Few
Examples of true single gene traits are…
- Bitter broccoli- PTC tasting
- White cats
- Wet/dry earwax
- Albinism
Hardy-Weinberg Equilibrium assumes (3)…
Infinite population, random mating and no evolutionary forces acting
p^2 + 2pq + q^2 = 1, where
p is the dominant and q is the recessive allele
The equation Harvey-Wineberg equation can be used to determine the (theoretical)…
Frequencies of homozygous (pp , qq) heterozygous (2pq) genotypes
Autosome
A non-sex chromosome
Identify 6 autosomal recessive traits in humans…
1) Albinism
2) Phenylketonuria
3) Tay-Sachs
4) Cystic Fibrosis
5) Sickle-cell Anaemia
6) Haemochromatosis
Haemochromatosis is the result of an autosomal recessive allele and results in excess iron. It is treated by…
Chelation or phlebotomy (blood letting)
Identify 3 autosomal dominant conditions…
1) Polydactyly
2) Hypercholesterolemia
3) FASPS (Familial advanced sleep phase syndrome)
In pedigree diagrams, autosomal recessive conditions generally occur in offspring of…
Unaffected parents, i.e. it appears to skip generations
In pedigree diagrams, autosomal dominant conditions are usually passed on in…
50% of offspring
Sex-linked genes ( have different / have the same ) inheritance patterns to autosomal genes
Have different
Serious X-linked disorder cases are all ( male / female ) inherited from ( recessive / dominant ) mother
Male, recessive
Y-linked disorders are rare, as they…
Tend to affect male fertility and thus are not passed on
although the advent of in vitro fertilisation has changed this
Léri-Weill Dyschondrostenosis
Mutation or lack of SHOX gene in PAR1 region on X or Y chromosome
Tortoiseshell cats are female because…
Cat coat colour is X linked and the tortoiseshell pattern results from X-inactivation
Genes are either autosomal or…
Sex-linked
