Inheritance Flashcards
What is meant by F1 and F2 generation?
In terms of true breeding speciemens what would the genotype be
Parent : homozygous
F1 is the first set of offspring - heterozygous
F2 is the second set of offspring - can’t predict
What is meant by true breading?
Produce genetically identical offspring, able to self-pollinate.
Are homozygous
What is mendelian inheritance?
The pattern of inheritance from parents to offspring of one gene with TWO alleles as the only options.
What are the three laws of mendelian inheritance?
Law of segregation
Law of independent assortment
Principle of dominance
What is the law of segregation?
An individual has two alleles for one gene
Only one allele, selected randomly is passed onto the offspring.
What is the law of independent assortment?
That genes at different loci seperate into gamates randomly
E.g inheriting alle 1 of gene 1 does not make you more likley to inherit allele 1 of gene 2
Each chromosome is inherited randomly and independently of other chromosomes
What is the principle of dominance?
That one allele masks the experession of another.
What is meant by autosomal dominant?
What are some example of diseases?
One mutated copy of a gene found on a non-sex chromosome, is sufficient to cause expression of a disease.
Huntington disease, Marfan syndrome
What factors affect the level of dominance?
What are the different types of dominance?
Dominance is relative to the function of the protein and the nature of the mutation (allele)
A condition may be
dominant - masks the other
incomplete dominance - partial effect over the other allele
Co-dominance - both alleles are expressed in the phenotype.
What is the difference between co-dominance and incomplete dominance?
Co-dominant - two phenotypes are expressed simultaneously
Incomplete dominance - results in a thrid phenotype
What is an autosome?
A chromosome that is not a sex chromosome, not pair chromsone 23
What is the pattern of huntingtons disease inheritance?
Mutation for repeat CAG sequence, more repeats is a more degenerative disease,
Less repeats causes a disease that appears later in life (often after passed to children)
Is a rare fatal neurological disease
Dominant and autosomal
What is an example of a sporadic autosomal dominant condition?
Retinoblastoma mutation
What is meant by an autosomal recessive condition?
A mutation on chromosome 1-22, requires two mutated alleles in order for it to be expressed.
Typically skip generations.
Has carriers.
What are some examples of autosomal recessive conditions?
Cystic fibrosis
Sickle Cell Disease
What is the pattern of inheritance and genetic trends in sickle cell disease?
Autosomal recessive pattern
Most commonly in African descent
Heterozygous characters may express a partial phenotype with some symptoms, also provides a genetic advantage more likley to have less severe malaria.
What is meant by X-linked Dominant condition?
Loci on the x-chromosome, only one copy needed to be expressed.
What is an example of an x-linked dominant condition?
Fragile X syndrome
Males experience more severe syndromes as only one copy of the allele
Fragile X causes more copies of the CGG repeats
Not life threatening, delays neurological development
What is a x-linked recessive condition?
Mutation on a x chromosome, that can be masked by a wild type allele on the corresponding gene on a second chromosome if present.
Females require two copies of the mutated allele to express the condition.
More commonly expressed in the phenotype of men compared for women.
What are some examples of the x-linked recessive conditions?
Haemophilia
Fabry disease.
What is the pattern of inheritance of Fabry disease?
An inherited disorder that is x-linked recessive conditions.
Affects mainly the heart and kidneys.
Often have problems with breaking down globotriaosylceramine (GL-3).
Is a lysosomal storage disorder.
What is the deal with Y linked disorders?
XY males are always affected.
Not many known
ONly around 200 genes on the y chromosome
Only passed from father to son, not in females
Are often sporadic as frequently cause infertility by affecting the AZF region responsible for sperm production.
What type of inheritance it blood group an example of?
Non-mendelian, co-dominance as in there are three potential alleles and of the two alleles that the patient poses both are expressed in the phenotype.
Give an overview of the inheritance of different blood groups.
There are three major alleles A, B and O
This creates four phenotypes blood group A, B, AB and O.
O is recessvie to all other blood groups and A/B are co-dominant.
