Modes Of Inheritance Flashcards
What is an autosomal dominant condition?
A condition where only one faulty allele is needed for the condition to be expressed
Who do autosomal dominant conditions manifest in?
They mainfest in heterozygotes
What are the effects of autosomal dominant conditions?
- Gain of function
- Insufficient amounts of protein being produced
- Dominant negative effect
What is an example of an autosomal dominant condition?
Huntingtons
What type of pedigree pattern do autosomal dominant conditions show?
Vertical pedigree pattern
What causes Huntingtons disease?
expansion of a CAG repeat which results in mutant proteins being produced which interfere with the functioning of normal nerve cells
What is meant by gain of function?
Gain of function is where the protein becomes hyperactive, and it is this hyperactivity which results in the onset of the disease
What is meant by a dominant negative effect?
Dominant negative effect is where the protein produced interferes with the functioning of the normal protein
How do autosomal dominant conditions effect men and women?
They affect men and women equally
What are autosomal recessive conditions?
where you need two copies of the allele in order for the condition to be expressed
What are the usual effects of autosomal recessive conditions?
Loss of function - having both copies results in a completely malfunctioning protein
What type of pedigree pattern do autosomal recessive conditions show?
Horizontal pedigree
What can increase the risk of autosomal recessive conditions?
Consangious marriages
Why can autosomal recessive conditions skip generations?
Due to the high chance of being a carrier
How are men and women affected with autosomal recessive conditions?
They are affected equally
What type of chromosomes are autosomal recessive genes located on?
Non-sex chromosomes
What percentage of DNA is shared between first cousins?
12.5%
Who do X-linked recessive conditions mainly affect?
Men
How can females have an X linked recessive condition?
They have to be homozygous for the condition
What is the chance of a daughter of an affected male being a carrier of an X Linked recessive condition?
100%
What is an X linked recessive condition?
Where the alleles are located on the sex chroosomes, and since males have XY, a portion of their second chromosome is missing, meaning males have an increased risk of the condition as if they only need the one recessive allele to have the condition
What happens to the daughters and sons of an affected father and unaffected mother of an X linked dominant condition?
Daughters - They are all affected
Sons - none affected
Who do Y linked disorders affect?
Only men as females do not have Y chromosome
What type of pedigree pattern do Y linked disorders show?
Vertical patern with only males affected
Who are all your mitochondria inherited from?
Mother
A mother has a mitochondrial condition. What happens to her children?
They are all affected
Why do the expression of mitochondrial conditions vary massively in a family?
When the mitochondria replicate, genes can be lost or gained meaning there is an enourmous amount of variation
What type of inheritance is it when children of unaffected parents are affected?
X Linked recessive
What type of inheritance is it when all children of an affected mother are affected?
Mitochondrial
