Inheritance Flashcards
What does a square represent on a pedigree diagram?
Male
What does a circle represent on a pedigree diagram?
Female
What does a coloured in shape represent on a pedigree diagram?
Affected individual
What does a diagonal line through a shape mean on a pedigree diagram
Deceased
What does a triangle represent on a pedigree diagram?
Miscarriage
What does a diamond represent on a pedigree diagram?
Unknown sex
What does an arrow pointing to a shape mean in a pedigree diagram?
They are the individual providing the pedigree information
How would you show the unborn baby of a pregnant mother on a pedigree diagram?
Draw their shape and put a P in the middle
What is a genotype?
The genetic makeup
What is a phenotype?
The physical characteristic
Where do an individuals two copies of each gene come from?
Mother and father
What does homozygous mean?
Two alleles of a gene are the same
What does heterozygous mean?
Two alleles of a gene are different
What does hemizygous mean?
Only one allele of a gene on the X chromosome
Males only
What does dominant mean?
The dominant allele in a heterozygote determines the phenotype
What does recessive mean?
The non-dominant allele in a heterozygote is called recessive
What is codominance?
When neither alleles is dominant over the other e.g. A and B in blood groups
What are the characteristics of an autosomal recessive disease?
E.g. Who is affected? Are they affected equally? Give an example of the disease
Heterozygous is unaffected
Males and females are affected equally
Skips generations
Cystic fibrosis
What are the characteristics of an autosomal dominant disease?
E.g. Who is affected? Are they affected equally? Give an example of the disease
Heterozygotes are affected Males and females are affected equally Homozygous not viable for life Cannot skip generations Huntington's disease
What are the characteristics of a x linked recessive disease?
E.g. Who is affected? Are they affected equally? Give an example of the disease
Hemizygous males and homozygous females affected
Disease more common in males
Males cannot pass to sons
Haemophilia A
What are the characteristics of an x linked dominant disease?
E.g. Who is affected? Are they affected equally? Give an example of the disease
Hemizygous males and heterozygous females are affected
Affected males cannot give trait to sons but will give to all daughters
E.g. Rett syndrome
Who is affected by Y linked inheritance?
All male children
Who is affected by mitochondrial abnormalities?
Passed from mother so all of her children
What is abnormal about albinism?
It is polygenic so more than one gene produces the phenotype as Genes on the chromosome are linked
What are polygenic genes?
Do not show independent assortment at meiosis
Genes close together are tightly linked
