8C- pedigree analysis Flashcards
horizontal lines
mating between two individuals
vertical lines
link between two generations
circles
females
squares
males
coloured
affected
uncoloured
unaffected
double horizontal lines
consanguieneous breeding
autosomal dominant traits
1 If both parents are affected, the offspring may be unaffected.
2 If neither parent is affected, the offspring must be unaffected.
3 If an offspring is affected, there must be an affected parent.
4 The trait cannot skip a generation.
autosomal recessive
1 If both parents are affected, the offspring must be affected.
2 If neither parent is affected, the offspring may be unaffected.
3 If an offspring is affected, there may be an affected parent.
4 The trait can skip a generation.
x linked dominant
1 If a male is affected, his mother must be affected.
2 If a male is affected, his daughters must be affected.
3 If a female is unaffected, her father must be unaffected.
4 If a female is unaffected, her sons must be unaffected.
5 The trait cannot skip a generation.
Sex-linked inheritance cannot be confirmed with certainty using just a pedigree.
x linked recessive
1 If a female is affected, her father must be affected.
2 If a female is affected, her sons must be affected.
3 If a male is affected, his mother may be affected.
4 The trait can skip a generation.
Sex-linked inheritance cannot be confirmed with certainty using just a pedigree.
y linked
1 Only males can show the trait.
2 All males in a lineage will show the same phenotype.
3 The trait cannot skip a generation.
Sex-linked inheritance cannot be confirmed with certainty using just a pedigree.
examples of autosomal dominant traits
Huntington’s disease, achondroplasia (dwarfism)
examples of autosomal recessive traits
Cystic fibrosis, Tay-Sachs disease, albinism, phenylketonuria (PKU)
examples of x linked dominant traits
Rett syndrome, fragile X syndrome
examples of x linked recessive traits
Red-green colour blindness, haemophilia
examples of y linked traits
Hypertrichosis pinnae auris, Y chromosome infertility
how to determine inheritance patterns
is this trait present in every generation?
YES/NO- dominant/recessive
do all affected females ahve an affected father and son
YES/NO- x linked/autosomal
do all affected males have an affected father and son
YES- y linked
what are carriers
organisms that are heterozygous and as a result carry the recessive allele but don’t display it
pedigree chart
a diagram showing the expression of a trait over multiple generations
consanguineous breeding
breeding of two individuals that are closely related. Also known as inbreeding
carrier
an organism that has inherited a copy of a recessive allele for a genetic trait but does not display the trait due to it being masked by the presence of a dominant allele
female to male transgender
square outside
circle inside
male to female transgender
circle outside
square inside
