Ch. 12: Mendelian Inheritance

Human Traits

I. Pedigrees

Pedigrees are a graphic representation of human inheritance.

Traits that are inherited by having 2 recessive

alleles.

Ex: Cystic Fibrosis- a disease that results in the formation and accumulation of thick mucus in the lungs and digestive tract.

https://www.youtube.com/watch?v=Twjg7v-pTO4

(A video on Cystic Fibrosis)

II. Simple Recessive Heredity

C = normal CC & Cc = normalc = cystic fibrosis cc = CF

Example of Inheritance: Cc x Cc

GR: 1CC: 2Cc: 1ccPR: 3 normal : 1 cystic fibrosis

Cystic Fibrosis

C c

C CC Cc

c Cc cc

Tay Sach’s Disease- A recessive disorder of

the central nervous system. Children born with this die at an early age due to lack of an enzyme that breaks down lipids that then accumulate in cells.

https://www.youtube.com/watch?v=CaWoeRY-gJY

(Tay Sach’s Video)

More Simple Recessive Inheritance

Phenylketonuria- a recessive disease that

does not allow people to convert a specific amino acid properly, causing mental retardation. Can be treated by avoiding phenylalanine in the diet.

https://www.youtube.com/watch?v=KUJVujhHxPQ (PhenylketonuriaVideo)

More Simple Recessive Inheritance

Traits that are inherited by having just one

dominant allele.

Ex: Huntington’s Disease: a lethal genetic disorder that effects the neurological function of a person, generally between the ages of 30-50.

https://www.youtube.com/watch?v=65xf1olEpQM

(Video on Huntington’s Disease)

II. Simple Dominant Heredity

h = normal HH & Hh= Huntington’s H = Huntington’s hh = normal

Example of Inheritance: Hh x Hh

GR: 1HH: 2Hh: 1hhPR: 3 Huntington’s : 1 normal

Huntington’s Disease

H h

H HH Hh

h Hh hh