Key stages of meiosis and mitosis
—Figure 2-15 correction
n= polidy (number of chromosomes) c= content of DNA
→ Figure 2-15 says 4n but should be 4c to be more correct
What patterns in a pedigree would reveal autosomal recessive inheritance?
(1) generally the disorder appears in the progeny of unaffected parents and
(2) the affected progeny include both males and females.
- examples: Cystic Fibrosis, PKU, Albinism
Homozygous recessives from inbreeding → affected personineachgeneration:
a/a a/a a/a a/a A/a a/a A/a a/a a/a a/a A/a a/a A/a
What patterns in a pedigree would reveal autosomal dominant inheritance?
(1) The phenotype tends to appear in every generation of the pedigree. Parents of affected children
show the phenotype.
(2) Half the offspring affected
(3) Affected fathers or mothers transmit the phenotype to both sons and daughters. examples:
Pseudoachondroplasia genotype(D): type of dwarfism D is null allele
D/+ Pseudoachondroplasia -in regards to height:Dallele is DOMINANT
-in regards to living:Dallele is RECESSIVE (two copies
D/D Lethal? = dead)
Behaves similar to the Mouse T (T-box) mutation
Note: Piebald, Polydactyly (more than ten fingers), and Huntinson’s Disease also autosomal dominant.
But the nature of the dominant mutation is different from dominant mutations due to haploinsufficient
gene. We’ll come back to this.
Ifon exame says:rare
genetic disorder →
assumed people coming
into famnot carriers Autosomal Polymorphisms
Brown vs. blue eyes*
Pigmented versus blonde hair
Chin dimples vs. none
Widow’s peak vs. none
Attached vs. free ear lobes
• in natural populations of organisms, a polymorphism is the coexistence of two or more common
phenotypes of a character
• the alternative phenotypes of a polymorphism (morphs) are often thought to be inherited as
alleles of a single autosomal gene in the standard Mendelian manner
• the interpretation of pedigrees for polymorphisms is somewhat different from that of rare