Transcript Molecular Basis for Relationship between Genotype and Phenotype

Molecular Basis for
Relationship between Genotype and Phenotype
genotype
DNA
DNA sequence
transcription
RNA
translation
protein
function
phenotype
organism
amino acid
sequence
Mutation: Levels of Hereditary Change
Gene (Point) Mutation:
One allele changes to a different allele.
Effects are limited to that locus.
Chromosome Mutation:
Changes occur at the chromosome level.
Multi-locus effects are not unusual.
Types of Chromosome Mutations
Changes in Chromosome Number
I.
Classes
A.
B.
II.
Euploidy
A.
B.
C.
III.
Aberrant Euploidy
Aneuploidy
Monoploid (x): chromosome number in a basic set
Euploidy: multiples of monoploid number
Polyploid: euploid with > two sets of chromosomes
Examples of Polyploidy
A.
Autopolyploidy : multiple chromosome sets from one
species
B.
Allopolyploidy:
chromosome sets from different
species
Meiotic Pairing in Triploids
Colchicine Induces Polyploidy
Chromosome Pairing in an Autotetraploid
Origin of the Amphidiploid Raphanobrassica
Origin of Three Allopolyploid Species of Brassica
Polyploidy in Animals
Parthenogenesis - development of unfertilized egg into
embryo
polyploidy in leeches, flatworms, brine shrimp
polyploidy in salamanders, lizards
Polyploid frogs and toads undergo sexual reproduction.
Polyploid fish (such as salmon, trout) are not unusual.
Triploid oysters are of economic value.
In general, polyploid mammals are not viable.