Week 2 Flashcards
How are new alleles originated?
New alleles originates through mutations of pre-existing allele
What is a mutation?
An heritable change the genomic DNA sequence.
Why could mutations occur?
- Errors during RNA replication
- DNA damage due to radiation or mutagenic chemicals.
What are the 4 differents type of modification of function in one allele due to mutation?
- Loss of function (null allele)
- Partial loss of function
- Improved function
- Change in function
What’s a null allele?
An allele that lost its function.
What’s complete dominance?
An allele shows complete dominance if the phenotype of a heterozigous individual is indistinguishable from the homozygous dominant.
What’s incomplete dominance?
In some cases the phenotype of the heterozygous us intermediate between the phenotype of both homozygous form.
What’s codominance?
Heterozygous shows the phenotype of both homozygous forms.
What’s a lethal allele?
An allele of an essential gene that fail to produce a functional product and it will be lethal only when it’s homozygous.
What’s conditional mutation?
Genotype and environment act together to determinate the phenotype of an organism.
What’s permissive temperature?
The range of temperatuor in which allele produce the gene products
What’s restrictive temperature?
The range of temperature in which the protein lose its function
What are the two parameters of conditional mutations?
Penetrace and Expressivity
What’s penetrance?
Proportions of individuals in a group with a given phenotype that show the effective phenotype
What’s expressivity?
The degree to which a phenotype is expressed in an individual
