Genotype , Phenotype , Inheritance Flashcards
Define homozygous
Two alleles of a gene are the same
Define heterozygous
Two alleles of a gene are different
Define hemizygous
Only one alleles of a gene on the X chromosome ( ie in males only)
Define dominant
The dominant allele in a heterozygote determines the phenotype
Define recessive
The non dominant allele in a heterozygote
What is co dominance ?
When two alleles of the same gene are both expressed.
What are the three alleles for Gene I ( blood type )
i^A , I^B , I^O
Which alleles in Gene I are dominant and recessive ?
- Alle A is dominant over allele O
- Allele B is dominant over allele O
- neither allele A or B is dominant over eachother , they are co dominant
- O is recessive
What are the potential genotypes for Blood group A?
I^A I^ A
I^A I^O
What are the potential genotypes for blood group O?
i^OI^O
What is an example of an autosomal recessive disorder ?
Cystic fibrosis
Are males and females equally affected in autosomal recessive disorders ?
Yes
Can disease skip generations in autosomal recessive diseases ?
Yes
By convention , why do we say that autosomal dominant diseased individuals are always heterozygous ?
Because those who are homozygous for the disease are usually non viable for life . So always assume they are heterozygous
Can the disease skip generations in autosomal dominant diseases ?
No
