Inheritance Flashcards
Define alleles
Different forms of the same gene
Define a genotype
Genetic information regarding the types of alleles present in a genome
Define a phenotype
The characteristics shown as a result of the genotype
Define a Dominant allele
If present at all, will show in the phenotype
Define a recessive allele
Must be present in homozygous form to show in phenotype
How is a recessive disease inherited
Parents being carriers by having one copy of the recessive allele
How can you test if an organism has a heterozygous or homozygous dominant genotype
A back cross
What is the mendelian ratio for monohybrid homozygous cross
1:2:1
What is the mendelian ratio for a dihybrid double heterozygous cross
9:3:3:1
How can a phenotype of co-dominance be expressed
As a mixed phenotype, eg, roan cattle that are patchy
As incomplete dominance, eg, pink carnations from white and red parents
How does linkage work
If two different genes are found on the same chromosomes there is a possibility for crossing over and so a Mendelian ratio is less likely
Name two conditions that are sex-linked
Duchenne Muscular dystrophy
Haemophilia
How do sex-linked conditions work
They are carried on the X chromosome and so if are present in a male genotype, will show in the phenotype. Females are often carriers and have male children with the conditions
Where are mutations more likely
In cells with short cycles
What phase of the cell cycle are mutations most likely in
S phase
