Inheritance Flashcards
Define homozygous
Both genes found at the same gene locus upon 2 homologous chromosomes contain the same allele
Define heterozygous
Where 2 genes found at the same gene locus on to 2 homologous chromosomes are different alleles
Define dominant allele
Allele within a heterozygous organism that is expressed in the phenotype
Define recessive allele
An allele that will only be expressed if the organism is homozygous recessive
Define co domainant
Where alleles of more tham 1 variety can contribute to the phenotype
What are the five steps to showing a genetic cross
Parental phenotype Parental genotype Gametes made Cross the gametes Work out the ratio
What is the “golden ratio” for a dihybrid cross?
9:3:3:1
Describe how co dominance occurs within snapdragons
One allele produces enzyme to form a red pigment
Another allele produces enzyme that doesnt make pigment
Both alleles are codominant so can be expressed at the same time
If the organism is heterozygous the colour will be pink becuase some red pigment produced but not loads
Why are the X and Y chromosomes significant for inheritance?
X chromomes is larger than Y chromosome
Therefore X contains more genes
Males ( human) only have one X chromomes so have a greater chance of having recessive conditions that occur in the X chromosome
What is autosomal linkage? When making population estimates with autosomal linked genes what assumptions need be made?
Autosomally linked genes are genes that occur on the same chromosome. Hence they are inherited together
Assume: no crossing over has occured
All linked genes remain together
What is epistasis?
Where one allele effects the expression of another within the phenotype
What does the Chi squared test, test? When would you accept a result ?
Tests wether a significant difference occurs between data sets, tests against the Null hypothesis
Observed vs expected
Accept hypothesis when 95% significant
