Mendelian Genetics Flashcards
What is law of segregation
A cell with Aa, after meiosis would be (A) and (a).
What is a gene
A code for a specific characteristic/trait
What is an allele
A version of a gene like purple or white petals
Dominant Allele
Is the trait that appears
Recessive allele
Only visible when homozygous
What is locus
Location of gene on chromosome
Carrier
They carry a copy of a recessive allele that causes a genetic disease (Hemophilia)
Purpose of test cross
Testing a heterozygous with a known homo recessive to determine if it is hetero. used to determine genotype of individual
Explain test cross
Cross Aa or AA with aa. Results will indicate genotype of female (in this case)
Genotype
combination of alleles
Phenotype
Physical trait observed
What is a dihybrid cross?
looking at two distinct traits, in total 4 genes observed
What is law of independent assortment
One gene will not affect the expression of another gene. Having blue eyes won’t affect your height
What is phenotypic ratio for dihybrid punett square of 2 heterozygous dihybrid cross
9:3:3:1
What is co-dmoinance
When you end up with a mixture of traits because you have two dominant traits
For example a roan animal, both traits would be expressed. In a cat, both black and white would be expressed
What is incomplete dominance
Where the alleles mix, red and white would make pink
Multiple alleles
some genes have more ethanol two alleles, in this case you would still only inherit 2 though
how many blood type alleles
3
Alles of blood type
Dominant - A and B
Recessive - O
What is a sex-linked allele
An allele found on a sex chromosome (Usually x because they are bigger)
Explain the inheritance of x-linked genes
If an x-linked trait is recessive than it appears more in males because males only have one x chromromosome, therefore it is easier to appear in males
An example would be colourblindness which is more common in men.
Explain y-linked traits
Not as common, only passed from male line
What are barriers bodies
Because females have two x chromosomes, they dot want to express both genes, therefore one chromosome must be deactivated, the deactivated one becomes a Barr body
What is a lethal allele
An allele that. usually causes a lethal trait, kills embryo or newborn, results in non-mendelian ratio
