Mandelian Genetics Flashcards
What is an ‘Allele’?
An ‘Allele’ is the type of gene a person inherits.
Difference between Dominant and Recessive genes.
Dominant: An allele that is expressed in a person and can mask a recessive allele (-T).
Recessive: Allele that can be masked by a dominant allele (-t)
What does Homozygous mean?
Homozygous is when their are two of the same alleles for a gene, either two dominant or two recessive (ex: TT/tt)
What does Heterozygous mean?
Heterozygous is when their are two different alleles for a gene. Dominant will always be expressed as (Tt)
Note: Dominants always mask out recessive. But that doesn’t mean that recessive genes aren’t there.
What’s a Genotype?
They are a chain of letters that represent the actual genetic makeup of an individual (-TT/Tt/tt)
What does Phenotype mean?
Phenotype is a trait that can be observed in a person (Blue eyes vs. Brown and Short vs. Tall)
What is Incomplete Dominance?
Incomplete Dominance is when not all of the alleles act in a ‘Purely’ Dominant or ‘Purely’ Recessive manner.
Sometimes, Heterozygous individuals get a phenotype that is halfway between the dominant and the recessive allele.
What is an example of Incomplete Dominance?
An example of Incomplete Dominance can be seen in Snap Dragon flowers.
Snap Dragons petal color experiences incomplete dominance between red petals (CR) and white petals (CW), heterozygous flowers (CRCW) appear pink.
If you were to cross both the Red & White flowers together, a Pink petal color would be observed.
What is Co-dominance?
Co-dominance occurs when heterozygous individuals express two alleles in full at the same time.
What’s an example of Co-dominance (in Humans)?
An example of Co-dominance in humans is in regards to blood type, more specifically the ‘AB’ blood type. This is because there is one ‘A’ allele and one ‘B’ allele. Both of those alleles are expressive and dominant, and because of this they are co-dominant.
