MONOHYBRID INHERITANCE Flashcards
the 3 main genotypes, which phenotype (dominant or recessive) will each genotype produce?
homozygous dominant, heterozygous or homozygous recessive. Both homozygous dominant and heterozygous genotypes produce a dominant phenotype, while a
homozygous recessive genotype will produce a recessive phenotype
what is the difference between a dominant and recessive allele?
A dominant allele will mask the recessive allele in a heterozygous individual. This means the visible phenotype reflects the dominant allele, while the recessive trait is only shown if the organism has two recessive alleles.
what are the conventions used for representing a dominant and recessive allele?
by using a letter. A dominant allele is
expressed using a capital letter (i.e. G), while a recessive allele is expressed
using a lowercase letter (i.e. g).
why do true genotype and phenotype ratios not always match the predicted ratios using punnett squares?
Actual trait ratios in offspring don’t always match predictions because each offspring is independent. This means one offspring’s traits don’t affect the next. With fewer offspring, it’s less likely that the real ratios will match what was expected.
define homozygous.
Used to describe an individual that has two identical alleles for a trait
define heterozygous.
used to describe an individual that has two different alleles for a trait
what is the difference between the two alleles in a full dominant-recessive relationship versus two alleles in a co-dominant relationship?
n a dominant-recessive relationship, the dominant allele hides the recessive one, so only the dominant trait is seen. In a co-dominant relationship, both alleles are fully expressed together, so you see traits from both alleles.
what is the difference between the two alleles in a full dominant-recessive relationship versus the two alleles in an incomplete dominant-recessive relationship?
In a dominant-recessive relationship, the dominant allele completely hides the recessive one, so only the dominant trait is seen. In an incomplete dominant relationship, both alleles blend together, resulting in a mixed trait. For example, red and white flowers may produce pink flowers.
what is the definition of a lethal allele?
Lethal alleles cause death in an individual when they are in their homozygous
form. Whereas when they are in their heterozygous form they allow the
individual to survive
what happens to the genotype and phenotype ratios when there is a lethal allele?
A lethal allele causes some genotypes to not survive, changing the expected ratios. This results in missing genotypes and altered visible traits, reducing the number of surviving offspring and affecting both genotype and phenotype ratios.
what is meant by the term “multiple alleles”
Multiple alleles refer to a gene that has more than two possible alleles.
Although multiple alleles may be present for a gene, an individual can only
ever have two alleles, one from each parent
Imagine there are two alleles: one allele for red hair colour and one allele for white colour. What phenotypes would you expect when the relationship between the two alleles is:
*Completely dominant
*Incompletely dominant
*Co-dominant
For red and white hair alleles: in a completely dominant relationship, only red hair shows; in incomplete dominance, heterozygous individuals have pink hair; and in co-dominance, individuals have both red and white hair.
what does co-dominant mean?
Both alleles are dominant and both are expressed if present (e.g. AB blood type)
