Chapter 14 & 15- Genetics Flashcards
What is a single gene trait?
A trait that is controlled by one gene that has two alleles. variation in this gene leads to only two possible phenotypes.
What is a test-cross?
The crossing of an organism with an unknown genotype, with a homozygous recessive organism
What is concept of dominance?
The idea that one trait is dominant over another and will always be expressed when present.
What happens in incomplete dominance?
The heterozygous offspring display an intermediate phenotype. Thus, all genotypes have their own phenotype.
What is codominance?
Every allele variation is expressed in the phenotype.
What is multiple allelism?
One gene has many alleles/variations.
What is epistasis?
A gene at one locus (location) alters the phenotypic expression of a gene at a second locus (location)
Traits influenced by more than one gene are what?
Polygenic (quantitative) traits
Characteristics of polygenic (quantitative) traits
- Dominant alleles contribute an increment to the phenotype. All dominant alleles are equal in their contribution.
- Phenotype is determined by the sum of all dominant alleles present.
- Shows continuous variation = range in phenotypes
- The amount of variation in a population is called Variance
Who do males inherit their X chromosome from?
Mom only
Who do males get the Y chromosome from?
Dad only
How many X chromosomes does a male inherit?
1
Where do females get their X chromosomes from?
1 X chromosome from dad and 1 X chromosome from mom
What is “deletion” in a chromosome structure?
A removal of a chromosome segment
What is “duplication” in a chromosome structure?
Repeats a segment
