Genetics Flashcards
(33 cards)
Define genotype.
Genetic constitution of an organism.
Define phenotype.
The expression of the genetic constitution of an organism and its interaction with the environment.
Define homozygous.
A pair of homologous chromosomes carrying the same allele for a single gene.
Define heterozygous.
A pair of homologous chromosomes carrying different alleles for a single gene.
Define recessive allele.
Allele only expressed if there are no dominant alleles.
Define dominant allele.
Allele that will always be expressed if present.
Define codominant.
Both alleles are equally dominant and expressed in phenotype.
Define multiple alleles.
More than two alleles for a single gene.
Define sex-linkage.
A gene whose locus is on the X chromosome
Define autosomal linkage.
Genes that are located on the same chromosome (NOT sex chromosomes)
Define epistasis.
When one gene modifies/masks the expression of a different gene at a different locus.
Define monohybrid.
Genetic inheritance cross of characteristics determined by one gene.
Define dihybrid.
Genetic inheritance cross of characteristics by two genes.
What is the genetic coding of a monohybrid? Give an example.
single letter.
i.e. B or b
What is the genetic coding of a codominant allele? Give an example.
Gene^allele.
I^A or I^B
What is the genetic coding of multiple alleles? Give an example.
Gene^allele.
I^A I^B
What is the genetic coding of sex-linkage? Give an example.
Chromosome^allele
X^B or X^b
What is the genetic coding of a autosomal linkage? Give an example.
single letter.
AaBb
What is the genetic coding of epistasis? Give an example.
single letter.
EeBb
What is the process of creating a dihybrid cross?
- Parental phenotype
i.e. Round, yellow and green, wrinkled - Parental genotype:
i.e. RRYY and rryy - Possible gametes:
i.e. 4x RY or 4x ry - Offspring genotype:
i.e. RrYy - Possible offspring phenotype:
i.e. Round, yellow - Proportion of each phenotype:
i.e. 100%
How does crossing over in meiosis affect genetics?
Results in new combinations of alleles so predicted gametes in punnet square may differ.
How does autosomal linkage affect genetics?
The dominant allele for each gene linked on the same chromosome will be inherited together.
How does autosomal linkage affect the predicted phenotype ratios?
A & B are linked and a & b are linked.
New possible gametes: AB or ab.
Instead of w/out: AB, Ab, aB, ab
How does autosomal linkage and crossing over together affect genetics?
Because of AL, you would expect two phenotypes. But if you also experience crossing over, then you can observe more than two phenotypes.
