Genetics Flashcards
What is a gene?
A discreet unit of DNA that codes for a protein.
Heritable factor.
What is a locus?
The position of gene on a chromosome.
What is an allele?
An alternative form of a gene that produces a distinguishable phenotypic effect.
What is a genotype?
The alleles contained in an organisms cells.
What is a phenotype?
The characteristics of an organism determined by it’s genotype and it’s environment.
What does homozygous mean?
An organism that possesses 2 identical alleles of the same gene.
What does heterozygous mean?
An organism that possesses 2 different alleles of the same gene.
What is a dominant allele?
Allele which is always expressed in the phenotype if it is present in the genotype.
What is a recessive allele?
Allele which is only expressed in the phenotype when the dominant allele is not present.
What is codominance?
When both alleles affect the phenotype of a heterozygous individual.
What is F1?
First filial generation, the first hybrid offspring of two pure breeding parents.
What is F2?
Second filial generation, the offspring from interbreeding the F1 generation.
• Crossing two true-breeding parents differing
in two characters produces dihybrids in the?
F1 generation, heterozygous for both
characters
What is the medelian law of segregation?
the members of a pair of homologous chromosomes segregate during meiosis and are distributed to different gametes.
When might Inheritance of characters by a single
gene deviate from simple Mendelian patterns?
— When alleles are not completely dominant or
recessive (incomplete dominance/codominance)
— When a gene has more than two alleles
— When a gene produces multiple phenotypes
