t7 Flashcards
What is a genotype?
All of the alleles that an organism carries on its chromosomes.
Genotype determines potential traits of an organism.
Define phenotype.
Observable characteristics of an organism which are the result of the genotype as well as environmental factors.
Phenotype includes traits such as height, color, and behavior.
What does it mean for an organism to be diploid?
It carries two alleles for each gene that it possesses on each chromosome.
Most eukaryotic organisms are diploid.
What is a dominant allele?
Only a single allele is required for the characteristic to be expressed in the phenotype.
Dominant alleles mask the effect of recessive alleles.
What are the two forms of dominant alleles?
- Heterozygous dominant
- Homozygous dominant
Heterozygous dominant has one dominant and one recessive allele, while homozygous dominant has two dominant alleles.
What is a recessive allele?
The characteristic is only expressed if there is no dominant allele present.
Requires two recessive alleles (homozygous recessive) for expression.
What is codominance?
Both alleles are expressed equally and contribute to the phenotype.
May result in a blend of traits or both traits being visible.
What does ‘pure breeding’ mean?
It refers to a homozygous pair of alleles.
Pure breeding individuals produce offspring with the same traits.
What is an allele?
An alternative form of a gene.
Alleles can be dominant, recessive, or codominant.
What is a locus?
The specific position of the gene on the chromosome.
Each gene’s locus is consistent across homologous chromosomes.
Where are alleles found on chromosomes?
At the same loci on the homologous pairs of chromosomes.
This means that alleles for a gene are located in the same position on each chromosome of a pair.
