Inheritance Flashcards
Locus definition
Physical location occupied by a gene on a chromosome
Gene definition
A specific sequence of nucleotides (a t c g) in DNA molecule which codes for a RNA/polypeptide.
Basic unit of hereditary
Allele definition
An alternative form of the same gene responsible for variation in a particular characteristic
Alleles of a gene occupy the same gene locus on homologous chromosome
Slight difference in nucleic acid sequence
Occurs in pairs in diploid individual, only 1 of a pair is represented in a gamete
Codominance definition
2 alleles are expressed equally in the phenotype of heterozygote
Codominant of each other
Incomplete dominance definition
One allele for a specific trait not completely dominant over other allele, resulting in heterozygote offspring having phenotype which is intermediate of homozygous parents
Genotype definition
The genetic make up of an organism with respect to alleles under consideration
Phenotype definition
Observable characteristics
Test cross definition
Crossing of an organism having unknown genotype with homozygous recessive organism to determine unknown genotype
Sex linkage definition
Gene carried on sex chromosomes are sex-linked
Why compare X more often for sex link?
Y chromosome smaller than X chromosome, Carries very few genes compared to X. Characteristics determined by genes carried on the non-homologous region of X chromosome will appear in males, even if they are recessive. Thus males have higher tendency to inherit sex-linked diseases as they only have 1 X chromosomes, whereas females have 2 X-chromosomes.