USC FNP bridge course 4.2 Principles of inheritance
Principles of inheritance
In human cells the nuclei contain a diploid number of chromosomes. Genetic information is carried on 23 pairs of homologous chromosomes- one from the mother and one from the father
22 pairs of autosomes and 1 pair is sex chromosomes.
In rare cases someone may carry an extra chromosome.
Gene is a unit of DNA that carries the genitic information for one protein
allele is different forms of a gene.
Genotype is a set of alleles, the genetic composition
the phenotype is related to the protein that is made and how that is expressed.
Important terms in genetics
Genotypes for selected human phenotypes
Genotype is either uppercase or lower case.
review of common terms
capital letters and lower case is one particular allele of a particular gene. Upper case is dominant.
If you have an upper case and lower case the one that is dominant (upper case) shows up as the phenotype.
Same alleles for the dominant or recessive trait
one dominant and one recessive, two different alleles are present.
The dominant phenotype will be expressed.