BLGY1232 Patterns of Inheritance
Key terms;
Genotype – the sum total of the genetic information contained in an organism; the
genetic constitution of an organism with respect to one or a few gene loci under
consideration
Phenotype – the observable characteristics of an individual resulting from the
interaction between the genotype and the environment in which development
occurs
Locus – the place at which a particular mutation or a gene resides in a genetic map;
often used interchangeably with gene
Allele – one of a number of alternative forms of a gene, each possessing a unique
nucleotide sequence; different alleles of a given gene are usually recognized,
however, by the phenotypes rather than by comparison of their nucleotide
sequences
Diploid – a cell, tissue or organism having 2 chromosome sets
Haploid – a cell, tissue, or organism having one chromosome set
Homozygous – a cell or organism having identical alleles at given locus on
homologous chromosomes
Heterozygous – a cell or organism having different alleles at given locus on
heterologous chromosomes
Dominant – a relationship between 2 alleles where is one is dominant it is expressed
in the phenotype of the heterozygote
Recessive – the allele that is not expressed in the phenotype if there is a dominant
allele present
Wildtype – the prevailing phenotypes or the prevailing alleles, if any, in a natural
population
Mutant – an allele different from a pre-existing one as a result of mutation; or an
individual carrying such an allele
Self fertilization (selfing) – producing offspring using gametes derived from a single
organism
Cross fertilization (crossing) – producing offspring by fusing gametes derived from
different organisms
True breeding/ pure breeding strains – strains of organisms that when mated
randomly among themselves always produce identical progeny as they are
homozygous at the loci under study
Pleiotropgy – an effect whereby a single mutant gene affects 2 or more apparently
otherwise unrelated aspects of the phenotype of an organism
Mendelian Genetics
Gregor Mendel first discovered and formulated the laws of inheritance to found the
science of genetics
Mendel’s first laws – the principle of segregation states that the 2 members of a
gene pair segregate from each other in the formation of gametes diploid
organisms produce haploid gametes
Key terms;
Genotype – the sum total of the genetic information contained in an organism; the
genetic constitution of an organism with respect to one or a few gene loci under
consideration
Phenotype – the observable characteristics of an individual resulting from the
interaction between the genotype and the environment in which development
occurs
Locus – the place at which a particular mutation or a gene resides in a genetic map;
often used interchangeably with gene
Allele – one of a number of alternative forms of a gene, each possessing a unique
nucleotide sequence; different alleles of a given gene are usually recognized,
however, by the phenotypes rather than by comparison of their nucleotide
sequences
Diploid – a cell, tissue or organism having 2 chromosome sets
Haploid – a cell, tissue, or organism having one chromosome set
Homozygous – a cell or organism having identical alleles at given locus on
homologous chromosomes
Heterozygous – a cell or organism having different alleles at given locus on
heterologous chromosomes
Dominant – a relationship between 2 alleles where is one is dominant it is expressed
in the phenotype of the heterozygote
Recessive – the allele that is not expressed in the phenotype if there is a dominant
allele present
Wildtype – the prevailing phenotypes or the prevailing alleles, if any, in a natural
population
Mutant – an allele different from a pre-existing one as a result of mutation; or an
individual carrying such an allele
Self fertilization (selfing) – producing offspring using gametes derived from a single
organism
Cross fertilization (crossing) – producing offspring by fusing gametes derived from
different organisms
True breeding/ pure breeding strains – strains of organisms that when mated
randomly among themselves always produce identical progeny as they are
homozygous at the loci under study
Pleiotropgy – an effect whereby a single mutant gene affects 2 or more apparently
otherwise unrelated aspects of the phenotype of an organism
Mendelian Genetics
Gregor Mendel first discovered and formulated the laws of inheritance to found the
science of genetics
Mendel’s first laws – the principle of segregation states that the 2 members of a
gene pair segregate from each other in the formation of gametes diploid
organisms produce haploid gametes
