Studying Inheritance Flashcards
What is a genotype?
The genetic constitution (make-up) of an organism that describes all the alleles that an organism contains. The genotype sets the limits within which the characteristics of an individual may vary
What happens when populations are geographically isolated?
There is no interbreeding between members of each population so their genes become isolated, and over time they will change which can result in the formation of a new species
What is a phenotype?
The observable characteristics of an organism which is the result of the interaction between the expression of the genotype and the environment
What is a change to the phenotype that does not affect the genotype called?
A modification
What is a gene?
A section of DNA that is a sequence of nucleotide bases that usually determines a single characteristic of an organism
What is an allele?
A version of a gene
What are homologous chromosomes?
A pair of chromosomes that have the same gene loci and therefore determine the same features
Define homozygous
A condition in which the alleles of a particular gene are identical
Define heterozygous
Where the alleles of a particular gene are different
Define dominant
An allele that is always expressed in the phenotype of an organism
Define recessive
Where the effect of an allele is apparent in the phenotype of a diploid organism, but only in the presence of another identical allele
Define homozygous dominant
Where there are two dominant alleles
Define homozygous recessive
Where there are two recessive alleles
Define diploid
A term applied to cells in which the nucleus contains two sets of chromosomes
Define haploid
Cells that contain only a single copy of each chromosome e.g the sex cells or gametes
What does co-dominant mean?
Co-dominance is where two alleles both contribute to the phenotype as they are both equally dominant
Define multiple alleles
Where a gene has more than two allelic forms
What is mono hybrid inheritance?
The inheritance of a single gene
What is the law of segregation?
In diploid organisms, characteristics are determined by alleles that occur in pairs. Only one of each pair of alleles can be present in a single gamete
How many pairs of chromosomes do humans have?
23
