Inheritance Flashcards
Definition of gene
A section of a molecule of DNA that codes for a specific protein
Definition of alleles
Alleles are different versions of a particular gene.
Definition of phenotype
The observable characteristics of an organism.
Definition of genotype
The combination of alleles that control each characteristic.
Definition of dominant
A dominant allele is always expressed, even if only one copy is expressed
Definition of recessive
A recessive allele is only expressed is two copies are present (therefore no dominant allele present)
Definition of homozygous
When the 2 alleles of a gene are the same
Definition of heterozygous
When the 2 alleles of a gene are different
Definition of codominance
When both alleles within a genotype are expressed in the phenotype of an individual
What are the 2 main types of variation?
Continuous and discontinuous variation
Define continuous variation
A characteristic that changes gradually over a range of values e.g. height
Define discontinuous variation
A characteristic with only a limited range of possible values
Why do people have a wide range of heights but have a specific blood group?
Height is continuous.
Height is polygenic and depends on the combination of many genes.
Blood group is discontinuous
Blood group is monogenic
Define polygenic
A characteristic, such as height or skin colour, that is influenced by two or more genes
Pair of chromosomes for men
XY
