7A - Inheritance Flashcards
What does ‘codes for’ mean?
Contains the instructions for.
Define gene:
A sequence of bases on a DNA molecule that codes for a protein (polypeptide), which results in a characteristic, e.g. a gene for eye colour.
Define allele:
A different version of a gene. There can be many different alleles of a single gene, but most plants and animals, including humans, only carry two alleles of each gene, one from each parent. The order of bases in each allele is slightly different - they code for different versions of the same characteristic.
Define genotype:
The genetic constitution of an organism - the alleles an organism has.
Define phenotype:
The expression of the genetic constitution and its interaction with the environment - an organism’s characteristics.
Define dominant:
An allele whose characteristic appears in the phenotype even when there’s only one copy. Dominant alleles are shown by a capital letter.
Define recessive:
An allele whose characteristic only appears in the phenotype if two copies are present. Recessive alleles are shown by a lower case letter.
Define codominant:
Alleles that are both expressed in the phenotype - neither one is recessive.
Define locus:
The fixed position of a gene on a chromosome. Alleles of a gene are found at the same locus on each chromosome in a pair.
Define homozygote:
An organism that carries two copies of the same allele.
Define heterozygote:
An organism that carries two different alleles.
Define carrier:
A person carrying an allele which is not expressed in the phenotype but that can be passed on to offspring.
What do genetic diagrams show?
The possible genotypes of offspring.
Are human haploid or diploid organisms?
Diploid.
What does diploid mean?
Has two sets of chromosomes so have 2 alleles for each gene.
