6.2 Patterns of inheritence Flashcards
What is continuous variation? What is an example?
When the individuals in a population very within a range. No distinct categories eg heigh and weight.
What is discontinuous variation? What is an example?
Where there are two or more distinct categories that each individual falls into with no intermediates. eg blood group.
What is phenotypic variation?
variation within an organisms phenotype.
What 3 factors can influence phenotypic variation?
- Genotype
- The environment
- Genotype and the environment
What is myogenic?
When characteristics are controlled by only one gene.
What is polygenic ?
where characteristics are influenced by many genes
What is a gene?
A sequence of bases on a DNA molecule that codes for a protein.
What is an allele?
When there is more then one version of the same gene they are called alleles.
What is a locus ?
the specific location where the allele for each gene is found on a chromosome.
What is a genotype?
It is all of the alleles an organism has.
What is a phenotype?
the characteristics of an organism
What is homozygous?
Where an organism carry’s two alleles that are the same. eg AA or aa
What is heterozygous?
When an organism carry’s two different alleles eg Aa
How is a dominant allele shown?
with a capital letter eg A
What is a recessive allele?
Those who’s characteristics only appear in the phenotype when two copies are present
How are recessive alleles shown?
With lowercase letters eg a
What is a codominant allele?
We’re both alleles are expressed in the phenotype because neither one is recessive.
what is a carrier?
A carrier is a person carrying an allele which is not expressing the phenotype, but that can be passed on to offspring.
What is epistatis?
Where the allele of one gene masks the expression of alleles of other genes
What will the ratio be for recessive epistatic alleles ?
9:3:4
What is the ratio for dominant epistatic cells?
12:3:1
