17) Inherited Change Flashcards
What is genotype?
The genetic makeup of an organism, describing all the alleles they have
What is Phenotype?
The observable characteristics of an organism
What is a gene?
A section of nucleotide bases coding for a particular polypeptide
What is a locus?
The position of a gene on a particular DNA molecule
What is an allele?
A different form of the same gene
How many pairs are in homologous chromosomes?
2
What is homozygous?
Where the same allele is on each chromosome
What is heterozygous?
Where there is a different allele on each chromosome
What is meant if an allele is dominant?
It is the allele that is expressed in the phenotype
What is meant if an allele is recessive?
It needs both alleles to be expressed
What is meant if an organism is diploid?
There are 2 pairs of chromosomes
What is meant by codominant?
When 2 alleles work together and both contribute to the phenotype
What is pure breeding and what would it produce in plants?
- breeding between members of the same species
- produces homozygous dominant plants
What is the first filial?
Offspring of 2 different pure-bred species that are cross-bred
What is an enzymatic mechanism?
The mechanism that brings about a characteristic from the proteins to the visible feature
How many chromosomes does a gamete contain?
23
What occurs in the phenotype of codominant alleles?
A blend of both features
What is an example of incomplete dominance?
Speckled chickens
What is incomplete dominance?
When the dominant allele isn’t completely expressed when the recessive allele is around
Is there a clear dominant allele in incomplete dominance?
No, both features are mixed
What is an example of incomplete dominance
Snapdragon flowers - these can be red, pink or white
What is a polygenic trait?
When there are many genes coding for one trait such as height and skin colour, so all genes work together to code for the trait
e.g. AABbCc, Aabbcc, AaBbCc
What can influence polygenetic traits?
Environmental factors, although this doesn’t alter the genetic state
What is epistasis?
When one gene depends on another gene in order for it to be expressed