Patterns of inheritance 6.2 Flashcards
Continuous variation
Individuals in population vary within range
Numbers specific numbers
discontinuous variation
When there’s two more distinct categories
variation can be influenced by
Environment
GENES
Codominant
Alleles that are both expressed in the phenotype
Both are dominant
LOCUS
The fixed position of a gene on a chromosome
Alleles are found at the same locus on each each chromosome in a pair
homozygote
Organism that carries two copies of the same allELE
HETEROZYGOTE
Organism that carries two different audios
GENE
Set a sequence of bases on DNA that codes for protein which results in a characteristic
ALLELE
A different version of a gene
monogenic cross - RR x rr
3:1
dihybrid cross. - RRYY x rryy
9:3:3:1
Codominant cross - both homozygous
1:2:1
sex linked genes are mainly carries on the
x chromosome because it longer than y
Autosomal genes
chromosomes which arent sex linked
genes on the same autosome are linked
On the same autosome, so they’ll stay together during independent assortment
Alleles are passed on to offspring
epistatic gene
The allele of the epistatic gene mask the expression of the alleles on other genes
genotype
alleles of a gene possessed
by that individua
phenotype
observable characteristics of an organism
speciation
splitting of a genetically similar population, into two or more populations that undergo genetic differentiation and eventually reproductive, isolation, leading to the evolution of two or more new species
allopatric speciation
Information of two different species from one original species due to geographical isolation
Sympatric speciation
formation of two different species from one original species due to reproductive isolation, while the populations inhabit the same geographical location
Stabilising selection
Occurs when the organisms environment remains unchanged the intermediate phenotypes are favoured and extreme phenotypes are selected against.
Directional selection
A type of natural selection that occurs when an environmental change favours a new phenotype and results in a change in the population mean
disruptive selection
Favours the extreme phenotype, and the intermediate phenotype is selected against
Genetic drift
when probability affects which individuals in a population survive, breeding pass on their genes, and not the environmental selection pressures
Occurs when there is a gradual change in a little frequency in a small population due to chance
Genetic bottleneck
when a large population suffers a dramatic fall in numbers, due to a major event occurring reducing the genetic diversity, so the alleles are lost
