Evolution Of Population Flashcards
Population
A group of the same species living together are reproducing viable offspring
Evolution
A change in allele frequencies over generations
What is the one mechanism of adaptive evolution
Natural selection
Polygenic inheritance
Multiple genes that code for a trait a contribute for a phenotype
Living things are made of 4 categories of macromolecules called
Lipids
Polysaccharides
Polypeptides
Polynucleotide ( nucleic acid)
In prokaryotes. What happens to mRNA
Nothing it is ready to go after transcription took place
In eukaryotes what happens to mRNA
It gets sliced. The introns are removed and the exons are left to leave a mature mRNaa that’s shorter.
Genetic code
A list of codons
All organisms have the same genetic code which hints at a common ancestor for everything
Codon
Three nucleotide sequence of mRNA that specifies an amino acid
Organisms use how many amino acids
20 and they’re are only 4 nucleotides so 3 are needed to soecify amino acids 3^3
Redundancy
Genetic code is redundant. It is repetitive since there are more codons needed to specify 20 amino acids so different codons can mean the same amino acid
(Genetic code is not ambiguous)
Codon can only mean one amino acid
Allows for silent mutation.
Is all variation in species genetic
No. Environmental reason such as diet can lead to a different appearance not genetically though
What are the 3 mechanisms of evolution
Genetic drift
Gene flow
And natural slelection
Genetic drift
Is the loss of alleles from an allele pool from an entirely random event that doesn’t look at maladaptive or adaptive traits
Genetic drift happens to all populations. But the effects become more pronounced the smaller the population is.
Population is fixed
The allele frequencies of p or q are either 1 or 0
However not permanent because of mutation
Gene flow
Genes from one population to another
Both population undergo evolution
One instance of genetic drift is the founder effect which is?
A small number of individuals from a population become isolated and may become founders of a new population
Ex a flock a birds that encounters a storm a some get separated and start a new population
Bottle neck effect
A large majority of the population is eliminated and they’re only a few survivors
Genetic makeup is limited as they start new population. Genetic variation is limited and the population may be sic work less to extinction
Gene flow and natural selection acting together
This will undo natural selection as gene flow is random
Directional selection
The selection resulting in one of the two extremes being disfavored
The curve shifted to one direction or the other.
Distruptive selection
Disfavored the intermediate phenotype unimodial distribution turns to bimodal two humps on curve
Stabilizing selection
The medium get more favored and the extremes get removed
Incremental mutations allow for what
Drastic differences in phenotype because of natural selection that picks for adaptability
Sexual selection
Survival is only half the succesubulity.
Reproduction also requires mating event ma that may require genes that are favored by a mate
Heterozygote advantage
Of the three possible organisms for one gene , the heterozygous is the best in terms of fitness so they will be their greatest in terms of numbers
Ex human gene responsible for sickle cell disease
Frequency dependent selection
The frequency of one trait over another determines the success of that trait
