Changes in the genetic makeup of a population Flashcards
Population genetics and variation
What is a population
Is a group of organisms of the same species living in a specific region at a given time
Population genetics and variation
Define monomorphic population
Is one in which there exist only one variant of a trait
Population genetics and variation
Define polymorphic population
Is one in which there exists more than one variant of a trait.
Population genetics and variation
Name 4 variable characteristics group
Structural (ie number of toes)
Biochemical (ie dif metabolic characteristics)
Physiological (ie some people can smell substance other cant)
Behavioural (ie dif strategies of coping with stress)
Population genetics and variation
Two types of variations
Define
-Continuous variation 🧍♂️
-Discontinuous variation🩸
- Where there are an infinite number of variant along a spectrum (eg height)
- Where there are a discrete and finite number of variants (eg blood groups)
Causes of variation (phenotype)
First way a gene can affect ones phenotype
Monogenic traits
traits that are determined by purely a single gene. (specific and discrete phenotype therefore, exhibit discontinuous variation) -not effected by environment
Causes of variation (phenotypes)
Second way a gene can affect ones phenotype
Polygenic traits define
Polygenic traits, traits that are controlled by many genes (may exhibit continuous or discontinuous depending on # of genes note if many genes there is environmental impact = continuous)
Mutations
Define
- spontaneous mutation
- induced mutation
Occurs during DNA replication
Caused by environmental factors eg smoking
Causes of variation (phenotype)
Environment
Example; Children in Africa being starved, they would be thinner and shorter than an individual who is well fed.
Gene pool and allele frequencies
Allele define👖👽🧬
Each of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.
Gene pool and allele frequencies
Gene pool define
All genetic information contained within that population. (aggregation of all the alleles in all organism in a population)
Gene pool and allele frequencies
What is the Hardy-Weinberg equilibrium In a given population, if... -🤼🤼🤼 -🎲 -🤰 -🚣♀️ Therefore....Then allele frequencies will remain constant and therefore the proportion of individuals with each phenotype will remain roughly constant.
- Pop is large
- Mating is random and not selective
- all offspring are viable and equally fertile
- The pop is close (ie no migration)
Gene pool and allele frequencies
Factors that affect allele frequencies
Non-random mating (selection)
Define -Natural selection
-Artificial selection
- Is a major mechanism by which evolution occurs- hence the well-known phrase evolution by natural selection
- instigated by humans in selective breeding
Gene pool and allele frequencies
Factors that affect allele frequencies
Open population (migrating)
Migration, whether it is immigration or emigration (not a representative sample), is also known as gene flow. Gene flow can alter allele frequencies as well.
Gene pool and allele frequencies
Factors that affect allele frequencies
Small population (genetic drift)
If you have small population, allele frequencies will change purely by change. This random fluctuation in allele frequencies is known as genetic drift.
Small population (genetic drift)
Define the bottleneck effect (greatly reduce genetic diversity)
is the phenomenon where allele frequencies are highly volatile secondary to a sudden drop in the population ie major natural disaster (death)
Small population (genetic drift)
Define founder effect (greatly reduce genetic diversity)
is the phenomenon where allele frequencies are highly variable in a small population that has emigrated from a large population and formed a new separate population.
Define sexual selection
It doesn’t matter how long an individual lives but how often they reproduce.
Mutations
Define
create new alleles when they occur within a gene. These mutations enter the gene pool if they can be passed on between generations.
Mutations
Define germline mutations 🥚🍳
is a mutation that happens in reproductive tissue and able to pass on offspring.
Mutations
Define somatic mutation
Every other mutation not reproductive therefore cannot be passed on.
Mutations
Define the two types of mutation
- point mutations
- block mutations
- changes to a single base pair
- changes to entire segment of dna
Point mutations
Define silent mutations
Are base substitution mutation that lead to no change in the amino acid sequence of the corresponding protein.
Point mutations
Define missense mutations
Are base substitution mutations that lead to a change in the amino acid sequence by the replacement of one amino acid with another. (AAC–>ACC)
Point mutations
Define nonsense mutations
Are base substitutions that lead to the mutated triplet coding for stop, prematurely the amino acid sequence in the polypeptide chain.
Block mutations
Define duplication
Part of dna breaks off one chromosome and joins its homologous partner.
Block mutations
Define inversion
Is where a segment of dna is ;chopped up’ and reinserted in the same place, but backwards
Block mutations
Insertion
Is whee a segment of dna from another molecule is copied and inserted into the middle of another segment of dna.
Block mutations
Block deletion
Is where a segement of dna is removed
Block mutation
Translocation
Is where a segment of dna from one molecule detaches and re-inserts itself in another molecule
Natural selection
Darwin suggest that the process by which random evolutionary changes are selected for by nature in a consistent, orderly, non random way.
Allopatric speciation define🌏
Is the phenomenon whereby a new species is formed due to the geographical isolation of two populations of the same species.
Define species
Is complete set of all organism able to mate and produce viable and fertile offspring under natural conditions.
Allopatric speciation
The differences in phenotypic characteristics (isolated mechanism) - - - -
- Mating calls may no longer be recognized between populations
- The genitalia of the organism of two pop may be incompatible
- Mating seasons may be different
- Produce sterile offspring
Selective breeding define
Is a method of breeding where animals with particular phenotype that are beneficial to the breeder, are allowed by the breeder to reproduce to a greater capacity than other animals of the same population.
Selective breeding
Define artificial selection
where breeder acts as selective pressure
