Genetic Changes in a Population Over Time Flashcards
Gene pool
Refers to the sum of all alleles at the gene loci of a population of a species at a time
Allele frequency
the relative proportion of a particular allele in a gene pool
Mutation
any change to the DNA of an organism that is UNPREDICTABLE and RANDOM
Beneficial, Neutral and Harmful mutations
Neutral - have no effect on survival
Beneficial - increases the likelihood of survival
Harmful - decreases the likelihood of survival
Spontaneous mutation v induced mutation
spontaneous: mutation arise during cell division
induced: mutation caused by ionising radiation or chemical mutagen
inheritability of mutations
only germline mutations (in reproductive tissue) is inheritable; somatic mutations are not (organs)
aneuploidy
the incorrect number of chromosomes (one or multiple extra/less) → result of non-disjunction
polyploidy
refers to a condition in which an organism has more than two matched sets of chromosome (ie strawberries)
Point mutation
amount of DNA changed is less than a gene (single/multiple bases)\
- substitution
- deletion
- insertion
Substitution mutation
whereby a single base or small group of bases are replaced
→ nonsense; mutation causes STOP codon»_space; results in truncated/shortened polypeptide chain
→ missense; conservative»_space; translates diff aa. Protein has same chem. nature and retains functionality
non-conservative»_space; translates diff aa. Changes functional shape of protein due to different chem. nature
→ silent: translates same aa. No functional change to protein
frameshift mutation
deletion or additions of a nucleotide that changes the ribosome reading frame from the point of mutation
- every aa from the point of mutation can potentially change
- disruption to the function and shape of the protein
Block mutation
changes to segments of the chromosome
- inversion; segment falls out, rotates 180, rejoins
- translocation; segment of chromosome moves to a different (non-homologous) chromosome
- duplication; extra length of chromosome is added
- block deletion; segment is removed altogether from chromosome
Gene flow
the movement of alleles in and out of a population by migration»_space; causes a change in allele frequency in the gene pool
- immigration (introduces new alleles into gene pool)
- emigration (removes some alleles from the population)
Genetic drift
drastic change in allele frequency due to a random event
- bottleneck effect
- founder effect
Bottleneck effect
when majority of the population is eradicated as a result of a catastrophic event
- reduced genetic diversity → loss of alleles (via inbreeding)
- unrepresentative sample of original population’s gene pool
Founder’s effect
when a few individuals leave the population to begin a new one in an isolated location
- reduced genetic diversity → loss of alleles (due to only parent alleles being present)
- non-random sample of population
- genetic diversity can increase by accumulating mutations
Natural Selection
the process by which new heritable traits evolve and persist in a population
Natural Selection Steps
‘Please Veronica, Send Pasta, Girl Friend. Sincerely, Reggie.’
Phenotypic variation; population has different phenotypes → natural selection can occur
Selection pressure; condition or factor that influences which phenotypes are most successful in the population → new selective pressure introduced
Genetic fitness; organisms that are the desired phenotype have greater genetic fitness → more likely to survive and breed
Survival and reproduction; the population becomes adapted to the environment → passed on their alleles to the next generation
Selective pressures
PANDA PAW
Predators
Availability of shelter, food
Nutrient supply
Disease
Accumulation of waste
Phenomena (natural disasters)
Abiotic factors (temp, CO2)
Weather conditions (floods, storms)
Selective breeding
the process by which humans select the allele frequency of the desired traits in the gene pool
- decreased genetic diversity → detrimental to the species should natural selective pressures change
Bacterial resistance
bacteria lack check and repair mechanisms for DNA
- accumulation of mutations at a faster and higher rate
Antibiotic resistance mechanisms in bacteria
- modifying the chemical structure of antibiotics
- producing cellular transporters to remove antibiotics
- adjusting bacterial physiology to evade the antibiotic
scientific and social strategies against antibiotic resistance
scientific - research different types of antibiotics
social - limit the use of antibiotics → natural remedies to lesson symptoms of infection + gives immune system time to produce immuno. memory against the strain
Viral antigenic drift
accumulation of mutations cause change to the antigens on the surface of a virus
- influenza (neuraminidase and hemagglutinin)
highly conserved proteins
proteins experience less nucleotide/amino acid mutations
- thus conserving the 3D functional shape and function of the protein
