chapter 11 bio

what are the main processes that drive evolution?

mutation, natural selection, gene flow, genetic drift

what is allele frequency?

the relative proportion of a particular allele in a population

what is mutation?

changes in DNA which is the source of new alleles in a population

how do mutations occur?

they occur randomly as errors during cell replication, it can be spontaneous or as a result of mutagens

what is a neutral mutation?

a mutation that has no effect on survival

what is a beneficial mutation?

a mutation that increases the likelihood of survival

what is a harmful mutation?

a mutation that decreases the likelihood of survival

what is the difference between somatic mutations and germline mutations?

somatic mutations occur in body cells and only affect the individual whereas germline mutations occur in the gametes and can be passed on to offspring

what is natural selection?

the process where individuals that are more suited to their environment are more likely to survive and produce offspring

what are environmental selection pressures?

environmental conditions or factors that affects the survival and reproduction success of individuals based on phenotype

examples of environmental selection pressures

extreme temperature changes, mate availability, competition for resources

what is biological fitness?

the ability of an organism to survive and produce viable offspring

what is adaptive value?

the measure of how well a trait or phenotype can help the survival and reproduction of individuals

what happens to traits if the environment remains unchanged?

traits with high adaptive value will continue to be useful to the organism and there will be little change to the allele frequencies

what is an adaptation?

traits that are well suited to an organism’s environment

what is gene flow?

the transfer of alleles between populations

when does gene flow occur?

when individuals join or leave a population

why is gene flow important?

gene flow increases genetic diversity and helps species adapt to changing environments

what is genetic drift?

when allele frequencies change randomly over time as a result of chance events

why does genetic drift affect small populations with little to no gene flow the most?

the random death of one individual can significantly alter the allele frequencies and results in the loss of genetic diversity

what is the bottleneck effect?

the impact of the sudden and substantial population reduction on the remaining population

why does a bottleneck affect genetic diversity?

the number of reproductive pairings are limited leading to inbreeding and an increased number of homozygous individuals

what is the founder effect?

when a small group of individuals is genetically isolated from a larger population by migration, new geographic barriers or habitat fragmentation

how does founder effect affect genetic diversity?

there is increased inbreeding as the population only has a small portion of the alleles of the original population

what is selective breeding?

the process by which humans decide which individuals may breed and leave offspring to the next generation

steps of selective breeding

determine the desired trait, interbreed parents that have the desired trait, select the offspring with the best form of the trait and interbreed the offspring, continue the process until the population reliably reproduces the trait

how does selective breeding affect genetic diversity?

selective breeding makes similar individuals interbreed decreasing the frequency of other alleles of traits reducing genetic diversity

how are genetic abnormalities increased by selective breeding?

due to interbreeding, homozygous individuals become more prominent meaning there is a higher chance for recessive conditions to occur

what is antibiotic resistance?

the ability of bacteria to survive in the presence of an antibiotic that they were once susceptible to

how do bacteria resist antibiotics?

reduce the intake of the drug, alter the target molecule, pump the drug out of the cell, enzymatically deactivate the drug

what is vertical gene transfer?

the passing of genetic material from parent to offspring in bacteria

how does overuse and improper use of antibiotics attribute to bacterial resistance to antibiotics?

every time antibiotics are used, there is a chance of selecting resistant bacteria that can produce whole colonies of resistant bacteria

what is horizontal gene transfer?

extra copies of plasmids can be shared with other bacteria of the same or closely related species providing the antibiotic resistant gene

what is antigenic drift?

small gradual point mutations where the changes to the antigen structure is minor so a host’s immune system can still recognise the virus if a similar virus has infected them before

what is antigenic shift?

an abrupt change in the genome of a virus which significantly changes its antigens

what is one way that antigenic shift occurs?

if an individual is affected by two different strains of a virus, the viruses can swap blocks of genetic material which make a new virus

why does antigenic shift increase the virulence of viruses?

the virus essentially becomes a new virus which the human population has no pre-existing immunological memory to so it can infect individuals rapidly

what is the problem with vaccination for new viruses?

vaccines cannot be made before a virus has been observed in a population where during development time people can become ill and die

how does quarantine prevent the spread of viruses?

it isolates the infected from interacting with vulnerable people to prevent the spread of viruses

why can quarantine not work for some viruses?

some viruses have a significant lag time between infection and symptoms appearing meaning infected individuals can spread the pathogens to many people before quarantine.