3.4.4 genetic diversity and adaptation Flashcards
define genetic diversity
the number of different alleles of genes in a population
what can occur due to genetic diversity?
natural selection
what are factors that affect genetic diversity?
- migration : increases
- founder effect : decreases
- genetic bottlenecks : decreases
- selective breeding : decreases
how are mutations harmful?
- individuals inheriting alleles with harmful mutations will die, so not pass on the mutation
how are mutations beneficial?
- increase individuals chance of surviving
- meaning they are more likely to reproduce and pass on the beneficial allele
- the frequency of the allele will increase
what is an allele?
different forms of a gene
define evolution
the gradual change in species over time through adaptation and selection has led to the huge diversity of living organisms on the Earth
what does natural selection result in?
- species that are better adapted to their environment
- adaptations may be anatomical, physiological or behavioural
what are the types of natural selection?
- directional
- stabilising
- disruptive
outline directional selection
- individuals with alleles for extreme characteristics are selected for
- have increased reproductive success
- allele becomes beneficial in response to environmental change
outline stabilising selection
- individuals with alleles for the phenotype towards the middle of the range
- mean stays the same
- range is smaller, so standard deviation is smaller
- beneficial alleles will increase in frequency in a gene pool with few alleles ( reducing genetic diversity)
explain how antibiotic resistance occurs
- random mutation in DNA of bacterium leads to an advantageous gene that provides resistance to a certain antibiotic
- the multiplication of this advantageous allele can occur through binary fission or through conjugation
- antibiotic resistant bacteria survive and have increased reproductive success
- less competition from non-resistant bacterial strains
- advantageous allele passed to offspring
- over time whole population becomes antibiotic resistant
what are aseptic techniques?
techniques used to avoid contamination of the sample from microorganisms.
it is important because it helps us get reliable data
name some examples of aseptic techniques
- wipe down surfaces with antibacterial cleaner, both before and after
- use Bunsen burner so that convection currents draw microbes away from the culture
- flame the wire hoop before using it to transfer bacteria
- keep all vessels containing bacteria open for the minimum amount of time
what is random fertilisation?
- in sexual reproduction any egg can be fertilised by any sperm which results in a huge number of different combinations of alleles and genetic variation
