3.4.4 Genetic Diversity

genetic diversity

the total number of different alleles of genes in a population

-provides ability to adapt and natural selection to occur

natural selection

-a random mutation can result in new alleles of a gene so there is variation

-there is a limit to population size due to resources, competition and predation

-the new allele from the mutation may benefit the individual as they can compete better so survive and reproduce

-the advantageous allele is passed and inherited by next generation

-so new allele increases in frequency in population over many generations

TYPES of selection -directional

-occurs when environmental conditions change

-individuals with phenotypes suited to new conditions will survive and pass on extreme genes

-over time the mean of the population will move towards these characteristics

e.g. antibiotic resistance

TYPES of selection -stabilising

-occurs when the environmental conditions stay the same

-individuals with phenotypes closest to the mean are favoured and are more likely to pass on alleles

-tends eliminate the phenotypes of extremes

e.g. human birth weights

3 types of ADAPTATION

-behavioural

-physiological

-anatomical

ASEPTIC techniques BEFORE method

1) use autoclave to sterilise petri dish to prevent contamination of bacteria affecting results

2) flame neck of bacteria bottle

3) use disinfectant on working surfaces

4) sterilise equipment with Bunsen burner

METHOD for bacteria

1) use sterile pipette to transfer bacteria to plate + use spreader to spread bacteria in plate 

2) soak paper discs in different antibiotics using forceps + transfer to petri dish - also make sure to use a control

3) loosely tape lid to allow oxygen for bacteria

4) leave for 48 hours at 25C

5) measure diameter and calculate area using πr²