Genetic Diversity And Adaptatino Flashcards
Why do we have genetic variation
Organisms of the same species have very similar genomes but differences in the DNA base sequences
Although these differences are small ,because of the size of the genome we have a great genetic variation in species
What is genetic diversity
Genetic variation being transferred from one generation to the next
It is the number of different alleles of genes in a population
How to we have new alleles
Mutations occur changing the DNA base sequences.
New alleles mat be advantageous or bad or have no effect on the phenotype (degenerate code)
New alleles are not always expressed and may remain hidden until further generations (recessive)
Why do we need genetic diversity
So natural selection can occur and strengthen a species
Creates different phenotypes
Increases chance of survival for an organism
Fitness definition
The ability for an organism to be better suited to its environment
Thus individuals with favoured phenotypes have a better fitness
Benefits of a population with a large gene pool or genetic diversity
Strong ability to adapt to changes in an environment
Thus a small gene pool men s a species can be vulnerable to extinction
Eg. Cheetahs - small fragmented populations of individuals remaining - species is less likely to recover from environmental changes
Why must we use logarithms when investigating bacteria
Bacteria grows at a rapid rate so very large numbers can be produced in hours
Large numbers can be difficult to manage
Logarithmic scales allow a wide range of values to be displayed on a single graph
How to identify a log scale
Not equal intervals between numbers on y axis
Example of an everyday log scale
Ph - concentration of hydrogen ions massively varies between each ph level
How can new alleles arise
In populations through random mutation
How do new alleles increase in frequency over several generations
Allele causes an increased chance of survival
Increased reproductive success
Allele is passed down onto next gen
It multiplies from there
What are selection pressures
Pressures caused by the environment that increase the likelihood that certain individuals with specific alleles survive to reproduce and that allele thus spreads
How does the founder effect occur
A small number of individuals start a new population
The total number of alleles in this population is limited
A small gene pool is present
All the individuals are very similar and thus susceptible to extinction
Which alleles are in this new population is entirely based on chance
What is genetic drift
When a population is very small, chance can affect which alleles get passed onto the next generation
Overtime , some of these alleles can be lost if never being passed onto next generations
This gradual change in allele frequency is genetic drift
What is the bottleneck affect
When a large population has a dramatic fall in numbers
Genetic diversity reduces
Alleles are lost
Surviving individuals breed with close relatives - all are same
Susceptible to extinction from diseases
what are selection pressures
environmental factors that affect the chance of survival of an organism
has an effect on allele frequency due to stimulating natural selection
what is stabalising selection
natural selection where allele frequencies are kept constant (stable) over generations
example of stabalisisng selection
birth weights - very high and very low births will not live
thus the intermediate weight is naturally selected to be maintained
what is directional selection
natural selection that produces a gradual change in allele frequencies over generations
occurs due to a change in environment or a new allele that is advantagous is now present
example of directional selection
antibiotic resistance being more common
presence of antibiotics is a selection pressure
mutation in allele = advantagous - live longer and the bacteria reproduce
allele frequency increases
it is directional as the phenotype is being favoured
how would a population respond to a selection pressure from environment factors
directional natural selection
favourable alleles = live longer and reproduce
unfavourable alleles = die because unable to cat prey or smthn, no reproduce
what is an anatomical adaptation
a structural or physical feature
what is physiological adaptation
biological proccesses in an organism
behavioral adaptations
the way an organism behaves
what is evolution
the change in adaptive features of a population over time as a result of natural selection
how are two new species formed
if the populations of one species are ioslated and become so different in phontype that they can no longer interbreed to make fertile offspring
why do we use aseptic technique
techniques to ensure that the microbes being investigated dont escape or become contaminated with other unwanted bacteria
what is the practicle for testing for bacteria antibiotic resistance
disc diffusion method
examples of aseptic techniques
washing hands
no food or drink
disinfecting work surfaces
no growth of organisms at body temp
sterile swabs when transferring cultures
gloves
goggles
only remove petri dishes when neccesary
having a lit bunsen in the room
method of disc diffusion for antibiotic resistance
pre soak paper discs with different antibiotic solutions ( same concentration)
spread a sample of the diluted bacteria broth onto the surface of the sterile agar plate
press the paper discs into the agar - make sure that they are evenly distributed in the plate
keep the agar plate in the incubator overnight
remove the agar plate from the incubator and examine the results
results of the disc diffusion for antibiotic resistance
bacteria will diffuse outwards from each paper disc so that a gradient of antibiotic forms
if the bacteria haS BEEN KILLED BY THE ANTIBIOtic, a clear section will be around the disc
best antibodies will have the largest clear zones
