15. Genetic Diversity Flashcards
(12 cards)
What is genetic diversity? And how does it arise?
The number of different alleles of genes in a population.
Its a factor that enables natural selection to occur.
Arise due to:
- mutation - result in new allele of genes.
- independent segregation/ crossing over non sister chromatids during meiosis
- random fusion of haploid gametes to produce diploid zygotes
Whats the name for competition between different species and name competition between the same species?
Different species : interspecific
Same species: Intraspecific
What must a sample be and why do we calculate a mean?
Sample must be random and large.
Calc mean and standard deviations of mean as SDs all you to interpret mean values and conclude if they’re sig diff.
Whats continuous and discontinuous variation?
Continuous: Quantitive, affected by environment, changes gradually .e.g. height.
Discontinuous: qualitative, distinct category, control by few genes, unaffected by environment. E.g. eye colour, blood group.
What is natural selection?
- random mutation produces new allele of genes.
- Many mutations harmful but in certain environments, new allele of gene might benefit its posessor leading to increased reproductive success,
- advantageous allele inherited by members of next generation.
- As result , over generations, new allele increases in frequency in gene pool of the pop.
What is the standard deviation and whys it better than the range?
SD: a measure of dispersion of values around the sample mean.
Less effected by outliers and gives a better measure of overall variation. The larger the SD value, the greater the variation in sample.
If they overlap, no sig difference.
What does it mean in error bars overlap?
If overlap, means could be same and difference is due to chance.
Don’t overlap, difference not due to chance.
If error bars don’t overlap at P=0.05 means theres less than 5% probability that difference of 2 means is due to chance (reject null hypothesis.) or theres a sig diff between 2 means.
What does the T test used for? Whats the null hypothesis when carrying out the t-test?
Investigate difference between 2 means.
Null hypothesis: ‘theres no sig diff between the 2 different means.’
- if diff is sig at P=0.05 then reject null. Accept<critical value<reject
Whats stabilising selection?
- environmental conditions stable
- selective pressure at both ends of distribution.
- favours mean and tends to eliminate the extremes.
- reduces variability, size of range within pop, SD decreases over time.
What is directional selection?
- environmental change may produce new selection pressure that favours extreme characteristic (more necessary for survival.)
- favours extremes
- overtime selection means these will be predominate and mean will shift.
E.g. thicker fur in cold climate is advantageous.
An example of directional selection is natural selection and antibiotic resistance.
How do antibiotics become resistant to bacteria?
- bacteria replicate quickly by binary fission so when mutations occur, it increases in number quickly.
- mutation/ variation result in new allele, the new allele is more advantageous when antibiotic present. Bacteria with resistant allele able to survive and reproduce successfully. Passed on to offspring. Increases allele frequency in population over time.
What aseptic techniques can be used when investigating effect of antimicrobial substances on microbial growth? How do you calculate zone of inhibition?
- disinfect surface using virkon to prevent contamination of unwanted bacteria.
- wash hands/ wear gloves-prevent contamination of bacteria on hands.
- lift lid of petri dish slightly to prevent contamination of unwanted bacteria.
- store dish upside down to prevent contamination dropping.
- work near to bunsen
- flame neck of bottle
-sterile equipment
Zone of inhibition: use callipers measure diameter, area is pir^2
