Investigating Diversity Flashcards
What is observable characteristics
Each observable characteristic is determined by a gene or genes. The variety within a characteristic depends on the number and variety of alleles of that gene
What are the limitations of observable characteristics
It has a large number of them coded for by more then one gene. They are polygenic. This means they are not discrete from one another but rather vary continuously. It is often difficulty distinguish one from another
How may characteristics be modified
By the environment. Differences may therefore be the result of different conditions rather than different alleles
How do we compare DNA sequences? How can we measure genetic diversity of a species
In computerised systems, each nucleotide can be tagged with a different fluorescent dye.
By sampling its dna of its members and sequencing it to produce a pattern of coloured bands. Analysis of these patterns allows us to compare one species with another or one individual with another of the same species to determine how diverse they are.
This can also determine evolutionary relationships between species
What happens to a species bases after a mutation
They will change. Over time the new species will accumulate more and more differences in its dna
How can mRNA be used to measure dna diversity and genetic diversity
By comparing the base sequence of mRNA. The base sequences on mRNA are complimentary to those of the strand of dna from which they were made
How can the sequence of amino acids in proteins measure genetic diversity
By measuring the amino acid sequence of their proteins. The degree of similarity in the amino acid sequence of the same protein in two selfies will also reflect how closely related the two species are
Explain what causes the DNA sequence of genes to change over a period of time
Mutations
What’s interspecific variation
If one species differs from another
What’s intraspecific variation
Members of the same species also differ from each other
Why might individuals not be representative of the population as a whole?
Sampling bias - the selection process may be biased. The investigators may. Be making unrepresentative choices, either deliberately or unwittingly.
Chance- even if sampling bias is avoided, the individuals chosen may, by pure chance, not be representative
Describe random sampling
- Divide study area into a grid of numbered lines, e.g. by stretching two long tape measures at right angles to each other
- Using random numbers, from a table or generated by a computer, obtain a series of coordinates
- Take samples at the intersection of each pair of coordinates
How can we remove chance from the sampling process
Using a large sample size - the more individuals that are selected the smaller is the probability that chance will influence the result and the less influence anomalies will have
Analysis of the data collected - accepting that chance will play a part, the data collected can be analysed using statistical tests to determine the extent to which chance may have influenced the data
On a normal distribution curve what does the mean and standard deviation measure
Mean - at the maximum height of the curve
SD- width of the curve
What’s standard deviation formula
The sum of ( x-mean value)squared / n-1
All square rooted
N- total number of values in the sample
X- measured value
