Investigating diversity

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  • Created by: Hindleyc
  • Created on: 09-09-18 22:16
How can genetic diversity within or betweens species be measured?
By comparing the frequency of measurable or observable characteristics, the base sequence of DNA, the base sequence of mRNA. the amino acid sequence of the protein encoded by DNA and mRNA
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What is the comparison of observable characteristics?
Method based on the fact that each observable characteristic is determined by a gene or genes (with environmental influences)
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What does the variety within a characteristic depend on?
The number and variety of alleles of that gene plus enivronmental influences
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What does using observable characteristics have?
Limitations as a large number of them are coded for by more than one gene- polygenic meaning they are not discrete from one another but rather vary continuously so often difficult to distinguish one from another
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What else?
Characteristics can also be modified by the environment so differences may therefore be the result of different environmental conditions rather than different alleles eg height diet can influence
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What was this method replaced by?
Directly observing DNA sequences themselves - made possible through advances in gene technology made over recent years.
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What is needed to compare the DNA base seq?
Base seq of DNA of any organism- determine exact order of nucleotides on DNA, DNA sequencing- computerised systems each base tagged w/ coloured dye
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What next?
Coloured bands- analysis compare species or individuals- pattern scanned by lasers and interpreted by computer software to give DNA (base sequences) and determine evolutionary relationships b/w species
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Comparison of base seq of mRNA
mRNA coded for by DNA - base seq on mRNA complementary to those of the strand of DNA from which they were made so measure DNA diversity therefore genetic diversity by comparing base seq mRNA
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Comparison of AA seq in proteins?
Seq determined by mRNA therefore DNA so genetic diversity within and between species is measured by comparing the AA seq of proteins
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What is looked at?
Degree of similarity in AA seq of same protein in 2 species will reflect how closely related a species are. 2 seq compared - count similarities or differences in each sequence
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What is DNA hybridisation?
Degree of similarity b/w genomes- genetic resemblance compared
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step 1
Heat to break H bonds DNA denatured and separated into 2 complementary strands,
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2
cool and incubate at 50 and 60 so single strands will associate with complementary partners and reform helix
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3
radioactive/ fluorescent markers to DNA of species
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4
Both strands cooled so strand combine with complementary base
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5
more similar the 2 species the more closely related are share many bases- higher temp needed
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Null H?
No difference/ effect
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Less than 0.05
reject null - result is important accept experimental
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more than 0.05
null H accepted
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0.05?
Proability of result being due to chance
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Card 2

Front

What is the comparison of observable characteristics?

Back

Method based on the fact that each observable characteristic is determined by a gene or genes (with environmental influences)

Card 3

Front

What does the variety within a characteristic depend on?

Back

Preview of the front of card 3

Card 4

Front

What does using observable characteristics have?

Back

Preview of the front of card 4

Card 5

Front

What else?

Back

Preview of the front of card 5
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