Genetic Diversity Flashcards
What is genetic diversity?
The total number of different alleles of genes in a population
A large number of different alleles in a species/population means?
High genetic diversity
Why is genetic diversity important?
If an environment changes, high genetic diversity increases chance of adaption to new environment
What increases genetic diversity?
Mutations in DNA forms new alleles
Gene flow when different alleles introduces into population due to migration and reproduction
4 ways to measure genetic diversity
the frequency of measurable or observable characteristics
the base sequence of DNA
the base sequence of mRNA
the amino acid sequence of the proteins encoded by DNA and mRNA
Observation to measure genetic diversity
Different number of alleles encode for different polypeptides thus cause different observable characteristics within phenotype.
So find frequency of these observable characteristics = variety of different alleles
Mutations to measure genetic diversity
Comparing the same allele across different species/ within species to find frequency of different bases to show how many mutations of single base substitutions occurred.
More differences = more evolutionary divergence
Amino acid sequence to measure genetic diversity
Select common polypeptide chain and find frequency of amino acid differences in 1° structure.
Because variation in alleles change mRNA transcribed thus amino acid sequence of polypeptide chain
The less genetically related….
The more differences in amino acid sequence/mutations/observable characteristics and less similarities in these across the species/within the species
Thus showing more genetic variation and so diversity
Immunology techniques to find genetic diversity
Extracting a shared protein across different individuals and using it as an antigen to see the relative binding ability to the same antibody.
Why does the immunology technique work
B cells release antibodies complementary to the antigen (protein) of our selected organism
To produce antibody-antigen complex
Comparing to other organisms: if the same antibody binds more (produces more complexes) it is closely related or if binds less (less complexes) it is distantly related
Why does the immunology technique work
B cells release antibodies complementary to the antigen (protein) of our selected organism
To produce antibody-antigen complex
Comparing to other organisms: if the same antibody binds more (produces more complexes) it is closely related or if binds less (less complexes) it is distantly related
Limitations of observation method
Phenotype can be affected by environment
Having similar characteristics doesnt necessarily mean closely related by genetics
Different life cycle stages/ sex differences within species may be mistaken for different species
How do mutations increase genetic diversity?
Causes a change in base sequence of dna spontaneously
Leads to creation of new allele that encodes for a new polypeptide synthesised so new phenotype expressed
How can we suggest relationships between different organisms of the same species/different species?
Base sequences of DNA
Amino acid sequence of a protein
Why does comparing the base sequence of DNA provide more evolutionary info than amino acid sequence of a protein?
-Due to the triplet code, there are more bases coding for a polypeptide than there are amino acids in a polypeptide;
-The triplet code is degenerate: amino acids may not change even if the base sequence has between organisms
How do differences in base sequence/ AA sequence show a CLOSE relationship between organisms?
Mutations change the base sequence of DNA;
This causes change in the base sequence of mRNA and so the amino acid sequence of a protein;
Mutations build up over time;
Less mutations in base sequence/less differences in amino acid sequence occur between more closely related species;
More closely related species share a more recent common ancestor
How do differences in base sequence/ AA sequence show a DISTANT relationship between organisms?
Mutations change the base sequence of DNA;
This causes change in the base sequence of mRNA and so the amino acid sequence of a protein;
Mutations build up over time;
More mutations in base sequence/more differences in amino acid sequence occur between more distantly related species;
More distantly related species share an earlier common ancestor;
