Investigating diversity Flashcards
(17 cards)
How was genetic diversity traditionally measured?
By observing the characteristics (phenotypes) of organisms
Why can observable characteristics reflect genetic diversity?
This is because each characteristic is determined by one or more genes, and variation is due to different alleles
What is a limitation of using observable characteristics to measure genetic diversity?
Many characteristics are polygenic, meaning they are influenced by multiple genes and show continuous variation
How can the environment affect observable characteristics?
Environmental factors like nutrition can influence traits such as height, making it hard to determine if variation is genetic or environmental
What modern method is now used to assess genetic diversity more accurately?
Direct observation of DNA sequences, made possible by advances in gene technology
Why is using observable characteristics no longer the preferred method for measuring genetic diversity?
This is because it’s imprecise; differences may result fro environmental factors rather than genetic differences
How are DNA bases identified during sequencing in modern machines?
Each base is tagged with a fluorescent dye: adenine (green), thymine (red), cytosine (blue) and guanine (yellow)
How are DNA base sequences read and analysed efficiently?
Lasers scan the fluorescent bands, and computer software interpret them to give the DNA sequence
What can DNA base sequence comparisons reveal about different species
They can show evolutionary relationships and how closely related species are
What happens to DNA sequences when a new species evolves?
Initially, the new species’ DNA is similar to the ancestor’s, but mutations cause it to accumulate differences over time
What is expected of DNA base sequence similarity between related species?
More closely related species will have more similar DNA base sequences
How is mRNA related to DNA?
mRNA is coded for by DNA and has base sequences complementary to the DNA strand from which it was transcribed
How can amino acid sequences be used to measure genetic diversity?
By comparing the sequences of the same protein in different individuals or species to count similarities and differences
Why can mRNA base sequences be used to measure genetic diversity?
This is because they reflect the DNA sequence, allowing indirect comparison of DNA diversity
What does a high number of differences in amino acid sequences suggest about the evolutionary relationship between species?
That the species are more distantly related and are from a common ancestor further back in time
What does a high similarity in amino acid sequence between two species suggest?
That the species are closely related and share a recent common ancestor
What are two ways to compare amino acid sequences between species?
1/ Counting the number of similarities
2/ Counting the number of differences
