6.3.2 Comparing Genomes Flashcards
What is a genome?
A genome contains all of the genes within an organism
Advances in technology have allowed scientists to sequence the genes within an organism’s genome
Sequencing projects have read the genomes of a wide range of organisms from flatworms to humans
Genome-wide comparisons can be made between individuals and between species
How can we sequence DNA to determine protein sequences?
The genetic code can be used to predict the amino acid sequence within a protein
Once scientists know the amino acid sequence they can predict how the new protein will fold into its tertiary structure
This information can be used for a range of applications, such as in synthetic biology
What is synthetic biology?
The design and creation of new biological systems.
e.g. The alteration of a significant part of an organisms genome to enable it to perform a function that it would not be able to form in nature
What is bioinformatics?
Bioinformatics is a field of biology that involves the storage, retrieval, and analysis of data from biological studies
These studies may generate data on DNA sequences, RNA sequences, and protein sequences, as well as on the relationship between genotype and phenotype
High-power computers are required to create databases
The large databases contain information about an organism’s gene sequences and amino acid/protein sequences
Once a genome is sequenced, bioinformatics allows scientists to make comparisons with the genomes of other organisms using the many databases available
This can help to find the degree of similarity between organisms which then gives an indication of how closely related the organisms are
This can be useful for scientists looking for organisms that could be used in experiments as a model organism for humans
E.g. The nematode worm Caenorhabditis elegans is an animal that has been used as a model organism for studying the genetics of organ development, neurone development and cell death. It was the first multicellular organism to have its genome fully sequenced and as it has few cells (less than 1000), and is transparent, it has been a useful model organism
Bioinformatics has contributed to the study of genetic variation, evolutionary relationships, genotype-phenotype relationships, and epidemiology
How can genetic variation and evolutionary relationships be investigated through comparing genomes?
The genetic variation within a species can be investigated
Many individuals of the same species have their genomes sequenced and compared
A species that has a high level of genetic variation will exhibit a large number of differences in base sequences between individuals
The evolutionary relationships between species can be investigated by comparing the genomes of different species
Species with a small number of differences between their genomes are likely to share a more recent common ancestor than species with a large number of differences
The protein cytochrome c is involved in respiration, and so is found in a large number of species (including plants, animals, and unicellular organisms). For this reason it is especially useful for making comparisons between different species
Why are genotype-phenotype relationships important?
Genome sequencing can aid the understanding of gene function and interaction
Genotype-phenotype relationships are explored by “knocking out” different genes (stopping their expression) and observing the effect it has on the phenotype of an organism
When an organism’s genome sequence is known, scientists can target specific base sequences to knock out
What is epidemiology?
Epidemiologists study the spread of infectious disease within populations
The genomes of pathogens can be sequenced and analysed to aid research and disease control
Highly infectious strains can be identified
E.g. the Delta variant of SARS-CoV-2 (a well-known coronavirus)
The ability of a pathogen to infect multiple species can be investigated
E.g. Ebola can infect primates as well as humans
The most appropriate control measures can be implemented based on the data provided
Potential antigens for use in vaccine production can be identified
What is the human genome project?
A genome project works by collecting DNA samples from many individuals of a species. These DNA samples are then sequenced and compared to create a reference genome
More than one individual is used to create the reference genome as one organism may have anomalies/mutations in its DNA sequence that are atypical of the species
The Human Genome Project (HGP) began in 1990 as an international, collaborative research programme
It was publicly funded so that there would be no commercial interests or influence
DNA samples were taken from multiple people around the world, sequenced, and used to create a reference genome
Laboratories around the globe were responsible for sequencing different sections of specific chromosomes
It was decided that the data created from the project would be made publicly available
As a result, the data can be shared rapidly between researchers
The information discovered could also be used by any researcher and so maximised for human benefit
By 2003 the human genome had been sequenced to 99.9% accuracy
The finished genome was over 3 billion base pairs long but contained only about 25,000 genes, a surprisingly low number
Work is currently underway to sequence the human proteome and the human epigenome
What is the application of the human genome project?
The information generated from the HGP has been used to tackle human health issues with the end goal of finding cures for diseases
Scientists have noticed a correlation between changes in specific genes and the likelihood of developing certain inherited diseases
For example, several genes within the human genome have been linked to increased risk of certain cancers
If an individuals BRCA1 and BRCA2 genes are mutated then they are substantially more likely to develop breast cancer
There have also been specific genes linked to the development of Alzheimer’s disease
