21.2-3 principles and using DNA sequencing

what is the DNA to be sequenced mixed with in DNA sequencing

• a primer

• DNA polymerase

• an excess of nucleotides

• terminator nucleotides

what machine is used in DNA sequencing

a thermal cycler

what are terminator bases

• have a hydrogen atom instead of a hydroxyl group on the 3’ carbon

• a phosphodiester bond cannot form between the 3’ and 5’ end of another nucleotide

• if a terminator nucleotide is added, the sequencing reaction is therefore stopped

what is the process of DNA sequencing

1. heated to 96 degrees to break the double stranded DNA into single strands

2. cool to 50 degrees and allows the primers to anneal

3. heat to 60 degrees and DNA polymerase builds up new DNA strands by adding nucleotides with the complementary bases to the single stranded DNA

4. as chain terminating bases available, this results in many DNA fragments at different lengths

5. the fragments are separated by their lengths through capillary sequencing

6. lasers detect the colours of the fluorescent markers on the terminator bases and are used to determine the final base

how has DNA sequencing been progressed

• next generation sequencing

• clusters are sequenced and imaged at the same time

• improved computer technology also increases efficiency

what is computational biology

using bioinformatic data to build theoretical models of biological systems

what is bioinformatics

the development of the software and computing tools needed to analyse biological data

why is analysing the human genome important

• understanding patterns of inheritance and disease suseptibility

• most diseases are a combination of genes and the environment

why is analysing pathogens genomes important

• helps to identify the source and spread of infection

• helps to identify the correct treatment options

• helps to identify regions of pathogenic genomes which may be suitable targets for drug and vaccine development

uses of genome wide comparisons in identifying species

• DNA barcoding

• scientists can identify species from a short section of DNA from a conserved region of the genome

• can be sequenced quickly but also varies enough to give clear differences between species

use of genome wide comparisons in searching for evolutionary relationships

• the more closely related organisms are, the more similar their DNA is

• the mutation rate of DNA can be used to calculate how long ago 2 species diverged from each other

what is proteomics

the study and amino acid sequencing of an organism’s entire protein complement

what are spliceosomes

• join together exons before being translated into a proteins

• alternative splicing - exons are joined in different combinations allowing one gene to produce multiple types of proteins

how does protein modification work

• some proteins are lengthened or shortened by other proteins after they have already been synthesised

• this can produce a number of different proteins in addition to that coded for by the gene base sequence itself

what is synthetic biology

the design and construction of novel, articificial biological pathways, organisms or devices, or the redesign of existing biological systems

techniques which are included in synthetic biology

• genetic engineering

• use of biological systems in industrial processes

• the synthesis of new, functional genes

• the synthesis of new organisms