B1. Genome Projects

Question 1

A genome is …

In genome projects, scientists work to determine the complete genome sequence of an organism. Their success depends on the ____________of the organism and the _____________that is available.

Answer 1

A genome is the entire set of DNA, including all the genes, in an organism.

In genome projects, scientists work to determine the complete genome sequence of an organism. Their success depends on the complexity of the organism and the technology that is available.

Question 2

Sequencing genomes

Improvements in technology have allowed us to sequence the genomes of a variety of organisms, from bacteria to humans. Gene sequencing methods only work on ___________of ____, so if you want to sequence the entire genome of an organism, you need to chop it up into __________pieces first. The smaller pieces are ____________and then put back in order to give the sequence of the whole genome.

Answer 2

Improvements in technology have allowed us to sequence the genomes of a variety of organisms, from bacteria to humans. Gene sequencing methods only work on fragments of DNA, so if you want to sequence the entire genome of an organism, you need to chop it up into smaller pieces first. The smaller pieces are sequenced and then put back in order to give the sequence of the whole genome.

Question 3

Sequencing proteomes

The proteome of an organism is…
You might remember that while some parts of the genome code for specific proteins, some parts don’t code for anything at all (the DNA is ___-________)

Simple organisms (3)
Complex Organisms (3)

Answer 3

The proteome of an organism is all the proteins that are made by it. You might remember that while some parts of the genome code for specific proteins, some parts don’t code for anything at all (the DNA is non-coding)

Simple organisms

• Simple organisms such as bacteria, don’t have much non-coding DNA. This means it is relatively easy to determine their proteome from the DNA sequence of their genome.
• This can be useful in medical research and development. For example, identifying the protein antigens on the surface of disease-causing bacteria and viruses can help in the development of vaccines to prevent the disease
• Being able to determine the proteomes of disease-causing bacteria and viruses also allows pathogens to be monitored during outbreaks of disease, which can lead to better management of the spread of infection, and can help to identify antibiotic resistance factors (e.g. mechanisms of antibiotic resistance)

Complex Organisms

• More complex organisms contain large sections of non-coding DNA.
• They also contain complex regulatory genes, which determine when the genes that code for particular proteins should be switched on and off.
• This makes it more difficult to translate their genome into their proteome, because it’s hard to find the bits that code for proteins among the non-coding and regulatory DNA.

Question 4

Tip: Remember, vaccines contain _________(or molecules that code for them) that cause your body to produce __________cells. If you’re later infected by a pathogen with the same ________, your _______cells will quickly recognise it and divide to produce ___________against it.

Answer 4

Tip: Remember, vaccines contain antigens (or molecules that code for them) that cause your body to produce memory cells. If you’re later infected by a pathogen with the same antigens, your memory cells will quickly recognise it and divide to produce antibodies against it.

Question 5

Developing new sequencing methods (read)

In the past, many sequencing methods were labour-intensive, expensive and could only be done on a small scale.

Example
During the 1970s, Frederick Sanger developed a technique in which a sample of DNA was tagged with radioactive bases, separated into four lanes on a gel and allowed to migrate. The result was photographed by X-ray. As each lane represented one of the four bases, the sequence of the DNA could be worked out by combining the results in each lane. This was a time-consuming process as only one sample could be run at a time and X-ray photographs had to be taken manually.

Now these techniques are often automated, more cost-effective and can be done on a large scale.
Example
Pyrosequencing is a recently developed technique that can sequence around 400 million bases in a ten hour period (which is super fast compared to older techniques).
With newer, faster techniques such as pyrosequencing available, scientists can now sequence whole genomes much more quickly

Answer 5

In the past, many sequencing methods were labour-intensive, expensive and could only be done on a small scale.

Example
During the 1970s, Frederick Sanger developed a technique in which a sample of DNA was tagged with radioactive bases, separated into four lanes on a gel and allowed to migrate. The result was photographed by X-ray. As each lane represented one of the four bases, the sequence of the DNA could be worked out by combining the results in each lane. This was a time-consuming process as only one sample could be run at a time and X-ray photographs had to be taken manually.

Now these techniques are often automated, more cost-effective and can be done on a large scale.
Example
Pyrosequencing is a recently developed technique that can sequence around 400 million bases in a ten hour period (which is super fast compared to older techniques).
With newer, faster techniques such as pyrosequencing available, scientists can now sequence whole genomes much more quickly