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OCR A-level Biology > Manipulating Genomes > Flashcards

Flashcards in Manipulating Genomes Deck (32)
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How does Fred Sangers method use the varying lengths of fragments to work out the base sequence?

The the fragments are part of the same chain of cDNA

If a one base fragment ends in T
And a two base fragment ends in G then the sequence is TG
And if a 3 base sequence ends in C then it is TGC.

This process can be repeated to work out an entire length of DNA


What type of enzymes are used to isolate a gene?

Restriction enzymes


How can someone clone DNA?

Isolate the gene to be cloned (restriction enzymes)

Insert the gene into a bacterial plasmid

The bacteria is cultured and divides many times

Re-isolate the genes


What is Pyrosequencing?

A faster and more effective method of sequencing a genome

It works by detecting the different light emissions of bases when synthesising complementary strand of DNA


How does Pyrosequencing differ from Sangers method of genome sequencing?

Pyrosequencing is sequencing by synthesis, whereas Sangers method is sequencing by termination


What was the Human Genome Project?

A project started in 1990 to sequence the human genome

Completed in 2003


What did the human genome project tell us about how genes are transferred in evolution?

We share 99% of our genes with chimpanzees

This shows that the genes that work well and provide an advantage are highly conserved throughout evolution


How can genome comparison be used to classify species?

Can compare genomes to see the number of identical genes

The more identical genes, the closer the relationship


What are the areas on DNA where mutations can occur called?

Single Nucleotide Polymorphisms (SNP's)


What can happen to a certain chemical group in DNA to affect regulation and expression?


Can lead to certain genetic diseases


How does already having an organism's genome mapped make genetic sequencing more efficient?

Because if they know which gene codes for which protein they can easily just compare the section of DNA where the said gene is located

This saves them from having to look through the whole genome which would take forever


What is Synthetic Biology?

A branch of biology that aims to design and build useful biological devices and tools

e.g Biofuels, Biomedicine, Biosensors etc


How is Synthetic Biology used in Information Storage?

You can encode vast amounts of information onto a strand of DNA

One project has encoded the complete works of William Shakespeare onto 1 strand of DNA


How is Synthetic Biology used in the Production of Medicines?

E Coli and Yeast have been genetically engineered to produce Artemisinin (a powerful antimalarial drug)

Previously it was only able to be extracted from plants at a small yield


How is Synthetic Biology used in creating Novel Proteins?

Specially designed proteins

e.g one similar to haemoglobin that binds to oxygen but won't bind to carbon monoxide


How is Synthetic Biology used in the production of Biosensors?

Genetically modified Bioluminescent bacteria have been produced

They can be seen to glow under the correct conditions

E.g a bacteria that glows if air is polluted with petroleum pollutants


How is Synthetic Biology used in Nanotechnology?

Can create material used for nanotechnology

e.g amyloid fibres that are used to make biofilms


Why is there an ethical dispute over synthetic biology?

Some people think it is wrong to be creating new life from scratch

Some think that it is leading to potential issues like resistance to drugs etc

Others say that it is not about creating new life by creating new systems that can be used to overcome current challenges (e.g treating un-treatable illnesses)


What is a Tandem repeat sequence?

Repetitive sequences of DNA that don't code for a protein


Describe and Explain a use of Tandem Repeat sequencing?

Used in paternity tests

Because people's DNA profiles may be different by The number and location of Tandem Repeats would be passed on


Describe the process of DNA profiling

DNA sample taken

DNA digested by restriction enzymes which cut DNA into fragments

DNA fragments separated by Gel Electrophoresis (large fragments travel less)

The banding patterns are compared to find a match


Give some examples of uses of DNA Profiling

Forensic science (e.g Identifying the remains of King Richard 3rd)

Maternity and Paternity disputes

Analysis of disease (diagnosing genetic disorders)


What does PCR stand for and what does it do?

Polymerase Chain Reaction

It is used to amplify a sample of DNA so that it can be analysed


What discovery allowed the PCR process to become more efficient?

Discovery of a new thermophilic bacterium (Thermophilus aquaticus)

The polymerase enzyme found is this bacteria can withstand much higher temperatures before denaturing


Describe the process of PCR

DNA sample mixed with free nucleotides, primers, Mg2+ ions and DNA Polymerase enzyme

Mixture heated to 95 degrees to break hydrogen bonds between base pairs to make 2 single strands

Cooled to 68 degrees so that primers can bind to the bases

Polymerase enzyme binds to where the primers are

Polymerase catalyses reaction between free nucleotides and the single strands of DNA in a 5' to 3' direction

A new strand of DNA is formed


Give some examples of uses of PCR

Tissue Typing - reduce transplant rejection risk

Detection of Oncogenes - genes that lead to cancer

Detection of mutations

Identifying viral infections - Covid PCR tests

Forensic Science - DNA profiling to identify criminals

Research - Amplify DNA from extinct species


What is an electrophoresis plate made out of?

Agarose gel covered in a buffer solution


Which electrodes do the DNA fragments move from and too in electrophoresis? Why?

Towards the anode (positive electrode)

This is because phosphate groups in DNA give it a negative charge so they move toward the positive electrode (anode)


What are the two ways to mark a DNA probe?

Radioactive Marker

Fluorescent marker


What is the structure and function of a DNA probe?

Used to locate specific areas on a length of DNA

Short, single-stranded length of DNA that is complementary to the section of DNA you are trying to locate


Give some examples of uses of DNA probes

Locating a target gene in genetic engineering

To locate the same gene across a variety of different species in species comparison

Identify the absence or presence of a specific allele that causes a genetic disease


What is a microarray?

A piece of apparatus that contains multiple DNA probes so that it is easy to identify the presence or absence of multiple genes with 1 DNA sample