Manipulating Genomes

Question 1

How does Fred Sangers method use the varying lengths of fragments to work out the base sequence?

Answer 1

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

Question 2

What type of enzymes are used to isolate a gene?

Answer 2

Restriction enzymes

Question 3

How can someone clone DNA?

Answer 3

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

Question 4

What is Pyrosequencing?

Answer 4

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

Question 5

How does Pyrosequencing differ from Sangers method of genome sequencing?

Answer 5

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

Question 6

What was the Human Genome Project?

Answer 6

A project started in 1990 to sequence the human genome

Completed in 2003

Question 7

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

Answer 7

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

Question 8

How can genome comparison be used to classify species?

Answer 8

Can compare genomes to see the number of identical genes

The more identical genes, the closer the relationship

Question 9

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

Answer 9

Single Nucleotide Polymorphisms (SNP’s)

Question 10

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

Answer 10

Methylation

Can lead to certain genetic diseases

Question 11

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

Answer 11

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

Question 12

What is Synthetic Biology?

Answer 12

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

e.g Biofuels, Biomedicine, Biosensors etc

Question 13

How is Synthetic Biology used in Information Storage?

Answer 13

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

Question 14

How is Synthetic Biology used in the Production of Medicines?

Answer 14

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

Question 15

How is Synthetic Biology used in creating Novel Proteins?

Answer 15

Specially designed proteins

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

Question 16

How is Synthetic Biology used in the production of Biosensors?

Answer 16

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

Question 17

How is Synthetic Biology used in Nanotechnology?

Answer 17

Can create material used for nanotechnology

e.g amyloid fibres that are used to make biofilms

Question 18

Why is there an ethical dispute over synthetic biology?

Answer 18

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)

Question 19

What is a Tandem repeat sequence?

Answer 19

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

Question 20

Describe and Explain a use of Tandem Repeat sequencing?

Answer 20

Used in paternity tests

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

Question 21

Describe the process of DNA profiling

Answer 21

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

Question 22

Give some examples of uses of DNA Profiling

Answer 22

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

Maternity and Paternity disputes

Analysis of disease (diagnosing genetic disorders)

Question 23

What does PCR stand for and what does it do?

Answer 23

Polymerase Chain Reaction

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

Question 24

What discovery allowed the PCR process to become more efficient?

Answer 24

Discovery of a new thermophilic bacterium (Thermophilus aquaticus)

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

Question 25

Describe the process of PCR

Answer 25

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

Question 26

Give some examples of uses of PCR

Answer 26

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

Question 27

What is an electrophoresis plate made out of?

Answer 27

Agarose gel covered in a buffer solution

Question 28

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

Answer 28

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)

Question 29

What are the two ways to mark a DNA probe?

Answer 29

Radioactive Marker

Fluorescent marker

Question 30

What is the structure and function of a DNA probe?

Answer 30

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

Question 31

Give some examples of uses of DNA probes

Answer 31

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

Question 32

What is a microarray?

Answer 32

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