Biotechnology

Question 1

Describe the purpose of biotechnology

Answer 1

Molecular biologists need tools to cut, join, and replicate DNA to analyze certain genes or alter their proteins. These tools may be living organisms or biological molecules that help manipulate pieces of DNA molecules to another, forming recombinant DNA (pieces of DNA made of sequences originating from at least two different sources)

Question 2

What are the most common biological tools?

Answer 2

Restriction enzymes (endonucleases)
Methylates
Ligases

All come from living organisms (bacteria)

Question 3

Describe restriction enzymes

Answer 3

Enzymes that are able to cleave/cut DNA into fragments at very specific palindromic sequences. They are molecular scissors that disrupt the phosphodiester bonds and as a result, the hydrogen bonds between the base pairs are also disrupted.

They act like an immune system. When a virus like bacteriophage attacks a bacterial cell, it injects its DNA. The bacteria’s restriction endunucleases starts to scan this foreign DNA for recognition sites and cuts the foreign DNA into fragment. Therefore the virus’ DNA is no longer useful.

There are different examples of restriction enzymes that recognize specific DNA sequences. They are all isolated and purified solely from bacteria.

Each enzyme recognizes a characteristic sequence of nucleotides that is known as a recognition site that is found within a double-stranded DNA, consisting of 4 to 8 nucleotides.

Question 4

What are the two types of restriction enzyme cuts?

Answer 4

Blunt and sticky

Question 5

Which enzymes produce blunt and sticky ends?

Answer 5

AluI and HaeIII produce blunt ends

BamHI, HindIII, and EcoRI produce sticky ends

Question 6

Which ends are more useful tools for molecular biologists and what do they use them for?

Question 7

Describe methylates

Answer 7

Enzymes found in eukaryotes and prokaryotes that add a methyl group to one of the nucleotides found in a recognition site, altering its chemical composition.

They are important because they help protect a gene fragment from being cut in an undesired location.

Ex. Methyl groups prevent the restriction enzyme from binding.

Question 8

Describe DNA ligases

Answer 8

Enzymes used to join together DNA blunt or sticky ends by reforming the phosphodiester bonds. If genes are cut out of a source of DNA, there has to be a way to join them to foreign target DNA

Question 9

Which enzyme can join blunt or sticky ends?

Answer 9

T4 DNA ligase