Cell Biology:DNA

Lesson 2 – Recombinant DNA (Inquiry into Life pg. 500-507)

Today’s Objectives Describe Recombinant DNA,

including: Define recombinant DNA Describe a minimum of 3 uses for

recombinant DNA

Recombinant DNA Definition:

DNA having genes from 2 different organisms, often produced in the laboratory by introducing foreign genes into a bacterial plasmid

A vector is used to introduce recombinant DNA into a cell

A plasmid is the most common vector They are small rings of DNA found in bacteria The plasmid has to be removed from the bacteria

and has to have a foreign gene inserted into it

Insertion of Foreign Genes An enzyme

(restriction enzyme) breaks the plasmid DNA ring

The new foreign DNA can now be attached to the plasmid

The enzyme ligase acts like glue which sticks the foreign DNA to the plasmid and recreates the ring

Insertion of Foreign Genes

Recombinant DNA The plasmid DNA

is then put back into the bacteria

This bacteria will now replicate every cell the same as the one just put in

Eventually there are many copies of the foreign gene

Applications of Recombinant DNA Recombinant human insulin

Human insulin gene inserted into bacteria E. Coli, used to treat diabetes

Recombinant human growth hormone (HGH) Treats patients with pituitary gland deficiencies to support normal

growth and development Inserted into livestock to produce larger specimens

Recombinant blood clotting factor VIII Blood clotting protein administered to patients with bleeding

disorders Recombinant hepatitis B vaccine

Control of hepatitis B virus Diagnosis of HIV infection

Methods for diagnosing HIV have been developed using recombinant DNA

Herbicide and Insect resistant crops Used in agriculture to reproduce genes that help crops resist attack

by insects and protect crops from herbicides

Applications of Recombinant DNA Generate DNA libraries which will catalogue

all the base sequences of known genes Identify specific genes

In 1998, the gene that mutates to cause prostate cancer was identified

Produce synthetic copies of genes Insert genetic material into chromosomes that

will help regulate cell function to make organisms genetically “better”

Viral DNA Viral DNA (DNA from a virus) can also be used as a

vector to carry recombinant DNA into a cell When a virus containing recombinant DNA infects a cell,

the viral DNA enters Here it can direct the reproduction of many more viruses Each virus derived from a viral vector contains a copy of

the foreign gene, therefore viral vectors allow cloning of a particular gene

Viral Vectors Viral vectors are also used to create genomic

libraries A genomic library, or gene bank, is a collection of

engineered viruses that carry all the genes of a species

Purpose: Break up DNA into manageable chunks for research Can analyze specific strands of DNA/amino acid

sequences to determine their function, which can then be inserted into other cells

Stores all of the DNA for a species It takes about 10 million viruses to carry all the

genes of a mouse

Summary Segments of DNA (particular genes) can be

inserted into bacteria and the bacteria will produce these genes

If desired genes are used – like those that produce certain chemicals (vaccines, antibodies, etc.) then these proteins become much more available

Protein hormones like insulin (regulates blood-sugar levels) can be made using yeast cells

Interferon, a protein used in cancer treatments to help the immune system is now mass-produced in this way

Antibiotic Resistance More and more bacteria are becoming resistant

to our common antibiotics, and to make matters worse, more and more are becoming resistant to all known antibiotics

The problem is known as multi-resistance, and is generally described as one of the most significant future threats to public health

Antibiotic resistance can arise in bacteria in our environment and in our bodies

Antibiotic resistance can then be transferred to the bacteria that cause human diseases, even if the bacteria are not related to each other

Antibiotic Resistance Antibiotic resistance-carrying plasmids from

different bacteria can meet and exchange genetic material

The result is plasmids consisting of genes that have each been adapted to different bacterial species

Antibiotic Resistance This facilitates further adaptation and

mobility, and consequently the spread of antibiotic resistance between different bacterial species

Antibiotic Resistance Widespread abuse of antibiotics, particularly

in agriculture, is rapidly increasing the proliferation of multi-resistant bacteria

Antibiotic Resistance Left unchecked, multi-resistant bacteria

represent one of the greatest future health concerns in the world and could see the return of previously controlled diseases that affected humans in the past……

WITHOUT THE ABILITY TO STOP THEM

Currently, bacteria are developing multi-resistance faster than scientists can develop new antibiotics to control them

Are you scared yet?!