Genetic Engineering

Genetic Engineering:

• Genetic Engineering: process of altering biological systems by the purposeful manipulation of DNA

• Applications:– Production of proteins (insulin, hormones, vaccine)– Agriculture: plants can be more suitable for growth

and resistant to insects and bacteria– Medicine: diagnosis, medication, gene

replacement therapy

Methods:

• Breeding • Investigation (Genetic testing for disease, test

paternity, investigating crime scenes)• Cloning (genes of interest, plants/animals)

Breeding

• Breeding Methods: are used to get desirable traits– Selective breeding: choosing an organism with

desirable traits– Inbreeding: mating closely related organisms that

have desired traits• Decreases variation

– Hybridization: mating organisms that are not closely related for a mixture of both genes

Hybrids usually are sterile!

Test Cross Activity

• Test cross is one way to determine genotype– HH or Hh? Cross it with a hh and observe

offspring– If any express the recessive trait hh then the

parent was Hh• Pg:347• Read • Critical Thinking #1-5

Gene Cloning• Why? • Some people lack the essential proteins like

insulin, thyroxine, etc• Create organisms that have characteristics of

other organism

How to clone genes?

1. Identify gene of interest2. Cut it out using a restriction enzyme

• Restriction enzyme recognizes a specific DNA nucleotide sequence and cuts at that site

3. Cut a vector (usually a plasmid (circular DNA) of a bacteria)4. Insert cut gene of interest into vector using sticky ends

(called splicing)5. Insert the plasmid back into the host (bacteria)– This technique is called Recombinant DNA to create a

transgenic organism (organism that contains foreign genes)

Diagram of Cleavage

GAATTCCTTAAG

GAATTCCTTAAG

G AATTCCTTAA G

Diagram of Recombinant DNA

Activity in Text Book

• Mini Lab 13-1 on pg 351• Follow all steps in procedure • Answer analysis question #3

Gel Electrophoresis

• Gel Electrophoresis: separates molecules based on their rate of movement through a gel under the influence of an electric field, based on the size and charge of the molecules

How does Gel Electrophoresis work?

• DNA fragments are made using restriction enzymes• A mixture of fragments is placed in one end of the

gel• An electric voltage is applied to the gel• DNA (which is negative) would move to the positive • Since there are tiny holes in the gel, the small

pieces move farther in the gel• This creates a unique DNA “fingerprint”

What can this be used for?

• Since each person has a unique sequence of DNA, the restriction enzyme creates different size pieces for each persons DNA called a DNA fingerprint

• Related people have similar DNA and therefore their DNA will be cut into similar size pieces

• It can be used to determine paternity and help identify unknown DNA samples

Gel Electrophoresis

Activity in the textbook

• Activity 13-3 Questions 1-3• Pg 361

PCR

• Is the technique that allows us to make many copies of genes.

• First lets review some concepts….• How does DNA replicate in cells? Steps?– DNA unwinds and unzips– Free nucleotides attach to their complementary

bases– DNA polymerase attaches them together

Steps in PCR: Machine assisted DNA replication

• PCR stands for polymerase chain reaction• DNA of interest is placed in machine• DNA is heated

– Heat will break the weak hydrogen bond btw the strands• Free nucleotides are added• DNA polymerase is added creating the new complementary

strands• Steps are repeated to create a large amount of DNA• Does your DNA polymerase work at high temperatures?

The DNA polymerase used is called taq polymerase…. From bacteria that live in hot springs..

Cloning an organism…… OH DOLLY!

• Steps:– Donor cell is taken from a sheep– An egg cell from a different sheep is taken– The nucleus is extracted– The empty egg is fused with the donor cell– The cell is implanted into a female sheep– Will eventually become a clone of the donor

Cloning an organism

Challenge question…

• Would a clone have more mutations than a normal offspring?

• Would a clone have the same survival rate as a normal offspring?

• What are some dangers of this new technology?

• Should the government put restrictions on human cloning?

HW

• Questions 1-20• Pg 365-366• WRITE QUESTION AND ANSWER…..