Chapter 13 Frontiers of Genetics

13.1 Biologists have learned to manipulate DNA

Technology The Application of scientific knowledge for human benefit

Past

Present

Biotechnology Humans using other organisms for human benefit

Biotechnology Past

Biotechnology Present

Genetic Engineering modification of an organism by altering its genetic material.

13.3 Biologists can genetically engineer plants and animals

The GMO Controversy Are genes inserted into plants harmful to humans? “superweeds” produced from herbicide resistant genes Engineered proteins different from natural proteins? Allergies?

genetic material from a Transgenic A GMO that has genetic material from a a different species

Genetically Modified Plants Plants can be genetically modified to contain pesticides they don’t normally contain

Genetically Modified Animals Goals (examples): Sheep – better quality wool Pig – leaner meat Milk – produced with beneficial protein

Genetically Modified Organisms (GMOs) Organisms that have had 1 or more genes transplanted into their genomes, by scientists

B. Tools in Genetic Engineering

1. Bacterial Plasmid A small circular piece of BACTERIAL DNA. used to deliver a gene from one organism into a bacterial cell.

Plasmids can move in and out of bacterial cells

Bacterial enzymes that cut DNA “Molecular scissors” Sequence specific RESTRICTION ENZYMES Bacterial enzymes that cut DNA “Molecular scissors” Sequence specific Sticky ends

Restriction Enzyme hugging the DNA

A Restriction Site

The region of broken H bonds are called Sticky Ends

13.2 Biologists can engineer bacteria to make useful products.

A. Recombinant DNA Technology Combining genes from different sources – even different species – into a single DNA molecule

Gene Splicing Pieces of DNA are “glued” together

Gene Splicing a. Donor: organism that donates the desired gene. DNA is “cut out” with a restriction enzyme.

Gene Splicing b. Restriction Enzyme: the same restriction enzyme is used to cut the donor DNA and the plasmid.

-Restriction Enzyme used on two different DNA molecules

-Complimentary sticky ends are created

The plasmid and the donor gene must be cut with the same restriction enzyme.

Gene Splicing c. Plasmid: Circular piece of DNA found only in bacteria. Plasmid is cut with the same restriction enzyme at the donor DNA

Gene Splicing d. Splice: Complimentary sticky ends of the 2 different DNA are connected using the enzyme ligase.

Gene Splicing This results in the formation of a new plasmid, called a recombinant plasmid.

Gene Splicing e. Host Cells: Cells that the recombined plasmids are placed in.

Useful Products From Genetically Engineered Microorganisms: 1. pesticides 2. therapeutic drugs 3. insulin 4. growth hormone

The plasmid, with its new gene, is taken up by a “host” bacterial cell. Host cell

The plasmid is taken into a host cell where it produces a product and replicated when the cell divides.

Gene Splicing f. Vector: Carries the new gene into the receiving cell (ie. plasmid, virus)

Gene Splicing Pieces of DNA are “glued” together Plasmid Donor Recombined DNA Host

B. Cloning Making a genetically identical copy of an organism. Mitosis forms clone cells

a. Unicellular Cloning Making exact copies of an organism by the process of mitosis.

An easy way to make exact copies of valuable plants Plant Cloning - An easy way to make exact copies of valuable plants b. Multicellular Cloning

Animal Cloning nucleus from the desired animal is used to make genetically identical clones. surrogate animals are used in the process.

C. Mass Producing DNA

Polymerase Chain Reaction Technique that makes many copies of a DNA segment without using living cells

PCR step 1 – “Melt” the DNA The H-bonds are broken

PCR step 2 – Add primer Small segments of DNA

Polymerase adds more bases. PCR step 3 - Replication Polymerase adds more bases.

PCR amplifies the amount of DNA Times as much as original Cycle # Formula Times as much as original 1 21 2 22 4 3 23 8 40 240 1.1 x 1012

D. Comparing DNA

Electric attraction is used to sort the cut pieces of DNA. Gel Electrophoresis DNA is cut with restriction enzymes. Electric attraction is used to sort the cut pieces of DNA.

Gel Electrophoresis Separation of pieces of DNA is based on size. Small pieces move faster than large pieces.

The Gel is a soft material that is mostly water. Positive Charge Negative Charge The Gel is a soft material that is mostly water. DNA has a net negative charge

Wells – different samples of DNA are placed in each well. Negative Charge Wells – different samples of DNA are placed in each well. Positive Charge

Negative Charge Positive Charge The DNA fragments are pulled through the gel toward the positive electrode. Smaller fragments travel faster than large fragments. Positive Charge

Negative Charge 1 2 5 6 7 8 3 4 The DNA fragments move in straight lanes toward the positive end of the gel. Positive Charge

Lane one has a sample of DNA with fragments of known sizes. 1 Lane one has a sample of DNA with fragments of known sizes. The fragments are measured using the unit called kilobases.

This lane has DNA taken from the crime scene.

Which lane(s) shows DNA from the same person? Positive Charge Negative Charge 1 2 5 6 7 8 3 4 Which lane(s) shows DNA from the same person?

DNA Fingerprinting A specific banding pattern is produced by gel electrophoresis

Place the following steps in the correct order for completing a DNA Fingerprint using PCR and Gel Electrophoresis   Small sections of DNA move faster to the positive side of the gel plate than large sections Place DNA samples in wells of gel plate Compare banding patterns of DNA Fingerprints Apply Polymerase Chain Reaction (PCR) to DNA samples to make more of the sample Apply electric current to gel plate F. Use Restriction Enzymes on the DNA

Answer Apply Polymerase Chain Reaction (PCR) to DNA samples to make more of the sample Use Restriction Enzymes on the DNA samples Place DNA samples in wells of gel plate Apply electric current to gel plate A. Small sections of DNA move faster to the positive side of the gel plate than the large sections C. Compare banding patterns of DNA Fingerprints

E. Stem Cell Technology

13.5 Control mechanisms switch genes on and off

Cellular Differentiation The changes that a cell undergoes as it becomes more specialized.

Cellular Differentiation A particular cell will only express genes that code for proteins with functions in that cell…

Differentiation is controlled by the genes of the embryo.

Where would the glycolysis enzyme gene need to be active?

transparent protein gene Where would the transparent protein gene need to be active?

Where would the insulin gene need to be active?

Where would the hemoglobin gene need to be active?

have the potential to develop into various types of cells Stem Cells have the potential to develop into various types of cells

Consider the genes of a zygote…

A zygote has all of the genes for all of the traits of an organism.

Are all of the genes available for use even in a mature individual?

Development

During embryonic development _____________increases and _______________ decreases.

During embryonic development differentiation increases and _______________ decreases.

During embryonic development differentiation increases and nuclear potency decreases.

Embryonic STEM CELLS are Pluripotent Cells

Nuclear (DNA) Potency pto – permanently turned off. Totipotent Genes pto Use Example Totipotent None Can develop into a complete organism plus placental Zygote Pluripotent A few Can give rise to most tissues. EmbryonicStem cells Multipotent Many Can perform the tissue’s function. Specialized tissue cells pto – permanently turned off.

Human Blastocyst Hollow ball of cells Inner mass of cells Stem cells