Chapter 13 Lecture- Biotech

Copyright Pearson Prentice Hall

Biology

Biology


13-1 Changing the Living World


Selective Breeding

Selective Breeding

Selective breeding allows only those organisms with desired characteristics to produce the next generation.Nearly all domestic animals and most crop plants have been produced by selective breeding.

Humans use selective breeding to pass desired traits on to the next generation of organisms.


Hybridization

Hybridization is the crossing of dissimilar individuals to bring together the best of both organisms. Hybrids, the individuals produced by such crosses, are often hardier than either of the parents.

Inbreeding Inbreeding is the continued breeding of individuals with similar characteristics. Inbreeding helps to ensure that the characteristics that make each breed unique will be preserved.Serious genetic problems can result from excessive inbreeding.


Breeders increase the genetic variation in a population by inducing mutations.

Mutations occur spontaneously, but breeders can increase the mutation rate by using radiation and chemicals.Breeders can often produce a few mutants with desirable characteristics that are not found in the original population.


Increasing Variation

Producing New Kinds of BacteriaIntroducing mutations has allowed scientists to develop hundreds of useful bacterial strains, including bacteria that can clean up oil spills.


Producing New Kinds of Plants

Polyploidy produces new species of plants because the chromosome number changes. Polyploids are often larger and stronger than their diploid relatives..Polyploidy in animals is usually fatal.


13-2 Manipulating DNA


Scientists use their knowledge of the structure of DNA and its chemical properties to study and change DNA molecules.


Scientists use different techniques to:extract DNA from cellscut DNA into smaller piecesidentify the sequence of bases in a DNA moleculemake unlimited copies of DNA


In genetic engineering, biologists make changes in the DNA code of a living organism.


DNA Extraction

DNA can be extracted from most cells by a simple chemical procedure.The cells are opened and the DNA is separated from the other cell parts.


The Tools of Molecular Biology

Cutting DNA

Most DNA molecules are too large to be analyzed, so biologists cut them into smaller fragments using restriction enzymes.


Each restriction enzyme cuts DNA at a specific sequence of nucleotides.

Restriction enzyme EcoR I cuts the DNA into fragments Sticky end

Recognition sequences

DNA sequence


Recognition sequences

DNA sequence

Restriction enzyme EcoR I cuts the DNA into fragments Sticky end

A restriction enzyme will cut a DNA sequence only if it matches the sequence precisely.

In gel electrophoresis, DNA fragments are placed at one end of a porous gel, and an electric voltage is applied to the gel. The negatively-charged DNA molecules move toward the positive end of the gel.

Gel electrophoresis can be used to compare the genomes of different organisms or different individuals. It can also be used to locate and identify one particular gene in an individual's genome.

DNA plus restriction enzyme

Mixture of DNA fragments

Gel

Power source

Gel Electrophoresis

Longer fragments

Shorter frag ments

Active art


1. restriction enzymes cut DNA into fragments. 2. DNA fragments are poured into wells on a gel.

DNA plus restriction enzyme

Mixture of DNA fragments

Gel



3. An electric voltage moves the DNA fragments across the gel.The smaller the DNA fragment, the faster and farther it will travel.

Power source



4. The pattern of bands can be compared with other samples of DNA.

Longer fragments

Shorter frag ments


Using the DNA Sequence

Knowing the sequence of an organism’s DNA allows researchers to study specific genes, to compare them with the genes of other organisms, and to try to discover the functions of different genes and gene combinations.


Reading the Sequence

In DNA sequencing, a complementary DNA strand is made using a small proportion of fluorescently labeled nucleotides.


Using the DNA Sequence

DNA Sequencing

DNA strand with unknown base sequence

DNA fragments synthesized using unknown strand as a template

Dye molecules


Each time a labeled nucleotide is added, it stops the process of replication, producing a short color-coded DNA fragment.

When the mixture of fragments is separated on a gel, the DNA sequence can be read.

Base sequence as “read” from the order of the dye bands on the gel from bottom to top:

T G C A C

Electrophoresis gel

Cutting and Pasting Short sequences of DNA can be assembled using DNA synthesizers. “Synthetic” sequences can be joined to “natural” sequences using enzymes that splice DNA together.


These enzymes also make it possible to take a gene from one organism and attach it to the DNA of another organism.

DNA molecules that contain genes from more than one organism are sometimes called recombinant DNA.


Making Copies

Polymerase chain reaction (PCR) is a technique that allows biologists to make copies of genes. A biologist adds short pieces of DNA that are complementary to portions of the sequence.

DNA heated to separate strands

PCR cyclesDNA copies

1 2 3 4 5 etc.1 2 4 8 16 etc.

Polymerase Chain Reaction (PCR)

DNA polymerase adds complementary strand

DNA fragment to be copied


DNA is heated to separate its two strands, then cooled to allow the primers to bind to single-stranded DNA.

DNA polymerase starts making copies of the region between the primers.


13-3 Cell Transformation

Recombinant DNA

Host Cell DNATarget gene

Modified Host Cell DNA


During transformation, a bacteria cell takes in DNA from outside the cell. The foreign DNA becomes inserted in the cell’s own DNA.


Foreign DNA is first joined to a small, circular DNA molecule known as a plasmid.Plasmids are found naturally in some bacteria and have been very useful for DNA transfer.


The plasmid has a genetic marker—a gene that “marks” cells that have successfully incorporated the foreign DNA. Ex. Production of identifiable protein, antibiotic resistance.


Recombinant DNA

Gene for human growth hormone

Gene for human growth hormone

Human Cell

Bacteria cell

Bacterial chromosome

Plasmid

Sticky ends

DNA recombination

Bacteria cell containing gene for human growth hormone

DNA insertion

Movie


Transformation in PlantsIn nature, a bacterium exists that produces tumors in plant cells. Researchers can inactivate the tumor-producing gene found in this bacterium and insert a piece of foreign DNA into the plasmid. Recombinant plasmids are used to infect plant cells.


When their cell walls are removed, plant cells in culture will sometimes take up DNA on their own.

DNA can also be injected directly into some cells.Cells transformed by either procedure can be cultured to produce adult plants.

TRANSFORMATION = taking in foreign DNA

Complete plant generated from transformed cell.

Inside plant cell, Agrobacterium inserts part of its DNA into host cell chromosome.

Plant cell colonies

Transformed bacteria introduce plasmids into plant cells.

Agrobacterium tumefaciens

Cellular DNA

Gene to be transferred

Recombinant plasmid

Transformation

Transforming Animal Cells

Many egg cells are large enough that DNA can be directly injected into the nucleus.Enzymes may help to insert the foreign DNA into the chromosomes of the injected cell.DNA molecules used for transformation of animal and plant cells contain marker genes.


13–4 Applications of Genetic Engineering


Transgenic OrganismsAn organism described as transgenic, contains genes from other species.


Genetic engineering has spurred the growth of biotechnology.


Transgenic bacteria can produce large quantities of important substances useful for health and industry, including human proteins:

•insulin•growth hormone•clotting factor


Transgenic animals have been used to study genes and to improve the food supply. Mice have been produced with human genes that make their immune systems act similarly to those of humans. This allows scientists to study the effects of diseases on the human immune system.


Researchers are trying to produce transgenic chickens that will be resistant to the bacterial infections that can cause food poisoning.


Transgenic plants are now an important part of our food supply.Many food plants contain a gene that produces a natural insecticide, so plants don’t have to be sprayed with pesticides.


A clone is a member of a population of genetically identical cells produced from a single cell.In 1997, Ian Wilmut cloned a sheep called Dolly.

Dolly and Bonnie

Donor Nucleus

Fused cell

Embryo

Egg Cell

Foster MotherCloned Lamb

Cloning Dolly


Cloning

Cloning Dolly


Cloning Dolly


Cloning Dolly


Cloning Dolly


Cloning Dolly


Cloning Dolly


Researchers hope cloning will enable them to make copies of transgenic animals and help save endangered species.

Studies suggest that cloned animals may suffer from a number of genetic defects and health problems.


13-1

The usual function of selective breeding is to produce organisms that

a. are better suited to their natural environment.

b. have characteristics useful to humans.

c. can compete with other members of the species that are not selected.

d. are genetically identical.


13-1

Crossing a plant that has good disease-resistance with a plant that has a good food-producing capacity is an example of

a. inbreeding.

b. hybridization.

c. polyploidy.

d. crossing over.


13-1

New species of plants that are larger and stronger are a result of

a. monoploidy.

b. diploidy.

c. polyploidy.

d. triploidy.


13-1

The function of inbreeding is to produce organisms that

a. are more genetically diverse.

b. are much healthier.

c. are genetically similar.

d. will not have mutations.


13-1

Increasing variation by inducing mutations is particularly useful with

a. animals.

b. bacteria.

c. plants.

d. fungi.


13-2

Restriction enzymes are used to

a. extract DNA.

b. cut DNA.

c. separate DNA.

d. replicate DNA.


13-2

During gel electrophoresis, the smaller the DNA fragment is, the

a. more slowly it moves.

b. heavier it is.

c. more quickly it moves.

d. darker it stains.


13-2

The DNA polymerase enzyme Kary Mullis found in bacteria living in the hot springs of Yellowstone National Park illustrates a. genetic engineering. b. the importance of biodiversity to

biotechnology. c. the polymerase chain reaction. d. selective breeding.


13-2

A particular restriction enzyme is used to

a. cut up DNA in random locations.

b. cut DNA at a specific nucleotide sequence.

c. extract DNA from cells.

d. separate negatively charged DNA molecules.


13-2

During gel electrophoresis, DNA fragments become separated because

a. multiple copies of DNA are made.

b. recombinant DNA is formed.

c. DNA molecules are negatively charged.

d. smaller DNA molecules move faster than larger fragments.


13-3

Plasmids can be used to transform

a. bacteria only.

b. plant cells only.

c. plant, animal, and bacterial cells.

d. animal cells only.


13-3

An unknowing pioneer in the concept of cell transformation was

a. Luther Burbank.

b. Frederick Griffith.

c. Oswald Avery.

d. James Watson.


13-3

One reason plasmids are useful in cell transformation is that they

a. are found in all types of cells.

b. prevent gene replication.

c. counteract the presence of foreign DNA.

d. have genetic markers indicating their presence.


13-3

A common method of determining whether bacteria have taken in a recombinant plasmid is to a. introduce them into plant cells. b. introduce them into animal cells. c. treat them with an antibiotic. d. mix them with other bacteria that do not have

the plasmid.


13-3

Successful transformation of an animal or a plant cell involves a. the integration of recombinant DNA into the

cell’s chromosome. b. changing the cell’s chromosomes into

plasmids. c. treating the cell with antibiotics. d. destroying the cell wall in advance.


13–4

Insulin-dependent diabetes can now be treated with insulin produced through the use of

a. transgenic plants.

b. transgenic animals.

c. transgenic microorganisms.

d. transgenic fungi.


13–4

Transgenic tobacco plants that glow in the dark were produced by transferring the gene for luciferase from a

a. clone.

b. bacterium.

c. firefly.

d. jellyfish.


13–4

The first mammal to be cloned was a

a. sheep.

b. horse.

c. dog.

d. cat.


13–4

In producing a cloned animal, an egg cell is taken from a female and its nucleus is removed. A body cell is taken from a male. The clone from this experiment will

a. look just like the female.

b. be genetically identical to the male.

c. have a mixture of characteristics from both animals.

d. resemble neither the male nor the female.


13–4

Animals produced by cloning have been shown to

a. all be perfectly healthy.

b. suffer from a number of health problems.

c. live longer than uncloned animals.

d. be less intelligent than uncloned animals.

Education

Chapter 13 Lecture- Biotech