CP.Chapter 13.genetic engineering.pptx - CollinsBiology

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GENETIC ENGINEERING

CHAPTER 13


Changing
the Living World

Selective Breeding

Allowing
animals with
desired traits to reproduce
and pass traits to the next
generation.


a. Dog
breeding


b. Cattle


c. Horses



Selective Breeding

Inbreeding
-

continued breeding
of individuals with similar
characteristics or are closely related.

Traits are preserved in each
generation.

Pure
-
Breeds

Genetically similar and this can
cause problems.


More likely to have a recessive
disorder(s).

Dogs


blindness, joint
problems, etc.


Selective Breeding

Hybridization


crossing
individuals who are not
similar.


To get the best traits of
each parent in the offspring.


Genetically “stronger”
than the parent

Mutts


DOC

RAGNAR

Increasing Variation

Mutation is the driving
force behind genetic
variation.


Can be done by selective
breeding.

Bacteria have been
made this way.

Pseudomonas



bacteria made to “eat”
oil and clean up oil
spills.


See Fig. 13
-
3



Increasing Variation
Con’t

Plants

Can be made
polyploid

(many sets of chromosomes).

Makes new species of
plants that are stronger.

Ex.


day lilies &
banana

See Fig. 13
-
4


MANIPULATING DNA

INTRODUCTION

DNA structure and chemical make
up has been studied and techniques
developed to change the DNA code.


Techniques to take out (extract)
DNA from cells.


DNA is cut into smaller pieces to
identify the sequence and to make
copies of a piece of DNA.


TOOLS OF MOLECULAR
BIOLOGY

Genetic Engineering


Making changes in the
DNA code of a living
organism.


DNA Extraction


cells
are opened (
lysed
) and
DNA is separated from the
other organelles.

TOOLS OF MOLECULAR
BIOLOGY (CONT’D)

Cutting DNA


DNA
can be cut into smaller
pieces to be studied.


Restriction enzymes


used to cut DNA at
specific sequences.

ex.


BAMIII,
HINDIII, etc




TOOLS OF MOLECULAR
BIOLOGY (CONT’D)

Gel electrophoresis


used to
separate DNA

DNA mixture placed on a gel
-
pad and is exposed to electricity

DNA molecules are
negatively charged and move
down the gel bed based on size.

Smaller the DNA fragment
size, the faster it moves down
the gel bed.

Used to compare genomes of
organisms and to locate & identify
specific genes.

USING THE DNA SEQUENCE


DNA sequence can be
read, studied and/or
changed.


Knowing the sequence
allows scientists to study
genes & compare them with
genes of different
organisms.

Try to discover the
function of a gene.


READING THE SEQUENCE

Scientists prepare
DNA fragments with
colored dyes.


Each colored dye = a
base in the DNA
chain.


The DNA sequence
can now be “read”


Cutting and Pasting

Changing of the DNA
sequence

Synthetic (changed
sequences) can be joined to
natural (unchanged) DNA
sequences forming
recombinant DNA.

Recombinant DNA
(
rDNA
) is made by
combining DNA sequences
from different sources.


MAKING COPIES

Researchers need to make many copies of
a sequence of DNA.


Done using PCR


PCR


Polymerase chain reaction


Kary

Mulis


inventor of PCR & won the Nobel
Prize.


Primers


short pieces of DNA that
provide a place for the DNA
polymerase (enzyme) to attach and
start copying.

DNA is heated to separate the two
strands

DNA is cooled and the primers can
bind to the one strand of DNA.

DNA polymerase binds to the single
-
strand of DNA and starts to make
copies.

SEE FIG. 13
-
8


CELL TRANSFORMATION

Transformation


A
cell takes in DNA from
outside the cell and
becomes part of that
cell’s DNA.


Bacteria are
transformed using
recombinant DNA
methods

TRANSFORMATION CONT’D

STEPS:

Foreign DNA joins to the
bacteria’s single circular DNA
and creates a PLASMID.


Plasmid has 2 features:

Carries the DNA sequence
to start replication

Genetic marker


a gene
that shows which bacteria
carry the plasmid and which
do not. Usually a protein

This technology helps
researchers to study proteins
and genes.

See Fig. 13
-
9, pg. 327.



APPLICATIONS OF GENETIC
ENGINEERING
-


TRANSGENIC ORGANISMS

Organisms that contain genes from
other organisms



Genes are inserted in different
organisms


Used to grow new organisms

Usually plants

Transgenic Microorganisms


bacteria

Used to make substances for
health care industry.


Ex.


insulin, growth hormone &
clotting factors


Allows companies to make substances
in large quantities very cheap.



Transgenic Animals

Animals have
been given extra
growth hormone
so they can grow
quicker.


Genes are
inserted so that the
meat is less fatty.


TRANSGENIC PLANTS


In 2006, 89% of soybean grown
in US were transgenic or
“genetically modified” (GM
foods).


Genes that produce insecticides
or genes that resist weed
-
killers.


Rice


genes are inserted to
make the rice produce Vitamin A.


GM plants may one day
produce human
antiboides

&
plastics.



CLONING

Clone


member of a population of
identical cells made from a single cell.

Bacteria


easy to grow


Ian
Wilmut



Scottish scientist

1997 he cloned a sheep


Dolly (SEE

FIG.13
-
14, pg. 333)

Steps in cloning


Egg cell nucleus is removed

That cell is fused with a cell from
another adult.

The embryo that results is placed
into a foster (surrogate) mother.


Scientists have successfully cloned
cows, pigs and mice
(this is
done
regularly).