Biogenetic Engineering & Manipulating Genes - Troy High School

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Biogenetic Engineering &
Manipulating Genes

Chapter 20

Intro. Q’s #6
-
for Chapter 20: Genetic Engineering

1)
What does the acronym PCR stand for and what does this process
do?

2)
What does Gel electrophoresis allow us to do?

3)
Give two applications of DNA profiling.

4)
What are the advantages and disadvantages of genetic screening?

5)
Describe what genetic engineering is and explain how such items as
restriction enzymes, DNA ligase, and the production of “sticky
ends” are used.

6)
Name two “vectors” that can be used for gene transfer.

7)
Give two examples of genetically modified crops or animals

8)
Briefly explain the process of gene therapy and give an example
how it works.

9)
Explain what a clone is and how it could be formed.

10)
What are some of the ethical concerns about cloning? Give your
opinion if you think cloning is something we should

be doing.


Genetic Engineering


Chapter 14



DNA Technology

& Genomics


O.J. Simpson capital murder case,1/95
-
9/95



Odds of blood in Ford Bronco
not

being R. Goldman’s:



6.5 billion to 1


Odds of blood on socks in bedroom

not
being N. Brown
-
Simpson’s:


8.5 billion to 1


Odds of blood on glove

not

being from R. Goldman, N. Brown
-
Simpson, and O.J.
Simpson:


21.5 billion to 1


Number of people on planet earth:


6.1 billion


Odds of being struck by lightning in the U.S.:


2.8 million to 1


Odds of winning the Illinois Big Game lottery:


76 million to 1


Odds of getting killed driving to the gas station to buy a lottery ticket


4.5 million to 1


Odds of seeing 3 albino deer at the same time:


85 million to 1


Odds of having quintuplets:


85 million to 1


Odds of being struck by a meteorite:


10 trillion to 1

Recombinant DNA


Def:

DNA in which genes
from 2 different sources are
linked


Genetic engineering:

direct
manipulation of genes for
practical purposes


Biotechnology:

manipulation of organisms
or their components to
perform practical tasks or
provide useful products

Restriction Enzymes

Tools of Genetic Engineering


Restriction enzymes (endonucleases)


-
in nature, these enzymes protect bacteria from intruding
DNA;
they cut

up the DNA (restriction); very specific


Restriction site
:






-
recognition sequence for a particular restriction enzyme


Restriction fragments
:






-
segments of DNA cut by restriction enzymes in a
reproducible way


Sticky end
:



-
short extensions of restriction fragments


DNA ligase
:







-
enzyme that can
join the sticky ends

of DNA fragments


Cloning vector
:






-
DNA molecule that can carry foreign DNA into a cell and
replicate there (usually bacterial plasmids)

Producing Restriction Fragments


DNA ligase used to splice together cut plasmids
and chromosome fragments





After amplification, clones are:

-
identified

-
some are always stored in a genomic library

Tools for DNA Analysis & Genomics


PCR (polymerase chain
reaction)


Gel electrophoresis


Restriction fragment analysis
(RFLPs)


Southern blotting


DNA sequencing


Human genome

project


Polymerase Chain Reaction (PCR)

http://highered.mcgraw
-
hill.com/sites/0072437316/student_view0/chapter16/animations.html#



Amplification of any piece of DNA without cells
(in vitro)


Produces many identical copies of a DNA
segment


Materials: heat, DNA polymerase, nucleotides,
single
-
stranded DNA primers


Applications: fossils, forensics, prenatal
diagnosis, etc.

Polymerase Chain reaction (PCR)

Polymerase Chain Reaction


PCR

= common method of creating copies of
specific fragments of DNA


PCR rapidly amplifies a single DNA molecule into
many billions of molecules.


Small samples of
DNA can produce
sufficient copies to
carry out
forensic tests

DNA Profiling (DNA fingerprinting)


Two Applications:



-
Used in criminal investigations



-
Identify the remains of dead people


Restriction Fragment Analysis


Restriction fragment length polymorphisms (RFLPs)


Southern blotting
: process that reveals sequences and the
RFLPs in a DNA sequence


DNA Fingerprinting (DNA Profiling)

Gel Electrophoresis


DNA fragments placed into “wells” in
gel agarose


Electricity pulls on DNA fragments


Fragments travel at

different rates

based

on
size

and ability to

squeeze through

swiss
-
cheese
-
like

agarose

Gel Electrophoresis


separates nucleic acids or proteins on the basis of size and electrical charge
creating DNA bands of the same length


DNA has a net negative charge (use a positive charge in the gel)









Applications of RFLPs


DNA cut by restriction enzymes & separated on
gel electrophoresis


Distinct
banding patterns

reveal the slight
variations of DNA


Makes each individual
identifiable

Applications of RFLPs


R
estriction
F
ragment
L
ength
P
olymorphism


RFLPs have increased sites available for mapping
the human genome

Applications of RFLPs


RFLP analysis identifies mutant alleles


RFLP analysis reveals a unique genetic fingerprint
useful in solving cases of parenthood, rape, and
murder

DNA Sequencing


Determination of
nucleotide sequences
(Sanger method,
sequencing machine)


Genomics: the study of
genomes based on

DNA sequences


Human Genome


Project

Practical DNA Technology Uses


Diagnosis of disease


Human gene therapy


Pharmaceutical products
(vaccines)


Forensics


Animal husbandry
(transgenic organisms)


Genetic engineering in plants


Ethical concerns?

Genetic Screening

Def: Testing individuals in a population for the
presence or absence of a gene (allele)

Advantages
:


-
pre
-
natal diagnosis of genetic disorders


-
Could help stop the spread of a disorder


-
Can detect carriers of a potential disorder

Disadvantages
:


-
invasion of privacy


-
Individuals can become stigmatized in the
community


-
Discriminated against or feared


-
Employment and medical insurance

Cloning

Bacterial plasmids in gene cloning

Steps for Eukaryotic gene cloning

Plant Cloning


Tissue Culture Propagation



Bits of phloem can

be induced in the


lab to form clumps


of tissue that will


make roots & shoots




Orchid culture

Embryo Cloning


Medical technique which produces identical twins
or triplets



Duplicates nature



One or more cells are removed from a fertilized
embryo, encouraged to develop into one, identical twins
or triplets



Done for many years on

animals



Limited experimentation


on humans

Adult DNA Cloning


Untried on humans
-
potential of producing

a twin of an existing person

Therapeutic Cloning


Stem cells

removed from an embryo with intent of
producing tissue or a whole organ for transplant
back into the person who supplied the new DNA


Embryo dies in the process


Goal is to produce a
healthy

copy

of a sick person's

tissue or organ for

transplant

Therapeutic Cloning


Vastly
superior to organ transplants



Supply would be
unlimited

-

no waiting lists


Tissue or organ would have the sick person's
original

DNA



No immunosuppressant


drugs would need to


be taken

Adult DNA Cloning

Adult DNA Cloning

Stem

cell

clon
-
ing

Theraputic Stem Cell Cloning


Used

Intro. Q’s for Chapter 14: Genetic Engineering

1)
What does the acronym PCR stand for and what does this process
do?

2)
What does Gel electrophoresis allow us to do?

3)
Give two applications of DNA profiling.

4)
What are the advantages and disadvantages of genetic screening?

5)
Describe what genetic engineering is and explain how such items as
restriction enzymes, DNA ligase, and the production of “sticky
ends” are used.

6)
Name two “vectors” that can be used for gene transfer.

7)
Give two examples of genetically modified crops or animals

8)
Briefly explain the process of gene therapy and give an example
how it works.

9)
Explain what a clone is and how it could be formed.

10)
What are some of the ethical concerns about cloning? Give your
opinion if you think cloning is something we should

be doing.


Chromatin


Def: complex of DNA and proteins


DNA Packing




Histone proteins


(+ charged amino acids w/ phosphates of DNA
that are
-

charged)


Nucleosome





-
”beads on a string”; basic unit of


DNA packing


Heterochromatin






-
highly condensed interphase DNA


(can not be transcribed)


Euchromatin




-
less compacted interphase DNA


(can be transcribed)

DNA Libraries


Collection of DNA fragments that have been
incorporated into plasmids

Steps for Eukaryotic Gene Cloning


Isolation of cloning vector (bacterial plasmid) &
gene
-
source DNA (gene of interest)


Insertion of gene
-
source DNA into the cloning
vector using the same restriction enzyme; bind the
fragmented DNA with DNA ligase


Introduction of cloning vector into cells
(transformation by bacterial cells)


Cloning of cells (and foreign genes)


Identification of cell clones carrying the gene of
interest