Genetic Engineering The transfer of genetic info into an organism to ...

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12 Δεκ 2012 (πριν από 8 χρόνια και 7 μήνες)

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BIOPL 2400

9/1/2009 3:20:00 PM

Genetic Engineering

The transfer of genetic info into an organism to introduce a desirable trait

Result is called a transgenic organism or Genetically Modified Organism
(GMO)



It’s Genome has been altered



Cloning
-

making identical copies of an organism

o

Separate issue (is not genetic engineering though it can be
part of it)

Are GMOs safe?

Are they necessary/ potential problems

What are the techniques used



Are the techniques safe?

80% of soybeans grown are genetically modified



the plants are producing pest
icides

GMOs already present in our culture

Most examples are in plant systems/agriculture



Some medical examples largely in the testing stage



Genetic profiling

o

Raises possibilities of curing genetic diseases

o

Questions about alteration



“designer babies”

Plant GMOs



H
erbicide tolerance


potential to decrease spraying of herbicides



Pesticides in plants

decrease spraying of pesticides



Stress Tolerance


resistance to environmental stresses



Altering quality of food


nutrition

(increasing nutrient value)
,
ae
sthretic qu
ality

Animal GMOs



Transgenic mice


used for research into human diseases



BioSteel


gene for silk from spiders inserted into goat eggs


goats
developed then produce protein in milk which can be harvested and
used as fiber
-
lightweight



Transgenic Salmon


grow to market size in half the time of non
-
transformed

Gene Therapy



Inserting gene to correct genetic disorders



Production of insulin and other drugs



Vaccines

Phenotypes and Genotypes

Phenotypes is the physical appearance of the organi
sm

These traits are inheritable


passed on to offspring as individuals sexually
reproduce



Natural selection



We can select desirable traits and move them from one organism to
another

o

i.e. tomato plant



we can select desirable traits (i.e. pear
-
shape)

Throug
h breeding programs desirable traits can be selected and passed on
to offspring



Artificial Selection



Novel hybrids can be created

o

Creating organisms we are interested in

o

i.e. Kale, Brussels sprouts, broccoli, Cabbage, Cauliflower



they are actually the sam
e species



breeders have altered their genetic makeup to
make the different cultivars (hybrids)

Is Genetic engineering merely accelerating traditional breeding processes?

One difference


Genetic Engineering can cross the species boundary



Introduce genes
from different species into an organism



Much quicker than traditional breeding



Traditional breeding must occur within species



Genetic Engineering can take a gene from an animal and put it into
a plant

Phenotypes and Genotypes



The genetic makeup of an indiv
idual is the Genotype

o

Genotype determines the phenotype



The information which leads to a phenotype is contained within the
chromosomes



Genes


region of the chromosome which carries the information
for one trait

o

i.e. blood type, hair color



DNA (Deoxyribon
ucleic Acid)


chemical structure of a gene



Chromosomes contain genes. Genes contain the information



Genome is the collection of all the genes



Human contains about 32,000 genes

Sexually reproductive individuals have 2 sets of chromosomes (or a multiple
of
2)


diploid

Chromosomes found in the nuclei of cells

Biochemical reactions of living organisms that ultimately determine the
phenotype of an organism

All activity takes place inside the cell

Cells organized into tissues

Tissues organizes into organs

Orga
ns make up organism

Prokaryotes and Eukaryotes
-

2 basic branches of life



Prokaryotes don’t have much organization or complexity

o

Their processes occur in the cytoplasm

o

Bacteria



Eukaryotes

o

More organized and complex

o

Organelles
-

membrane bound structures
such as nucleus,
chloroplast, etc.

BIOPL 2400

9/1/2009 3:20:00 PM

Genotypes and Phenotypes



All the genetic material makes up the Genotype of an Organism



Phenotype is t
he physical appearance of the organism

o

Physical traits



These traits are inheritable
-
passed on to offspring



Collectively all the chromosomes make up the genome

o

Found in the nucleus

Cells



Cells divide, Expand and then become specialized



Differentiation


De
velopment of a cell into a specific cell type



Gene expression plays a role in determining cell fate

o

Other factors include location, environment, etc.



All cell start out the same



All cells have the same genetic information

Differentiation



Activation of
certain genes results in specialization

o

This activation determines what the cell will turn into



Totipotency


All cells contain the same genetic information



Stem cells


fate not yet determined, can be manipulated

o

Catch cells before the cell differentiates

o

Cell can’t go back once its differentiated



Plants continuous produce stem cells during vegetated growth

o

Naristeps


continuously produce stem cells

o

Easier to collect stem cells from plants than animals

Mitosis



As cells divide, Chromosomes are duplicated a
nd passed on to
daughter cells by the process of mitosis

Meiosis



Meiosis


the process by which cells divide to form gametes



Gametes (sperm and egg) contain half the number of chromosomes



Genetic makeup of gametes is variable



During Sexual Reproduction, th
e full complement of genetic
material is restored



Go from diploid to haploid during the process

The information which leads to a phenotype is contained within the
chromosomes

Genes


region of the chromosome which carries the information for on trait

Genes

contain information, which is passed on to offspring

The chemical reactions in the cell are what dictate the chemistry of the cell
(the physical trait of the cell)

The information itself codes for the production of proteins which are either
structural or
enzymes which catalyze the chemical reactions of life



Storing information to proteins

DNA in the Nucleus

Protein synthesis occurs in the ribosome

RNA carries information from nucleus to the ribosomes

DNA



Nucleotides


sugar, phosphate, and a nitrogenous ba
se



Double stranded molecule



Adenine, Guanine (group of bases called Purines), Cytosine, and
Thymine (group of bases called Pyrimidines)



Base Pairing is key: A
-
T and C
-
G links strands



Sequence of bases down strand is the key

o

Information for coding proteins



There is polarity to each strand



James Watson and Francis Crick helped to discover the structure of
DNA

o

They mainly interpreted other people’s work rather than
discover things themselves

Replication of DNA



Need to conserve the sequence of the bases



Semi
-
co
nservative: one strand retained when DNA is copied



Chromosomes must be duplicated prior to mitosis

DNA


Transcription


RNA


Translation


Protein

DNA to Protein


Transcription and Translation



RNA


Different

type of

sugar

than DNA
, one different base
(Uracil)

o

RNA single stranded



Messenger RNA (mRNA)


carries information from DNA to
cytoplasm for translation into protein


single stranded



Transcription


transfer of information from DNA to mRNA

Introns


non coding regions are spliced out (removed)

Exo
ns


actual coding regions remain

Cap and poly


A tail added for recognition by ribosome



BIOPL 2400

9/1/2009 3:20:00 PM

Leading strands and Lagging strands

Transcribe info from DNA into RNA

RNA


Different sugar, one different base

Messenger RNA (mRNA)


carries information form DNA to cytoplasm for
translation into protein



Single stranded

Transcription


transfer of information from DNA to mRNA



Strand unzips



RNA polymerase catalyzes reaction



adds RNA nucleotides



match bases



Link
to make mRNA



Only one strand of DNA is used

mRNA is modified



not all of the sequence is used to make proteins (parts will be
deleted)



Introns


non coding regions are spliced out (removed)



Exons


actual coding regions remain



Cap and poly
-
A tail added for
recognition by ribosome

Translation



Synthesis of protein via transfer RNA (tRNA)



Protein


a chain of Amino Acids



3 base pairs codes for one Amino acid, called a codon

o

one codon codes for one amino acid



Occurs out in the cytoplasm at ribosome

o

Ribosome also

made up of rRNA



mRNA travels from nucleus to cytoplasm



3 base pairs on the tRNA called an anticodon

o

certain anticodon code for different protein

o

first two bases are key



those with the same first two
bases
code for the same
protein

(i.e. UAG and UAC code

for the same protein)



bond between two amino acids called a peptide bond



Release factor I what causes the sequence to stop

Control of Gene Expression



Promoter regions can determine whether or not a gene is activated

o

Promoter regions where genes are
turned on or off



Binding proteins to Cis elements (regions on the
Promoter regions) to turn genes on or off



Cis elements and Trans factors



Cis elements
-

regions of DNA to which trans factors bind



Regulatory genes code for trans factors that activate othe
r genes



Positive gene regulation

Promoters can be constituative


always on



You can select a promoter you are interested in

Promoters can be active at stages of development

Can become active under certain environmental conditions

Can be useful in genetic e
ngineering

Transforming an Organism



Find your gene of interest



Make lots of copies of your gene


cloning



Insert it into genome of organism



Determine if gene is functional



Regenerate organism



Much easier to do in plants