3.5 GENETIC MODIFICATION AND BIOTECHNOLOGY Flashcards
GEL ELECTROPHORESIS
restriction enzymes
fragments are placed into small depression or wells at one end of the gel.
An electrical current is applied to the gel (positive on one side and negative on the other).
The fragments of DNA will fall out and embed in the gel based on their size and charge.
The smallest particles that are charged go the farthest in the gel, while the large non-charged particles fall out and embed in the gel the quickest.
BEFORE GEL ELECTROPHORESIS
restriction enzymes are used to cut DNA into fragments of various lengths and different charges
RESTRICTION ENZYMES
cut DNA into fragments at specific base sequences in each sample.
PCR
is a laboratory technique that takes a single or few copies of DNA and amplifies them to generate millions or more copies of a particular DNA sequence.
PCR STEPS
Denaturation
Annealing
Elongation
DENATURATION
DNA sample is heated to separate it into two strands
ANNEALING
DNA primers attach to the opposite ends of the target gene sequence
ELONGATION
A heat-tolerant DNA polymerase (Taq polymerase) copies the strand
DNA PROFILING
is a method or technique used to identify individuals on the basis of their DNA profiles in comparison to an unknown sample of DNA.`
DNA PROFILING USE EXAMPLES
paternity test to identify the biological father of a child. Scientists can take a blood sample which contains a father’s DNA and a blood sample from a child which contains the child’s DNA. They can then run a gel electrophoresis to compare the banding patterns between the father and the child.
criminal investigations where a small sample of blood, semen, hair or other cells where DNA is present is collected.
DNA PROFILING PROCESS
PCR can be applied to these small samples of DNA to amplify the DNA into millions of copies to create enough DNA to be analyzed for the investigation.
Using restriction enzyme to cut the DNA into fragments that are separated through gel electrophoresis and DNA profiling, the DNA sample can be compared to a suspect’s DNA to prove if they are innocent or guilty.
DNA profiling can also be used to support ancestral relationships between organisms for evolutionary studies.
Fluorescent marker may be added to show the colour.
GENETIC MODIFICATION
A gene produces a certain polypeptide in an organism.
Since the genetic code is universal, when a gene is removed from one species and transferred to another the sequence of amino acids in the
polypeptide produced remains unchanged.
GENE TRANSFER
Gene transfer is taking one gene from an organism and inserting it into another organism.
GENE TRANSFER EXAMPLE
An example of gene transfer is for the production of human insulin produced by the pancreatic cells.
GENE TRANSFER
INSULIN PRODUCTION
First, insulin production genes are cut off using restriction enzyme.
Use the same restriction enzyme to cut the bacteria plasmid open
Place the gene into the plasmid using DNA ligase. (antibiotic resistance may also be put in to make the plasmid attractive)
Put the plasmid back in the bacteria.
Bacteria go through replication and production of human insulin.
Harvest and purify the insulin.
BT CORN
combine with soil bacterium that produces insecticidal toxin – give resistance to insects
BT CORN +VE (7)
Higher crop yield (more production = more money) - crop yield is a debatable benefit
Less or no pesticides used because already resistant to harmful pests
Can use pest resistant crops or modified crops in areas where water availability is limited
Could add genes for certain proteins, vitamins or possible vaccines (less cost than producing in a lab)
Crops last longer or don’t spoil during storage
Increased disease resistance
Increased hardiness: grow in more locations/seasons
BT CORN -VE
Long term effects on humans are unknown
Non-targeted organism will be affected by the toxin
Transfer gene could mutate
Increased resistance to toxin evolves in pest
Accidental release may result in competition with native species
Biodiversity reduced
Super weed may appear
CLONE
a group of genetically identical organisms or a group of cells derived from a single parent cell.
CLONES AND SEXUAL REPRODUCTION
Organisms that reproduce asexually, produce genetically identical offspring
CLONE HUMAN EXAMPLE
Identical twins in humans are also clones (monozygotic twin)
CLONE AND BACTERIA
Bacteria uses binary fission to clone itself
CLONE AND TUBERS
Underground stems called tubers in potatoes can form new potato plants which are clones of the original parent potato plant
CLONE AND RUNNERS
growing stems used to reproduce asexually
EMBRYONIC STAGE CLONING
At the very early embryo stage, cells are still pluripotent (meaning they can become any type of tissue)
These cells can be separated artificially in a laboratory in order to create more than one of the same organism
CLONING DIFFERENTIATED CELLS
Once cells start to differentiate and embryos develop into a fetus and eventually an adult cloning becomes much more difficult
CLONING DIFFERENTIATED CELLS STEPS
- Remove a differentiated cell nucleus
- Enucleate a donor egg cell
- Insert nucleus into the cell
- Treat with electricity and put in back to the womb
- Produce genetically indentical organism
EXAMPLE OF CLONING DIFFERENTIATED CELLS
Therapeutic cloning is an example of cloning using differentiated cells
USE OF CLONING DIFFERENTIATED CELLS
This type of cloning can be used to create a specific tissue or organ
CLONING DIFFERENTIATED CELLS AND SCNT
to reproduce organisms like dolly the sheep. This is done through somatic-cell nuclear transfer.
EMBRYONIC STAGE CLONING USES
The separated pluripotent cells can then be inserted into the uterus of a surrogate mother or mothers in order to produce genetically identical
offspring
EMBRYONIC STAGE CLONING REQUIREMENTS
The separation of cells has to happen early in development, preferably the 8 cell stage