Biotechnology: Principles 1 Flashcards
what do we mean by biotechnology
Biotechnology deals with techniques of using live
organisms or enzymes from organisms to produce products
and processes useful to humans.
it is used in a restricted sense
today, to refer to such of those processes which use genetically modified organisms to achieve the same on a larger scale. Further, many other processes/techniques are also included under biotechnology. For example, in vitro
fertilisation leading to a ‘test-tube’ baby, synthesising a gene and using it, developing a DNA vaccine or correcting a defective gene, are all part of biotechnology.
what is european federation of biotechnology definition of biotech?
The European Federation of Biotechnology (EFB) has
given a definition of biotechnology that encompasses both
traditional view and modern molecular biotechnology.
The definition given by EFB is as follows:
‘The integration of natural science and organisms,
cells, parts thereof, and molecular analogues for products
and services’.
what are the two core techniques that enable the growth of biotechnology?
(i) Genetic engineering : Techniques to alter the
chemistry of genetic material (DNA and RNA), to introduce these into host organisms and thus change the phenotype of the host organism.
(ii) Maintenance of sterile (microbial contamination-free) ambience in chemical engineering processes to enable growth of only the desired microbe/eukaryotic cell in large quantities for the manufacture of biotechnological products like antibiotics,
vaccines, enzymes, etc.
what techniques of genetic engineering are used to overcome the transfer of undesirable genes b/w organisms
Asexual
reproduction preserves the genetic information, while sexual reproduction
permits variation. Traditional hybridisation procedures used in plant and
animal breeding, very often lead to inclusion and multiplication of
undesirable genes along with the desired genes.
The techniques of genetic
engineering which include creation of recombinant DNA, use of
gene cloning and gene transfer, overcome this limitation and allows us
to isolate and introduce only one or a set of desirable genes without
introducing undesirable genes into the target organism.
how to ensure that any alien piece of dna in an organism undegoes replication and is transferred.
Most likely, this piece of DNA would
not be able to multiply itself in the progeny cells of the organism. But,
when it gets integrated into the genome of the recipient, it may multiply
and be inherited along with the host DNA. This is because the alien piece
of DNA has become part of a chromosome, which has the ability to
replicate.
what is gene cloning
In a chromosome there is a specific DNA sequence called the
origin of replication, which is responsible for initiating replication.
Therefore, for the multiplication of any alien piece of DNA in an organism
it needs to be a part of a chromosome(s) which has a specific sequence
known as ‘origin of replication’. Thus, an alien DNA is linked with the
origin of replication, so that, this alien piece of DNA can replicate and
multiply itself in the host organism. This can also be called as cloning or
making multiple identical copies of any template DNA.
How was the first vector/ gmo made?
The construction of the first recombinant
DNA emerged from the possibility of linking a gene encoding antibiotic
resistance with a native plasmid (autonomously replicating circular
extra-chromosomal DNA) of Salmonella typhimurium. Stanley Cohen and
Herbert Boyer accomplished this in 1972 by isolating the antibiotic
resistance gene by cutting out a piece of DNA from a plasmid which was
responsible for conferring antibiotic resistance.
The cut piece of DNA was
then linked with the plasmid DNA. These plasmid DNA act as vectors to
transfer the piece of DNA attached to it.
The linking of antibiotic resistance gene
with the plasmid vector became possible with the enzyme DNA ligase,
which acts on cut DNA molecules and joins their ends. This makes a new
combination of circular autonomously replicating DNA created in vitro
and is known as recombinant DNA. When this DNA is transferred into
Escherichia coli, a bacterium closely related to Salmonella, it could
replicate using the new host’s DNA polymerase enzyme and make multiple
copies.
three basic steps in genetically
modifying an organism
(i) identification of DNA with desirable genes;
(ii) introduction of the identified DNA into the host;
(iii) maintenance of introduced DNA in the host and transfer of the DNA
to its progeny.
what is the defense mechanism of E coli against bacteriophage
In the year 1963, the two enzymes responsible for restricting the growth
of bacteriophage in Escherichia coli were isolated. One of these added
methyl groups to DNA, while the other cut DNA. The later was called
restriction endonuclease.
These 2 enzymes are methylase and restriction endonuclease.
what was the first discovered RE
The first restriction endonuclease–Hind II,
Besides Hind II, today we know more
than 900 restriction enzymes that have been isolated from over 230 strains
of bacteria each of which recognise different recognition sequences
what is the method of naming of RE
The convention for naming these enzymes is the first letter of the name
comes from the genus and the second two letters come from the species of
the prokaryotic cell from which they were isolated, e.g., EcoRI comes from
Escherichia coli RY 13. In EcoRI, the letter ‘R’ is derived from the name of strain. Roman numbers following the names indicate the order in which
the enzymes were isolated from that strain of bacteria.
what are the 2 types of nucleases
Restriction enzymes belong to a larger class of enzymes called
nucleases - an enzyme that cleaves the chains of nucleotides in nucleic acids.
These are of two kinds; exonucleases and endonucleases.
Exonucleases remove nucleotides from the ends of the DNA whereas,
endonucleases make cuts at specific positions within the DNA.
what are recognition sequences?
Restriction endonucleases always cut the DNA molecules at a particular point by recognising the specific sequence of 4-6 base pairs.
These series of base pairs are always palindromic.
These specific bp sequences are c/a recognition sequences.
Recoginiton sequences are unique to each RE.
Each restriction endonuclease functions by ‘inspecting’ the length of
a DNA sequence. Once it finds its specific recognition sequence, it
will bind to the DNA and cut each of the two strands of the double
helix at specific points in their sugar -phosphate backbones
(Figure 11.1). Each restriction endonuclease recognises a specific
palindromic nucleotide sequences in the DNA.
what are palindromic DNA
the palindrome in DNA is a sequence
of base pairs that reads same on the two strands when orientation of reading is kept the same. For example, the following sequences reads
the same on the two strands in 5’ à 3’ direction. This is also true if
read in the 3’ à 5’ direction.
5’ —— GAATTC —— 3’
3’ —— CTTAAG —— 5’
this is the restriction sites of ecor1
what are restriction sites?
Restriction enzymes cut the strand of DNA a little away from the centre
of the palindrome sites, but between the same two bases on the opposite
strands.
These specific points are called restriction sites.
