Genetics and Genetic Engineering
Introduction
DNA, also known as, deoxyribonucleic acid is the structural molecule that contains
instructions, such as growth and development, for all living things. DNA has the ability to
store genetic information, code and even transfer information. This is all possible because of
its unique structure.
Structure and Function
DNA is a polymer composed of double-stranded helix molecules which are joined together
by complementary base pairings. The base pairings are held by
hydrogen bonds. One of the features of DNA are nucleotides.
Nucleotides are units of monomers that consist of deoxyribose sugar,
phosphate and a base. Every nucleotide has the same structure that
consists of the same type of sugar and phosphate. The only difference
would be the type of base that is present.
The bases could be either adenine, thymine, cytosine or guanine. In
order for the two strands to chemically bond, the bases must
compliment each other. For example, Thymine bonds with adenine and
guanine bonds with cytosine. Furthermore, the bonds between a
nucleotide, a phosphate group and the deoxyribose sugar are very
strong which benefits the structure of the sugar-phosphate backbone.
The two nucleotide strands in a DNA molecule are known as a leading
strand and a lagging strand. These DNA strands are antiparallel because they run in
opposite directions.One strand runs from a 5’ end to a 3’ end whilst the other strand runs
from a 3’ to a 5’ end. In the leading strand, 5’ would be found at the top whilst 3’ is found at
the bottom of the lagging strand.The deoxyribose sugar contains carbon atoms and has a
similar shape to that of a pentagon with 5 points. The carbon atoms surround the
deoxyribose sugar and are numbered points that are read in a clockwise direction.
DNA Replication
DNA is the biological procedure of a cell producing a replication by imitating an original
strand from a DNA molecule. This happens during the beginning of cell division. This is what
happens during DNA replication:
● Initiation:
1. First, the DNA molecule needs to be unzipped and unwound
from its double helix structure. Helicase is the enzyme that is
responsible for carrying out this step. This is accomplished by
helicase breaking the hydrogen bonds between the
complementary bases. Therefore, we get a replication fork.
2. As the DNA helix unwinds, the enzyme topoisomerase inhibits it from being
wound again. Then, SSBP (single-stranded binding protein) makes sure that the
DNA strands do not join together.
, ● Elongation:
3. DNA polymerase is used to join DNA
nucleotides in the leading strand together into a chain.
The polymerase however, would not know where to
begin. This is where DNA primase comes in. The
primase makes and applies a primer on each of the
DNA stands. This helps the polymerase know where to
begin. The lagging strand initiates replication by binding
to several primers. Furthermore, DNA polymerase
would then add sections of DNA known as Okazaki
fragments to the lagging strand.
● Termination
4. After all the complementary bases have matched up a
new enzyme known as exonuclease gets rid of the primer in
all the gaps and they’re then filled with
more complementary nucleotides.
Finally, the newly produced strand is
proofread to make sure there are no
mistakes in the sequence so that DNA
ligase can join the DNA sequence into
2 ongoing strands. DNA is
semi-conservative because it is made up of one previous
strand and one newly synthesised strand. After a while,
the DNA strands wind up into a double helix structure.
Structure Features Function
DNA DNA (deoxyribonucleic acid) has DNA consists of 4 The main job of DNA
the structure of a double helix nitrogenous bases is that it contains
shape. DNA is made up of known as adenine, instructions, for
nucleotides that are made up of thymine, guanine, things such as
nitrogenous bases cytosine, phosphate growth and
and deoxyribose development, for all
sugar living things. DNA
has the ability to
store genetic
information, code
and even transfer
information
mRN mRNA (messenger RNA) are mRNA is similar to mRNA transfers
A single stranded molecules in DNA in terms of genetic information
eukaryotic cells nitrogenous bases from the nucleus into
however instead of the cytoplasm
thymine there is
uracil
Introduction
DNA, also known as, deoxyribonucleic acid is the structural molecule that contains
instructions, such as growth and development, for all living things. DNA has the ability to
store genetic information, code and even transfer information. This is all possible because of
its unique structure.
Structure and Function
DNA is a polymer composed of double-stranded helix molecules which are joined together
by complementary base pairings. The base pairings are held by
hydrogen bonds. One of the features of DNA are nucleotides.
Nucleotides are units of monomers that consist of deoxyribose sugar,
phosphate and a base. Every nucleotide has the same structure that
consists of the same type of sugar and phosphate. The only difference
would be the type of base that is present.
The bases could be either adenine, thymine, cytosine or guanine. In
order for the two strands to chemically bond, the bases must
compliment each other. For example, Thymine bonds with adenine and
guanine bonds with cytosine. Furthermore, the bonds between a
nucleotide, a phosphate group and the deoxyribose sugar are very
strong which benefits the structure of the sugar-phosphate backbone.
The two nucleotide strands in a DNA molecule are known as a leading
strand and a lagging strand. These DNA strands are antiparallel because they run in
opposite directions.One strand runs from a 5’ end to a 3’ end whilst the other strand runs
from a 3’ to a 5’ end. In the leading strand, 5’ would be found at the top whilst 3’ is found at
the bottom of the lagging strand.The deoxyribose sugar contains carbon atoms and has a
similar shape to that of a pentagon with 5 points. The carbon atoms surround the
deoxyribose sugar and are numbered points that are read in a clockwise direction.
DNA Replication
DNA is the biological procedure of a cell producing a replication by imitating an original
strand from a DNA molecule. This happens during the beginning of cell division. This is what
happens during DNA replication:
● Initiation:
1. First, the DNA molecule needs to be unzipped and unwound
from its double helix structure. Helicase is the enzyme that is
responsible for carrying out this step. This is accomplished by
helicase breaking the hydrogen bonds between the
complementary bases. Therefore, we get a replication fork.
2. As the DNA helix unwinds, the enzyme topoisomerase inhibits it from being
wound again. Then, SSBP (single-stranded binding protein) makes sure that the
DNA strands do not join together.
, ● Elongation:
3. DNA polymerase is used to join DNA
nucleotides in the leading strand together into a chain.
The polymerase however, would not know where to
begin. This is where DNA primase comes in. The
primase makes and applies a primer on each of the
DNA stands. This helps the polymerase know where to
begin. The lagging strand initiates replication by binding
to several primers. Furthermore, DNA polymerase
would then add sections of DNA known as Okazaki
fragments to the lagging strand.
● Termination
4. After all the complementary bases have matched up a
new enzyme known as exonuclease gets rid of the primer in
all the gaps and they’re then filled with
more complementary nucleotides.
Finally, the newly produced strand is
proofread to make sure there are no
mistakes in the sequence so that DNA
ligase can join the DNA sequence into
2 ongoing strands. DNA is
semi-conservative because it is made up of one previous
strand and one newly synthesised strand. After a while,
the DNA strands wind up into a double helix structure.
Structure Features Function
DNA DNA (deoxyribonucleic acid) has DNA consists of 4 The main job of DNA
the structure of a double helix nitrogenous bases is that it contains
shape. DNA is made up of known as adenine, instructions, for
nucleotides that are made up of thymine, guanine, things such as
nitrogenous bases cytosine, phosphate growth and
and deoxyribose development, for all
sugar living things. DNA
has the ability to
store genetic
information, code
and even transfer
information
mRN mRNA (messenger RNA) are mRNA is similar to mRNA transfers
A single stranded molecules in DNA in terms of genetic information
eukaryotic cells nitrogenous bases from the nucleus into
however instead of the cytoplasm
thymine there is
uracil
