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This is the first section of the BTEC applied science Unit 11 Genetics and Genetic engineering. I have uploaded two separate documents which cover all the aspects of the assignment. Please feel free to send me a message if you are having any issues.
DNA, also known as deoxyribonucleic acid is a polymer of nucleotides when joined together the
strand of DNA becomes two polynucleotide chains giving DNA a double strand, this also gives rise as
to why DNA can be described as a double helix. When referring to DNA as a nucleotide it has three
basic units; a sugar molecule in this case for DNA deoxyribose, a nitrogenous base which are firstly
adenine and guanine these two bases are located in the purine group as they hold a two ring
structure alongside the two other bases called thymine and cytosine. These two bases are a part of
the purine base they differ from the pyrimidine’s because the purines have a single ring structure.
Another difference found in these base pairs is that adenine {A} and guanine [G] are held together by
two hydrogen bonds whereas thymine {T] and cytosine {C} contain three hydrogen bonds, even
though hydrogen bonds are quite weak the more bonds provide a greater stability for the structure.
This allows me to explain the complimentary base pairs which means the normal arrangement of
bases in nucleotides paired with their opposites. In this case, Adenine complimentary base pairs with
thymine [A-T} alongside guanine which complimentary base pairs with cytosine [G-C] this
arrangement is important as they allow DNAs double helix structure to be formed. In this case DNA
is vital as it provides all the genetic information and instructions so cells can function accordingly and
make proteins. Proteins are needed for human life as they aid in growth and development giving
unique characteristics to organisms.
Messenger RNA {mRNA)
This nucleic acids role is to transfer genetic information from genes to ribosomes to aid in protein
synthesis. Messenger {Mrna} is considered a polymer because it has many ribonucleotides, these
polynucleotides are covalently bonded together due to their tiny monomers, and this allows the
polymer to turn into a polynucleotide chain. This single stranded nucleic acid is compacted together
by a phosphodiester bonds which are the main backbones of nucleic acid strands. Every
ribonucleotide has a ribose pentose sugar attached to it, a nitrogenous base either involving uracil,
cytosine, guanine and adenine and a phosphate group.
Transfer RNA {tRNA}
Transfer RNAs role is to transfer amino acids to MRNA for protein synthesis and synthesis within the
cells cytoplasm. This nucleic acid has a curled up structure alongside three hairpin loops which can
be described to look like a clover leaf.
What is fascinating about transfer RNA is that this single
stranded molecules opposite ends contain three anticodons.
Anticodons are nucleotide bases, when three nucleotides
form a unit of genetic code in a transfer RNA molecule. The
reason that an anticodon sequence is needed for Transfer
RNA is so the sequence can rule out the amino acid that the
Transfer RNA can attach to specifically. Therefore, an amino
acid can form into a larger peptide chain
Amino acids in transfer RNA are
binded to the end of the tRNA molecule.
, Ashleigh Clarke
Unit 11 – Learning aim A
Ribosomal RNA [Rrna]
Synthesised within the nucleolus, ribosomal RNA function is to provide a structural framework for
ribosomes and attach to Trna for protein synthesis. The structure of this nucleic acid is a sphere
complex shape, this sphere travels slowly inside the ribosomal RNA moving along it to maintain a
correct positioning. In terms of size the molecule is considerably small ranging from 30S to 60S. Since
the ribosomal RNAs role is to maintain a correct alignment so ribosomes can be produced for
proteins it doesn’t require an anticodon nor codon - three nucleotides formed together to produce a
genetic code. This is due to the fact that it doesn’t have a general sequence like the transfer RNA
molecule.
Small interfering ribonucleic acid {SiRNA}
This is a double stranded nucleic acid as it is transcribed and broken down to a certain size and
length within the nucleus before entering the cytoplasm. SiRNAs role is to prevent the production of
specific proteins by analysing their nucleotide sequencing. It does this by being regularly synthesised
and reducing the translation of specific messenger mRNAs. Referring back to this nucleic acids size,
they are relatively short molecules approximately 20 - 25 nucleotides in length.
DNA replication
By disrupting the hydrogen bonds between the strands, the DNA Helicase unwinds the double helix
and exposes two strands that may be utilised as a template for reproduction. Splitting
complimentary base pairs (the two strands) into separate strands generating a fork in the replication
process The two new strands now serve as a blueprint for creating a new strand. Brand-new strand
DNA polymerase adds a new type of complementary strand to the mix extending new strands by
adding a nucleotide to the new chain started by the enzyme DNA primer a strand of DNA
polymerase makes a new strand of DNA by replicating DNA molecules.
Elongation
The DNA polymerase attaches to the DNA primer and begins synthesising a new strand of DNA, but it
can only add bases in one way. By binding to numerous primers, one of the new strands of DNA
(leading strand) is created constantly. It is impossible to make since the other strand (the lagging
strand) runs in the opposite direction. Disjointed fragments are also known as okazaki fragments.
DNA polymerase is a type of enzyme that adds to the complexity of DNA. To solve the issue of
directionality, nucleotides are broken down into small pieces.
Termination
When DNA synthesis is complete, the process of extending the DNA strands continues until there is
no more DNA template to duplicate. DNA polymerase adds nucleotides to the new strand using the
leading strand as a template. The sequence is produced by another DNA polymerase after the RNA
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