AQA A Level Biology Synoptic Esssay: The importance of polymers in living organisms
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A level Biology synoptic essay
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AQA
this is an example A level biology synoptic essay on the title "the importance of polymers in living organisms". This essay contains several topics discussed in great detail giving a in depth qualitative essay
Polymers are large, complex molecules composed of long chains of monomers joined
together via condensation reaction. They can be split into their monomers via
hydrolysis reaction. Polymers and monomers are also important in the production of
proteins and the different protein structures. The primary structure of a protein is the
sequence of amino acids in the polypeptide chain formed via condensation reaction.
The monomer units (amino acids) join together to produce these chains forming
peptide bonds. The secondary structure is he curling or folding of these polypeptide
chains into alpha helices or beta pleated sheets due to the formation of hydrogen
bonds. The tertiary structure forms due to the formation of hydrogen bonding, ionic or
disulphide bridges. The quaternary structure is the specific 3d shape of a protein that
is determined by the multiple polypeptide chains and/ or prosthetic groups bonded
together. .The tertiary structure forms the active site of an enzyme. Enzyme are
biological catalysts and are very important in many reactions such as digestion and
respiration. The enzymes active site is complementary to the substrate and has to be
for an enzyme substrate complex to form. The interactions of the polypeptide chains
and the formation of bonds between them allows the specific active site to form and
for an enzyme to be specific to a substrate. Polypeptide chains re also important in the
formation and functioning of antibodies. Antibodies are made up of two light and two
heavy polypeptide chains bonded together and they also have a variable region which
is determined but the amino acid sequence. Antibodies are vital for an effective
immune response to occur. They allow an antigen antibody complex to form and
destroy pathogens. Therefore polymers are very important in the structure of proteins,
enzymes and antibodies.
The importance of polymers is shown in the structure of DNA. DNA is composed of two
polynucleotide strands forming a double helix structure. The polynucleotide strands
are polymers which are formed via small monomer units called nucleotides. Each
nucleotide is composed of a deoxyribose sugar, a phosphate group and a nitrogenous
base (adenine, thymine, guanine or cytosine). These nucleotides join together forming
phosphodiester bonds via condensation reaction. The bond forms between the
phosphate group of one nucleotide and the deoxyribose sugar of another. The
nucleotides join up together in a long chain forming the phosphate sugar backbone
and the long polynucleotide strand. The complementary base pairing between the
nitrogen containing bases on the polynucleotide strand allows DNA to form a double
helix, providing it structural strength and rigidity. It also allows semi conservative
replication to take place, making sure each newly formed DNA molecule is an exact
copy of the previous one, the monomer nucleotides join together forming
phosphodiester bonds to produce the twin polynucleotide strands which are held
together by hydrogen bonds. The formation of the polynucleotide strand also allows
DNA molecules to form a helix shape and coil very tightly. This allows allot of genetic
information to fit into the strand in a fairly small space in the nucleus. Therefore
polymers are very important in the formation of a DNA strand, giving it structural
support and allowing it to successfully carry out tis role.
Polymers play a critical role in RNA, which is an essential molecule involved in the
process of protein synthesis in living organisms. RNA is also formed from many
repeating monomer nucleotides. However these nucleotides are composed of a ribose
sugar instead of a deoxyribose sugar and the nitrogen containing base thymine is
substituted for uracil. These monomer nucleotides join together to form a single
polymer chain of RNA which is smaller than a single DNA strand. RNA plays a major
role in transcription and translation. During transcription the RNA strand is made from
a DNA strand and a gene from the DNA strand is copied and turned into pre mRNA.
This pre mRNA undergoes splicing to remove the introns. The RNA strand transfers the
genetic information from the DNA to the ribosomes which carry out the process of
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