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| Some life-forms on earth. PC: Micro |
In today's post on MATESA TODAY, we want to learn about a natural polymer (giant molecule) that controls all life-forms on Earth - in plants, animals, micro-organisms, etc. This wonderful material carries the instructions that are associated with the transmission of genetic information: the shape of your nose, the colour of your eye, people's height, their skin colour, etc.
This publication gives us some basic insight into DNA. Sounds quite biochemical, but it has got the Materials Science aspect too - Polymers; though materials scientists primarily deal with synthetic polymers. But we usually take inspiration from nature to do new stuff, more technically, develop novel products. After all, we call it genetic material!
BASIC TERMS DEFINED
Polymer means "many parts" and designates a large molecule made up of smaller
repeating units.
Monomer is a molecule that combines with other molecules of the same or
different type to form a polymer.
WHERE IS IT FOUND?
DNA is found in the nucleus of the cell. The nucleus is the control center, or the brain of the cell, so it would make sense that DNA is found there. Nevertheless, some amounts of DNA can be found in the mitochondrion or chloroplast. DNA is a nucleic acid and it contains the genetic instructions for the function and development of living things. The role of DNA is to store genetic information.
NOW TO THE CHEMISTRY
WHAT IS DNA MADE OF?
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| DNA biopolymer |
Each nucleotide consists of a 5-carbon sugar (pentose deoxyribose), a nitrogen-containing base attached to the sugar, and a phosphate group. There are four different types of nucleotides found in DNA, differing only in the nitrogenous base. The four nucleotides are given one letter abbreviations as shorthand for the four bases.
- A is for Adenine (C10H12O5N5P)
- C is for Cytosine (C9H12O6N3P)
- G is for Guanine (C10H12O6N5P)
- T is for Thymine (C10H12O5N5P)
Two DNA strands form a helical spiral, winding around a helix axis in a right-handed spiral. The two polynucleotide chains run in opposite directions. The sugar-phosphate backbones of the two DNA strands wind around the helix axis like the railing of a spiral staircase.The bases of the individual nucleotides are on the inside of the helix, stacked on top of each other like the steps of a spiral staircase. The other groups of biopolymers are polypeptides (proteins) and polysaccharides (sugars). The closest relative of DNA is RNA (ribonucleic acid), which is a single strand.
HOW DOES DNA WORK?
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| Comparing DNA and 'sister' RNA |
Our cells read the genetic code three bases at a time in order to generate proteins (also biopolymers) that are essential for growth and survival. The DNA sequence that houses the information to make a protein is called a gene. Each group of three bases corresponds to specific amino acids, which are the building blocks of proteins.
For example, the base pairs T-G-G specify the amino acid tryptophan while the base pairs G-G-C specify the amino acid glycine. Some combinations, like T-A-A, T-A-G, and T-G-A, also indicate the end of a protein sequence. This tells the cell not to add any more amino acids to the protein.
Proteins are made up of different combinations of amino acids. When placed together in the correct order, each protein has a unique structure and function within your body.
HOW DOES DNA CODE A PROTEIN?
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| DNA coding of Protein. PC: ResarchGate |
So far, we’ve learned that DNA contains a code that gives the cell information on how to make proteins. But what happens in between? Simply put, this occurs via a two-step process:
First, the two DNA strands split apart. Then, special proteins within the nucleus read the base pairs on a DNA strand to create an intermediate messenger molecule.
This process is called transcription and the molecule created is called messenger RNA (mRNA). mRNA is another type of nucleic acid and it does exactly what its name implies. It travels outside of the nucleus, serving as a message to the cellular machinery that builds proteins (ribosome).
In the second step, specialized components of the cell read the mRNA’s message three base pairs at a time and work to assemble a protein, amino acid by amino acid. This process is called translation.
FUN FACT
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| PC: Quartz |
One gram of DNA can potentially hold up to 455 exabytes of data, according to the New Scientist. For reference: There are one billion gigabytes in an exabyte, and 1,000 exabytes in a zettabyte. The cloud computing company EMC estimated that there were 1.8 zettabytes of data in the world in 2011, which means we would need only about 4 grams (about a teaspoon) of DNA to hold everything from Plato's writings through the complete works of Shakespeare to Beyonce’s latest album (not to mention every photo ever posted on Social Media).
Encoding digital information (in 0's and 1's) on DNA is not a big deal. The herculean task is the difficulty in retrieving the information stored on DNA. Maybe with the spate of advances in technology and research, it can be possible. Want to take up the challenge?
THE BIG QUESTION???
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| PC: sciencemag |
Credits: Quartz, atdbio, healthline, The Elements of Polymer Science and Engineering (2nd Edition)
In a later article, we might look at the DNA much into detail in an even greater Materials Science perspective. Stay tuned for some delightful polymer science chemistry.
Read Also: Be A Survivor!
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