What is DNA? What classification does it fall under in biology, chemistry, and molecular biology?
Let’s start with this question. If you are asked to mention macromolecules, what would be the first on your list? Carbohydrates or proteins. Good. DNA is a macromolecule like any of these.
Macromolecules are essential for the growth, development, and physiological processes that go on in the bodies of living things. But that’s not the only reason why DNA fits into this classification. First, DNA is a macromolecule because of its complexity.
Now that this is established. I will go into the main article. You will get to learn more about DNA; what type of macromolecule it is, the transmission of information, and the concept of DNA differences across humans.
What is DNA?
DNA means deoxyribonucleic acid. It is one of the two known nucleic acids; the other being RNA (ribonucleic acid). DNA is the underlying molecule responsible for the transmission of genetic information and replication of traits and characteristics from parents to offspring.
DNA is a double-stranded helix composed of sugar, a phosphate group, and four nitrogenous bases. These bases are adenine (A), thymine (T), cytosine (C), and guanine (G). The difference between two DNAs is the sequence in which these bases encode genetic information.
Furthermore, the two basic functions of DNA are the transfer of hereditary information and protein synthesis. It successfully carries traits and characteristics from one generation and passes them down to another. This is the reason why you have the same physical features as your parents.
It is also the reason why you share similar physical features with your grandparents, great-grandparents, uncles, aunties, and cousins. While you can share similar DNA with these people, you do not have the same DNA with any of them.
Yes, this is true for even identical twins. Every DNA has a 0.001% allowance to account for the difference between two people.
In addition, DNA does not directly give rise to proteins. The process begins with the transcription of the genetic information into mRNAs. These mRNAs are then translated into amino acids, which ultimately form proteins.
The steps described above culminate in the transmission of information. You will find that later in the article.
What type of macromolecule is DNA?
Macromolecules are large molecules made up of smaller units (polymers made of monomers). The four macromolecules are carbohydrates, proteins, lipids, and nucleic acids. DNA is a nucleic acid.
Nucleic acids are macromolecules that contain repeating units of monomers. Therefore, DNA is made of repeating units of nucleotides (sugar, a phosphate group, and the four nitrogenous bases).
Another feature that makes DNA a macromolecule is its complexity. It is a long double helix structure with a sugar-phosphate backbone upon which the nitrogenous bases are arranged in different sequences.
The DNA strand in one human cell can extend up to 2 meters, but, it is not enclosed like that. It is coiled around histone proteins. Furthermore, the DNA of a living organism encodes so much genetic information in its sequence. That is a lot compared to the size that you can see!
How many monomers make up a DNA molecule?
The DNA in a human contains billions of units of nucleotides, which are monomers. You already know what makes up these nucleotide units.
In each nucleotide, the bases pair with each other; adenine to thymine (A-T) and guanine to cytosine (G-C). That is, the number of adenine in any nucleotide will always be equal to the number of thymine in that nucleotide, the same applies to guanine and cytosine.
Furthermore, the amino acids are arranged in such a way that the sequence on one strand in the double helix is different from the sequence of the other strand. The nucleotide sequence also differentiates one nucleotide from the other.
Moreover, both strands run in opposite directions. Each strand runs 5’ to 3’ and 3’ to 5’. The right way to read each DNA strand is in the 5’ to 3’ direction. Each strand encodes information for different genes and produces different proteins.
Where is genetic information stored in DNA?
Genetic information is stored in the nucleotide sequence of the DNA. Besides, nucleotides, sugar, and phosphate group are what make up the DNA. The bases carry all the genetic information. Additionally, everything about DNA occurs in the nucleus of every living cell.
How does DNA transmit information?
The process of transmission of information from the DNA to other parts of the cell is, in a few words, the process of converting DNA to protein.
This process begins with the transcription of DNA to mRNA and from mRNA to proteins. Instructions for the transmission of information are carried out according to the sequence of the nucleotide bases on the DNA.
The first step of transcription involves copying a specific segment of DNA in a matching RNA, the mRNA (messenger RNA). RNA polymerase binds to the promoter of the DNA, reads the DNA sequence, and arranges a strand of mRNA that has complementary nucleotides.
This occurs through the direct pairing of matching RNA nucleotides using the initial DNA sequence. However, there is a slight difference in the mRNA nucleotides. In RNA, uracil is the nucleotide that pairs with adenine, instead of thymine. So, the nucleotide pairs are A-U and G-C.
Then, translation begins. This is the step that converts mRNA to protein. The mRNA moves from the nucleus to the cytoplasm where the ribosomes read the nucleotides in codes of three called codons.
Each pair of codons codes for an amino acid and it forms a total of 20 amino acids. The ribosomes are specialized parts of cells that also know how to match identical amino acids to form proteins. Each protein has a unique structure and carries out a specific function.
FAQs
Is DNA the same in all cells?
All cells in all living organisms have the same DNA sequence. However, the gene expression varies with the function of each cell, the proteins, and the functional RNAs it contains.
Do all humans have the same bases in their DNA?
Yes, all humans have the same bases in their DNA. Every two people have a 99.6% resemblance in their genome. The 0.4% difference accounts for the variation and why no two persons have the same DNA.
Is DNA the same in all humans?
The DNA composition is the same in all humans. 0.001% of everyone’s DNA is where the difference between two people lies. Members of a family would naturally have more identical DNA than friends and neighbors.
Is DNA the same as chromosomes?
DNA makes up chromosomes. Chromosomes are threadlike, long chains of DNA molecules tightly coiled around histone proteins. The proteins serve as a support structure for the DNA molecules.
The DNA of the smallest chromosome in the human body contains up to 50 million pairs of nucleotides, and the largest chromosome contains 250 million pairs of nucleotides.
Conclusion
DNA is a complex macromolecule that comprises nucleotide units. Each nucleotide unit contains a sugar molecule, a phosphate group, and nitrogenous bases. The order of arrangement of the nitrogenous bases along the DNA backbone is the genetic code of any DNA.
These codes carry out instructions for the development of the organism carrying the DNA. This is the essence of DNA in living organisms. As you have learned in the article, DNA is responsible for hereditary, genetics, molecular biology, and evolution.
The concept of DNA is so complex that no two persons can have the same genome, not even identical twins.
Also, learn about the essential and nonessential amino acids in this guide.
Thanks for reading.