What does DNA contain?
How does DNA work?
The importance of DNA lies with the amount of information that it contains. DNA is essentially a “package insert” with the instructions necessary for living life at its best.
Do you know what DNA is?
As most people know from their academic studies, DNA stands for deoxyribonucleic acid and it is made up of units of biological building blocks called nucleotides.
Not only for humans, but for every organism, DNA is a vitally important molecule that contains everybody’s genetic make-up.
What is DNA made of?
The DNA molecule is made up of nucleotides. Each nucleotide contains three different components — a sugar, a phosphate group, and a nitrogen base.
Specifically, sugar in DNA is called 2’-deoxyribose and those molecules alternate with the phosphate groups, to make up the “backbone” of the DNA strand.
Also, each sugar in a nucleotide has a nitrogen base attached to it and four are the different types of nitrogen bases found in DNA:
- adenine (A)
- cytosine (C)
- guanine (G)
- thymine (T)
The famous 3-D structure is called a double helix. Looking at the picture above, its form looks a little like a ladder that’s been twisted into a spiral in which the base pairs are the rungs and the sugar phosphate backbones are the legs.
Also, the DNA in the nucleus of eukaryotic cells is linear, meaning that the ends of each strand are free; in a prokaryotic cell, the DNA forms a circular structure.
Types of cells
There are two types of cell — eukaryotic and prokaryotic.
Humans and many other organisms have eukaryotic cells, which means that their cells have a membrane-bound nucleus and several other membrane-bound structures called organelles.
DNA is within the nucleus but a small amount is also found in organelles called mitochondria, which are the powerhouses of the cell.
There is a limited amount of space within the nucleus and this implies that the DNA must be tightly packaged and the final products are the structures that we call chromosomes.
Organisms like bacteria are prokaryotic cells and these cells don’t have a nucleus or organelles. In prokaryotic cells, DNA is found tightly coiled in the middle of the cell.
When the cells divide: the replication
The cells of your body divide as a normal part of growth and development and this results in the necessity that each new cell has a complete copy of DNA.
In order to achieve this, DNA must undergo a process called replication, characterised by the two DNA strands to split apart. Consequently, specialized cellular proteins use each strand as a template to make a new DNA strand and when replication is completed, there will be two double-stranded DNA molecules. One set will go into each new cell when division is complete.
How health, disease, and aging work through your DNA
Together with DNA, there is the concept of genome. Genome is the complete set of the DNA with 3 billion bases, 20,000 genes, and 23 pairs of chromosomes.
Every person inherits half of your DNA from her/his father and half from her/his mother.
The importance of DNA for the growing
DNA contains the instructions that are necessary for every organism to grow, develop, and reproduce and, as we said before, these instructions are stored within the sequence of nucleotide base pairs.
The cells read this code three bases at a time in order to generate proteins 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. Some combinations, like T-A-A, T-A-G, and T-G-A, also indicate the end of a protein sequence. This information tells the cell not to add any more amino acids to the protein.
Proteins are made up of different combinations of amino acids and when placed together in the correct order, each protein has a unique structure and function within the body.
How do you get from the DNA code to a protein?
But what happens during the process from the DNA code to the protein? This occurs via a two-step process:
Transcription process: the two DNA strands split apart and special proteins within the nucleus read the base pairs on a DNA strand to create an intermediate messenger molecule.
The molecule created is called messenger RNA (mRNA) and it is another type of nucleic acid. It travels outside of the nucleus, serving as a message to the cellular machinery that builds proteins.
- Translation process: 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.
Mutations in the DNA
Estimates state that tens of thousands of DNA damage events occur every day in each of our cells This is in fact an important concept about DNA code: it can be damaged due to things like errors in DNA replication, free radicals, and exposure to UV radiation.
Nevertheless, the cells have specialized proteins that are able to detect those damages and can repair them, following several pathways.
DNA and aging
Thing is that unrepaired DNA damage can accumulate as we age, helping to drive the aging process and there are several factors involved.
Damage due to free radicals may play a large role in the DNA damage associated with aging, even though this mechanism may not be sufficient to explain the aging process. Several factors may also be involved.
One theory states that DNA damage is repaired more faithfully when we’re of reproductive age and having children and when we’ve passed our peak reproductive years, the repair process naturally declines.
Telomeres are stretches of repetitive DNA sequences that are found at the ends of your chromosomes that help to protect DNA from damage, but they also shorten with each round of DNA replication.
Their shortening has been associated with the aging process, but also with some lifestyle factors such as obesity, cigarette smoke, and psychological stress. Therefore, eating well, sleeping well and exercising may help keep people young.
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