What are DNA and genes?
Written by Nichole Isabelle J. Fidel
What are DNA and genes? You would often hear that parents pass on their traits and characteristics to their kids. Heredity is the term associated with the passing down of traits from parents to kids. Genetics studies how those traits pass down through the generation.
You need to distinguish both terms to understand how heredity and genetics work. Functional units often make up complex units.
For example, the gene is the primary and functional unit of heredity. Moreover, your DNA makes up your gene. DNA (deoxyribonucleic acid) contains genetic information and instruction about the cell.
Genes consist of portions of DNA. Your genes contain the information required to synthesize proteins. These proteins play a huge part in expressing a trait.
The human body contains around 25,000 to 35,000 genes. Each gene in your body has its own task.
You can find DNA everywhere—in plants, animals, and the human body. Each cell in your body contains DNA. Your DNA is so complex that scientists could not see what it looked like until 60 years ago.
The deoxyribonucleic acid dictates the activities of your cell. It tells how a living thing like you looks and works in simple terms. Your DNA determines your height, the color of your eyes, and other characteristics. It even determines whether you might be at risk of acquiring a disease.
You inherit your DNA from your parents, both your mother and father. DNA is essential since cells can’t function without these minute structures.
DNA, despite its very small size, is a very complex structure. Nucleotides serve as the building blocks of your DNA. This genetic information carrier has the following parts.
- Five-carbon sugar molecule
- Phosphate group
- Nitrogen-containing base
Among these, the nitrogen-containing base is what makes you, you. It is because of the sequence of the base that codes for the traits. You can find the genetic coding among the four nitrogenous bases:
- Adenine (A)
- Thymine (T)
- Cytosine (C) and
- Guanine (G)
These bases pair in a particular way. That is— adenine pairs with thymine and cytosine with guanine. These base pairs repeat themselves in different order along each strand of DNA.
The human DNA alone contains around 3 billion pairs of these nitrogenous bases. The arrangement of the bases is critical. It functions as a code that instructs cells to produce specific types of proteins.
You can think of deoxyribonucleic acid as a ladder. It is a double helix that coils into a spiral staircase form. Nucleotides run up on both sides. Located in the middle are the base pairs held together by hydrogen bonds.
Since these structures are tiny, you need to use an electron microscope to view them.
The healthy functioning of your DNA allows the healthy functioning of your DNA. The synthesis of proteins requires the presence of deoxyribonucleic acid. Also, the reproduction of an organism is dependent on the hereditary material.
Oftentimes, a process referred to as mutations happen. This occurs as a result of errors in the DNA. It is capable of causing sickness and other complications.
Where is DNA located?
You can find DNA in almost all living organisms. But, in the human body, you can find them inside your cells’ nucleus. You can also find DNA in the mitochondrion.
In your body, around 30 trillion cells are present. And inside these cells, most, but not all, contain DNA. Cells such as your red blood cells, hair cells, and nail cells do not have DNA.
A human cell has approximately six picograms (pg) of DNA. It is less than the weight of a grain of rice, which weighs around 29 billion picograms.
Your cells have a nucleus structure, which contains your deoxyribonucleic acid. The DNA found in the nucleus of your cell is nuclear DNA.
DNA is also found in the mitochondria—the cell’s powerhouse. This type of DNA is the mitochondrial DNA or the mtDNA. DNA found in the mitochondria is not linear; it is circular.
Mitochondria (sing. mitochondrion) are structures that convert energy from food. It transforms it into a form that cells can use for their activities.
The nucleus has a crucial role in our cells. It serves as the cell’s command center. It is because it contains the DNA, which carries the genetic instructions for the cell. These instructions are essential for an organism to develop, survive and reproduce.
Inside the nucleus is a thread-like structure called chromosomes. DNA composes each of your chromosomes. Your DNA packs itself several times around proteins called histones.
The histones found in the chromosome helps a chromosome maintain its structure. In order for the long DNA molecules to fit in the cell nucleus, it wraps around the histones. The result would be a compact shape for the chromosome.
Humans have over six feet of DNA distributed across 46 chromosomes.
You can find DNA in the chloroplast in other organisms such as plants and eukaryotic algae. For prokaryotes, such as bacteria, the cytoplasm stores DNA.
According to studies, the DNA of us humans and chimpanzees are 98 to 99 percent identical. But the question of whether two people have the same DNA is unlikely. The DNA of two human beings can only be 99.9 percent similar, but they are not the same.
The majority of our DNA dictates our humanness rather than our uniqueness.
As human species, we have little genetic diversity.
Two unrelated persons have a DNA difference of roughly one in every 1,000 base pairs. But, the human genome has three billion base pairs. Having an average of three million genetic differences between two strangers is small.
SNPs are responsible for the variation in genetics among people. SNP stands for single nucleotide polymorphisms. It occurs when a single letter of the genetic code alters.
The human genome contains an approximate number of 20 million recognized SNPs. It indicates that the odds of two people having the same DNA are equal to having a deck of 20 million cards.
Each SNP denotes a variation in a single DNA building unit known as a nucleotide. You can find SNPs throughout your DNA.
Literature suggests that they occur around once every 1,000 nucleotides on average. According to some studies, a person’s genome has four to five million SNPs.
These variations may be unique or shared by a large number of individuals. Scientists have identified over 100 million SNPs in populations worldwide.
The variations in your DNA serve as biological markers. It assists researchers in identifying genes connected with disease.
When SNPs occur within a gene or a regulatory region next to a gene, they may directly affect the disease. They can do so by changing the function of the gene.
The majority of single nucleotide polymorphisms do not affect your health or development. Yet, some of these genetic differences have been shown to be significant in studying human health.
SNPs are important since it aids in predicting the following:
- aid in predicting an individual’s response to specific treatments
- vulnerability to environmental factors such as pollutants
- risk of developing specific diseases.
Scientists may also use SNPs to trace disease gene inheritance within families.
What is the difference between chromosomes and genes?
Chromosomes are microscopic structures consisting of DNA and protein found inside your cells. Each chromosome contains distinct segments of DNA called genes—the unit of heredity.
Each gene has the instructions or recipe for producing a specific protein. These proteins dictate our growth and the characteristics we inherit from our parents. In simple terms, the proteins produced do the work within your cells and body.
The following factors influence your genes:
- nutrition (diet)
- chemical exposure
- instructions and messages from other genes
You can think of your chromosomes as strings of genes connected with non-coding DNA. The chromosomes which contain your genes are DNA-containing molecules.
You can find your chromosomes inside all the cells in your body except the RBCs. Red blood cells lack a nucleus, and since they lack a nucleus, they lack chromosomes.
When a cell is not dividing, the chromosomes are in their chromatin form. It is also known as the interphase of the cell cycle.
A long, thin strand is what it appears to be in this state. Shorter tubes form as the cell divides, as the strand repeats itself.
The centromere is where the two tubes come together before the separation. P arms are the shorter arms of the tubes. The longer arms are the q arms.
You can find 23 pairs of chromosomes in each of your body cells. It means that you have 46 chromosomes in each body cell.
Where do you get 46 chromosomes? 23 chromosomes from your mother’s egg (ovum) and 23 from your father’s sperm make up your DNA.
When fertilization happens, wherein the sperm and the egg unite, it creates the baby’s first cell. This cell replicates to generate all the infant’s cells. The infant now contains 23 pairs of chromosomes—identical to their parents.
Scientists term the 23rd pair of chromosomes the X/Y pair. The X/Y pairs determine your sex. If you have the XX chromosome, your sex is female. Having an XY chromosome would imply that you are a male.
Tightly coiled DNA makes up each of your chromosomes. If we extend it out, it may resemble beads on a thread. The beads referred to are your genes.
Each of your genes contains instructions for the production of a specific protein. You can find around 20,867 protein-coding genes in the human genome. Between the genes are non-coding DNA segments.
Siblings inherit DNA from their parents. Thus, it is safe to say that they share much of the same DNA with slight variations. The slight variations in the DNA account for the distinct characteristics they have.
The variations in the DNA are due to a process called genetic recombination. It occurs throughout the process of creating sperm and eggs in your body.
Genetic recombination reduces the number of chromosomes in normal cells by half. That is, from 46 to 23 chromosomes. It results in a full genetic bundle when sperm and egg join during conception.
Each child receives half of their DNA from each parent, but this is not always true. Full siblings will share a small amount of their DNA with both parents. On both the mother and father’s strands of DNA, the siblings will match at the same place.
Many causes can lead to changes in our DNA code. These include radiation exposure, chemical exposure, random mutations, and other unknown factors.
We are all unique because of the variations in our genetic code. Even identical twins are born with slight differences in their DNA.
Your DNA is a long molecule that coils itself to form your chromosome. There are roughly 3.1 billion DNA bases in each set of 23 chromosomes. There are around 3.2X10^9 DNA nucleotide pairs in your human genome.
Your cells undergo continuous division to produce new cells as you grow older. During the process of division, your chromosomes become a rod-shaped structure. During the division process, you see your chromosome in a rod-shaped structure.
Specific dyes stain your chromatin. Chromatin is a structure in your chromosome. In testing, the dyes generate distinct banding patterns sorted in size order. A karyotype is the result of this process.
Using these patterns, scientists can determine the size and shape of each
chromosome. Scientists often number the chromosomes in order and size. Autosomes are numbered chromosomes.
How many sexes do humans have?
A human has two sexes—male and female. Your sex chromosomes, the 23rd pair, determine your sex. Women have two X chromosomes in their cells, whereas men have both X and Y.
Egg and sperm cells have an X or Y chromosome, but only egg cells have an X chromosome. That is why when fertilization occurs; the male determines the sex of the offspring.
Having an XX chromosome indicates that you are a female. You are a male if you have XY chromosomes.
Females have 44 autosomal chromosomes in their bodies. According to some sources, they have a karyotype 46, XX. There are fewer chromosomes in eggs than male reproductive cells, making them unique.
Males have a 46, XY karyotype. Because only half of the chromosomes in sperm are present, sperm are distinctive.
The X chromosome is larger than the Y chromosome. It is intriguing since it means that these two chromosomes are distinct. Genetically, they’re also very diverse.
Other creatures share a similar condition, even if their chromosomes have different names.
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