Where Did My DNA Come From? : Understanding Genetic Inheritance
Everyone of you might have heard these sentences whenever a baby is born : “He looks like a mirror image of his dad” or “ She is the carbon copy of her mom”. We begin to seek similarities between children and their parents as they grow up.So,which parent makes the most genetic contribution?
The answer might depend on whether you’re talking about the overall amount of genes a child receives from both parents or,which parent’s genes are actually functioning more.In any case, scientists believe the answer isn’t exactly 50/50. So, whose genes are inherited more by the child? Let’s dive into the world of biological science and find the answer.
Gene-Carrier of Heredity
Genes are the basic units of heredity.Your genes serve as a blueprint for your body. A chemical called DNA is found inside almost every cell in your body. DNA is made up of millions of small chemicals called bases. A gene is a small segment of DNA, and each gene carries instructions that would determine your features,such as eye colour,hair colour,and height.
For each feature, there are multiple variants of genes. For example, one type of gene for eye colour provides instructions for blue eyes, whereas another type has instructions for brown eyes. In this case,the prominent feature(eye colour) would depend on which gene type is more dominant among the two.
Our genes are so little that every cell in our body has about 20,000 of them! The size of human genes ranges from a few hundred to over a million bases.Every human being possesses around 20,000 genes and 3,000,000,000 bases. Your entire sequence of genes and bases is called the genome.
Fun Fact: Your genome sequence would fit perfectly onto a DVD.
The Basics of Inheritance
The process by which genetic information is passed on from parent to children is known as inheritance. This explains why members of the same family exhibit similar characteristics.
You must have figured out by now that genes, which are short segments of DNA, are the instruction manual of what makes you who you are. In your body, DNA is found in the form of 23 pairs of chromosomes (which makes up a total of 46 chromosomes). Chromosomes are threadlike structures in our cells, made of a long DNA molecule, and wrapped around a protein.
Your father gave you one set of 23 chromosomes, and your mother gave you the other 23. Humans are classified as “diploid” because they contain two copies of DNA, which is labelled as “2n.” Almost every cell in your body has a copy of the 46 chromosomes that you inherited from your biological parents. The only exception is gametes, which only have 23 chromosomes rather than 46. Gametes are annotated as 1n since they only carry one copy of our genetic material.
Whose DNA is Inherited The Most?
How much DNA did your mother and father pass down to you? If you guessed 50 percent from each parent,you’re half right. Men inherit around 51% of their DNA from their mother and just 49% from their father, while women inherit 50% of their DNA from each parent.
All humans, both male and female, each inherit 23 chromosome pairs from their parents,a total of 46 chromosomes. Each pairing is made up of half the mother’s DNA and half the father’s DNA. Out of these pairs, 22 of the pairings have about the same length and size(known as autosomes).
The 23rd chromosome pairing involves two allosomes,commonly known as gametes or sex chromosomes. Gametes, which ultimately decide your gender, can be either an X or a Y. The X and Y chromosomes are not the same size as the 22 autosomes.
For men, the gamete chromosome pairing is XY and for women it is XX. This means, males get one X from mother and one Y from father. Females, on the other hand, inherit one X chromosome from each parent.
The Y chromosome found in males is around one-third the size of an X chromosome and as a result, contains significantly less DNA. An X chromosome has THOUSANDS more genes than a Y chromosome. Because of the size difference between the X and Y chromosomes, males get 51 percent of their DNA from their mothers and just 49 percent from their fathers.
Concept of Mitochondrial DNA
As a side note,there’s also another DNA hiding inside a cell organelle in your body. Although the majority of DNA is packaged in chromosomes within the nucleus, the cell organelle mitochondria carry a small amount of their own DNA. Mitochondrial DNA, or mtDNA, is the term given to this genetic material.
Mitochondria are cellular structures that transform food into a form that the body cells can utilise. Hundreds to thousands of mitochondria are found in the fluid around the nucleus of each cell (the cytoplasm). Human Mitochondrial DNA comprises about 16,500 DNA building blocks (base pairs) in humans and encodes for 13 proteins, constituting a small percentage of total DNA in cells.
Mitochondrial DNA is only passed down through the maternal line (from mothers to children). This means that you inherit all of the mitochondrial DNA from your mother. It’s simply another example of how females have an edge over males,as there is no such specific DNA that you inherit from your father.
According to certain research, our mitochondrial DNA- and hence our mother- has an important influence on our physical endurance.They observed that a mother’s capacity for exercise can better predict a child’s capacity than when fathers are taken into account.
Interesting Facts About DNA and Genes
- Your DNA could stretch from the earth to the sun and back for about 600 times. If unwound and joined together, each of the DNA strands in your body cells would be 6 feet long. With 100 trillion cells in your body, that implies that if all your DNA were put end-to-end, it would stretch over 110 billion miles. That’s hundreds of round trips to the sun!
- We’re all 99.9 percent similar to each other. Out of the 3 billion base pairs in the human genome, only 0.1% are unique to an individual. While that 0.1% is still what makes us unique, it means we’re all more similar than we are different.
- Genes make up only about 3% of your DNA. Genes are short segments of DNA, but not all DNA is genes. Genes are only about 1–3% of your DNA. The rest of your DNA controls the activity of your genes.
- Almost all the cells in our body have DNA, the only exception being red blood cells. Even though all red blood cells start with DNA, they simply destroy their nucleus once it is no longer needed as a part of their maturation process.
- The human genome contains three billion base pairs of DNA. It is estimated that if you type eight hours a day at 60 words per minute, it would take approximately 50 years to type the entire human genome.
- The biggest known human gene- dystrophin, is made up of around 2.4 million bases. Chromosome 1 contains the most genes- 3,168, while the Y chromosome has the fewest-about 344.
Over the last several years, scientists have made significant advances in genetic research, understanding more and more about our genes and how they function in our bodies. Scientists examine our genomes to understand our family relationships, trace our ancestors, and identify genes linked to diseases. This provides them with the resources they need to develop better ways to keep us healthy.
