#Noncoding DNA The human body has a set of instructions called the genome. It has about 3.2 billion parts (called DNA base pairs). Out of that, around 20,000 genes make proteins. These proteins help build and take care of our body. Even though 20,000 seems like a lot, it’s actually a small part of the whole genome. Also, each gene can make more than one type of #protein. Now here’s something surprising: tiny worms, with fewer than 1,000 cells, also have about 20,000 genes — just like humans! And many of their proteins are similar to human proteins. So, what makes humans so different from worms? Scientists don’t know everything yet, but they think the difference isn’t just about the number of genes — other things must be involved. The answer is not completely known, but the weight of current evidence suggests that much of the difference Most of the human genome — about 98.5% — does not make proteins. For a long time, scientists didn’t know what this part of the #DNA did. It was often called the “dark matter” of the #genome. But this idea changed after the ENCODE project started in 2007. The goal was to find out what all parts of the genome do. The surprising result was that about 80% of the genome actually has a role — it either attaches to proteins or helps control how genes are turned on or off, depending on the type of cell. So, while proteins build the body’s cells and tissues, the parts of the genome that don’t make proteins still do important work — like giving instructions or “plans” on how to build. In simple terms, the big difference between humans and worms isn’t just in the building blocks, but in the instructions on how to use them. The human genome contains many important DNA sequences that do not code for proteins. These include: 1. Promoter and enhancer regions: These are parts of DNA where special proteins (called transcription factors) attach to start or increase gene activity. 2. Binding sites for structural proteins: These help shape and organize the DNA inside the cell by forming higher-level structures called chromatin. 3. Noncoding regulatory RNAs: Over 60% of the genome is copied into RNA that doesn’t make proteins. However, these RNAs still play important roles in controlling genes. Two common types are microRNAs and long noncoding RNAs. 4. Mobile genetic elements (transposons): These are pieces of DNA that can move around within the genome. They make up more than a third of our DNA. They may help with gene regulation and DNA organization, though their exact role is still being studied. 5. Special DNA structures: These include telomeres, which protect the ends of chromosomes, and centromeres, which help chromosomes stay together and move properly during cell division. This has attracted a lot of attention because many—maybe even most—of the genetic changes linked to diseases are found in parts of the DNA that don’t make proteins.

1. Noncoding DNA
The human body has a set of instructions called the genome. It has about 3.2 billion parts (called DNA
base pairs). Out of that, around 20,000 genes make proteins. These proteins help build and take care of
our body.
Even though 20,000 seems like a lot, it’s actually a small part of the whole genome. Also, each gene can
make more than one type of protein.
Now here’s something surprising: tiny worms, with fewer than 1,000 cells, also have about 20,000 genes
— just like humans! And many of their proteins are similar to human proteins.
So, what makes humans so different from worms? Scientists don’t know everything yet, but they think the
difference isn’t just about the number of genes — other things must be involved.
The answer is not completely known, but the weight of current evidence suggests that much of the
difference Most of the human genome — about 98.5% — does not make proteins. For a long time,
scientists didn’t know what this part of the DNA did. It was often called the “dark matter” of the genome.
But this idea changed after the ENCODE project started in 2007. The goal was to find out what all parts
of the genome do. The surprising result was that about 80% of the genome actually has a role — it either
attaches to proteins or helps control how genes are turned on or off, depending on the type of cell.
So, while proteins build the body’s cells and tissues, the parts of the genome that don’t make proteins still
do important work — like giving instructions or “plans” on how to build. In simple terms, the big difference
between humans and worms isn’t just in the building blocks, but in the instructions on how to use them.

2. Noncoding DNA
The human genome contains many important DNA sequences that do not code for proteins. These include:
Promoter and enhancer regions: These are parts of DNA where special proteins (called transcription
factors) attach to start or increase gene activity.
Binding sites for structural proteins: These help shape and organize the DNA inside the cell by forming
higher-level structures called chromatin.
Noncoding regulatory RNAs: Over 60% of the genome is copied into RNA that doesn’t make proteins.
However, these RNAs still play important roles in controlling genes. Two common types are microRNAs and
long noncoding RNAs.
Mobile genetic elements (transposons): These are pieces of DNA that can move around within the
genome. They make up more than a third of our DNA. They may help with gene regulation and DNA
organization, though their exact role is still being studied.
Special DNA structures: These include telomeres, which protect the ends of chromosomes, and
centromeres, which help chromosomes stay together and move properly during cell division.
This has attracted a lot of attention because many—maybe even most—of the genetic changes linked to
diseases are found in parts of the DNA that don’t make proteins. This means that how genes are turned on
or off (gene regulation) might be more important in causing diseases than changes in the proteins
themselves.

3. Noncoding DNA
Recent studies of human DNA have revealed some surprising facts. For example, any two people are more
than 99.5% genetically the same. Even more amazing is that humans share about 99% of their DNA with
chimpanzees! The differences between people, including how we respond to diseases, the environment,
and medications, come from less than 0.5% of our DNA. While this may sound small, it still represents
around 15 million DNA base pairs.
The two main types of genetic differences among people are single-nucleotide polymorphisms (SNPs) and
copy number variations (CNVs). SNPs are the most common type—they are changes in a single "letter" of
the DNA and usually have only two possible forms in the population (like A or T at one spot). Scientists
have found over 6 million SNPs in humans, and their frequencies can vary widely between populations.
SNPs are found throughout the genome, including in genes and non-gene areas.
Only about 1% of SNPs are found in the parts of DNA that directly code for proteins, which makes sense
since those regions make up only 1.5% of our DNA. However, SNPs in non-coding regions can still affect
gene activity, especially if they fall in regulatory areas that control when and how genes are turned on or off.
Some SNPs don’t change anything and are called "neutral." Even these can be helpful because they may
be located near genes that do affect diseases, allowing researchers to use them as markers.
Scientists hope that patterns of SNPs can help identify people at higher risk for complex diseases like type
2 diabetes and high blood pressure. But most SNPs have only a small effect on disease risk, and it is still
unclear whether using them can lead to better ways to prevent these diseases.

5. Noncoding DNA
Copy number variations (CNVs) are a type of genetic difference
found in humans. They involve large stretches of DNA—ranging from
1,000 to millions of base pairs—that are either duplicated or deleted
in some people. Sometimes, CNVs are simple, with just one copy
added or removed, like biallelic SNPs. Other times, they can be
complex, with multiple different versions in the population.
It’s estimated that CNVs account for 5 to 24 million base pairs of
variation between two people. Around half of CNVs affect genes, so
they may play a big role in the differences we see between
individuals. However, scientists still know less about CNVs compared
to SNPs, so their role in disease isn’t fully clear yet.
Even with these discoveries, changes in DNA sequence alone can’t
explain all the differences in human traits. For example, identical
twins have the same DNA but can still look or act differently. This
might be due to epigenetics, which refers to inherited changes in
gene activity that don’t involve changes to the DNA sequence itself.
We’ll look into how epigenetics works next.