#241: Tale of YOUR Tail

Evolutionary DNA story for your

"Ye Alu Alu kya hai?"

If Alu did not exist, you'd have a monkey tail!😮

What's tale of tail? Why do you still have tail bone?

🧵How a small DNA change ate YOUR TAIL?👇🏼

From Chimpanzees to Orangutans,

Bonobos to even humans;

we all have tails that we lose in mother's uterus!!😮

Wait, not completely.

Coccyx (vestigial vertebrae) is left that we know as tailbone.

Where does genome come in this picture?

Genome

Every organism cell has full copy of organism's DNA

This is genome & has all info to make proteins..

..such protein with specific section of code is gene

But not every cell makes every protein↓

add to it: alignment of DNA

Bacteria (simpler organisms) had compact genome system: one after the other

In humans (complex organisms) genes are spaced so apart that only 1.5% of genome code for proteins

What to 98.5% called, then? JUNK DNA!!

Junk DNA is actually the DNA performing multiple functions

One such function = transposable element

Transposable element = DNA pieces shifting positions within genome

One such = ALU 😵💫

Alu

• Unique to primates

• Tiny element w/ 300 base pairs

(human body = 3bn base pairs for comparison)

• Present in 1.4 million locations in body

This is 'cz of its unique ability to 'jump' in human body

Now, something freaky happened with Alu 25 million years ago ↓

While jumping, the elements of the cell tend to insert self in different genomes

It happens w/ minimal consequence to evolution

EXCEPT if this insertion is happening in zygote😱

In this case, change to DNA stays permanent

..this happened with ALU (1 in a million chance!!)

Result? Ancient creatures missed the tail!

Since insertion happened in zygote,

imprinted in DNA of every cell → next gen lost tail

Fun part? Research is still on!

Fun part: we still don't know evolutionary benefits to tailless ape leading to its survival in nature

Regardless, it's remarkable how a tiny event with 1/10,00,000 probability changed the tale of our tail!

Here, focus on terms Junk DNA & Alu for UPSC & follow the links below!

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