SICKLE CELL DISEASE & HUMAN EVOLUTION

20/03/2013

EVOLUTION

SICKLE CELL DISEASE & HUMAN EVOLUTION

Sickle Cell Disease is a condition where the genetic code that codes for haemoglobin has been mutated and created a protein that no longer works properly. It is a fantastic example of how humans have evolved in response to the environment.

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(WARNING: COMPLEX BIOLOGY BELOW)

there is a cool diagram below the writing if you cant be bothered reading it, plus interesting stuff below that,

Let me explain.

Basically.

DNA is split into codes A, T, G or C

DNA code translates into mRNA

mRNA takes the sequences of DNA and copies the opposite.

Say a DNA strand that reads         

3’-ATCGATGTTC…-5’

And translates it into the opposite which is

                                                                 

5’-UAGCUACAAU…-3’

(Except for A-T, becomes A-U)

 

Anyway...

Three of these codes translate into different proteins

So in      5’-UAGCUACAAU…-3’

UAG – is 1 protein

CUA – is another

CAA – is another and so on…

DNA being used as a source 'code' to build Proteins

Please dont ask me how transcription works... that is just heavy!

Anyway,

Sickle Cells Disease is when these codes come out wrong, when the cell is making Haemoglobin.

Haemoglobin, (a huge protein made out of many smaller proteins) lives inside red blood cells and moves Oxygen (O₂) all over the body.

 

The cell makes the proteins and then puts them together. 

But, in Sickle Cell proteins, one of the letters is wrong and the wrong protein is put into the Haemoglobin

They malfunction and can kill the person they are in!

Cells Affected by Sickle Cell Disease on Right

 

But the occurrence of sickle cell disease is really common in certain areas.

Sickle Cell Disease Distribution

These areas are also where a disease called Malaria is often found.

Malaria Distribution

Indeed, Sickle Cell disease is an evolutionary trait that has bread into humans in these parts of the world.

 The Malaria Parasite can not reproduce properly in individuals with the condition.

 

It usually protects the hosts long enough for them to reproduce, and pass on their genetic code. 

Yet it condemns the older population to a high chance of developing a painful genetic disease related death.

This presents researches with a two pronged challenge. 

We need to be able to eliminate Malaria, and then after that be able to remove this genetic ‘defect’.

This also shows that not all evolutionary pressures are good. Indeed, some can make us more vulnerable and weaker. 

This is just another reason to hate mosquitoes