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While the twentieth century may be known as the century of a wide range of innovative discoveries, the twenty-first century may well be known as the century of biotechnology. Current technologies enable scientists to create genetically engineered organisms by using the basic building blocks of living matter, genes. This outstanding ability offers the world a number of advances, such as genetically modified processes, human cloning and organ traficking.

Firstly, one of the biggest advances, according to some scientists is the genetically engineered crops and foods. Genetically engineered crops are new kinds of crops. Biotechnologists use certain genes from one organism and introduce them into another to produce a desirable trait. Scientists have also used specific genes from soil bacteria; toxic to a number of different pests. However, while many argue that genetically engineered foods are beneficial in a number of ways such as to starvation reduction and pests, others argue that there are potentially harmful dangers that may result in a series of damages. For humans, there are many hazards such as allergic reactions, possibly even fatal ones, due to artificially introduced genes in food.

Secondly, the potential for the use of artificially grown organs and tissue to benefit humankind remains as controversial today as it was then. But after decades of failed attempts, new signs of progress are beginning to emerge in the ability to achieve successful transplantation between different species.

Finally, as genetic engineering goes further, the human beings are more willing to choose how long they want to live and even design a baby. Nowadays, humans have a lifespan in which can possibly go over eighty in a perfectly healthy way. However, designer babies are still controversial, mainly for moral and religious grounds.

In conclusion, genetically modified processes cannot determine the future of the mankind. All in all, humans tend to play god´s role that can be extremely dangerous to us in which is not nature´s way.
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such as genetically modified processes, human cloning and organ traficking.

'processes' do not have genes - they are not living things, Do you mean 'foods'.

You are writing about 'positive advances' but 'organ trafiking' (should be 'organ trafficking" means that this activity is illegal, as in drug trafficking. Perhaps, 'organ donations'.

"...one of the biggest advances, according to some scientists is the genetically engineered..."
The punctuation is not quite right:
"...one of the biggest advances, according to some scientists, is the genetically engineered..."
or, since you have a comma after 'firstly' and we are piling up the commas:
"...one of the biggest advances (according to some scientists), is the genetically engineered..."

"...genetically engineered crops and foods. Genetically engineered crops are new kinds of crops. Biotechnologists use certain genes from one organism and introduce them into another to produce a desirable trait."

Too many uses if the word 'crops'
Try: "...genetically engineered crops and foods. Biotechnologists use certain genes from one organism and introduce them into another to produce a desirable trait, and so create these new kinds of crops."

"Scientists have also used specific genes from soil bacteria; toxic to a number of different pests. However,..."

This doesn't 'flow' - the use of the semi-colon is wrong, and the sentence doesn't make sense.
Do you mean something like: Scientists have also used specific genes from soil bacteria to make crops toxic to a number of different pests.

"However, while many argue that genetically engineered foods are beneficial in a number of ways, (ADD a comma here) such as to starvation reduction and pests, others...

"...the human beings are more willing to choose how long .."
just 'people', not 'the human beings"

"...the future of the mankind." - the future of mankind

"All in all, humans tend to play god´s role that can be extremely dangerous to us in which is not nature´s way"
This sentence needs rewriting. Try:
All in all, when humans try to assume God's role, they could be taking us down a dangerous road and diverting us from nature's highway.
Comments  
Thank you very much . I will rewrite right now with this golden tips.
Peace brother.
Alexandre