Life cycle of a frog

The life cycle of a frog is controlled by genes that turn off and on.

One of the liveliest discussions to get involved in is that of nature versus nurture. Are we born with a set recipe that is unchanging or is everything adjustable to some degree?

One can ask some very thought-provoking questions when it comes to nature or nurture. Is my memory and love for questioning everything built into me or was it my raising? Can you be born a serial killer or was it your upbringing? Is your heart disease or diabetes just bad genes you were born with? There is an answer written in your DNA, and science is on the road to tackling these complex questions.

You also can think about some simple questions. What makes the arctic fox turn white in the winter or how does the tadpole become a frog? I could go on, but are these questions nature or nurture? The answer is that they are both.

Nurture, the environmental factors, can literally alter how your DNA is expressed. The field of epigenetics is simply focusing on what actually happens to the genome to turn off the tadpole or caterpillar genes and switch on the frog and butterfly genes. That is a massive change to go from a leaf-eating worm-like organism to a beautiful butterfly.

Changes in gene expression make us all. Sperm joined with an egg to get you started. You were just a single cell for a short time, but you began to divide, many times over. These cells all carried an identical set of your DNA, and they all looked exactly the same but something was about to happen.

That simple ball of cells was about to make all of your body systems and layout a body plan. Muscle cells, skin cells, retinal cells, and neurons are just a few of the more than 200 cell types that make us, and you have to organize them all into the proper locations to make a human. These cells are vastly different to look at and have very different functions, yet their genetic code is exactly the same.

So how did they become so vastly different? The genes that make up your DNA can be turned on at varying levels from high to low and turned off. Your “grow some hair gene” is off in your liver cells and heart cells, but the hair gene is still there. Your skin has the genetic ability to make an eye but the eye genes are silenced. What makes your cells different is not the physical code but simply the pattern in which the code is turned on and turned off (gene expression). Same genes in all your cells but different ones on and off in different cells.

Visit the web page to learn more. It is a great resource and covers the basics. Your cells became different via epigenetic modifications, and your environment can impact this on/off pattern of your genes today.

Be mindful of your habits, they will change the expression of your DNA and changes in your sperm or egg will pass to your kids.

Dr. Jack Brown is the Paris Junior College Science Division chairman.

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