Starters Genetics!

Genetics!

Genetics is far more interesting than it sounds. Genetics is  always in the news and is often very misunderstood. Therefore I decided to do a short piece about simple genetics and a few misconceptions that sadly are often heard.

What is DNA?

Let’s start by explaining what are DNA and RNA are. These are large molecules, polymers, made from lots of smaller molecules, called monomers. These monomers, called nucleotides, consist out of pentose sugar(=5 carbon sugar), a phosphate group and a nitrogenous base. In RNA and DNA some of these molecules differ. The sugar in RNA is ribose and in DNA deoxyribose, deoxy meaning lacking one oxygen. RNA also has a different nitrogenous base. The nitrogenous bases are divided in purines(=one ring) and pyrimidines(=two rings) The purines are (A) adenine and (G) guanine, and the pyrimidines in DNA are (T) thymine, (C) cytosine. In RNA only the T is replaced with the (U) uracil, also a pyrimidine.

What DNA on a molecular level looks like

Difference between RNA and DNA.

The difference between RNA and DNA is that DNA can be seen like the plans for proteins and RNA is made to protect the DNA. From DNA, where the sequence of these nucleotides decides what proteins are being made, the RNA is made. DNA gets ‘scanned’ by RNA polymerase, an enzyme which produces mRNA which is an anti-parallel copy of the DNA. This mRNA is read by other enzymes, who reads 3 nucleotides at a time and per sequence of 3 nucleotides sets 1 amino acid in a chain. These amino acids eventually form proteins which I will make a blog post about later.

Misconceptions

There are a lot of misconceptions about the workings of DNA and what its effect is on everyday life. DNA does for example not directly decide your personality or how you think. Educations, experience, how you were raised and your environment all help decide who you are. When you hear people say: “I’m fat because that’s in my DNA”, you should know its total nonsense. Your DNA might influence how fast you digest and how fast you lose weight but still you need to eat in excess to get fat.

So not every aspect of an organism can be made from its DNA, environment also plays a major part.

Not all diseases or traits are included in DNA. Bacteria, viruses and fungi can be pathogens as well. And for traits, environment also plays a part.

When we know the sequence of an organisms DNA we do not know the ‘blueprint’ of that organism. A lot of DNA isn’t used for anything and we have yet to figure out all te different mechanisms.

Genetically engineered foods are not per definition bad for you. In simple terms it’s just a fast forwarded technique of breeding. Instead of breeding plants to have a certain resistance or something of the like, we are able to pluck it out and paste it into the DNA.

The amount of chromosomes an organism has is not a measurement how complex the organism is. For example the ant Myrmecia pilosula male has one chromosome and the ferm Ophioglossum reticulatum has up to 1260. Humans however have 46.

Chromosomes are also not X-shaped. They are only X-shaped when the cell is about to divide. At that moment the chromosomes have copied themselves but are still attached at the “kinetochore”. That kinetochore is often situated in the middle of the chromosome, thus it gets an X-shape.

Sadly there are many more misconceptions but I don’t know any more examples at the time. Perhaps I will go into one of these subjects with more depth in the near future. Most possibly the genetic engineered ones.

Fun video about 18 things you should know about genetics;

References;

Peter J. Russel  Pearson International Edition iGenetics; A Molecular Approach. 3rd edition.

Pictures;

http://www.templeton.org/sites/default/files/imagecache/hero_image_520/genetics-640×360.jpg

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