A pair of genes that fight just right, and the radio up…

"The capacity to blunder slightly is the real marvel of DNA. Without this special attribute, we would still be anaerobic bacteria and there would be no music." ~ Lewis Thomas


Alright friends, it’s time to get another bio basic under your belt. Let’s talk DNA. It is constantly referenced in everyday life (and in this blog) and it is important to know at least the basics (I took an entire class on DNA – the science world knows a LOT! I’m keeping it basic).

Deoxyribonucleic Acid (DNA) is the basis of life. Every living organism, from single cell bacteria to humans, has the exact same basic structure of DNA. It is a long strand (polymer) of repeating units called nucleotides. A nucleotide has a backbone made up of a phosphate group and a sugar (a 5 carbon sugar called 2-deoxyribose). Hanging off of the sugar is one of four bases: adenine, guanine, cytosine, and thymine. These are the A, G, C, T that you remember hearing about in high school. This basic structure (a phosphate, a sugar and a base) makes up a single nucleotide. The nucleotides are then strung together to make a long chain of nucleotides by having the phosphate of one nucleotide bond with the sugar of another (creating a very strong phosphodiester bond – my favorite type of bond). To stabilize itself, DNA forms a double stranded molecule that twists around itself in a helix. The bases of each nucleotide will form hydrogen bonds with matching bases until there is a double stranded helical structure.


Dig deep and try to remember… A pairs with T and G pairs with C…

The order of these bases is what is important. There are a lot of proteins that are able to read DNA and turn the code created by the bases into proteins that can create living things. Everything you are made of and how you look and function comes from your DNA. The same is true for all living organisms. Ninety-nine percent of all human DNA has the same order of bases. The remaining 1% is what makes each person a little different from the next.

DNA is tiny, but it is super long. It will end up coiling itself up to save space. I mean, it does need to fit inside the nucleus of almost every cell in your body (I won’t go into mitochondrial DNA). In humans, DNA coils up and forms linier structures called chromosomes. We have 22 pairs on non-sex chromosomes (autosomal) and one pair of sex chromosomes (X and Y). The chromosomes come in identical pairs because that is what your body needs to have when it copies the DNA before a cell divides. DNA replication – that’s a whole other post.

When you talk about all the DNA in an organism, you are referring to the organism’s genome. The human genome contains around 3 billion base pairs. There are about 20,000-25,000 genes in the human genome, meaning that only around 2% of the 3 billion base pairs actually code for known things. The rest is random DNA or Junk DNA. Yup, that really is the scientific term for it, Junk DNA. It is not really “junk” and may/probably has a function, but scientists just don’t know what that function is.

DNA has a lot of other fun aspects to it. For instance, bacterial DNA comes in circular, not liner chromosomes. Organisms that live in more extreme environments often have higher G-C base pairings in their DNA. Guanine (G) binds with Cytosine (C) using three hydrogen bonds (compared to Adenine (A) and Thymine (T) using two) making it stronger and harder to break apart. DNA can come in a variety of helix types and has major and minor grooves which serve several functions… I could go on and on…

I think this is a good start to DNA. It should help demystify this crazy little double helix inside of you!

“Still Hungry for a Cure!”

Good morning friends! I hope everyone is having a lovely day! Today’s post is going to be about another interesting genetic disorder: Prader-Willi Syndrome (PWS).

Every human has lots and lots of DNA. All of you DNA is packaged up ever-so-carefully by your cells and stored in coiled bars known as chromosomes. Humans have 23 chromosomal pairs: one set from your mom and one set from your dad. Problems with your chromosomes can lead to some major problems in life. And this is the case with Prader-Willi Syndrome. PWS is caused by a problem on a person’s 15th chromosome. Several of the genes on the chromosome from the mom are disrupted and turned off (science jargon: silenced due to imprinting) and/or some of the genes on the chromosome from the dad are missing (deleted). The genes messed up are ones associated with regulating appetite. This is not a disorder created by one little DNA slip-up – a bunch of things are missing. The majority of time these chromosomal issues happen randomly at the time of conception. Very rarely will a parent pass this mutation along to another child. PWS is considered a rare disorder, but a very common rare disorder. Anywhere from one in 12,000 to 15,000 children are born with this disorder.

Ok, so a screwed up 15th chromosome… but what is PWS?

People living with PWS are never full – really, they are always hungry. A flaw in the part of the brain (hypothalamus) that controls hunger makes these people constantly looking to eat. They can become consumed with thoughts of food and eating. PWS also creates a metabolism that requires a lot less calories per day than a typical person. Needing fewer calories coupled with always being hungry can be a very dangerous and potentially fatal situation - supervision is a must. This is especially true for a child. With no supervision, a child with PWS could eat themselves to death.

At birth the baby will have a low birth weight, weak muscles and seem to have a hard time thriving/gaining weight. Typically between the ages of 2-5 is when the super appetite kicks in. PWS is also characterized by social and motor skill issues, lower IQs (around 70), small stature, small hands and feet, obesity, frequent skin picking, OCD tendencies and poor/incomplete sexual development. PWS people are also usually extremely flexible. There is no cure for PWS, but with treatment and a good support group, people can live long happy lives. Further research into PWS could lead to understanding (and possibly curing) the genetics of all obesity issues.

So there is yet another example of how powerful our genes are. Next time I really need to give an example of a positive mutation – a mutation does not always create a bad outcome.

One Singular Deletion…

Everyone that knows me knows I love love love genetics. I have not talked about genetics yet because I didn’t want to lose people in the jargon (or out of boredom). To change that, I decided to spark your interest in genetics with a super rare genetic condition I did a project on in college: Progeria.

Progeria (aka: Hutchinson–Gilford syndrome) is a genetic disease that causes early aging. It occurs in about 1 in 4 million births. Children born with this condition look average when they pop out, but within a few months they show a lack of growth. Kids with progeria will develop normally mentally, but physically they will be much smaller, with aged looking skin, extreme hair loss and undersized jaw and face bones compared to their larger skulls. With progeria, a 7 year old will face ailments that most people will not begin experiencing until their 50s, including hip problems, arthritis, and heart issues. Unfortunately there is no treatment or cure for progeria and the condition is fatal. Most progeria patients die by the age of 13 due to heart attack or stroke.

I know! I know! Wow, Robert, way to post a sad one. I did it because I want to show you how crazy genetics can be…

You would think a person born with progeria must have a bunch of genes and DNA screwed up or missing. Here is the crazy part – only 1 thing is different. That’s it - one single difference between a normal baby and a baby born with progeria.

Everyone flash back to middle school biology and learning about DNA. DNA is made up of A, T, C and G and the order of those letters determine what the gene does. Well in the middle of your first chromosome there is a gene called the lamin A gene. This gene encodes for the Lamin A protein. 1,824 letters into this gene, a single letter is screwed up and replaced with another (wrong) letter. This is known as a point mutation. You do not inherit point mutations, nor do pass them along – they just happen. They can cause good or bad results and occur all of the time. Your body has lots of ways of trying to fix them, but that’s a whole different post. This mutation in the lamin A gene causes a snowball effect in the body and ends up making the Lamin A protein non-functional. This Lamin A protein is known to help stabilize the nucleus of cells in the body – a SUPER important job. With it not working, the nucleus is unstable and then you get more of a snowball effects until you end up with progeria.

Isn’t that crazy? There are over 3 billion pairs of letters in the human genome and a mistake in only one can have such catastrophic events.

That’s why I think genetics is amazing.