Food for thought about how to live healthy!

Posts tagged ‘genetics’

DNA: Don’t Get It Twisted

In the field of medicine, DNA and genetics is a relatively new concept. The first pictures of DNA were taken just over 50 years ago. Now, people use DNA for everything: engineering crops, selective breeding of livestock, solving crimes, medical therapy. But what exactly is DNA? What is it made of? How does it work? What does it look like?

Well Italian scientists have captured the most high-resolution photo of DNA to date, and it looks something like THIS:

A high resolution photo of DNA taken by Italian scientists. It was captured by dehydrating a strand of DNA and using an electron microscope.

It kind of looks like a hairy caterpillar.

Some of you are saying “Didn’t scientists take pictures of DNA in the 50’s?” While we have had images of what DNA may look like, we haven’t really been able to look at DNA directly. Old pictures were taken with X-Ray techniques, which use light to reflect the image of DNA. It’s like trying to determine what a hand looks like by looking at its shadow. Well with the electron microscope, used to take the picture above, scientists can fire electrons at the DNA to determine it’s really shape. We can even see the double helix base pairs! How cool is that?

DNA stands for deoxyribonucleic acid. It is a double helix structure with four base pairs, adenine, guanine, thynine, and cytosine! The sequence of these base pairs determines how the DNA functions! For example, take the genetic sequence for eye color. A sequence of A-C-T-C-G-A might determine blue eyes while G-C-A-T-A-C might cause green eyes. Of course, that was just a short version. In reality, genetic code contain billions of base pairs and sequences that are responsible for EVERYTHING our body does. Much like a computer is programmed with simple 0110101 codes, our DNA functions the same way. And like a fingerprint, not one person’s genetic sequence is the same. Even identical twins have two different genetic makeups.

DNA resides in each of our cells in a structure called the nucleus. The nucleus is like the brain of the cell, and the cell functions as the DNA tells it to. The cell reads DNA via an intricate process called DNA Transcription and Translation. Sometimes, there is something wrong with the DNA. It may be damaged, incomplete, or unable to be processed. That’s when we have genetic disorders, such as heterochromia or red hair (yes, red hair is a genetic mutation of blonde hair!). When DNA becomes corrupt and damaged, whether it’s through age or an environmental factor or it’s just prone to be that way, that’s when cells become malignant and turn into cancer. From how many strands of hair we have to how tall we are, DNA controls it all.

The thing about DNA is it thrives off of diversity. That’s why inbred people were often kind of messed up. When you combine two very similar genetic sequences, the DNA can get confusing for the cell to process thus leading to a myriad of problems. While it’s legal in 19 states and in the District of Columbia to screw your first cousin (it’s also legal to marry them in 6 of those states), it’s generally not a good idea. Research has shown that offspring between first cousins have a 7 to 8 percent chance of developing a genetic disorder like Tay-Sachs or Cystic Fibrosis. Even though Charles Darwin, a guy who knew a thing or two about genetics, married his first cousin, it’s not recommended if you want a healthy baby.

After all, DNA, in it’s double helix shape, is already twisted enough.

Advertisements

Meiosis and Genetic Diversity

Do you ever wonder how everyone in your family has green eyes, but you have your great-grandpa’s brown eyes? Or how each member of your family can have a different blood type? (like my family, my sister is type O and I’m type AB) It’s all because of genetics and human’s are constantly creating new genetic sequences that allow us all to be diverse. This genetic diversity is due, in part, to the process of Meiosis, the cellular replication of human gametes (aka sex cells).

*I forgot to add this part at the end. The reason I picked Chromosome 21 was because one of the biggest genetic mutations occurs in Chromosome 21 as a trisomy. As I said in the video, humans are supposed to have two chromatids for every chromosomal set, so each cells contains 23 pairs, or 46 total, chromatids. A trisomy occurs when you have an extra chromatid for a chromosomal set, so you have three chromatids instead of a normal pair. Trisomy 21 results in Down’s Syndrome. No one really knows why Down’s Syndrome

What Do Beer, Bread, and Biomedicine Have in Common?

Yeast!

Yeast are fungal microbes that have been used by civilization for thousands of years. They are typically non-pathogenic, with exceptions being common skin and vaginal infections, and are easy to cultivate making them easy to harvest.  Whether it’s for baking, brewing, brandy, bowels, or biological research, yeasts are very important for two reasons: they undergo alcoholic fermentation and they are one of few eukaryotic cells that can be used for genetic recombination.

As explained in my last video blog, humans (and all eukaryotic organisms for that matter) need oxygen to create energy. When we are using more energy and oxygen than our body can produce at one time, our cells cannot use aerobic respiration to make energy and start undergoing anaerobic respiration. This often happens when we exercise, which is good for you, or if we’re very close to death, which is not so good for you.

Anaerobic respiration in normal eukaryotic cells such as ours results producing lactic acid and carbon dioxide as waste products. This is known as lactic acid fermentation. However, anaerobic respiration in yeast produces ethanol in a process known as ethanol fermentation or alcoholic fermentation. Only yeast and a bacteria called Z. Mobilis are known to undergo alcoholic fermentation.

Wine and brandy made by fermentation of yeast converting the natural sugars present in fruits, especially grapes. Beer and whiskey are made from grain starches that have been converted to sugar.

Ethanol fermentation is also important in making bread rise. It’s not the ethanol, but the carbon dioxide being baked that creates the bubbles and allows the dough to rise. Nearly all the ethanol is evaporated from the bread while it’s being baked.

Yeast is also a perfect specimen for biomedical research. Yeast are eukaryotic, like all the cells in our body. But yeast also have a few characteristics that bacteria have. Our cells contain all of our genetic code in the nucleus of the cell, making it difficult to harvest. Bacteria contain most of their DNA/RNA inside their nucleus with the exception of a genetic ring in their cytoplasm. Yeast are the only eukaryotic cells know to have this genetic ring as well. That ring allows scientists to take out specific genes and replace them with an artificial genetic code. The scientists then observe how the genetic code affects the cell’s function. Because the yeast is eukaryotic like our cells, the effects it undergoes will be similar to what effects our cells would have undergone. Scientists can also pinpoint which genetic chains cause certain defects.

Yeast is also easy to cultivate in a petri dish since they reproduce quickly. And since yeast infections aren’t fatal there’s little risk in doing research with them.

So the next time you buy a beer, raise a glass to the awesome biological awesomeness that is yeast!