Genes and More

The term gene, first created by Danish botanist Wilhelm Johannsen in 1909, comes from the Greek word for origin, genos.

The number of genes in an organism's complete set of DNA, called a genome, varies from species to species. More complex organisms have more genes. A virus has a few hundred genes. Honeybees have about 15,000 genes. Scientists estimate that humans have around 25,000 genes.

Each gene has many parts. The protein-making instructions come from short sections called exons. Longer "nonsense" DNA, known as introns, flank the exons. Genes also include regulatory sequences. Although scientists don't fully understand their function, regulatory sequences help turn genes on.

Each gene helps determine different characteristics of an individual, such as nose shape. Full of information, genes pass similar traits from one generation to the next. That's how your cousin inherited grandpa's nose.

Peas in a pod

The "Father of Genetics," Gregor Mendel, was an Austrian monk who experimented with plants growing in his monastery. He studied inheritance in pea plants during the 1860s.

Mendel observed that when he bred plants that had green pea pods with plants that had yellow pea pods, all of the offspring had green pods. When Mendel bred the second generation with one another, some of the baby pods had green pods and some had yellow pods.

He discovered that a trait, or phenotype, could disappear in one generation and could reappear in a future generation.

Individuals have two copies of each gene, one inherited from each parent. Mendel explained how these copies interact to determine which trait is expressed.

In all peas there is a gene for pod color. The pod color gene has green and yellow versions, or alleles. Mendel's green pod alleles are dominant, and the yellow pod alleles are recessive. In order to express a recessive form of the trait (yellow), individuals must inherit recessive alleles from both parents.

A plant that inherits one green allele and one yellow allele will be green. But it can still pass the recessive yellow allele onto its offspring. That's how some of Mendel's pea pods came out yellow.

More to it

Human diseases such as sickle cell anemia are passed down in a similar way.

However, genetics don't always work so simply. Most genetics and instances of heredity are more complex than what Mendel saw in his garden.

It often takes more than a single gene to dictate a trait; and one gene can make instructions for more than trait. The environment, from the weather outside to an organism's body chemistry, plays a large role in dictating traits too.

Lactose Intolerance is inherited worldwide by about 75% of adults to some degree. About 90% of Asians are Lactose Intolerant and usually under 20% of Northern Europeans.

Most of the world's adults suffer, to some degree, from Lactose Intolerance. If your ancestors are mostly Northern Europeans you are not likely to not have a problem, or it is likely to be far less severe.

What can you do about it? Not much, other than avoid those products that affect you or find substitutes. If you think you aren't going to be affected this one time...don't try it. The good news is there are now over the counter medications, simple pills, you can take prior to having that ice cream that often reduces the affect, or in some cases you may not be affected at all. The problem is finding the one that works for you.

Blue Eyes

Did you think blue eyes were disappearing? Not so, they're only 6,000 to 10,000 years old. That's right....we all had brown eyes. This means people with blue eyes have a single, common ancestor, according to new research.

The mutation occurred between 6,000 and 10,000 years ago. Before then, there were no blue eyes. Originally, we all had brown eyes. That genetic switch somehow spread throughout Europe and now other parts of the world.



"The question really is, 'Why did we go from having nobody on Earth with blue eyes 10,000 years ago to having 20 or perhaps 40 percent of Europeans having blue eyes now?" It seems that blue eyed people do produce more children. Why?????