A Basic Review!!!!

Be sure to read things over if you don’t understand. Feel free to e-mail me at geneticsrus@yahoo.com.

So here it is, what you’ve been waiting for. A basic review of what we’ve just learned!!! This review was put together for your benefit, because from here on out everything will deal with the genetics of eukaroytes!!! So it’s important that you completely understand the material just covered!!! Many people have a hard time understanding these new concepts so please e-mail me if you have questions!!! Let’s begin!!!!

Some important terms!!!!!

Here are some new important terms that you need to have engrained in your minds!!!!! Review these terms, and know them like the back of your hand!!!

Prokaroytes : Are “simple”, one-celled organisms that currently on the planet Earth. This includes the class of organisms known as bacteria and the new formed Archaea. An example of a bacteria would be the very popular E. coli bacteria. Shown toward your right is a basic prokaroyte cell. The important feature of a prokaroyte is the lack of a nucleus.

Eukaroytes: Are the “complex organisms that currently live on the planet Earth. This includes yeast, plants, flies, worms, and yes, humans!! Being the straight descendants of prokaroytes, eukaroytes have been around for 1.5 billion years!! Shown toward your right is a basic plant eukaroytic cell. The presence of nucleus is the important feature that determines a eukaroytic organism.

In addition eukaroytes possess other structures inside their cells, (which are called organelles). This is why we call eukaroyotes “complex”. These include ribosomes, vacoules, and the mitochondria are to name a few. However it’s the genetics of eukaroytes that is of interest so let’s jump into that area.

Introns: These are non-coding DNA or RNA segments that lay within genes of eukaryotic organisms. By non-coding, we mean no protein is generated from these DNA or RNA segments. From a DNA intron, as shown in toward your right, a RNA is generated, and then from that RNA intron, no protein is made. Exons: These are DNA or RNA segments that are used by a cell to generate a protein. From a DNA exon, a RNA exon is made, and from the RNA exon a protein is made.

Next, a cell will begin to “read” a gene. By reading, we mean a cell will convert the gene (DNA) into RNA. This includes both exons and introns which will eventually be turned into RNA. Thus, the new RNA strand will contain both exons and introns.

The next step is the formation of the protein from the RNA strand. Exons are used to create a protein. However introns are not used to form a protein. Therefore, they must removed. A special protein called a splicesome removes all introns that lay within a basic eukaroyte gene.

The next step is the addition of both the cap and tail to the exon-based RNA strand. Let’s take a quick look and see what a cap and tail is!!!!

CAP: The cap is a modified guanine (G) which is attached to the 5′ end of the exon-based RNA strand. The cap protects the RNA from being degraded by enzymes that degrade RNA from the 5′ end. (We’ll talk about enzymes in the next section.)

TAIL: This is a stretch of adenine (A) nucleotides that is attached to the 3′ end of the exon-based RNA strand. Shown toward your right is a model of this!!!!

Here’s a basic summary of what happens to a eukaroyte gene. Start from the top at “DNA” and work your way down until you get hit the word “Polypeptide”. This process happens to your genes everyday!!!

And there you have!!!! There’s your review. Remember the important thing is that you understand the concepts that were just presented to you!!!! Don’t be afraid read things over twice.