DNA sequencing, using the enzymatic extension reaction, makes use of the chemical difference between normal deoxyribonucleotide and dideoxyribonucleotide. Deoxyribonucleotide contain a hydroxyl group in position 3 of the sugar ring, and DNA polymerase conjoin the phosphate of the next nucleotide to the hydroxyl end.

A dideoxyribonucleotide can be added to a growing chain but  does not contain a hydroxyl group at position 3 so no further nucleotides can be added. Addition of a dideoxy nucleotide stops DNA synthesis.

The DNA to be sequenced is denatured in a tube.

Watch video to learn more…

Hi! I’m Guanine and Cytosine. I’m Thymine. Hello, I’m Adenine. We’re the four nitrogenous bases that hold the DNA strands together.

Is that a nitrogenous base that hold the DNA strand together? (looking at uracil)

Watch video to learn more…

Hello this is Dr. Sullivan, talking about Anatomy and Physiology I at Bucks County Community College.

In this particular video, discusses DNA structure. (We’re in Unit 4 right now which is entitled DNA and Protein Synthesis.) In this video we’ll just gonna talk about DNA Structure so we can understand how protein synthesis takes place due to the structure of DNA.

In this image that I have for you right here, you can see that we illustrated the coiling effect a molecule of DNA as it is bound together by structures called histones into a spherical structure called a nucleosome which is a combination of DNA and the histones that are holding it together. Those spherical structures are going to coil themselves into what’s called chromatin. Chromatin is genetic material and we gonna see when we talk about cell division how chromatin will eventually coil itself up….

Watch video to learn more… 

Ah life… a sunny day, a simple friend, and a complex biological story.

The Human Genome Project is a way of exploring our molecular selves. Almost all of our cells, the muscle cells that let us smile, the brain cell that perceive the humor and thinks, the cells of our eyes that take it all in, contain a complete set of all our genes – the genome.

If we could journey inside our self into a cell, we could see 23 pairs of chromosomes packed into a nucleus. Each chromosome contains a long chain of DNA. If all the chromosomes would unwound, the DNA in just one of our cells would stretch six feet long.

Watch video to learn more…

With computer animation, we can enter the cell to view this remarkable system at work.

After entering the heart of the cell, we see the tightly wind strands of DNA, store houses for the instructions necessary to build every protein in an organism. In a process known as transcription, molecular machine first unwinds a section of the DNA helix to expose the genetic instructions needed to assemble a specific protein molecule.  Another machine then copies this instructions to form a molecule known as messenger RNA (mRNA).

Watch video to learn more…

[DNA Chromosome Wrapping]

In this animation we’ll see a remarkable way our DNA is tightly packed up so the 6 feet of this long molecule fits into microscopic nucleus of every cell.

The process starts when DNA is wrapped around special DNA molecules called histones. The combined group of DNA and protein is called a nucleosome. Next, the nucleosome are packaged into a thread. The end result is a fiber known as chromatin. This fiber is then looped and coiled yet again.

Watch video to learn more…