Archive for the ‘FAQ’ Category
- 12.09.09
DNA Sequencing
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…
- 12.05.09
DNA Structure
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…
Fifty years ago, two scientist in England bolted together some grass part and discovered the secret of life.
“These were unlikely characters to be working on such an important problem.”
The directions for human being are written in code, 3 billion letters long. These instructions tell our body how to live, how to grow, how to die. Researcher call this code, the sequence.
Host: Welcome to the secrets of the sequence. I’m Lucky Severson.
Imagine, you are tipping back in mirror in English pub when two rather wild looking character announced loudly that they have discovered the secret of life. What would you think?
Watch video to learn more…
- 12.05.09
Biology: RNA
Part 5 – Ribonucleic Acid
Section A: What is RNA?
RNA is important in the direction of cellular activities. It’s also a link in the all important synthesis chain you see on your screen right now (DNA –> RNA –> Protein). RNA is needed to make each protein molecule in a cell and you now understand how important protein is for life.
You are about to learn how RNA is made from DNA. But before we get to that, we need to know what RNA is, and we can learn that by discussing the differences between RNA and DNA. Does anybody know?
I know, RNA has a ribose sugar whereas DNA has a deoxyribose sugar. DNA has the prefix deoxy because it has one less oxygen molecule on its ribose sugar…
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…
- 12.03.09
Molecular Visualizations of DNA
[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…
- 11.28.09
DNA 101 – Lecture for Kids!
Lesson 1: What are genes?
Your body is made up of 50 trillion cells. Cells come in many different varieties, with many different functions. But inside almost every cell is a nucleus containing 99.9% of your genes, and mitochondria containing a few more genes. All told, you have nearly 20,000 genes.
Your gene is a small part of a long molecule called DNA or deoxyribonucleic acid. If you line up all of the DNA containing of all your genes, it will measure 6 feet long! But it’s coiled so tightly that it fits in just 1 cell nucleus.
DNA is a double stranded molecule composed of sugar, phosphate and four different bases: Adenine, Thymine, Cytosine, and Guanine. These bases spell out the language known as the genetic code.
The number and order of these 4 bases determine for example, whether you are a chimp, a cow, a banana, or a human. Most genes are recipes for making specific proteins. These recipes are passed out from parents to children, from generation to generation.
When someone says, “You have your father’s hair”, what they mean is, “You appear to have inherited a gene or genes from you father that makes a protein that instructs your hair follicle cells to produce hair that curls like your father’s”. But they usually opt for the shorter version.
Genes tell the cell how to function and what traits to express. Most specifically, gene regulate to turn different genes to turn and off in different cell to control cell function.
The long molecules of DNA containing you genes are organized into pieces called chromosomes. Different species have different numbers of chromosomes.
- Humans usually have 46 chromosomes. Two sets of 23, more simply, 23 pairs of chromosomes.
- Chimpanzees has two sets of 24 or 24 pairs of chromosomes.
- Rhesus monkeys have 21 pairs of chromosomes.
- Cows have 30 pairs of chromosomes.
- Chicken have 39 pairs.
- Fruit flies have 4 pairs and
- bananas have 11 pairs.
So, what percentage of the DNA in your chromosome do you share with other species?
- You share 93% of your DNA with a Rhesus monkey.
- And 98.5% with our friend, chimpanzee.
- How about with other humans? 99.5%
So, what makes us different from one another?
Well, for one thing, SNPs!
An important technique that relies on hybridization of complimentary nucleic acid sequences is Fluorescent In Situ Hybridization or FISH. This technique makes use of fluorescent probes to detect and locate specific DNA sequences in cells and tissues.
In human genetics, FISH is commonly used to analyze chromosomal contents of cells and to detect mutational changes in chromosomes. For example, a deletion on Chromosome 22 associated with DiGeorge’s Syndrome.
FISH is so sensitive that it can detect single copies of specific genes in individual cells.
The Polymerase Chain Reaction, or PCR, is a crucial method for exponentially increasing the amounts of a specific DNA sequence. PCR is a cyclic process controlled by the temperature of the reaction mixture.
- First, the temperature is raised to 95C (205F) causing the template DNA to separate or denature.
- The temperature is then decreased to around 50C (122F) allowing the short primer DNA to hybridize to each strand of the template, a stop to the ends of the sequence to be amplified.
- The foremost stable enzyme, Taq, a DNA polymerase that is active at high temperatures, then binds to and extends the primers at the intermediate temperature of 72C (162F). So that the two new double stranded copies of the template are made.
This cyclic process of separating DNA strands, copying and reannealing the daughter strands, is repeated multiple times to increase the numbers of DNA products.