This video shows how rnai works in the cells. Video reference: Nature.com Info: RNA interference (also called "RNA-mediated interference", abbreviated RNAi) is a mechanism for RNA-guided regulation of gene expression in which double-stranded ribonucleic acid inhibits the expression of genes with complementary nucleotide sequences. Conserved in most eukaryotic organisms, the RNAi pathway is thought to have evolved as a form of innate immunity against viruses and also plays a major role in regulating development and genome maintenance. The RNAi pathway is initiated by the enzyme dicer, which cleaves double-stranded RNA (dsRNA) to short double-stranded fragments of 20–25 base pairs. One of the two strands of each fragment, known as the guide strand, is then incorporated into the RNA-induced silencing complex (RISC) and base-pairs with complementary sequences. The most well-studied outcome of this recognition event is a form of post-transcriptional gene silencing. This occurs when the guide strand base pairs with a messenger RNA (mRNA) molecule and induces degradation of the mRNA by argonaute, the catalytic component of the RISC complex. The short RNA fragments are known as small interfering RNA (siRNA) when they derive from exogenous sources and microRNA (miRNA) when they are produced from RNA-coding genes in the cell's own genome. The RNAi pathway has been particularly well-studied in certain model organisms such as the nematode worm Caenorhabditis elegans, the fruit fly Drosophila melanogaster, and the flowering plant Arabidopsis thaliana. The selective and robust effect of RNAi on gene expression makes it a valuable research tool, both in cell culture and in living organisms; synthetic dsRNA introduced into cells can induce suppression of specific genes of interest. RNAi may also be used for large-scale screens that systematically shut down each gene in the cell, which can help identify the components necessary for a particular cellular process or an event such as cell division. Exploitation of the pathway is also a promising tool in biotechnology and medicine. Historically, RNA interference was known by other names, including post transcriptional gene silencing, transgene silencing, and quelling. Only after these apparently-unrelated processes were fully understood did it become clear that they all described the RNAi phenomenon. RNAi has also been confused with antisense suppression of gene expression, which does not act catalytically to degrade mRNA but instead involves single-stranded RNA fragments physically binding to mRNA and blocking translation. info ref: http://en.wikipedia.org/wiki/RNAi

Added by: benchwork
Tags: rnai
Date: 2007-03-26

We show the details of casting protein gels, loading and running them. Murat KASAP Gurler AKPINAR

Added by: technician
Tags: SDS AGE
Date: 2007-09-06

http://www.retrovirals.com

Added by: asteri
Tags: replication
Date: 2008-04-28

Stem cells serve as the source of all the other specialized cells in the body, both when it forms during embryogenesis and when it replaces cells that have been lost to aging, injury or disease. These videos are created by RIKEN CDB and they explain the different types of stem cell found in the embryonic body and the adult and illustrate the roles of these "master cells" in development and regeneration. Video REff: http://www.cdb.riken.go.jp I also uploaded other 3 parts. Search " stem cells" on DnaTube and most probably you will find other videos.

Added by: siere
Tags: stemcell
Date: 2007-04-02

anatomy lab

Added by: sedaklc
Tags: mouse anatomy
Date: 2007-03-29

How are proteins synthesized? This interactive animation will help you to understand the process. For more information about protein synthesis: Legend: Process whereby DNA encodes for the production of amino acids and proteins. This process can be divided into two parts: 1. Transcription Before the synthesis of a protein begins, the corresponding RNA molecule is produced by RNA transcription. One strand of the DNA double helix is used as a template by the RNA polymerase to synthesize a messenger RNA (mRNA). This mRNA migrates from the nucleus to the cytoplasm. During this step, mRNA goes through different types of maturation including one called splicing when the non-coding sequences are eliminated. The coding mRNA sequence can be described as a unit of three nucleotides called a codon. 2. Translation The ribosome binds to the mRNA at the start codon (AUG) that is recognized only by the initiator tRNA. The ribosome proceeds to the elongation phase of protein synthesis. During this stage, complexes, composed of an amino acid linked to tRNA, sequentially bind to the appropriate codon in mRNA by forming complementary base pairs with the tRNA anticodon. The ribosome moves from codon to codon along the mRNA. Amino acids are added one by one, translated into polypeptidic sequences dictated by DNA and represented by mRNA. At the end, a release factor binds to the stop codon, terminating translation and releasing the complete polypeptide from the ribosome Text Reff: http://www.accessexcellence.org/RC/VL/GG/protein_synthesis.html

Added by: tubeman
Tags: proteinsynthesis
Date: 2007-04-01

Retrovirus life cycle. Ref.: Molecular Cell Biology by Lodish

Added by: sana
Tags: Retrovirus
Date: 2007-05-15

A short animation on the mechanism of prion diseases. The entry of the infectious prion proteins (red) is still up for debate. Once they enter the nervous tissue however, they are thought change normal PrP proteins in our brains to look like themselves (red to green change). The two red proteins then split and go on to find two more normal (green) proteins to convert. The process continues until a plaque forms (Death-Star at the end)and some other side-effects develop.

Added by: sana
Tags: Prions
Date: 2007-05-15

Human immunodeficiency virus (HIV) is a retrovirus that causes acquired immunodeficiency syndrome (AIDS, a condition in humans in which the immune system begins to fail, leading to life-threatening opportunistic infections). Previous names for the virus include human T-lymphotropic virus-III (HTLV-III), lymphadenopathy-associated virus (LAV), or AIDS-associated retrovirus (ARV)[

Added by: sana
Tags: hiv
Date: 2007-05-15

The structure of DNA is illustrated by a right handed double helix, with about 10 nucleotide pairs per helical turn. Each spiral strand, composed of a sugar phosphate backbone and attached bases, is connected to a complementary strand by hydrogen bonding (non- covalent) between paired bases, adenine (A) with thymine (T) and guanine (G) with cytosine (C). Adenine and thymine are connected by two hydrogen bonds (non-covalent) while guanine and cytosine are connected by three. This structure was first described by James Watson and Francis Crick in 1953.

Added by: sana
Tags: DNAStructure
Date: 2007-05-15

In genetics and developmental biology, somatic cell nuclear transfer (SCNT) is a laboratory technique for creating an ovum with a donor nucleus (see process below) . It can be used in embryonic stem cell research, or in regenerative medicine where it is sometimes referred to "therapeutic cloning." It can also be used as the first step in the process of reproductive cloning.

Added by: mnazirokur
Tags: nuclear
Date: 2007-05-24

Joseph G. Marx, PhD

Added by: siere
Tags: height="520" width="650"
Date: 2007-06-09

Monoclonal antibodies (mAb or moAb) are antibodies that are identical because they were produced by one type of immune cell and are all clones of a single parent cell. Given (almost) any substance, it is possible to create monoclonal antibodies that specifically bind to that substance; they can then serve to detect or purify that substance. This has become an important tool in biochemistry, molecular biology and medicine. When used as medications, the generic name ends in -mab (see "Nomenclature of monoclonal antibodies").

Added by: second
Tags: antibody
Date: 2007-07-30

This video shows how rnai is discovered in very simpe way. www.hhmi.org Text info: RNA interference (also called "RNA-mediated interference", abbreviated RNAi) is a mechanism for RNA-guided regulation of gene expression in which double-stranded ribonucleic acid inhibits the expression of genes with complementary nucleotide sequences. Conserved in most eukaryotic organisms, the RNAi pathway is thought to have evolved as a form of innate immunity against viruses and also plays a major role in regulating development and genome maintenance.

Added by: second
Tags: rnai
Date: 2007-09-01

This video shows structure of DNA and RNA. Ribonucleic acid or RNA is a nucleic acid polymer consisting of nucleotide monomers that plays several important roles in the processes that translate genetic information from deoxyribonucleic acid (DNA) into protein products; RNA acts as a messenger between DNA and the protein synthesis complexes known as ribosomes, forms vital portions of ribosomes, and acts as an essential carrier molecule for amino acids to be used in protein synthesis. Deoxyribonucleic acid, or DNA, is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms. The main role of DNA molecules is the long-term storage of information and DNA is often compared to a set of blueprints, since it contains the instructions needed to construct other components of cells, such as proteins and RNA molecules. The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information.

Added by: technician
Tags: rna
Date: 2007-09-13

no description

Added by: watchme
Tags: fertilization
Date: 2007-11-23

Vascular endothelial growth factor (VEGF) is an important signaling protein involved in both vasculogenesis (the de novo formation of the embryonic circulatory system) and angiogenesis (the growth of blood vessels from pre-existing vasculature). Text reff: wiki Video reff:

Added by: asteri
Tags: vegf
Date: 2007-12-05

Wiki text info: Apoptosis is a form of programmed cell death in multicellular organisms. It is one of the main types of programmed cell death (PCD) and involves a series of biochemical events leading to a characteristic cell morphology and death, in more specific terms, a series of biochemical events that lead to a variety of morphological changes, including blebbing, changes to the cell membrane such as loss of membrane asymmetry and attachment, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation . Processes of disposal of cellular debris whose results do not damage the organism differentiate apoptosis from necrosis. In contrast to necrosis, which is a form of traumatic cell death that results from acute cellular injury, apoptosis, in general, confers advantages during an organism's life cycle. For example, the differentiation of fingers and toes in a developing human embryo occurs because cells between the fingers apoptose; the result is that the digits are separate. Between 50 billion and 70 billion cells die each day due to apoptosis in the average human adult. For an average child between the ages of 8 and 14, approximately 20 billion to 30 billion cells die a day. In a year, this amounts to the proliferation and subsequent destruction of a mass of cells equal to an individual's body weight. Research on apoptosis has increased substantially since the early 1990s. In addition to its importance as a biological phenomenon, defective apoptotic processes have been implicated in an extensive variety of diseases. Excessive apoptosis causes hypotrophy, such as in ischemic damage, whereas an insufficient amount results in uncontrolled cell proliferation, such as cancer.

Added by: technician
Tags: apoptosis
Date: 2008-03-27

Helicases are a class of enzymes vital to all living organisms. They are motor proteins that move directionally along a nucleic acid phosphodiester backbone, separating two annealed nucleic acid strands (i.e. DNA, RNA, or RNA-DNA hybrid) using energy derived from nucleotide hydrolysis. Many cellular processes (DNA replication, RNA transcription, DNA recombination, DNA repair, Ribosome biogenesis) involve the separation of nucleic acid strands. Helicases are often utilized to separate strands of a DNA double helix or a self-annealed RNA molecule using the energy from ATP or GTP hydrolysis. They move incrementally along one nucleic acid strand of the duplex with a directionality specific to each particular enzyme. There are many helicases (14 confirmed in E. coli, 24 in human cells) resulting from the great variety of processes in which strand separation must be catalyzed.[citation needed] Helicases adopt different structures and oligomerization states. Whereas DnaB-like helicases unwind DNA as donut shaped hexamers, other enzymes have been shown to be active as monomers or dimers. Their precise mechanisms of action remain unclear. Text Reff: http://en.wikipedia.org/wiki/Helicase

Added by: benchwork
Tags: 06.2-DNA_helicase
Date: 2007-03-25

This is cool video showing the keratocyte cells. Keratocyte are fibroblastic stromal cell of the cornea. Keratocytes produce keratan-sulfate proteoglycans (KSPG), lumican and keratocan to form and sustain proper collagen interfibrillar spacing and fibril diameter of the cornea.

Added by: mnazirokur
Tags: 01.1-keratocyte_dance
Date: 2007-03-17