In this video, mitochondria ATP synthesis which involves the transfer of electrons from the intermembrane space, through the inner membrane, back to the matrix is shown.

Added by: mnazirokur
Tags: biology
Date: 2009-04-02

This video shows how RNA interference 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: RNA i RNA interference C elegans
Date: 2007-03-26

This video shows students dissecting animal which is not properly anesthesied and sedated.

Added by: sedaklc
Tags: mouse vivisection
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

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.

Added by: sana
Tags: HIV AIDS retrovirus viral core reverse transcriptase
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. It can be used as the first step in the process of reproductive cloning. This is how Dolly the shim was made.

Added by: mnazirokur
Tags: NuclearTransfer embryo ovum
Date: 2007-05-24

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

Day 1: fertilization: all human chromosomes are present; unique human life begins. Day 6: embryo begins implantation in the uterus. Day 22: heart begins to beat with the child's own blood, often a different type than the mothers'. Week 3: By the end of third week the child's backbone spinal column and nervous system are forming. The liver, kidneys and intestines begin to take shape. Week 4: By the end of week four the child is ten thousand times larger than the fertilized egg. Week 5: Eyes, legs, and hands begin to develop. Week 6: Brain waves are detectable; mouth and lips are present; fingernails are forming. Week 7: Eyelids, and toes form, nose distinct. The baby is kicking and swimming. Week 8: Every organ is in place, bones begin to replace cartilage, and fingerprints begin to form. By the 8th week the baby can begin to hear. Weeks 9 and 10: Teeth begin to form, fingernails develop. The baby can turn his head, and frown. The baby can hiccup. Weeks 10 and 11: The baby can "breathe" amniotic fluid and urinate. Week 11 the baby can grasp objects placed in its hand; all organ systems are functioning. The baby has a skeletal structure, nerves, and circulation. Week 12: The baby has all of the parts necessary to experience pain, including nerves, spinal cord, and thalamus. Vocal cords are complete. The baby can suck its thumb. Week 14: At this age, the heart pumps several quarts of blood through the body every day. Week 15: The baby has an adult's taste buds. Month 4: Bone Marrow is now beginning to form. The heart is pumping 25 quarts of blood a day. By the end of month 4 the baby will be 8-10 inches in length and will weigh up to half a pound. Week 17: The baby can have dream (REM) sleep. Week 19: Babies can routinely be saved at 21 to 22 weeks after fertilization, and sometimes they can be saved even younger. Week 20: The earliest stage at which Partial birth abortions are performed. At 20 weeks the baby recognizes its' mothers voice. Months 5 and 6: The baby practices breathing by inhaling amniotic fluid into its developing lungs. The baby will grasp at the umbilical cord when it feels it. Most mothers feel an increase in movement, kicking, and hiccups from the baby. Oil and sweat glands are now functioning. The baby is now twelve inches long or more, and weighs up to one and a half pounds. Months 7 through 9: Eyeteeth are present. The baby opens and closes his eyes. The baby is using four of the five senses (vision, hearing, taste, and touch.) He knows the difference between waking and sleeping, and can relate to the moods of the mother. The baby's skin begins to thicken, and a layer of fat is produced and stored beneath the skin. Antibodies are built up, and the baby's heart begins to pump 300 gallons of blood per day. Approximately one week before the birth the baby stops growing, and "drops" usually head down into the pelvic cavity.

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

This animation demonstrates why 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). The most important member is VEGF-A. Other members are Placenta growth factor (PlGF), VEGF-B, VEGF-C and VEGF-D. The latter ones were discovered later than VEGF-A, and before their discovery VEGF-A was called just VEGF. Crystal structure of Vammin, a VEGF-F from a snake venom A number of VEGF-related proteins have also been discovered encoded by viruses (VEGF-E) and in the venom of some snakes (VEGF-F). Text reff: wiki Video reff:

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

During viral replication, the integrated DNA provirus is transcribed into mRNA, which is then spliced into smaller pieces. These small pieces are exported from the nucleus into the cytoplasm, where they are translated into the regulatory proteins Tat (which encourages new virus production) and Rev.

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

DNA Transcription Hope it is helpful!

Added by: eburnsye
Tags: DNA Transcription science
Date: 2009-10-18

Stem cells which 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 is explained in this science video. This is the first part of 4 videos. 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 This part of video gives general overview of steam cells and other, differentiated cells.

Added by: siere
Tags: stem cell differentiation embrypgenesis embryonic stem cells
Date: 2007-04-02

LDL is needed in normal cell life. LDL (low density lipoprotein)enters the cells by receptor mediated uptake, meaning, it is active process. LDL comes in LDL particles docking on LDL receptors. Endocytosis begins, and particles are coated with clathrin. Afterwords, LDL particle dissolves.

Added by: sana
Tags: LDL low density lipoprotein endocytosis active transport
Date: 2007-05-11

Retroviruses are RNA viruses. Some of them are tumor inducing. They are binding on the cell's surface, than fused, and releasing RNA with polymerase, which is called in this case reverse transcriptase. It copies RNA to ssDNA (single stranded), and than to dsDNA (double stranded), which is then sent to nucleus to express viral genes. Ref.: Molecular Cell Biology by Lodish

Added by: sana
Tags: Retrovirus reverse transcriptase RNA ssDAN dsDNA
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 MadcowDesease subviral pathogens
Date: 2007-05-15

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 polypeptide. At the end, a release factor binds to the stop codon, terminating translation and releasing the complete polypeptide from the ribosome.

Added by: sana
Tags: Translation polypeptide tRNA ribosome
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).

Added by: sana
Tags: DNA Structure DNA
Date: 2007-05-15

In this video, stem cells are explained by Joseph G. Marx, PhD.

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

Receptor tyrosine kinase is activated when a growth factor, hormone or cytokine binds to one of the receptors and recruits the second receptor molecule. Receptor tyrosine kinase is very important, hence it not only plays role in normal cell growth, but in carcinogenesis.

Added by: Samuray
Tags: receptor tyrosine kinase activation phosphorylation
Date: 2007-07-14

Monoclonal antibodies are antibodies that are identical because they were produced by only one type of immune cell. Is is possible to create monoclonal antibodies with almost any substance. Monoclonal antibodies can serve to detect or purify substance. This has become an important tool in biochemistry, molecular biology and medicine.

Added by: second
Tags: antibody monoclonal Antibody immunology
Date: 2007-07-30