Skip to main content

Home/ 7E Science ASB/ Group items tagged techniques

Rss Feed Group items tagged

Kareena M

Kareena- "Forensic DNA"- Cutting Edge Technique - 0 views

  • Polymerase Chain Reaction (PCR) Analysis PCR analysis is a technique that allows technicians to create millions of precise DNA replications from a single sample of DNA. In fact, DNA amplification alongside PCR can let forensic scientists perform DNA analysis on samples that are as tiny as only a couple of skin cells. In contrast to some other DNA analysis techniques, PCR analysis has the advantage of analysing minuscule sample sizes, even if they are degraded although they must not be contaminated with DNA from other sources during the collection, storage and transport of the sample.
Abraham H

Forensic Techniques [Media 4] - 0 views

  • RFLP is a technique for analyzing the variable lengths of DNA fragments that result from digesting a DNA sample with a special kind of enzyme. This enzyme, a restriction endonuclease, cuts DNA at a specific sequence pattern know as a restriction endonuclease recognition site. The presence or absence of certain recognition sites in a DNA sample generates variable lengths of DNA fragments, which are separated using gel electrophoresis. They are then hybridized with DNA probes that bind to a complementary DNA sequence in the sample. RFLP was one of the first applications of DNA analysis to forensic investigation. With the development of newer, more efficient DNA-analysis techniques, RFLP is not used as much as it once was because it requires relatively large amounts of DNA. In addition, samples degraded by environmental factors, such as dirt or mold, do not work well with RFLP.
  • PCR Analysis Polymerase chain reaction (PCR) is used to make millions of exact copies of DNA from a biological sample. DNA amplification with PCR allows DNA analysis on biological samples as small as a few skin cells. With RFLP, DNA samples would have to be about the size of a quarter. The ability of PCR to amplify such tiny quantities of DNA enables even highly degraded samples to be analyzed. Great care, however, must be taken to prevent contamination with other biological materials during the identifying, collecting, and preserving of a sample.
  • Short tandem repeat (STR) technology is used to evaluate specific regions (loci) within nuclear DNA. Variability in STR regions can be used to distinguish one DNA profile from another. The Federal Bureau of Investigation (FBI) uses a standard set of 13 specific STR regions for CODIS. CODIS is a software program that operates local, state, and national databases of DNA profiles from convicted offenders, unsolved crime scene evidence, and missing persons. The odds that two individuals will have the same 13-loci DNA profile is about one in a billion.
  • ...1 more annotation...
  • Mitochondrial DNA analysis (mtDNA) can be used to examine the DNA from samples that cannot be analyzed by RFLP or STR. Nuclear DNA must be extracted from samples for use in RFLP, PCR, and STR; however, mtDNA analysis uses DNA extracted from another cellular organelle called a mitochondrion. While older biological samples that lack nucleated cellular material, such as hair, bones, and teeth, cannot be analyzed with STR and RFLP, they can be analyzed with mtDNA. In the investigation of cases that have gone unsolved for many years, mtDNA is extremely valuable. All mothers have the same mitochondrial DNA as their offspring. This is because the mitochondria of each new embryo comes from the mother's egg cell. The father's sperm contributes only nuclear DNA. Comparing the mtDNA profile of unidentified remains with the profile of a potential maternal relative can be an important technique in missing-person investigations.
Colin P

Cloned animals aren't identical - we're still far from the perfect clone - 1 views

  •  
    This science artical explains why cloned animals are not identical
  • ...1 more comment...
  •  
    This is a good one for technique!
  •  
    This is a good one for technique!
  •  
    so are you talking about the technique they have discussed here? Then you haven't tagged it correctly.
Kareena M

Forensic News Blog - 3 views

  • In 2012, readers searching for forensic science content now have many more ways to find
  • "The body chemistry of the person who left the fingerprint can tell us some things," said Shaler. "If the suspect is older or younger or a lactating mother, for example."The researchers used a form of physical vapor deposition -- a method that uses a vacuum and allows vaporized materials to condense on a surface creating a thin film. Normally, the deposition process requires exceptionally clean surfaces because any speck of dust or grease on the coated surface shows up as a deformity. However, with fingerprints, the point is to have the surface material's ridges and valleys -- topography -- show up on the new surface so analysts can read them using an optical device without the necessity of chemical development or microscopy."This approach allows us to look at the topography better and to look at the chemistry later," said Shaler. "We wouldn't have thought of this by ourselves, but we could do it together."One benefit of this approach would be the ability to retrieve fingerprints off fragments from incendiary or explosive devices and still be able to analyze the chemicals used in the device.The specific method used is a conformal-evaporated-film-by-rotation technique developed to create highly accurate copies of biological templates such as insect eyes or butterfly wings. Both are surfaces that have nanoscale variations."It is a very simple process," said Lakhtakia. "And fingerprints are not nanoscale objects, so the conformal coating is applied to something big by nanotechnology standards."
  • Investigators have found new DNA evidence in the murder of Peggy Hettrick, a case that was considered closed until genetic evidence freed a man who spent 10 years in prison, according to Colorado Attorney General John Suthers.The "touch DNA" tests weren't available in the late 1990s. Timothy Masters was convicted of murder in Hettrick's death in 1999, but his conviction was overturned in 2008 after defense lawyers used advanced DNA testing to uncover evidence suggesting a different suspect.The new evidence was taken from Hettrick's clothing. "We have done 'touch DNA,' and I think it has moved the ball forward. We will know more in the future," Suthers said. He wouldn't say whose DNA was found or identify the clothing on which it was found.Masters has not been exonerated in the case and remains a suspect."While we are not in a position to exonerate Tim at this time, I emphasize that he is presumed innocent and is no more a suspect than a variety of other people," Suthers said.
  • ...6 more annotations...
  • It's already difficult to obtain good fingerprints at a crime scene. In most cases, mostly partials will be found. In cases where there was some type of explosion or fire, other methods like this chemical method could be very helpful not just in recovering the print but also to find out some information on who the suspect could be.
  • relevant material.  Organized blogs devoted to forensic science have appeared that post both links and original content.  Organizations have twitter accounts and Facebook pages that make reaching readers much easier than in RSS days.
  • As you may know, your skin has "normal flora" bacteria living on it. This bacteria is beneficial to your health, but may also be used to identify you, according to emerging research. Scientists at the University of Colorado at Boulder are developing a method to identify individuals based on the unique bacteria found on their hands. When the amount of human DNA is too small to detect, bacterial DNA could be used in its place. Bacteria can be collected directly from hands or even touched surfaces and the DNA can be sequenced just like human DNA. The scientists found that very few bacteria were shared among test subjects. Even identical twins have different colonies of bacteria on their hands! Bacteria remain on our hands no matter how many times we wash them, so why not use them?
  • ..."Each one of us leaves a unique trail of bugs behind as we travel through our daily lives," said Fierer, an assistant professor in CU-Boulder's ecology and evolutionary biology department.....unless there is blood, tissue, semen or saliva on an object, it's often difficult to obtain sufficient human DNA for forensic identification, said Fierer. But given the abundance of bacterial cells on the skin surface, it may be easier to recover bacterial DNA than human DNA from touched surfaces, they said. "Our technique could provide another independent line of evidence."...The new technique would even be useful for identifying objects touched by identical twins, since they share identical DNA but they have different bacterial communities on their hands.
  • "On Wednesday, Human Rights Watch released a report showing that since 1995, only about 20 percent of rape kits, which contain physical evidence obtained from victims, could be confirmed as having been tested in Illinois. More than 4,000 kits had gone untested, the report found."
  • Law-enforcement experts said iPhone technology records a wealth of information that can be tapped more easily than BlackBerry and Droid devices to help police learn where you've been, what you were doing there and whether you've got something to hide.
  •  
    okay but which exact post do you want me to read?
  •  
    "New DNA Evidence May Exonerate Convicted Murderer"
  •  
    not a very strong, relevant post
Karan J

Genetic Engineering Methods - 0 views

  • The first technique of genetic engineering, the plasmid method, is the most familiar technique of the three, and is generally used for altering microorganisms such as bacteria. In the plasmid method, a small ring of DNA called a plasmid (generally found in bacteria) is placed in a container with special restriction enzymes that cut the DNA at a certain recognizable sequence. The same enzyme is then used to treat the DNA sequence to be engineered into the bacteria; this procedure creates "sticky ends" that will fuse together if given the opportunity. Next, the two separate cut-up DNA sequences are introduced into the same container, where the sticky ends allow them to fuse, thus forming a ring of DNA with additional content. new enzymes are added to help cement the new linkages, and the culture is then separated by molecular weight. Those molecules that weigh the most have successfully incorporated the new DNA, and they are to be preserved. The next step involves adding the newly formed plasmids to a culture of live bacteria with known genomes, some of which will take up the free-floating plasmids and begin to express them. In general, the DNA introduced into the plasmid will include not only instructions for making a protein, but also antibiotic-resistance genes. These resistance genes can then be used to separate the bacteria which have taken up the plasmid from those that have not. The scientist simply adds the appropriate antibiotic, and the survivors are virtually guaranteed (barring spontaneous mutations) to possess the new genes.
  • Next, the scientist allows the successfully altered bacteria to grow and reproduce. They can now be used in experiments or put to work in industry. Furthermore, the bacteria can be allowed to evolve on their own, with a "selection pressure" provided by the scientist for producing more protein. Because of the power of natural selection, the bacteria produced after many generations will outperform the best of the early generations. Many people strongly object to the plasmid method of genetic engineering because they fear that the engineered plasmids will be transferred into other bacteria which would cause problems if they expressed the gene. Lateral gene transfer of this type is indeed quite common in bacteria, but in general the bacteria engineered by this method do not come in contact with natural bacteria except in controlled laboratory conditions. Those bacteria that will be used in the wild - for example, those that could clean up oil spills - are generally released for a specific purpose and in a specific area, and they are carefully supervised by scientists.
  •  
    This is fine. Pick one of these that is RELEVANT to your topic and find a description of that technique.
Colin P

Technique to animal cloning - 1 views

  •  
    So I want you to choose ONE of these techniques and explain it in your own words. Find another article/video that summarizes that technique. Also you need to tag properly!
  •  
    This isn't a realiable source. Tag your posts name animal cloning and the media type.
  •  
    This is a great website that shows the different types of animal cloning. This was propabably help your group out!
Avantika B

Cloned human embryo makes working stem cells : Nature News - 0 views

  •  
    This is good for technique. What is the technique called and can you explain it briefly in your own words? Please tag correctly using the rubric
  •  
    Scientist in NY part of the Stem Cell foundation changed an adult egg cell to the beginning stages using high-tech cloning technology. This resulted in a self-reproducing chain of embryonic stem cells.The techique is basically cloning a human embryo to create a lot of working stem cells. This can be used for tissue therapy and for research.
Emma Chowdhury

DNA profiling - Wikipedia, the free encyclopedia - 0 views

  •  
    This technique is used to identify the DNA left on a crime scene. Actually, 99.9% of humans have the same DNA sequence, but there is enough unique DNA to identify the person.
Alisa H

http://www.oup.com.au/__data/assets/pdf_file/0007/197512/EDW_PSYCH_1_and_2SB_C08.pdf - 0 views

  •  
    This website shows the techniques/ how scientist determine nature vs nurture, on whatever their topic is.
  •  
    I am not clear. What technique do you want me to look at?
Alisa H

Nature Versus Nurture | USC News - 0 views

  • Using a newly applied scientific technique, researchers at the Keck School of Medicine of USC have reached surprising findings about the role of nature versus nurture in the development of the neural circuits in the auditory cortex, the area of the brain responsible for processing information about sound.
  •  
    what media type is this? and what is the technique ? They don't talk about it!
Yusuke K

Stem cells research - Portal Brasil - 0 views

  •  
    not sure what the technique used is
Yusuke K

Medical Devices Today: For Cutting-Edge Stem Cell Work, California Billions Still Unmat... - 0 views

  •  
    This is not a description of a technique
Simran Sabharwal

New Stem Cell Method Makes Functioning Liver Cells- Cutting Edge Techniques - 0 views

  •  
    This is good. Tag appropriately
  •  
    This article is easy to read and it's also very interesting.
Shweta Khorana

http://www.pressurebiosciences.com/downloads/publications/2011-09/2011_MAFS_v3x.pdf - 0 views

  •  
    good technique. How is it relevant to YOUR topic? Please explain
Yusuke K

Stem cell cutting-edge tech Media 4 - Yusuke - 0 views

  •  
    Is this your "technique" ? Then you will need a bit more detail on the actual technique. Also please TAG your articles appropriately!
  •  
    Can you tag this properly aswell.
Inga V.

BBC - GCSE Bitesize: Cloning methods in animals - 2 views

  • Fusion cell cloning
  • Fusion cell cloning involves replacing the nucleus of an unfertilised egg with the nucleus from a different cell.
    • Inga V.
       
      In fusion cell cloning they inject something into the egg that will produce the next sheep. The baby of this sheep that was born then will also become a clone of the A sheep.
  • ...1 more annotation...
    • Inga V.
       
      I chose fusion cell cloning. A fun fact about fusion cell cloning is that dolly, a famous cloned sheep, was also cloned this exact way.
  •  
    Great techniques. Choose one you want to focus on .
  •  
    Fusion cell cloning is basically taking the a body cell from A sheep and doing the same thing from the B sheep to then make a C sheep. The lamb of that sheep is then going to be a clone of the A sheep.
Alisa H

Behavioral Genetics--A second look at twin studies - 0 views

  • The classical twin study design relies on studying twins raised in the same family environments. Monozygotic (identical) twins share all of their genes, while dizygotic (fraternal) twins share only about 50 percent of them. So, if a researcher compares the similarity between sets of identical twins to the similarity between sets of fraternal twins for a particular trait, then any excess likeness between the identical twins should be due to genes rather than environment.Researchers use this method, and variations on it, to estimate the heritability of traits: The percentage of variance in a population due to genes. Modern twin studies also try to quantify the effect of a person's shared environment (family) and unique environment (the individual events that shape a life) on a trait.The assumptions those studies rest on--questioned by some psychologists, including, in recent work, Jaccard--include:
Inga V.

NIH OSE - Research in the News: Creating A Cloned Sheep Named Dolly (Grades 9-12) - 0 views

  • What is a Clone
  • In biology, a clone is a cell or an organism that is genetically identical to another cell or organism.
  • How was Dolly Created? Dolly is different. She was generated from a specialized adult cell, not from an unspecialized embryonic cell.
  • ...7 more annotations...
  • Why is Dolly so special?
  • Why did researchers create Dolly?
  • created Dolly because they are trying to find ways to produce livestock that carry specific genetic traits.
  • find ways to produce animals that carry certain proteins in their milk.
  • if researchers can develop animals with desirable characteristics, they can then clone those animals to produce entire herds that carry the same traits.
  • Scotland tried 277 times to create cloned sheep, and they succeeded only once.
  • Dolly is special because she disproves the notion that cells from an adult animal are too specialized to generate a new organism.
    • Inga V.
       
      This basically says that Dolly is special proves the theory wrong that the cells from an adult animal are too specialized to make a new baby.
  •  
    This is a science article and it has lots of information about animal cloning. It explains what a clone is in detail, has lots of diagrams to show what it means and lots of information about dolly.
Emma Chowdhury

Forensic DNA technology: A powerful tool for judicial reform | Science and Technology, ... - 0 views

  • Recent advances in forensic DNA testing are now paving the way for reforming the manner by which cases are resolved in courts of law through the way suspected offenders are apprehended during a criminal investigation. Firstly, the availability of new markers which are more variable across different populations, adds to the increased power of discrimination once more genetic markers are used. From the time when DNA testing only involved seven to nine genetic markers to evaluate if crime scene evidence matches a suspect’s profile, as well as to determine relationships, to the current battery of 21 autosomal markers and 23 male-specific markers, the capacity of DNA profiling to differentiate individuals has increased significantly. The use of automated and expert systems for large-scale analysis has also been found to reduce manual errors and to increase output per unit time. The use of several dyes in a single multiplex system provides more information from the same amount of genetic material compared to reactions targeting only one genetic marker but requiring the same amount of DNA that was common in the early 1990s.
  •  
    This is about how they have new technology for forensic DNA sciences, so they make less mistakes and can find the person quickly. For example, they now have automatic systems to test DNA.
  •  
    What is the media type???
1 - 20 of 29 Next ›
Showing 20 items per page