...579 Atomic force microscopy and other scanning probe microscopies Helen G Hansma and Lía Pietrasanta The highlight of the past year is the unfolding and refolding of the muscle protein titin in the atomic force microscope. A related highlight in the intersection between experiment and theory is a recent review of the effects of molecular forces on biochemical kinetics. Other advances in scanning probe microscopy include entropic brushes, molecular sandwiches and applications of atomic force microscopy to gene therapy. Address Department of Physics, University of California, Santa Barbara, CA 93106, USA Current Opinion in Chemical Biology 1998, 2:579–584 http://biomednet.com/elecref/1367593100200579 © Current Biology Ltd ISSN 1367-5931 Abbreviations AFM atomic force microscopy/microscope SFM scanning force microscopy/microscope SICM scanning ion conductance microscopy/microscope SPM scanning probe microscopy/microscope STM scanning tunneling microscopy/microscope A new journal, Probe Microscopy, was launched in 1997 as a forum specifically devoted to the science and technology of SPM. AFM and SFM have been also newsworthy items in Science and Nature in the past year [14••,15•–17•,18••,19]. An introduction to AFM is covered well in a recent issue of Current Opinion in Chemical Biology, which describes and illustrates the design and mode of operation of AFM [4••]. The AFM images sample surfaces by raster-scanning a sharp tip back and forth over the surface. The tip is on...
Words: 4570 - Pages: 19
...WEEK 1- INTRODUCTION TO FORENSIC SCIENCE Quote "Every contact leaves a trace." - Edmond Locard (1877 - 1966) Learning Objective(s) At the end of this topic, you should be able to: 1. Define 'Forensic Science'; 2. Explain the limits of Forensic Science; 3. Identify the types of forensic work; 4. Describe Locard's Exchange Principle; 5. Differentiate Reconstruction & Re-enactment. Synopsis To illustrate the scope and diversity of Forensic Science, place it in its legal context, and describe the various types of forensic work. There will also be a discussion of Comparison leading to Association, Reconstruction versus Re-enactment, Locard's Exchange Principle, and the limits of Forensic Science. Various case studies will also be analysed throughout the lecture. Case Studies Felicia Lee; Walter Dinivan; Madam Jetkor Miang Singh; Roberto Calvi; Buck Ruxton & the Jigsaw Murders; Acid Bath Haigh; 2005 London Bombings; "Brides in the Bath"; Gareth Williams; The Woodchipper Murder WEEK 2- CHEMICAL ANALYSIS IN FORENSIC SCIENCE Quote "Actus non facit reum nisi mens sit rea" The act is not culpable unless the mind is also guilty. Learning Objective(s) At the end of this topic, you should be able to: 2A. Atomic Structure & Spectroscopy 1. Explain the structure of the atom and Bohr's model; 2. Differentiate between emission and absorption spectroscopy; 3. Explain the chemistry behind EDX and SEM-EDX; 4. Explain the chemistry in NAA; 2B. Molecular...
Words: 1646 - Pages: 7
...When the two strands of DNA double helix are separated, each can serve as a template for the replication of a new complementary strand, producing two daughter molecules each of which contains two DNA strands with an antiparallel orientation. The enzymes involved in DNA replication process are template-directed polymerases that can synthesize the complementary sequence of each strand with extraordinary fidelity. This complex leads to the local denaturation and unwinding of an adjacent A + T rich region of DNA. The interaction of proteins with the origin is what defines the start site of replication and provides a short region of single stranded DNA essential to initiation of synthesis of the nascent DNA strand. Then helicase binds and allows for processive unwinding of double stranded DNA into single stranded DNA. As helicase unwinds the DNA, DNA single stranded protiens bind and stabilize the single stranded DNA. The polymerase III holoenzyme binds to template DNA as a part of a multi protein complex that consists of several polymerase accessory factors. DNA polymerase synthesizes DNA only in the 5 ' to 3 ' direction and only one of the several different types of polymerases is involved at the replication fork. As the DNA strands are anti parallel, the DNA polymerase functions asymmetrically. On the leading (forward) strand, the DNA is synthesized continuously. On the lagging strand (retro strand) the DNA is synthesized in short (1-5 kb) fragments. These DNA fragments are called...
Words: 1062 - Pages: 5
...discusses how a man used technology wrong to create a park full of dinosaurs for money. The reason why relying on technology posed serious dangerous issues was because of the fact the power to create the dinosaurs was not understood and ultimately the park organizers knew nothing about the creatures they created until it was too late and people’s lives were in danger and deaths resulted. This can be seen through three direct examples in the novel, one being the electrical fences which stopped working due to a power outage and the T-Rex’s got out putting people’s lives in danger and killing others, second being by which the computers were used to track data but tracked the wrong data instead, and finally genetic engineering which used frog DNA making the animals able to change sex and...
Words: 924 - Pages: 4
...Confidence will grow in the lab with certification as well. Once a lab is deemed certified, it must continue to demonstrate quality and adaptability to remain certified. If not, or if the lab suffers any setback or does not abide by the bylaws of the ASCLD, revocation of the certification will occur. Labs that want to be certified should also draft a memo, or justification letter, to the ASCLD and to its management for becoming certified. The memo should state all reasons why the lab is wanting certification, the program it specializes in (type of lab, in other words) and why certification would help the lab. All labs also need testing requirements, such as testing for DNA, using the principles of ASCLD. All labs deal with biological matter, so there has to be safety standards set in order to protect workers from exposure. A good example of this is if someone was exposed to blood collected form a scene or evidence, or a victim. OSHA sets standards and regulations that must be followed, so labs need to have policies in place, and visible to all employees. There are examples of all such a memos...
Words: 1438 - Pages: 6
...How has our knowledge of DNA improved the study of criminal forensics? Introduction Through genetics, the study of DNA, we are able to figure out what and how genes are responsible for many things like our hair color or why do some people look a lot like their parents and others don’t. It also allows us to understand better how species evolve and how are they related to each other. It is important to understand how DNA mutates, changes and replicates in order to get information about what mechanisms cause DNA to change. In the 1970s scientists developed a DNA sequencing technique and other methods to manipulate and analyze DNA. This gave them the basic tools to start exploring the DNA blueprint which provided the techniques for a vast international project called The Human Genome Project (MRC). The Human Genome Project which was a major international project with the goal of decoding all our genetic information by 2003. A rough draft was done in June 2003 and it was a huge milestone that helped us understand how our genes can determine who we are (Genome Project). Many of today’s advances in DNA and biotechnology allow scientists and medical doctors to potentially cure genetic disorders through gene therapy by inserting, deleting or manipulating genes (Tillery, page 686). Another use of DNA technology is the creation of mutation by transferring DNA from one organism to another through techniques like cloning and introducing new DNA sequence into an organism to alter...
Words: 1437 - Pages: 6
...altered by the insertion of a modified gene or a gene from another organism using the techniques of genetic engineering. Explain how transgenic organisms work. What is the process? A flowchart is helpful: The genes of one species are modified, or transplanted into another organism. Transgenic Organisms are possible due to recombinant DNA technology (the procedure used to combine DNA segments) . This technology gives scientist the ability to practically cut, paste and copy molecules of DNA. This allows scientists to remove the gene from one organism and place it into another organism, giving it a trait encoded into that gene. Plants are commonly used in these experiments, the flowchart shows this process. The steps in the process are: The plasma is removed from bacterium, and the T-DNA is cut by a restriction enzyme Foreign DNA is cut by the same enzyme The foreign DNA is inserted into the T-DNA of the plasmid...
Words: 994 - Pages: 4
...‘unofficially’ regulate DNA analysis and force ‘private companies to adopt its technological system’” (Edmond 130). These debates in the courtroom have led to regulations that are in place to ensure the proper gathering and testing of DNA evidence so that only accurate evidence is admitted in court. Suspects have a right to a fair trial and following the DNA wars, fair trials include correct evidence to be presented otherwise they may be acquitted or a mistrial may be declared. One of the factors to ensuring correct evidence is a process known as the chain of custody. The chain of custody, if followed properly, keeps track of continuity of possession. Evidence must be correctly...
Words: 1602 - Pages: 7
...blastomere into an enucleated oocyte to produce an offspring, which gave them suspicion of cloning in 1987 (Prather, 2016). The history of cloning gives rise to our ethical and moral guards about the issue of the use of stem cells or adult cells to proliferate and make another organism. The first mammal to be cloned using an adult mammary gland cell are two lambs at Roslin Institute in Scotland, a year later Dolly the sheep is cloned. The premise of the procedure included removing the nucleus from a somatic cell of the animal to be cloned, transfer it into a hosts de-enucleated, unfertilized egg cell (oocyte), and then implant the re-nucleated embryonic cell in the womb of the chosen surrogate mother (Ogden, 2014). Another technique that can be used is genetic engineering, using incomplete DNA sequences extracted from the specimen, and insert the DNA fragments from close living relatives or from those manufactured synthetically (Ogden, 2014). Using one’s cells to multiply another organism takes away a lot from that individual and raises many ethical concerns ranging from autonomy, informed consent, and individuality. In order to protect the welfare of the human population there is current legislation in place for consumable cloned food, but cloned extinct species there are many uncertainties. One example includes: pre-market approval of the cloned product under the scope of regulation number 258/97 (Vaque, 2014). Regulation is being placed upon consumable products, so it is only...
Words: 2296 - Pages: 10
...Electrophoresis for the Separation of DNA Fragments Pei Yun Lee, John Costumbrado, Chih-Yuan Hsu, Yong Hoon Kim Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles Video Article Chapters 0:05 Title 1:31 Preparation of the Gel 3:21 Setting up Gel Apparatus and Separating DNA Fragments 4:55 Observing Separated DNA Fragments 5:43 Results: Agarose Gel Electrophoresis of PCR Products 6:23 Conclusion Cite this Article Lee, P. Y., Costumbrado, J., Hsu, C. Y., Kim, Y. H. Agarose Gel Electrophoresis for the Separation of DNA Fragments. J. Vis. Exp. (62), e3923, doi:10.3791/3923 (2012). Abstract Agarose gel electrophoresis is the most effective way of separating DNA fragments of varying sizes ranging from 100 bp to 25 kb1. Agarose is isolated from the seaweed genera Gelidium and Gracilaria, and consists of repeated agarobiose (L- and D-galactose) subunits2. During gelation, agarose polymers associate non-covalently and form a network of bundles whose pore sizes determine a gel's molecular sieving properties. The use of agarose gel electrophoresis revolutionized the separation of DNA. Prior to the adoption of agarose gels, DNA was primarily separated using sucrose density gradient centrifugation, which only provided an approximation of size. To separate DNA using agarose gel electrophoresis, the DNA is loaded into pre-cast wells in the gel and a current applied. The phosphate backbone of the DNA (and RNA) molecule is negatively...
Words: 2118 - Pages: 9
...week. These were later used by the majority of lab students who had reached the cloning stage. My first PCR with plasmid pgbr22 failed, but the second was successful. PCR with pmCherry had to be completed 3 times to get a successful result and PNIC-BSa4 PCR had to be completed twice to get a successful result. The three practice PCRs were completed the 5th week of lab. Protein expression using PfDXR was started in week 3 and the sample of protein was purified the following week. I received my target protein Rickettsia prowazskii FabG (RpFabG), responsible for epidemic typhus, during week 5 of research. I worked on designing tail primers for this specific protein with two other researchers in my group that also had the same target. A virtual RE Digest gel was also done with PNiCBSa4 accepting vector and Fab G 3-ketoacyl-ACP reductase insert to help visualize and understand the next steps for our research. Primary PCR was completed with an oligo primer mix for RpFabG, followed by Secondary PCR and PCR2. The sample was nano-dropped after PCR2 to determine that the concentration was high. My first attempt had a concentration average of 9.4ng/uL, so I had to restart and complete primary PCR twice before being able to move onto secondary PCR. The primary and secondary PCR gels showed that the concentration was weak so I made a second oligo-mix after consulting with Dr. B. I completed primary and secondary PCR once again with both the old and new oligo-mixes. With the old oligo-mix, primary...
Words: 794 - Pages: 4
...Tommie Brown Grand Canyon University The History of Criminal Investigations DNA Overturned June 29, 2016 Many cases have been solved with good investigation work and the technology of DNA. As a result of this technology many convicted criminals have been released due to DNA overturned in their cases. This was true in the case of Anthony Capozzi who spent 22 years in prison for a crime he did not commit (innocenceproject.org). In the mid-1980s Capozzi was wrongfully convicted of committing two sexual assaults in Buffalo, New York. It was DNA testing that proved his innocence (innocenceproject.org). The true perpetrator’s identity was revealed and DNA testing also revealed that this criminal committed multiple rapes and murders. The crimes itself consist of several women being raped along the bike path in Delaware Park. The crimes took place around December of 1983 and July of 1984. The attacker had it all planned out as he would wait for the right moment then move in for the attack. The attacker apparently surprised his victims from behind by threatening them with a gun. Once the victim was at his mercy he went on to rape them and when finished he gave them instructions to remain on the ground for up to 20 minutes before they move (innocenceproject.org)...
Words: 1161 - Pages: 5
...Fingerprint identification has been around for a long time. Dating back to 1856, Sir William Hershel began using fingerprints by requiring people to not only sign business contracts but to impress their hand on the back of the contract. In the beginning, his intentions were not directed at personal identification. The print was simply used to frighten him out of all thought of repudiating him signature (The History of Fingerprints). As Hershel s fingerprint collection grew, he began to note that the linked impressions could prove or disprove identity. During the 1870 s, Dr. Henry Faulds, a British Surgeon of Tsukiji Hospital in Japan, studied skin furrows after taking notice of finger marks on prehistoric pottery. He then devised a method of classification. Mr. Faulds passed on an explanation of his classification system, along with samples of the forms he had design for recording inked impressions, to Charles Darwin. However, because of Mr. Darwin s old age and ill health, he informed Faulds that he would pass the material on to his cousin Francis Galton. Sir Francis Galton, a British anthropologist, published a book called Fingerprints. The book included the first classification system for fingerprints can be identified. Galton identified the characteristics by which fingerprints can be identified. These same characteristics are in use today and are often referred to as Galton s Details. In 1892, Argentine Police Officer, Juan Vucetich, made the first criminal fingerprint identification...
Words: 3136 - Pages: 13
...Modern Database Applications | [Type the document title] | | | Contents 1. Gray, J. (2009). Jim Gray on eScience: A transformed scientific method. The Fourth Paradigm: Data-intensive scientific discovery 2 2. Rowley, J. (2007). Wisdom hierarchy: Representations of the DIKW hierarchy. Journal of Information Science 3 3. Goldman, N. (2013). Towards practical, high-capacity, low-maintenance information storage in synthesized DNA. 4 4. Gray, J. (1981). The transaction concept: virtues and limitations. In: VLDB '81: Proceedings of the seventh international conference on Very Large Data Bases 5 5. Codd, E. F. (1970). A Relational Model of Data for Large Shared Data Banks. Communications of the ACM 7 6. Chen, P. (1976). The entity-relationship model: Toward a unified view of data. ACM Transactions on Database Systems 8 1. Gray, J. (2009). Jim Gray on eScience: A transformed scientific method. The Fourth Paradigm: Data-intensive scientific discovery Gray states that there is need to distinguish data-intensive science from computational science; he defines an emerging fourth paradigm for scientific exploration. This paradigm is derived from the deluge of data being produced within scientific research fields, and the necessity for tools which can be utilised within the whole research cycle; data capture, curation, analysis and visualisation. He identified that currently the data being produced is not being organised, or published in a systematic...
Words: 3050 - Pages: 13
...the Gattaca movie produced in a 1997, many futuristic technologies regarding that time has been shown. Now is 20 years past the time that the movie was initially released and we are using some concept technologies used in the movies such as electric cars. One of the futuristic technologies showed in the movie was the rapid identification of people from their genetics. The question is have we discovered a method to identify a person from his DNA as shown in the movie? In the movie, each time the main character, Vincent, was entering the Gattaca facility, he was going through some processes for his identity verification. They were gates that required the people to place his finger on the designated pad to verify the identity. The device identified the person using the blood droplet taken from...
Words: 753 - Pages: 4
