MY SCIENCE BLOG IS COMPLETE


I FINISHED MY BLOG 17/12/08

Week 6+7 case study

THE CRIME

october 30th 1975

October 30, 1975: In the town of Greenwich, Connecticut, the night before Halloween was commonly known as "mischief night" or sometimes "doorbell night". On this particular evening, 15-year-old Martha Moxley, and her friends, set out for an night of harmless pranks; spraying shaving cream, throwing eggs and toilet paper around the neighborhood before stopping at the home of Tommy and Michael Skakel.

more on the skakel brothers

The Skakel brothers were well know in the neighborhood for their behavior and lack of discipline -- and also because they were the nephews of Ethel Skakel-Kennedy, widow of the late Senator Robert F. Kennedy.

back to the crime

The Moxley's and Skakel's lived in Belle Haven, a gated community in Greenwich, an affluent area of town where Hollywood actors live and former President George Bush grew up. Sometime between 9:30 and 11 p.m. that night, Martha left the Skakel house. Home was only 150 yards away, but Martha never made it. Martha's body was found the next day under a tree in her back yard. Her jeans and underwear had been pulled down, but there was no apparent evidence of sexual assault. She had been beaten so hard with a 6-iron that the shaft had shattered. A jagged piece of it was used to stab her through the neck. Police later learned that the club was part an expensive, Toney Penna, set which had belonged to Tommy and Michael Skakel's mother Anne.

Mrs. Skakel had died of cancer two years earlier leaving her husband Rushton to raise their large and reportedly unruly family. Their son, Tommy, then 17, was said to be the last person seen with Martha. According to Martha's diary, she had fended off several past attempts by Skakel to "get to first and second base," said Martha's mother, Dorthy Moxley. The day Martha's battered body was found, Greenwich police did a cursory search of the house with Rushton Skakel's permission, but they never obtained a warrant to do a thorough search. This lack of a warrant in the investigation led to accusations of "special treatment" for the well-connected, influential family.

OK

so far we have a 15 year old girl who was murdered and found the next day in the back garden dead under a tree.the last person in contact with her was a skavel boy who is a bad person and may have a reason to kill her and they have been brought up on death when their mother died.

what the csi done to help

they examined a crime scene and discovered a shattered 6-iron, the one that was used in the murder, they used fingerprinting to see if there was any fingerprints. one partial print was found and it belonged to... the skavel brother who was her boyfriend.

they brought the brother into questioning and he was cleared of murder as the 6-iron was supposedly stolen a few days before the murder

NO MORE EVIDENCE WAS FOUND

BUT

many years later... well january 2007 michael skavel, the brother who went out with martha moxley, was charged guilty due to contradictions in his timeline and the murder weapon with his fingerprints.

this is my case study for science

microscopes

Microscopes – Help Scientists Explore Hidden Worlds

The microscope is an invaluable tool in today's research and education. It is used in a wide range of scientific fields, where major discoveries in biology, medicine and materials research are based on advances in microscopy.

From the simple light microscope different techniques have evolved, aimed at making it possible to see certain objects or processes. Scientists use electron microscopes in order to get extraordinary resolution, microscopes that give three-dimensional images of surfaces or biological molecules, and microscopes that mark out specific substances.

From Thrilling Toy to Important Tool

the microscope has unveiled the secrets of nature. The human eye has a resolution in the order of 100 um (10-4 m), which is about the thickness of a hair. With the microscope, whole worlds become available, filled with knowledge that can serve as inspiration to our fantasy. The exploration of microcosmos has led to numerous discoveries, without which we would be left with the limited knowledge our eyes give us.

The development of the conventional microscope at the end of the 16th century would lead to a great step forward for science, particularly in biology and medicine. In the beginning though, the microscope was mainly a toy in rich homes. But many important discoveries followed. The first scientific results based on microscopy dealt with the circulating blood system and changed our view of the human body. Scientists have also discovered and explored life's own building block – the cell. Different types of bacteria and the following struggle against diseases, as well as studies of different materials and their qualities are other valuable results.

Through ingenious inventions, the limit of what scientists could reveal from the hidden expanded continuously during the seventeenth and eighteenth centuries. Finally, at the end of the nineteenth century physical limits in the form of the wavelength of light stopped the quest to see further into the microcosmos. With the theories of quantum physics, new possibilities appeared – the electron with its extremely short wavelength could be used as "light-source" in microscopes with unprecedented resolution. The first prototype of the electron microscope was constructed around 1930. In the following decades, smaller and smaller things could be studied. Viruses were identified and with magnifications up to one million, even atoms finally became visible.

Since photography has developed hand in hand with different techniques of microscopy, the public has been able to follow close in the footsteps of scientists. Pictures of cell division, nerves that make up the brain and single atoms have changed our view of the human body and nature itself. Even today our ability to lurk into nature increases further, owing to new techniques of microscopy for studying delicate processes within the cell or the building of materials atom by atom with nanotechnology.

Time Line
14th century – The art of grinding lenses is developed in Italy and spectacles are made to improve eyesight.

1590 – Dutch lens grinders Hans and Zacharias Janssen make the first microscope by placing two lenses in a tube.

1667 – Robert Hooke studies various object with his microscope and publishes his results in Micrographia. Among his work were a description of cork and its ability to float in water.

1675 – Anton van Leeuwenhoek uses a simple microscope with only one lens to look at blood, insects and many other objects. He was first to describe cells and bacteria, seen through his very small microscopes with, for his time, extremely good lenses.

18th century – Several technical innovations make microscopes better and easier to handle, which leads to microscopy becoming more and more popular among scientists. An important discovery is that lenses combining two types of glass could reduce the chromatic effect, with its disturbing halos resulting from differences in refraction of light.

1830 – Joseph Jackson Lister reduces the problem with spherical aberration by showing that several weak lenses used together at certain distances gave good magnification without blurring the image.

1878 – Ernst Abbe formulates a mathematical theory correlating resolution to the wavelength of light. Abbes formula make calculations of maximum resolution in microscopes possible.

1903 – Richard Zsigmondy develops the ultramicroscope and is able to study objects below the wavelength of light.

1932 – Frits Zernike invents the phase-contrast microscope that allows the study of colorless and transparent biological materials.

1938 – Ernst Ruska develops the electron microscope. The ability to use electrons in microscopy greatly improves the resolution and greatly expands the borders of exploration.

1981 – Gerd Binnig and Heinrich Rohrer invent the scanning tunneling microscope that gives three-dimensional images of objects down to the atomic level.

this is my study on microscopes

Cromatography

this is what a chromatography experiment will come out like

Hello, everyone, and welcome to the wonderful world of chromatography! What is chromatography, you ask?? Well, quite simply, it is a broad range of physical methods used to separate and or to analyze complex mixtures. The components to be separated are distributed between two phases: a stationary phase bed and a mobile phase which percolates through the stationary bed.

A mixture of various components enters a chromatography process, and the different components are flushed through the system at different rates. These differential rates of migration as the mixture moves over adsorptive materials provide separation. Repeated sorption/desorption acts that take place during the movement of the sample over the stationary bed determine the rates. The smaller the affinity a molecule has for the stationary phase, the shorter the time spent in a column.

In any chemical or bioprocessing industry, the need to separate and purify a product from a complex mixture is a necessary and important step in the production line. Today, there exists a wide market of methods in which industries can accomplish these goals. Chromatography is a very special separation process for a multitude of reasons! First of all, it can separate complex mixtures with great precision. Even very similar components, such as proteins that may only vary by a single amino acid, can be separated with chromatography. In fact, chromatography can purify basically any soluble or volatile substance if the right adsorbent material, carrier fluid, and operating conditions are employed. Second, chromatography can be used to separate delicate products since the conditions under which it is performed are not typically severe. For these reasons, chromatography is quite well suited to a variety of uses in the field of biotechnology, such as separating mixtures of proteins.

Gas Chromatography

Gas chromatography makes use of a pressurized gas cylinder and a carrier gas, such as helium, to carry the solute through the column. The most common detectors used in this type of chromatography are thermal conductivity and flame ionization detectors. There are three types of gas chromatography that will be discussed here: gas adsorption, gas-liquid and capillary gas chromatography.
Gas adsorption chromatography involves a packed bed comprised of an adsorbent used as the stationary phase. Common adsorbents are zeolite, silica gel and activated alumina. This method is commonly used to separate mixtures of gases.
Gas-liquid chromatography is a more common type of analytical gas chromatography. In this type of column, an inert porous solid is coated with a viscous liquid which acts as the stationary phase. Diatomaceous earth is the most common solid used. Solutes in the feed stream dissolve into the liquid phase and eventually vaporize. The separation is thus based on relative volatilities.
Capillary gas chromatography is the most common analytical method. Glass or fused silica comprise the capillary walls which are coated with an absorbent or other solvent. Because of the small amount of stationary phase, the column can contain only a limited capacity. However, this method also yields rapid separation of mixtures.

Liquid Chromatography

There are a variety of types of liquid chromatography. There is liquid adsorption chromatography in which an adsorbent is used. This method is used in large-scale applications since adsorbents are relatively inexpensive. There is also liquid- liquid chromatography which is analogous to gas-liquid chromatography. The three types that will be considered here fall under the category of modern liquid chromatography. They are reverse phase, high performance and size exclusion liquid chromatography, along with supercritical fluid chromatography.
Reverse phase chromatography is a powerful analytical tool and involves a hydrophobic, low polarity stationary phase which is chemically bonded to an inert solid such as silica. The separation is essentially an extraction operation and is useful for separating non-volatile components.
High performance liquid chromatography (HPLC) is similar to reverse phase, only in this method, the process is conducted at a high velocity and pressure drop. The column is shorter and has a small diameter, but it is equivalent to possessing a large number of equilibrium stages.
Size exclusion chromatography, also known as gel permeation or filtration chromatography does not involve any adsorption and is extremely fast. The packing is a porous gel, and is capable of separating large molecules from smaller ones. The larger molecules elute first since they cannot penetrate the pores. This method is common in protein separation and purification.
Supercritical fluid chromatography is a relatively new analytical tool. In this method, the carrier is a supercritical fluid, such as carbon dioxide mixed with a modifier. Compared to liquids, supercritical fluids have solubilities and densities have as large, and they have diffusivities and viscosities quite a bit larger. This type of chromatography has not yet been implemented on a large scale.

Ion Exchange Chromatography

Ion exchange chromatography is commonly used in the purification of biological materials. There are two types of exchange: cation exchange in which the stationary phase carries a negative charge, and anion exchange in which the stationary phase carries a positive charge. Charged molecules in the liquid phase pass through the column until a binding site in the stationary phase appears. The molecule will not elute from the column until a solution of varying pH or ionic strength is passed through it. Separation by this method is highly selective. Since the resins are fairly inexpensive and high capacities can be used, this method of separation is applied early in the overall process.

Affinity Chromatography

Affinity chromatography involves the use of packing which has been chemically modified by attaching a compound with a specific affinity for the desired molecules, primarily biological compounds. The packing material used, called the affinity matrix, must be inert and easily modified. Agarose is the most common substance used, in spite of its cost. The ligands, or "affinity tails", that are inserted into the matrix can be genetically engineered to possess a specific affinity. In a process similar to ion exchange chromatography, the desired molecules adsorb to the ligands on the matrix until a solution of high salt concentration is passed through the column. This causes desorption of the molecules from the ligands, and they elute from the column. Fouling of the matrix can occur when a large number of impurities are present, therefore, this type of chromatography is usually implemented late in the process.

there is a much more complicated way of Affinity Chromatography and this is it, get your thinking hat on again!!!

An intriguing chromatographic technique based on the natural specificity of some biopolymers is affinity chromatography.
There are a number of proteins and other biological macromolecules that complex with some other biological entity with a high degree of specificity. This fact is made use of in product recovery operations via the use of affinity chromatography.
Suppose a certain biomolecule (a) is attached to a solid used to pack a chromatographic column. Now consider a molecule (b) in solution, which has a specific affinity for (a). It is but natural that (b) will want to get out of solution and bind to (a), right? It's this attraction of (b) for (a) which is defined as the partition coefficient 'K'. Now since 'K' for (b) is going to be much higher than that of any other proteins in solution, it will bind to the column while the rest of the complex solution will merely pass through the column with insignificant amounts of non-specific binding occuring.
What are some examples of molecules which may be used for this technique?
ENZYME + INHIBITOR <=> ENZYME-INHIBITOR COMPLEX
ANTIBODY + ANTIGEN ---> ANTIBODY-ANTIGEN PRECIPITATE
LECTIN + CELL WALL -----> LECTIN-CELL-WALL COMPLEX

hang on theres more

With the advent of Monoclonal Antibody production, which allows the synthesis of a single type of antibody with a very high specific binding constant to its corresponding antigen (a particular protein or other molecule), the preparation of affinity columns has become not only routine, but commercial. With such 'immunosorbent' column seperation, some important practical and theoretical differences arise compared to more conventional forms of chromatographic resolution. They are as follows:
1. The dominant cost in the process is the antibody needed to make the immunosorbent column. Generally speaking, this is much more costly than the antigen-containing broth itself. As a result,
2. A small column of repeated, high capacity use is required.
3. Elution of the adsorbed product requires breaking the antigen-antibody complex. Now this means that denaturing conditions must be employed. Since the antibodies themselves are proteins too, loss of some antibody binding affinity typically occurs, resulting in gradual loss of column capacity.
4. A first cycle on a new column gives poorer recovery than successive operations, apparently due to some irreversible binding.
5. A major economic goal in designing any affinity chromatography setup is determination of optimal elution buffer wash volumes and concentrations.

and more...

Now let us look at a specific example where affinity chromatography is used, namely, in the purification of human leukocyte interferon made in E. coli.
Proteins synthesized in genetically engineered organisms and intended for injection into animals must be stringently purified. Pyrogens from E. coli, including the outer envelope lipopolysaccharide (LPS) must be removed or inactivated. Hence product recovery operations such as affinity chromatography are an important step in the manufacturing process.
Given below is a schematic representation of the typical steps involved in processing human leukocyte interferon produced by recombinant DNA techniques. This will give you an idea of where exactly affinity chromatography is usually involved in the realm of bioprocessing.
HUMAN LEUKOCYTE INTERFERON

E. coli EXTRACTION BY MECHANICAL BREAKAGE

POLYETHELYNEIMINE PRECIPITATION

AMMONIUM SULFATE PRECIPITATION OF SUPERNATENT

DIALYSIS OF PELLET

* IMMUNOADSORBENT COLUMN (MONOCLONAL ANTIBODIES)

CATION EXCHANGE CELLULOSE CHROMATOGRAPHY

SO, Thank you everybody, for reading so patiently to what I had to say about affinity chromatography....

I hope you enjoyed the show...

THIS IS MY BLOG ON CHROMATOGRAPHY

your headache is back

dna fingerprinting

a picture of DNA fingerprinting

DNA. It's what makes you unique. It's the stuff that tells each and every one of your body's 10 trillion cells what it's supposed to be and what it's supposed to do. And although your DNA is different from that of every other person in the world—unless you have an identical twin—it's the same in every cell that makes up your body. That DNA is unique from person to person but the same from cell to cell in one person can be a handy thing, especially when it comes to DNA fingerprinting. DNA fingerprints can be used for anything from determining a biological mother or father to identifying the suspect of a crime. And, as may someday prove to be the case with Sam Sheppard, it can be used to clear someone's name. But what exactly is a DNA fingerprint? Well, it certainly isn't an inky impression of a DNA strand. Compared to unimaginably small DNA, a fingerprint is HUGE. So what is it that we're looking at, and how is one of these fingerprints made?

DNA fingerprinting is a term that has been bandied about in the popular media for about fifteen years, largely due to its power to condemn and save, but what does it involve? In short, it is a technique for determining the likelihood that genetic material came from a particular individual or group. 99% of human DNA is identical between individuals, but the 1% that differs enables scientists to distinguish identity.

The DNA alphabet is made up of four building blocks – A, C, T and G, called base pairs, which are linked together in long chains to spell out the genetic words, or genes, which tell our cells what to do. The order in which these 4 DNA letters are used determines the meaning (function) of the words, or genes, that they spell.

But not all of our DNA contains useful information; in fact a large amount is said to be “non-coding” or “junk” DNA which is not translated into useful proteins. Changes often crop up within these regions of junk DNA because they make no contribution to the health or survival of the organism. But compare the situation if a change occurs within an essential gene, preventing it from working properly; the organism will be strongly disadvantaged and probably not survive, effectively removing that altered gene from the population.

For this reason, random variations crop up in the non-coding (junk) DNA sequences as often as once in every 200 DNA letters. DNA fingerprinting takes advantage of these changes and creates a visible pattern of the differences to assess similarity.

Stretches of DNA can be separated from each other by cutting them up at these points of differences or by amplifying the highly variable pieces. ‘Bands’ of DNA are generated; the number of bands and their sizes give a unique profile of the DNA from whence it derived. The more genetic similarity between a person, the more similar the banding patterns will be, and the higher the probability that they are identical.

THIS IS MY BLOG ON DNA FINGERPRINTING

week 2 BLOOD TYPES

BLOOD types blood types are usually passed down though parents

here is a table showing diffrent blood types and how they are recognised

here is a load of info on blood types so you better be ready to get confused or get a headache. to make it easier ive made it as simple as possible or your head will probably explode

get your concentration hats on..... NOW

If you have blood group A then you've got A antigens covering your red cells.

Blood group B means you have B antigens,

while group O has neither,

and group AB has some of both.

The ABO system also contains lots of little antibodies in the plasma, antibodies being the body's

natural defence against foreign antigens.

So blood group A has anti-B in their plasma,

blood group B has anti-A (you probably get the picture at this stage).

To complicate matters though, group AB has none and group O has both of the antibodies.

Which means giving someone blood from the wrong ABO group could be fatal.

The anti-A antibodies in group B attack group A cells and vice versa.

Which is why group A blood must never be given to a group B person. Group O negative is a different story.

the Rh antigen changes everything.

Some of us have it, some of us don't.

If it is present, the blood is RhD positive, if not it's RhD negative.

So, for example, some people in group A will have it, and will therefore be classed as A+ (or A positive).

While the ones that don't, are A- (or, wait for it...A negative).

And so it goes for groups B, AB and O.

This effectively doubles the number of different blood types to be matched, because you shouldn't mix blood type A+ with blood type A-.

84% of the population is Rh positive. (And yes, that means the other 16% of the population is running around with Rh negative blood.)

this is my blog on blood,

hope your head gets better soon

Week 1 FINGERPRINTS

Fingerprints are used to identify us,

we all have unique prints,

none are ever the same,

not even twins.

there are different types of prints like:

Loop

whorl

ark

CSI usually use a powder substance to trace fingerprints at a crime scene

or

they may use a laser scanner like this picture at the top

or

they may use a spray which reveals fingerprints on difficult surfaces(paper etc.)

But sometimes,

when they match fingerprints to a suspect,

they get it wrong like they did with Shirley mckie

here is what happened:

Shirley McKie
Error in identification. Shirley McKie was a police detective in 1997 when she was accused of leaving her thumb print inside a house in Kilmarnock, Scotland where Marion Ross had been murdered. Although detective constable McKie denied having been inside the house, she was arrested in a dawn raid the following year and charged with perjury. The only evidence was the thumb print allegedly found at the murder scene. Two American experts testified on her behalf at her trial in May 1999 and she was found not guilty. The Scottish Criminal Record Office (SCRO) would not admit any error, but Scottish first minister Jack McConnell later said there had been an "honest mistake".
On February 7, 2006, McKie was awarded £750,000 in compensation from the Scottish Executive and the SCRO.[ Controversy continues to surround the McKie case with calls for the resignations of Scottish ministers and for either a public or a judicial inquiry into the matter.]

this is my study on fingerprints

what i am going to do

Over the next few weeks I am going to be doing the following:

week 1 fingerprints

week 2 blood types

week 3 DNA fingerprinting

week 4 chromatography

week 5 microscopes

week 6&7 case study (looking at a particular crime and how it was solved)

hi everyone

Hello, I'm Charlotte W

I'm in 8bh2 for science and this is my homework project about ... C.S.I crime scene investigators and their methods of finding diffrent evidence.

I will put up a timetable of what I will be doing on this blog on in a few days and keeping you updated on my work.