NOTE: Free essay sample provided on this page should be used for references or sample purposes only. The sample essay is available to anyone, so any direct quoting without mentioning the source will be considered plagiarism by schools, colleges and universities that use plagiarism detection software. To get a completely brand-new, plagiarism-free essay, please use our essay writing service.
One click instant price quote
INTRODUCTION: The magnetic south and north poles of the earth create magnetic field lines in which these bacteria travel. These bacteria were found to contain iron, which is comparable to ferromagnet's or magnetite produced synthetically. This iron is found to line up to the magnetic field lines similar to how a compass works. Many of the principles of magnetism can be explained by observing these bacteria. NARRATIVE: The physical principles behind magnetic bacteria rely on the earths magnetic field. The ability for organisms to follow the earths magnetic field lines has only recently been discovered in some species of birds, bees, dolphins, and bacteria.
These organisms were found to contain ferromagnetic containing organelles called magneto somes. Since the discovery of the lodestone, the historical ferromagnetic iron needle compass has lead explorers around the globe. Magnetic fields have played a major role in the discovery of the world and current mapping technologies. The magnetotaxic bacteria were found to contain an organelle chain in their cytoplasm which are called magneto somes. These magneto somes have been examined with X-ray emission to contain the ferromagnetic iron. This iron is kept in a constant orientation to the cytoplasm and the cell wall of the bacteria.
Biologists have determined that their is a evolutionary standpoint for this magnetism. One reason for this could be that the majority of bacteria are anaerobic. That is they do not require oxygen to survive, and oxygen can sometimes be toxic to these bacteria. Also a dip angle is incorporated.
The bacteria work exactly like a compass. The needle of a compass is suspended for free rotation around the axis. The needle is angled so that one end of the needle points lower that the other. This feature compensates for the angle between the earths magnetic field lines and the earths surface. This angle is called the dip angle. The dip angle would help to move the bacteria down deeper into swamps and marshes and away from the oxygen.
This brings up an important point about dip angles on the equator. The dip angle on the equator is 0 degrees, and thus the bacteria would not move in a north or south pole seeking direction. In actuality magnetic bacteria collected at the equator move in a 50 % north and 50 % south direction. Different studies have been done where these bacteria were collected in the geographical northern and southern hemispheres. Bacteria were collected in Massachusetts and also in Tasmania and New Zealand, both the same distance from the equator. They found that the bacteria in both regions migrated against magnetic field lines to deeper anaerobic conditions.
Natural selection allows the deeper anaerobic bacteria to survive and reproduce, while the weaker magnetic bacteria die in the presence of high levels of oxygen contained within the earths atmosphere. The earths polarity has been found to reverse periodically and this proves advantageous to magnetic bacteria. These bacteria can still migrate downwards and can change direction in response to changing magnetic field polarity and strength. Ferromagnetic material has a net magnetic effect per atom. Each atom aligns itself into a domain. The individual atoms have a net magnetic field, but these fields cancel each other out when put together.
These domains attribute to the actual orientation of the material in earths magnetic field. When the un magnetized ferromagnet is placed in a magnetic field such as the earths, the domains grows in a parallel direction to the external field. When this occurs the object is said to exhibit ferromagnetism or a strong magnetic force. The direction of the earths magnetic field is defined as the direction that a north seeking magnetic pole of the compass points towards the corresponding south pole near earths geographic north. A compass is simply a small permanent magnet designed so that it can rotate to whatever direction it naturally seeks. In particular, a compass needle will align itself with the local magnetic field direction in such a way that the north pole of a compass needle points in the south magnetic earth field direction.
The earth also acts like a permanent bar magnet having north and south magnetic poles with field lines travelin from north to south magnetic poles or south to north geographic lines. So when the north pole of a compass magnet points along the local field line of earths magnetic field it is actually pointing towards a magnetic south pole. Thus what we call the northern direction is actually in the direction of a magnetic south pole. The bacteria have a magnetic dipole contained within them.
Experiments were done with external magnets on the bacteria. It was noted that when a south pole of a magnet was brought near the bacteria, they moved towards it. Consequently when the north pole of a magnet was brought near a bacteria they moved away. The earths magnetic field strength is 10 - 4 Tesla. Experiments were done by producing a magnetic field with strength similar to earth with what are called Helmholtz coils. There are two coils separated by a uniform distance, which is related to the radius of one of the coils.
They also are arranged so that they produced a uniform magnetic field between the coils. These coil experiments found that if the magnetic field produced by the coils was greater that the earths magnetic field, the bacteria moved in the direction of the coils magnetic field. The organisms were able to turn completely around in 180 degrees to follow the external magnetic field. The strength of this field is controlled by varying the current traveling through the coils. An increase in the current would produce an increase in the magnetic field strength.
B = uo I / 2 r. The direction of the magnetic field produced can be predicted with the right hand rule. The right hand rule is related to the bacteria in that a 90 degree angle produces the greatest force for the magnetic field direction. The magnitude of the magnetic field (B) can be defined also as the torque exerted on a compass needle when it makes a certain dip angle.
That is the greater the torque, the greater the magnetic field strength. Torque is defined as t = rain . The torque produced on the compass needle or the bacteria help to orient these objects in the earths magnetic field. When the bacteria or compass needle are parallel to the magnetic field, the net torque will be 0. But as the bacteria or needle approaches 90 degrees, the torque becomes greater along with the magnetic field. Torque and magnetic field strength are positively correlated.
Tampering with the bacteria also changes the effects of magnetic field lines. If the bacteria is hit, consumed, or heated it may loose its magnetic effect. At a temperature known as the curie temperature the earths magnetic field lines loose effectiveness in controlling bacteria. It is not possible to magnetize an object at this temperature and any object that was magnetized loses its effectiveness on other objects. At this curie temperature the magnet becomes weaker, turning from a ferromagnetic bacteria (strong magnet), to a paramagnetic bacteria (weaker magnet). When the curie temperature is above room temperature, ferromagnetic materials are permanently magnetized.
Paramagnetic bacteria will only be attracted to a strong magnetic field, because they are a weak magnet. But due to the weakness of the magnetic fields of the earth (10 - 4 Tesla) the bacteria are not really attracted that well. CONCLUSION: The puzzle of magnetic bacteria illustrates not only the scientific method but also the important idea that modern science is multidisciplinary (Such as biology, chemistry, and physics). Life seems to evolve itself to survive in new habitats. It has also recently been discovered that early bacterial life may have existed on Mars. In conjunction with magnetic bacteria, magneto somes containing magnetite or iron particles have been discovered in the fossil remnants of these ancient bacteria.
This supports evidence that these bacteria were anaerobic due to low oxygen levels on Mars compared to Earth. Also the magnetic field strength constants on Mars may be different producing different movements of these bacteria due to the polarity of the planet. The study of magnetic bacteria is beneficial for our understanding of life on other planets and the universe as a whole.
Free research essays on topics related to: north pole, south pole, earths magnetic, magnetic field, magnetic
Research essay sample on Earths Magnetic Magnetic Field
