Microtubules

Microtubules
__Discovery of Microtubules__

===They named the newly discovered organelle, neurotubule, because they were first observed within neurons. The fixation used during that time did not preserve cells long enough to study them completely, and so microtubules were never observed in any other cells but neurons. Later, in 1963, the scientists Banch, Sabatini, and Barnette further investigated the early findings and used glutaraldehyde as a fixation to preserve the cell. Only then were they able to break down and explain the actual structure of a microtubule. Based on their findings they named these complex organelles, microtubules, meaning small tubes. ===
 *  Microtubules were first discovered in 1953 by the two scientists De Robertis and Franchi. **

**__Where are they found?__**

=All eukaryotic cells contain microtubules in order to assist them with motility, support, and transporting nutrients within the cell. Microtubules are most commonly found in the cytoskeleton of a cell. The cytoskeleton is a network of protein fibers that provides a cell with structural support, motility, and movement of organelles within the cell. It is made up of three protein filaments: microtubules, microfilaments, and intermediate filaments. Though microtubules are able to work alone, they can also adhere to proteins creating more complex structures called, flagella, cilia, or centrioles. Prokaryotes do not contain microtubules because they have a completely different structure to their flagella and do not require the microfilaments for support. =


 * __Structure of Microtubules__ **


 * Microtubules are the largest cytoskeletal filaments in a cell, with a diameter of 25 nanometers. They **
 * are hollow tubes assembled from protein subunits called tubulin. There are two types of tubulin, alpha, and beta. These tubulins join to create dimers, which then connect to form long chains called polymers. Next, polymers are stacked to create sheets which are then rolled up into a microtubule. Microtubules are dynamic, meaning subunits can be removed making them smaller, or they can be added, making the microtubule longer. Alpha and Beta tubulins are dissolved and scattered throughout the cytoplasm. When a microtubule is assembled or disassembled , tubulins form the surrounding cytoplasm are readily available  for use. Sub units are units assembled into microtubules by microtubule <span style="font-family: &#39;Bree Serif&#39;; font-size: 12pt;"> organizing <span style="font-family: &#39;Bree Serif&#39;; font-size: 16px;">caters <span style="font-family: &#39;Bree Serif&#39;; font-size: 12pt;"> found in <span style="font-family: &#39;Bree Serif&#39;; font-size: 16px;">various <span style="font-family: &#39;Bree Serif&#39;; font-size: 12pt;"> locations within the cell. All eukaryotic cells have a microtubule organizing <span style="font-family: &#39;Bree Serif&#39;; font-size: 16px;">center <span style="font-family: &#39;Bree Serif&#39;; font-size: 12pt;"> near the nucleus called the centrosome. **


 * <span style="color: #4a86e8; font-family: &#39;Bree Serif&#39;; font-size: 32px;">__Function__ ****<span style="color: #4a86e8; font-family: &#39;Bree Serif&#39;; font-size: 32px;">__of Microt__ ****<span style="color: #4a86e8; font-family: &#39;Bree Serif&#39;; font-size: 32px;">__ubules__ **


 * <span style="font-family: &#39;Crete Round&#39;; font-size: 14pt; vertical-align: baseline;">Microtubules may work alone or join other proteins to form complex organelles such as cilia, flagella, or centrioles. In animal cells, during the metaphase part of cell division, centrioles send out microtubules to cling to the chromosomes. When this happens it is called a mitotic spindle. As the ****<span style="font-family: &#39;Crete Round&#39;; font-size: 14pt; vertical-align: baseline;">microtubules become shorter, the chromosomes split and each go their separate ways, creating two new daughter cells. **




 * <span style="font-family: &#39;Crete Round&#39;; font-size: 14pt; vertical-align: baseline;">In cells that have cilia and flagella, when the centrioles multiply, they move to the edge of the cell membrane and anchor themselves creating basal body's. Next, ten pairs of microtubules grow out of each basal body, one from the center, and nine from the rims of the basal bodies. There is always a gap left between each of the outer microtubule pairs in order to make space for the embedded motor proteins. Each motor protein is attached to a pair of microtubules and uses their legs to walk along the adjacent microtubules. The force applied by the motor proteins causes the microtubules to bend, creating the synchronized movements of the cilia and flagella. This movement helps the cell move from one location to the other. **

==
 * <span style="color: #4a86e8; font-family: &#39;Bree Serif&#39;; font-size: 32px;">__What are Neurotubules?__ **


 * <span style="background-color: #ffffff; color: #2d3639; font-family: &#39;Times New Roman&#39;; font-size: 14pt; vertical-align: baseline;">Neurotubules are microtubules that are found within a neuron. A neuron is a nerve cell **<span style="background-color: #ffffff; color: #222222; font-family: "Times New Roman"; vertical-align: baseline;"> **and the basic units of the nervous system. It is the most important part is the** **brain** **it carries electrical impulses.** <span style="background-color: #ffffff; color: #2d3639; font-family: "Times New Roman"; font-size: 14pt; vertical-align: baseline;">**Neurotubules transport numerous substances along the axon between the soma and the axon terminal of a neuron.**



=**<span style="color: #4a86e8; font-family: &#39;Bree Serif&#39;; font-size: 32px;">__Analo__ ****<span style="color: #4a86e8; font-family: &#39;Bree Serif&#39;; font-size: 32px;">__gy:__ **=

<span style="font-family: &#39;Times New Roman&#39;; font-size: 30pt; vertical-align: baseline;">Pixels : Image
<span style="color: #4a86e8; font-family: &#39;Times New Roman&#39;; font-size: 24pt; vertical-align: baseline;">Many pixels create an image

<span style="font-family: &#39;Times New Roman&#39;; font-size: 30pt; vertical-align: baseline;">Tubulin : Microtubules
I chose this analogy because many tubulin make up the microtubules, just like many pixels make up an image.


 * <span style="color: #4a86e8; font-family: &#39;Bree Serif&#39;; font-size: 32px;">__Words to Know:__ **


 * <span style="background-color: #ffffff; font-family: &#39;Times New Roman&#39;; font-size: 12pt; vertical-align: baseline;">Cilia- A <span style="background-color: #ffffff; color: #222222; font-family: &#39;Times New Roman&#39;; font-size: 12pt; vertical-align: baseline;">re microscopic, hair-like structures that extend outward from the surface of many animal cells. **
 * <span style="font-family: &#39;Times New Roman&#39;; font-size: 12pt; vertical-align: baseline;">Flagella- <span style="background-color: #ffffff; color: #222222; font-family: &#39;Times New Roman&#39;; font-size: 12pt; vertical-align: baseline;">In protists, a long, whiplike membrane-enclosed organelle used for locomotion or feeding. In bacteria, a long, whiplike proteinaceous appendage, used for locomotion. A whip. **
 * <span style="font-family: &#39;Times New Roman&#39;; font-size: 12pt; vertical-align: baseline;">Centriole- <span style="background-color: #ffffff; color: #222222; font-family: &#39;Times New Roman&#39;; font-size: 12pt; vertical-align: baseline;">a minute cylindrical organelle near the nucleus in animal cells, occurring in pairs and involved in the development of spindle fibers in cell division. **
 * <span style="font-family: &#39;Times New Roman&#39;; font-size: 12pt; vertical-align: baseline;">Fixation- <span style="background-color: #ffffff; color: #222222; font-family: &#39;Times New Roman&#39;; font-size: 12pt; vertical-align: baseline;">The process by which photosynthetic organisms such as plants turn inorganic carbon. **

===<span style="background-color: #ffffff; font-family: &#39;Times New Roman&#39;; font-size: 12pt; vertical-align: baseline;">glutaraldehyde <span style="font-family: &#39;Times New Roman&#39;; font-size: 12pt; vertical-align: baseline;">- <span style="background-color: #ffffff; color: #222222; font-family: &#39;Times New Roman&#39;; font-size: 12pt; vertical-align: baseline;">a compound C5H8O2 that contains two aldehyde groups and is used as a disinfectant and in fixing biological tissues. ===


 * <span style="color: #4a86e8; font-family: &#39;Bree Serif&#39;; font-size: 32px;">__Work Cited:__ **