Civil Rights
Movements, leaders, victories and the continuing fight for equality.
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Explore the people, places, events, achievements, struggles and stories that shaped our journey.
Movements, leaders, victories and the continuing fight for equality.
Innovation, patents, science, technology and world-changing contributions.
Pioneers, champions, Negro Leagues, records, activism and excellence.
Meet the people whose lives, choices and achievements shaped the journey.
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Mansa Musa was the ruler of the Mali Empire in West Africa. Details recorded here should be sourced; unknown information is left blank.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
Intracellular bacteria are bacteria that have the capability to enter and survive within the cells of the host organism.[1] These bacteria include many different pathogens that live in the cytoplasm and nuclei of the host cell's they inhabit. Mycobacterium tuberculosis is an example of an intracellular bacterial species.[2] There are two types of intracellular bacteria: facultative intracellular bacteria, which can grow extracellularly or intracellularly, and obligate intracellular bacteria, which can grow only intracellularly.[3]
Examples of facultative intracellular bacteria include members of the genera Brucella, Legionella, Listeria, and Mycobacterium. These bacteria invade the human body and replicate inside the cells, evading the immune system and causing disease by disrupting the human's cells normal function. Diseases caused by facultative intracellular bacteria include Listeriosis (Listeria monocytogenes), Typhoid Fever (Salmonella typhi), Legionnaires' disease (Legionella pneumophila), and Salmonellosis (Salmonella enterica) to name a few.[3] While they can invade the human body, they are also capable of living extracellularly. These bacteria can replicate within the environment, sustain their metabolic state, and survive harsh conditions by using mechanisms such as a bacterium-containing vacuole, lysosome resistance, and entering a survival state called persistence.[4]
Examples of obligate intracellular bacteria include members of the orders Rickettsiales and Chlamydiales and members of the genus Mycoplasma.[1] These bacteria need the human host to be able to reproduce and when they have invaded the body, they cause disease. Unlike facultative intracellular bacteria that can grow within or outside of a host's body, obligate bacteria cannot survive without host cells. These bacteria cannot reproduce outside of the host cell because they lack the metabolic processes and enzymes needed to reproduce, which the host cell gives them.[3] Diseases caused by obligate intracellular bacteria include chlamydia (Chlamydia trachomatis) and Rocky Mountain Spotted Fever (Rickettsia rickettsii).[3]
Hosts usually come into contact with the bacteria through the skin, but there are chances of contracting the bacteria from a bite, such as that of ticks, mites, and/or mosquitoes (Rickettsia rickettsii).[5] Listeria monocytogenes is found in soil, water, and also decaying animals and plants. It is generally transmitted through food being processed or handled in areas contaminated with L. monocytogenes.[6] Legionella pneumoniae are found in aquatic conditions, such as artificial water systems, like that of hot tubs and showers.[7] Salmonella typhi and Salmonella enterica are both transmitted orally through feces or through food and/or water that has the bacteria.[8] Chlamydia trachomatis is spread by having unprotected sex.[9] Mycobacterium tuberculosis is spread through the air when being near anyone with tuberculosis.[10]
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Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
Intracellular pH (pHi) is the measure of the acidity or basicity (i.e., pH) of intracellular fluid. The pHi plays a critical role in membrane transport and other intracellular processes. In an environment with the improper pHi, biological cells may have compromised function. Therefore, pHi is closely regulated in order to ensure proper cellular function, controlled cell growth, and normal cellular processes. The mechanisms that regulate pHi are usually considered to be plasma membrane transporters of which two main types exist — those that are dependent and those that are independent of the concentration of bicarbonate (HCO−3). Physiologically normal intracellular pH is most commonly between 7.0 and 7.4, though there is variability between tissues (e.g., mammalian skeletal muscle tends to have a pHi of 6.8–7.1). There is also pH variation across different organelles, which can span from around 4.5 to 8.0. pHi can be measured in a number of different ways.
Every organism requires energy to be active. However, to obtain energy from its outside environment, cells must not only retrieve molecules from their surroundings but also break them down. This process is known as intracellular digestion. In its broadest sense, intracellular digestion is the breakdown of substances within the cytoplasm of a cell. In detail, a phagocyte's duty is obtaining food particles and digesting it in a vacuole. For example, following phagocytosis, the ingested particle (or phagosome) fuses with a lysosome containing hydrolytic enzymes to form a phagolysosome; the pathogens or food particles within the phagosome are then digested by the lysosome's enzymes. Intracellular digestion can also refer to the process in which animals that lack a digestive tract bring food items into the cell for the purposes of digestion for nutritional needs. This kind of intracellular digestion occurs in many unicellular protozoans, in Pycnogonida, in some molluscs, Cnidaria and Porifera. There is another type of digestion, called extracellular digestion. In amphioxus, digestion is both extracellular and intracellular.
Intracellular transport is the movement of vesicles and substances within a cell. Intracellular transport is required for maintaining homeostasis within the cell by responding to physiological signals. Proteins synthesized in the cytosol are distributed to their respective organelles, according to their specific amino acid's sorting sequence. Eukaryotic cells transport packets of components to particular intracellular locations by attaching them to molecular motors that haul them along microtubules and actin filaments. Since intracellular transport heavily relies on microtubules for movement, the components of the cytoskeleton play a vital role in trafficking vesicles between organelles and the plasma membrane by providing mechanical support. Through this pathway, it is possible to facilitate the movement of essential molecules such as membrane‐bounded vesicles and organelles, mRNA, and chromosomes. Intracellular transport is unique to eukaryotic cells because they possess organelles enclosed in membranes that need to be mediated for exchange of cargo to take place. Conversely, in prokaryotic cells, there is no need for this specialized transport mechanism because there are no membranous organelles and compartments to traffic between. Prokaryotes are able to subsist by allowing materials to enter the cell via simple diffusion. Intracellular transport is more specialized than diffusion; it is a multifaceted process which utilizes transport vesicles. Transport vesicles are small structures within the cell consisting of a fluid enclosed by a lipid bilayer that hold cargo. These vesicles will typically execute cargo loading and vesicle budding, vesicle transport, the binding of the vesicle to a target membrane and the fusion of the vesicle membranes to target membrane. To ensure that these vesicles embark in the right direction and to further organize the cell, special motor proteins attach to cargo-filled vesicles and carry them along the cytoskeleton. For example, they have to ensure that lysosomal enzymes are transferred specifically to the golgi apparatus and not to another part of the cell which could lead to deleterious effects.
Intracellular bacteria are bacteria that have the capability to enter and survive within the cells of the host organism. These bacteria include many different pathogens that live in the cytoplasm and nuclei of the host cell's they inhabit. Mycobacterium tuberculosis is an example of an intracellular bacterial species. There are two types of intracellular bacteria: facultative intracellular bacteria, which can grow extracellularly or intracellularly, and obligate intracellular bacteria, which can grow only intracellularly.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Brown v. Board of Education in 1954.
