Cell function

 

The cell is the constituent unit of living matter, can be an individual alone or participate with other similar elements in the formation of more complex organisms. The individuality of the cell is related to its structure and the miscibility with the environment of substances that compose it. Its structure consists of some elements that are distinct and constant at any time of cellular life, except in the reproductive period. For their functions and materials development cells take nutrients from the outside, the nutrients (and with them any ineffective or toxic) can cross the cell membrane by physicochemical phenomena or penetrate your pores.

Some cells can perform photosynthesis, converting light energy into chemical energy, these cells can be blue-green algae and cyanobacteria.

The description of cell division to understand it, is defined as cellular function that ensures the survival of the species through reproduction, through which a cell is capable of giving rise to two daughter cells or may , similar to it. Classically, have been classified to the forms of reproduction in the following varieties: the asexual (direct division, budding or budding, IVISION endogenous carioquinesis (mitosis, meiosis) and sexual (and heterogàmiva isogàmica).

As for the share of microbiology is possible to do justice to the extraordinary variety of life profusividad or protists, only a few representatives from each of the subgroups have been described very briefly. There is unfortunately a book that provides a more extensive view of the entire biological group. Understanding the comparative biology of eukaryotic protists is further hampered by terminological difficulties, because botanists and zoologists have completely different names applied to structures common to the three subgroups.

 

The cell performs three types of functions: nutrition, relationships and reproduction.

• Nutrition includes the incorporation of food into the cell, their transformation and assimilation of substances used to form the cell and its own field.
• According to their nutrition, cells are autotrophic and heterotrophic cells.
  
  
• Autotrophic cells produce their own organic matter from inorganic matter of the physical environment around it, using the chemical energy contained in inorganic matter.
• Heterotrophic cells produce their own organic matter from organic matter containing foods you eat.
• The relationship includes the development of appropriate responses to stimuli captured.
• Reproduction is the formation of new cells or daughter cells from an initial cell or stem cell.
• There are two processes of cellular reproduction: mitosis and meiosis.
• By mitosis, from a stem cell daughter cells originate with the same number of chromosomes and the same genetic information as the parent cell.
• By meiosis, from a stem cell form four daughter cells, all of which have half the number of chromosomes as the parent cell.

COMPONENTS OF THE CELL 

Cytoplasm is surrounded by a membrane. It is divided into organelles, organelles and inclusions. The cytoplasmic organelles include cell membrane (plasma), endoplasmic reticulum (ergastoplasm), Golgi apparatus, centrioles (or centrosome), mitochondria, annular lamellae, fibrils and filamentous structures, lysosomes and microtubules.

Core: Compound nuclear membrane, chromatin and nucleolus.

 

CELL MEMBRANE (PLASMA)

Is a highly selective filter which retains unequal concentrations of ions on both sides of it and allows nutrients to enter the cell and waste products come out of it.

Several models have been proposed for the plasma membrane. In all, the "fluid mosaic model" Singer and Nicholson is more in line with our current knowledge. This model assumes that the cell membrane consists of a bimolecular layer of phospholipids, which are interleaved units globular protein at varying intervals to form a mosaic with the lipid layer. It has been demonstrated that these proteins are members of the membrane hydrophobic and hydrophilic regions, and it is likely that the hydrophobic portions are included in the central layer of membrane lipids, with the hydrophilic regions exposed on the surface.

ENDOPLASMIC RETICULUM

It is divided into granular and smooth. The present granular endoplasmic reticulum on the walls of their cisterns ribosomes. There occurs protein synthesis. Ribosomes bind to RNA chains.

Smooth endoplasmic reticulum (AGRANULOSO)

In contrast to the rough endoplasmic reticulum, the smooth, as the name implies, no ribosomal granules. This organelle or vesicular tubular shaped and are more likely to appear as a wealth of interconnected pipes in shape and size variables such as accumulation of flattened cisterns, characteristic of rough endoplasmic reticulum. The membranes of smooth endoplasmic reticulum originate from the rough endoplasmic reticulum, and can bind directly or indirectly therewith, by means of small vesicles, with the Golgi apparatus. The smooth endoplasmic reticulum does not participate in protein synthesis.

RIBOSOMES

They are found in all cells except mature erythrocytes and can be attached to the rough endoplasmic reticulum and be part of it, or be free in the cytoplasm.

Whether they are free or bound, ribosomes are usually in clusters called polyribosomes or polysomes. These clusters represent groups of ribosomes attached by a chain of messenger RNA. It has been suggested that free ribosomes synthesize proteins that the cell uses for its own purposes, such as replication, whereas the membrane bound ribosomes synthesize proteins that are secreted by the cell and used elsewhere in the body.

 GOLGI APPARATUS

The apparatus or Golgi complex consists of stacks of flat bags located in the cytoplasm of many cells.

The participates in Golgi membrane flow, transport and concentration of materials secretion and release of the cell, in the synthesis of some secretory products, including glycoproteins and mucopolysaccharides, and the formation of primary lysosomes.

 Lysosomes

Are membrane-bound cytoplasmic structures that appear grainy during inactivity, but adopting the appearance of vesicles when activated. Is believed to originate in the Golgi apparatus, but in some cells or under certain conditions, may result from some portions of the endoplasmic reticulum

Because in digestion, their appearance depends on its functional state, resulting in a variety of aspects, or pleomorphism. Lysosomes are found in all cells except erythrocytes, but are particularly abundant in macrophages, neutrophilic leukocytes, liver cells and cells of the proximal tubule of the kidney.

In some long-lived cells (eg, neurons, heart muscle and liver cells) accumulate large amounts of residual bodies (lipofuscin) with age.

 MITOCHONDRIA

Characteristically, membrane-bound organelles are very flexible and free in the cytoplasm. Sometimes they are contractile and mobile. Are likely to swell in certain physiological states.Are very important in energy metabolism as the main source of adenosine triphosphate (ATP) and are the site of many metabolic reactions. In them lies the cytochrome for electron transfer capable of binding energy derived from oxidations of the Krebs cycle to yield ATP.

Mitochondria are the main source of energy for cells. Additionally, concentrated calcium and calcium half generally retained within the cytoplasm. 

 

mitochondrial cytopathies

Mitochondriopathies are many and various diseases with a common origin. All of which are caused by the alteration of some of the cells mitochondria. These organelles, or organelles, are inside, in the same way that the organs in the human body and have an important role in living organisms. Mitochondria are the "factory" of energy in cells and in charge of your breathing.

Because of the importance of exercising the functions, are involved in many diseases and biological processes such as aging. Thus, it is essential to know how they work and what implications in various pathologies. Neither mitochondria nor mitochondrial damage should be outside the knowledge of the general population, since the involvement of these diseases has been linked as well known as Alzheimer's and Parkinson's, or other minorities such as Huntington Korea.

Each body cell has hundreds of mtDNA molecules. Dividing the cell to form daughter cells, this altered DNA is distributed randomly. The result is the appearance of numerous and very different diseases, which may be caused by abnormalities in the mitochondria. Although each tissue characterized by different abilities to remove defective organelles, some are damaged for various reasons, such as oxidative stress and accumulation of calcium.

Microorganisms, bacteria and pathogens

Included within the pathogen microorganisms (bacteria, protozoa, fungi, viruses ...) that in certain environments, pose a risk to human health and, consequently, is necessary todisinfect. The great capacity of adaptation and survival of both microorganisms present, far superior to other forms of life, and particularly complex intervention against them.

Bacteria are unicellular microorganisms that live in the air, soil, water, animals and plants. They are usually responsible for the putrefaction and decomposition of organic matter and some cause diseases to humans, animals, plants and even other microorganisms.

Viruses are organisms very simple structure that can reproduce only within living cells specific (plants, animals and bacteria), using their metabolism.

Fungi are multicellular organisms that obtain nutrients from plants, food and animals in damp, warm environments. They have a great ability to withstand time, shielding forming capsules that allow them to survive in adverse conditions, waiting for the next year or more favorable terms.

Protozoa are unicellular organisms such as bacteria that thrive in moist environments. They live in all types of aqueous media, such as freshwater, salt water or internal fluids of higher organisms.

Disinfection can be regarded as the set of activities aimed at the destruction or reduction of microorganisms present in the environment, surfaces or objects using primarily chemical agents. It is therefore to reduce levels of microbial contamination to the limits considered acceptable from the standpoint of risk-based teóricosanitario representing in each case on the activity performed in-place concrete. Disinfection is a standard in schools, hospitals, locker rooms, services, transport vehicles and medical vehicles such as ambulances.

A virus is a small infectious agent that can only replicate inside the cells of another organism. The word is from the Latin ''virus'' referring to poison and other noxious substances, first used in English in 1392. ''Virulent'', from Latin ''virulentus'' (poisonous), dates to 1400. A meaning of "agent that causes infectious disease" is first recorded in 1728, The term ''virion'' is also used to refer to a single infective viral particle. The plural is "viruses".

Viruses are too small to be seen directly with a light microscope. Viruses infect all types of organisms, from animals and plants to bacteria and archaea. although there are millions of different types. Viruses are found in almost every ecosystem on Earth and these minute structures are the most abundant type of biological entity. The study of viruses is known as virology, a sub-specialty of microbiology.

Unlike prions and viroids, viruses consist of two or three parts: all viruses have genesmade from either DNA or RNA, long molecules that carry genetic information; all have a protein coat that protects these genes; and some have an envelope of fat that surrounds them when they are outside a cell. Viroids do not have a protein coat and prions contain no RNA or DNA. Viruses vary from simple helical and icosahedral shapes, to more complex structures. Most viruses are about one hundred times smaller than an average bacterium. The origins of viruses in the evolutionary history of life are unclear: some may have evolved from plasmids—pieces of DNA that can move between cells—while others may have evolved from bacteria. In evolution, viruses are an important means of horizontal gene transfer, which increases genetic diversity.

Viruses spread in many ways; plant viruses are often transmitted from plant to plant by insects that feed on sap, such as aphids, while animal viruses can be carried by blood-sucking insects. These disease-bearing organisms are known as vectors. Influenzaviruses are spread by coughing and sneezing. The norovirus and rotaviruses, common causes of viral gastroenteritis, are transmitted by the faecal-oral route and are passed from person to person by contact, entering the body in food or water. HIV is one of several viruses transmitted through sexual contact or by exposure to infected blood.

Viral infections in animals provoke an immune response that usually eliminates the infecting virus. These immune responses can also be produced by vaccines, which give immunity to specific viral infections. However, some viruses including HIV and those causing viral hepatitis evade these immune responses and cause chronic infections. Microorganisms also have defences against viral infection, such as restriction modification systems.

Antibiotics have no effect on viruses, but a few antiviral drugs have been developed. However, there are relatively few antivirals because there are few targets for these drugs to interfere with. This is because a virus reprograms its host's cells to make new viruses and almost all the proteins used in this process are normal parts of the body, with only a few viral proteins.

 

Bacteria

Bacteria are unicellular microorganisms that have a size of few micrometers (0.5 to 5 microns, usually) and various shapes including spheres (cocci), rods (bacilli) and helices (spirilla). Bacteria are prokaryotes and therefore, unlike eukaryotic cells (animals, plants, fungi, etc.) Have no defined or core have generally membranous organelles internally. Generally possess a cell wall composed of peptidoglycan. Many bacteria have flagella or other displacement systems and are mobile. The study of bacteria is responsible for bacteriology, a branch of microbiology.

In the human body are approximately ten times as many bacterial cells as human cells, with a large amount of bacteria on the skin and in the tract digestivo.4 Although the protective effect of the immune system makes the vast majority of these bacteria is innocuous or beneficial some pathogenic bacteria can cause infectious diseases, including cholera, syphilis, leprosy, typhus, diphtheria, scarlet fever, etc.. The most common fatal bacterial diseases are respiratory infections, with mortality for tuberculosis only about two million people a year

The first bacteria were observed by Anton van Leeuwenhoek in 1683 using a single lens microscope of his own design. Initially called animalículos and published his observations in a series of letters to the Royal Society. The name bacterium was introduced later in 1828 by Ehrenberg. Derived from the Greek βακτήριον-α, Bacterion-a, which means small stick.

A breakthrough in the study of bacteria was the discovery by Carl Woese in 1977 that the archaea have a storyline different from bacteria. This new phylogenetic taxonomy was based on the 16S ribosomal RNA sequencing and divided the prokaryotes into two different evolutionary groups, in a system of three domains: Archaea, Bacteria and Eukarya

Protozoa

Protozoa, also called protozoa, are microscopic, unicellular Eukarya, heterotrophic fagótrofos, predators or | detritivores]], sometimes mixotrophs (partly autotrophic) living in damp or directly in aquatic environments, whether salt water or water sweet, asexual reproduction by bipartition can be sexual also isogametos or exchanging genetic material by conjugation. In this very diverse group taxa fit a remote kinship, which fall into many different phyla of the kingdom Protista, defining a polyphyletic group, with no value in the classification according to current criteria.

Characteristics

Protozoa generally range from 10-50 microns, but can grow up to 1 millimeter, and can easily be viewed through a microscope. They move with a whip-like tails called flagella. They are the family of the protist. Found about 30,000 different types. Protozoans exist in aqueous environments and soil, occupying a range of trophic levels. As predators, prey algae, bacteria, unicellular or filamentous and microfungi. Protozoa play a role as herbivores and as consumers in the coupling of the decomposition process of the food

chain.Classification

Rhizopods or Sarcodina (Rhizopoda). Protozoa such as amoebae, move through linkers, ie, forming temporary appendages from its surface and a projection of the cytoplasm. The linkers are deformations of the cytoplasm and plasma membrane that occur in the displacement direction and trailing behind the rest of the cell. The pseudopods are also used to capture food, which fall into the interior, in a process called phagocytosis. According to the pseudopodia are very thick or very thin, are of two types: with lobopodios (thick) as Lobosea (Amoebozoa) and filopodia usually accompanied by a variety of exoskeleton with microtubules and are such as radiolarians, foraminifera, nuclearias, heliozoa and other .

Ciliates (Ciliophora). This is the traditional group most closely identified as a natural group

in the rankings with more modern edge, although they are cromistas opalinatas also fit into this concept. Cilia are surrounded by and have a complex internal structure but similar to the flagella, which are also related to cytoskeleton and centrioles. The paramecium (Paramecium genus) is a very popular representative of the group. Furthermore, the cilia are very numerous short filaments and that with its movement causes displacement of the cell.

Flagellates or mastigophores (Mastigophora). They are distinguished by the possession of one or more flagella. The flagella filaments are longer than the cilia whose movement drives the cell. Often occur in small numbers. The unicellular naked (cell wall), equipped with only one or two flagella, represent the original form from which derive all eukaryotes. Why are so many and varied different protists that fit this concept. Plants for example derived ancestrally biflagellate protozoan that acquired plastids by endosymbiosis with a cyanobacteria. Several protozoa carry plastids and are therefore autotrophs or mixotrophs as dinoflagellates and euglenas. The Metamonada have two or multiple flagella, are mostly anaerobic and symbionts or parasites of animals. Among the uniflagelados are choanoflagellates, ancestral animals and chytrids, ancestral fungi.

Sporozoa or Apicomplexa. Parasites with a phase of sporulation (division multiplex) and without mobility. There are several distinct groups without further relationship and are not all protists, but no animals and fungi. The best known example is the protozoan parasite (genus Plasmodium) that causes malaria and belongs to the group of apicomplexan, best-known group that usually reserved for himself the name Sporozoa. The haplosporidians are considered part of Cercozoa. These two groups were brought together for a long time under the name of Cnidosporidios. The Ichthiosporea are a more recent and are within Choanozoa. Microsporidia are now assigned to the kingdom Fungi and mixosporidias or mixozoos the animal kingdom.

 

 

fungal infections

Fungi are a kingdom of unicellular or multicellular living organisms that form tissues and cells which are grouped to form a highly branched filamentous body.

The filament assembly is called a fungus mycelium, and each strand is called hyphae. Sometimes the cells that form the mycelium may seem false tissues. The fungi cells have a cell wall of chitin, a substance of an animal arthropods. Rarely also accumulate cellulose.

Fungi are heterotrophic feeding, since they can not perform photosynthesis because they have chlorophyll. They have external digestion, poured abroad as digestive enzymes, protein substances that act on dividing food into simple molecules that attack food. Fungi absorb food after digesting them.

According to their lifestyle, fungi may be saprophytes, parasites and symbionts. Saprophytic fungi such as mushrooms or truffles, feed on decaying substances. Parasitic fungi feed on the internal fluids of other living beings. The fungal symbionts are associated with other agencies and mutual benefit.

The fungi live in humid, with abundant organic matter decomposition and hidden from sunlight. They can also inhabit aquatic or live within certain parasitándolos living.

The reproduction of the fungi may be asexual, by spores, and sexually.Haploid hyphae may result in mitosis, ie asexually, spores called conidia or conidiospores. Diploid hyphae resulting from the union of two haploid hyphae can give rise to sexual reproduction, to spores in ascus type structures or type basidium. There are two kinds of hyphae: hyphae coenocytic, with no partitions between cells, and septate hyphae, with them.

This includes certain parasites of potatoes and vine between oomycetes, mold and pests of flies and caterpillars among zigomicetes, many parasites, molds, truffles, morels and yeasts from the ascomycetes, blight and scab, and most species edible between blasidiomicetes. Varies according to where the meaning and extent of the meaning of names mushroom.

multicellular parasites

The parasite is a living being temporarily or permanently living at the expense of another organism of a different species, which is the host, obtaining in this nutrition and purple, which can result in damage and has a dependency that forced and unilateral. 

Parasites have certain characteristics to ensure sustainability, to resist the adverse factors and maintain their power to infect. When the parasite has reached a certain stage of development is known as infectious form.

Classification of parasites 

Parasites can be classified taking into account different criteria: 

1 - according to dwell in the interior or on the outside of the host, are classified as:
• Endoparasites, which may be intracellular, as Leishmanias sp. Or extracellular eg Fasciola hepatica 

• Ectoparasites, such scabei Sarcoptes (scabies) 

It is usually called the invasion of internal infection and external infestation by ectoparasites

2 - as the residence time of the parasite in its host are classified as: 

• Permanent, require the host throughout its life cycle, such as Enterobius vermicularis, and most human parasites 

• Temporary, the parasite to the host just looking for food, for example Triatoma infestans
• Newspapers, require the host during a stage of its life cycle, such as Necator americanus

3 - as the capacity to produce injury or disease in humans, are classified as: 

• Pathogens 

• No pathogenic 

Pathogens in certain circumstances not produce symptoms or cause damage to the host, as in the carriers. Under special conditions of susceptibility of the host, the pathogens can not increase their capacity to produce injury in this case are considered opportunistic parasites. 

4 - according to need, are classified as: 

• Required, is required of at least one guest to meet all or a part of their life cycle
• Optional: when a free-living organism can be adapted to parasitic life, such as Strongyloides stercoralis

. • Accidental, when a free-living organism reaches a host and continues its cycle it without adapting to the parasitic life, such as Naegleria fowleri 

4 - like all living organisms, parasites are classified into taxonomic groups that are, in descending order: kingdom, phylum, class, order, family, genus and species.
The biological unit is the species, with morphological, physiological and genetic well defined.

 The scientific name of the parasites, like all living things, is expressed in two words, usually derived from Latin and is the same in all the languages, the first represents the genre and should be capitalized, the second is the name of the species and is written in lower case 

What grouped under the name of parasites is a diverse range of life forms ranging from unicellular to multicellular organisms, and include three groups: 

• protozoa , metazoan or helminthes, arthropod parasites