cell function

The shape depends on the adaptation to a particular function.

ways:

· Globular or spherical: it is the most common

· Starry: nerve cells (neurons) and bone cells (osteocytes or osteoblasts)

· Fusiform: muscle cells (fibers)

· Polyhedron (prism): plant cell and epithelial cells

Cells with a variable: amoeba and leukocytes (amoeboid movement to deform

move or capture food)   

Cell Size

Usually between 5 and 60

Å = Armstrong = ten thousandth of a micron

Special cases:

large:

· Acetabularia: unicellular algae of 10 cm.

· Muscle cells of some cetaceans: 15 cm.

· The egg of the Ostrich: 7-8 cm.

small:

· Mycoplasmas: prokaryotic cell type 1/10 micron

· Bacteria: 0'2 - 0'5?

· Number of cells

From 1 to unicellular organisms to multicellular any amount in the

Eukaryotic Cell Structure Animal

· Wrap cell

- Membrane secretion:

Glycocalyx (glycocalyx, glycocalyx, glycocalyx) in some animal cells

* Glycocalyx: Made oligosaccharides (glucidic parts of glycoproteins (and glycolipids of the

plasma membrane

- Cell Wall in all plant cells      

- Plasma membrane:

¨ Two layers:

à outer (fibrous)

internal à (amorphous)

Phosphates (bony shell form) Polysaccharides:

¨ Chitin (exoskeleton)

¨ Chondroitin (tissues)

· Plasma membrane:

Generally ¨ is 75 Å thick

organelles and diseases

Cell Organelles

Key parts of the cell

A cell is formed by a plasma membrane, cytoplasm and nucleus.

Plasma Membrane: Structure consisting of a lipid bilayer formed by phospholipids arranged next to each other, forming a fluid layer with proteins inserted into this (integral proteins), peripheral proteins (external and internal). The center of the membrane is hydrophobic and internal and external ends are hydrophilic.

The cytoplasm: This consists of the cytosol (liquid fraction of the cytoplasm surrounding the organelles and has a gelatinous consistency as). The cytoplasm has a cytoskeleton, organelles and inclusions. In the cytoplasm are dissolved proteins, sugars, minerals, hormones and enzymes.

Cytoskeleton: Formed by filamentous protein fibers. These structures are dynamic, constantly build and break down and give way to the cells, and also allows movement of the organelles. This consists of Microtubules (tubulin), intermediate filaments and microfilaments (actin).

Organelles:

a)    rough endoplasmic reticulum, RER network is a flat bags delimited by a membrane whose roughness is due to the presence of ribosomes on its surface. Its function is to receive therein the newly made protein and ribosomes pemite by folding them. Normally

b)    this organelle is abundant in secretory cells.

b) Ribosomes: organelles are not membrane consisting of two subunits of RNA and proteins. They can be found free or attached to the RER. Its function is to synthesize proteins.

c) Smooth endoplasmic reticulum, REL: A network of flattened sacs, such as the RER without ribosomes on its surface, which gives a smooth, not rough. Its function is to synthesize lipids (cholesterol, steroids and phospholipids). In the liver, its function is to detoxify the cell of drugs and toxins.

d) Golgi apparatus: A stack of flattened cisterns parallel. Located near the nucleus and is highly developed in seretoras cells. Its functions are: to receive vesicles with proteins, sugars chemically modify, store and distribute them to your specified sites (organelles, plasma membrane, drainage, etc.)., Factories lysosomes participate in the construction of the cell wall of plant cells and produce polysaccharides as mucus. The whole process is done by budding of vesicles.

e) Lysosomes: are bounded by a membrane vesicles, which contain large quantities of hydrolytic enzymes and whose optimum pH is acidic. Acid pH due to a proton pump exists in the membrane. Its function is intracellular digestion, digest endocytosed material, including bacteria and viruses. Also involved in autophagy, ie surrounding the organelles aged in large vacuoles and are hydrolysates. Autolysis involved in, ie, break lysosomes, as in the tadpole's tail.

f) Peroxisomes: These are spherical vesicles surrounded by membrane. Are organelles self replicate. Generates hydrogen peroxide (peroxide), which is used by an enzyme (catalase) to oxidize various substances. Also performed on 30 of the catabolism of fatty acids.

g) Mitochondria: organelles are involved in two membranes. The inner membrane invaginates, forming folds called mitochondrial cristae. Mitochondria have the shape and size of bacteria, possess their own DNA and circular and divided independent of the cell 

that contains them. Within the mitochondria cellular respiration occurs (Krebs cycle, electron transport chain and oxidative phosphorylation). Its ultimate goal is to synthesize ATP for the cell.

h) centriole: microtubule organizing center. This structure forms the fibers of the cytoskeleton, cilia, flagella and the mitotic spindle.

i) Plastid: An example is the chloroplast, photosynthesis takes place. Has a double membrane, like the mitochondria and the nucleus. The inner membrane is the thylakoid. The green color of chloroplasts is because chlorophyll. Lesser extent are also the pigments carotene and xanthophylls. Other chromoplasts are plastids that accumulate lipid pigment colors, leucoplasts and amyloplasts to store starch.

j) Cell wall: Around the membrane plant is a cell wall made of cellulose and pectin. This cell wall substances passes freely passing through the membranes. Its function is to prevent the burst due to accumulation of cell water.

k) Vacuoles: spherical fluid-filled compartments in plants. Is very large and contains water, nutrients, wastes, ions and salts. It can give an osmotic pressure to allow the entry of water into the plant cell. Inside may also have crystals, pegmentos (anthocyanins are blue and red ranges) and tannins (brown give), alkaloids (cocaine, caffeine, protein, nicotine, quinine, strychnine, mescaline, boldine and active compound tetrahydrocannabinol marijuana) and terpenes (with herbs like mint and eucalyptus and many flowers).

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. 

pathogenic organisms

Pathogens, including viruses, bacteria or cysts, capable of causing disease (typhus, cholera, dysentery) in a receiver (eg a person). There are different types of organisms that cause disease NO. These are called non-pathogenic. Regards

host specificity

In biology, host means "hosting", ie, a guest is an organization that hosts a parasite or symbiont. A host organism can become or be more likely to be by:

Genetic factors.

Age.

Physiological conditions.

Interurrentes diseases or preexisting.

BEHAVIOR or lifestyle: One of the most important factors for the acquisition of human or animal disease and the qe else can intervene, as they can be changed through education or prevention modificandociertas husbandry practices:

Personal hygiene.

Food handling.

Diet.

Exercise.

Leisure activities or hobbies.

Contacts.

Consumption of toxic: Snuff, alcohol and other drugs

Host resistance

The pathogenicity of the organism is restrained or provided by the host immune resistance. The properly vaccinated against smallpox are immune to this virus. This fact was discovered by Jenner in England, when he noticed that milkmaids who had been affected by the smallpox vaccine, a disease of cattle and was acquired by manipulating the udders of the animals did not suffer the deadly smallpox. Moreover, in patients with AIDS, whose virus decreases immunity, may have disease germs usually harmless. are caused by viruses, bacteria, protozoa, fungi, some invertebrate pathogen are a kind of parasite that attack the body

Virus

is a microscopic infectious agent that can only multiply within the cells of other organisms. Viruses infect all types of organisms, from animals and plants, to bacteria and archaea. Viruses are too small to be observed with the aid of a microscope, so that they are said to submicroscopic.

Viruses vary in shape from simple helical and icosahedral to more complex structures. The evolutionary origin of viruses is still uncertain, some might have evolved from plasmids (pieces of DNA that move between cells), while others may have originated from bacteria. Moreover, from the viewpoint of the evolution of other species, viruses are an important means of horizontal gene transfer, which increases the diversity genética.9

Viruses spread in many different ways and each virus has a different method of transmission. These methods are the vectors of transmission, which are other organisms that passed between carriers. Plant viruses often spread by insects that feed on the sap, including aphids, while animal viruses are usually spread by blood-sucking insects. Moreover, other viruses do not require vectors: the influenza virus (rhinovirus) is spread through the air through sneezing and coughing and norovirus are transmitted by the fecal-oral, or by hands, food and contaminated water. Rotavirus is often spread by direct contact with infected children. HIV is one of the many viruses that are transmitted by sexual contact or by exposure to infected blood.  The word comes from the Latin virus referring to poison or any harmful substance, and was first used in English in 1392. Virulent, from Latin virulentus (poisonous), dates from 1400. The mention of "agent that causes infectious disease" was first used in 1728, before the discovery of viruses by Dmitri Ivanovski in 1892. The adjective "viral" in 1948. The term "virion" is also used to refer to a single infectious virus particle. The plural is "viruses".

Human diseases caused by virus, more commonly known, are polio, influenza, smallpox, measles, yellow fever, encephalitis, mumps, trachoma, etc.. Currently it is believed that some cancers are also of viral origin. Viral infections in general, can not be treated with antibiotics without signing on, the interferon biological product synthesized by the tissues invaded by a virus, is active against infections caused by others.

The existing treatments against viral infections are often not entirely satisfactory, since most drugs that destroy the virus also affects cells which reproduce. Alpha-adamantanamine is used in some countries to treat respiratory infections caused by influenza A and isatin-beta-thiosemicarbazone, effective against smallpox. Certain substances similar to precursors of nucleic acids may be useful against serious infections by herpes.

A promising antiviral agent is interferon, which is a non-toxic protein produced by some animal cells infected with viruses and may protect against other cell types such infections. Currently we are studying the effectiveness of this substance to fight cancer. Until recently, these studies were limited by their limited availability, but new techniques of cloning the genetic material, produce large amounts of this protein. In a few years will know if the interferon is really effective as an antiviral agent.

The only effective way to prevent viral infections is the use of vaccines. Vaccination against smallpox worldwide in the 1970s, eradicated the disease. They have developed many vaccines against human viruses and other animals. Among the people who have infections include measles, rubella, polio and influenza. Immunization with a vaccine stimulates antiviral body's immune mechanism, which produces antibodies that will protect you when you return to contact with the virus. Vaccines contain viruses forever altered so they can not cause disease

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.

Bacteria are the most abundant organisms on the planet. Are ubiquitous, found in

all terrestrial and aquatic habitats, growing up in the most extreme as in the hot springs and acidic wastes, radioactive, 1 in both the sea depths of the earth's crust. Some bacteria can even survive in extreme conditions of outer space. Is estimated to be found around 40 million bacterial cells in a gram of soil and a million bacterial

 cells in a milliliter of fresh water. In total, it is estimated that approximately 5 × 1030 bacteria in the world

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

designates a group of eukaryotic organisms that are among the molds, yeasts and mushrooms. They are classified into a different realm of plants, animals and bacteria. This differentiation is due, inter alia, that possess cell wall composed of chitin, unlike plants, containing cellulose and because some grow and / or act as parasites of other species. Currently considered as a heterogeneous group, polyphyletic, consisting of bodies belonging to at least three independent storylines.

Fungi are found in diverse habitats: be pirófilos (Pholiota carbonaria) or coprophilous (Psilocybe coprophila). According to their ecology, can be classified into four groups: saprophytes, lichenized, mycorrhizal and parasites.

Fungi are of great economic importance: yeasts are responsible for the fermentation of beer and bread, and gives the collection and cultivation of mushrooms and truffles. Since 1940 have been used industrially to produce antibiotics and enzymes (especially proteases). Some species are biocontrol agents of pests. Others produce mycotoxins, bioactive compounds (eg alkaloids) that are toxic to humans and other animals. Fungal diseases affecting humans, animals and plants in the latter affects the food security and crop yields.

Fungi come in two main forms: filamentous fungi (formerly called "molds") and yeast.

commonalities

Other eukaryotic cells fungi possess bounded by a sterol-rich plasma membrane and containing a core which contains the genetic material in the form of chromosomes. This genetic material contains genes and other coding and noncoding elements such as introns. Possess organelles such as mitochondria, and ribosomes 80S.8 As such compounds possess soluble carbohydrate reserves and polyalcohols (eg mannitol), disaccharides (such as trehalose) and polysaccharides (such as glycogen, which, moreover, is present in animals) 

As animals, fungi lack chloroplasts. This is due to their heterotrophic nature, requiring obtained as a carbon source, energy and reducing power organic compounds

to like plants, fungi have cell walls and vacuoles. They reproduce in a sexual and asexual, and, like ferns and mosses produce spores. Because of their life cycle, usually possess haploid nuclei, as mosses and algae. Bear resemblance to fungi and bacteria euglenoid.

multicellular parasites

These are the major multicellular parasites of the intestine; Hookworms (Ancylostorna duodenale). Worms are about 3 mm long, fitted with hooks that oral are fixed to the wall of the duodenum, where they suck the blood of the wearer. If the infestation (hookworm) is severe, manifested by chronic anemia, abdominal pain and weight loss. The larvae can reach the intestine directly penetrate the mouth or skin wounds and travel through the blood to the lungs, where they pass into the throat and are swallowed. Roundworm (Ascaris lunsbricoides). They are pinkish-white worms, up to 30 cm long. The infestation (ascariasis), common among children in unhealthy regions, occurs when you take food or water contaminated with human feces containing the eggs, its symptoms include bloating, malnutrition, growth retardation and the presence of worms in the stool. Pinworms (Enterobius vermicularis). are worms Whites from 3 to 12 mm long that infest the large intestine (oxiurasis). During sleep, females down to the anus, in whose folds lay their eggs, causing intense itching. If the person scratches, the eggs are stuck to the nails, making them easier to spread. The eggs also stick to the bedding, where their ability to infestation may last for several weeks. The oxiurasis occurs even under the best conditions hygiene, particularly among children 3 to 15 years of age. Tapeworms. Are flatworms, up to 10 m length, which are fixed with suckers or hooks to the gut wall. There are two main species, the solitary or pork tapeworm (Taenia solium) and the beef tapeworm (Taenia saginata).

Infestation (taeniasis) is caused by eating raw or undercooked meat of cattle parasitized, can be asymptomatic, but sometimes causes abdominal pain, diarrhea, anemia or weight loss. Naturopathic advice is said that garlic, carrot and pumpkin seeds serve to weaken various parasitic worms, but you also have potent plant remedies used to paralyze and expel them, which calls for consultation with a therapist