organelles


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organelles

specialized intracellular structures; e.g. mitochondria, Golgi apparatus, centrioles, granular and agranular endoplasmic reticulum, vacuoles, microsomes, lysosomes, plasma membrane and fibrils (Table 1)
Table 1: Cell organelles
StructureCharacteristic
Cell membraneBimolecular lipid and protein membrane that surrounds the cell
• Bi-layer of non-polar lipid molecules (phosphatidylcholine, phospharidylethanolamine, cholesterol) that acts as a barrier to water and hydrophilic solutes
• Proteins:
  • Structural proteins

  • Protein pumps that actively transport ions such as sodium out of the cell

  • Carrier proteins that carry molecules such as glucose into the cell

  • Ion channel proteins, such as sodium ion channels in nerve fibres to which molecules of local anaesthetic attach to prevent the passage of the pain-inducing nerve impulse

  • Receptor proteins, such as insulin receptors which facilitate the passage of glucose into the cell

  • Immunoglobulin proteins, which form part of the immune response mechanism

  • Enzyme proteins, such as alkaline phosphatase

Cell cytoplasmThe gel-like matter contained within the membrane envelop:
• Contains and supports specialized organelles, including the cell nucleus, endoplasmic reticulum, the Golgi apparatus, mitochondria and lysozomes
• Stores substances (glycogen and lipids)
• Synthesizes and metabolizes essential substances (amino acids, fatty acids, monosaccharides)
• Synthesizes and translates protein
• Contains microtubules which help maintain the form of the cell and form intercommunication channels between organelles
Cell cytoskeletonA complex network of structural elements (microtubules, intermediate filaments and microfilaments) which determine the shape of the cell, its ability to move and its response to external stimuli
Cell nucleusPresent in all eukaryotic cells capable of mitosis
Contains the cell genome (DNA) and the means of replication and transcription of RNA
Separated from the cytoplasm by the nuclear envelop (which disappears during mitosis and meiosis)
Contains the nucleolus, where ribosomes are synthesized
Intercellular connectionsThere are two types of intercellular connections: tight junctions and gap junctions
Cell adhesion molecules (CAMs)Structures (receptor integrins, immunoglobulin adhesion molecules, Ca+-dependent cadherins and carbohydrate-binding selectins) within the cell membrane that bond to laminins within the extracellular matrix to attach adjacent cells to one another and to the basal membrane
References in periodicals archive ?
When the investigators analyzed brain tissue from deceased ALS patients with the mutations, the scientists detected a buildup of TIA1-containing organelles called stress granules in the neurons.
Thereafter, the maternal (uniparental) transmission of organelles that resulted from "the active digestion of male organelle nuclei (genomes) in young zygotes" was observed in almost all algae and land plants.
The endosymbiosis hypothesis was first proposed in the 1960s by biologist Lynn Margulis, who believed that organelles such as chloroplasts and mitochondria, the energy-producing organelles in all eukaryotic organisms, were originally free-living organisms that were conscripted into the bodies of larger cells.
The protein seems to work by making sure the organelles are in the right locations so they can be divided between the daughter cells.
Contains more depth with organelles being more distinct to one another.
During the process, nutrients are recycled by the lysosome, an internal organelle, to produce metabolites that can be used by the cell.
The genes governing production of mitochondria, both in the nucleus and in the organelle itself, can be defective, and the defects can be passed from mothers to their children.
However, I do like his analogies, especially the mangrove tree of life and his description of the relationship between a cell and its organelles as rooms aboard a ship.
These results suggest that the lysosomal system plays a key role in the degradation of cellular organelles.
Cells metabolize their old proteins and cell organelles by breaking them down in a process called autophagy.
Their topics include hardware and software from microscopes to cameras used in Ca2+ recordings, bioluminescent Ca2+ indicators, intracellular calcium-sensitive microelectrodes, Ca2+ imaging of the intracellular organelles endoplasmic reticulum and mitochondria, in vivo Ca2+ imaging of the living brain using the multi-cell bolus loading technique, and Ca2+ imaging of glia.
This Olis "Clarity" series allows investigators to record metabolic activity in living cells and suspensions of sub-cellular organelles.