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cell (plasma membrane (bilayer of phospholipids and embedded proteins, it…
cell
plasma membrane
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it is selectively permeable to ions and organic molecules and regulates the movement of substances in and out the cell.
osmosis, movement of water molecules from a higher conc. to a low conc. down a concentration gradient, no energy is required. eg water
simple diffusion, moving down a concentration gradient from a higher conc. to a lower conc. until equilibrium is achieved, no energy is required eg oxygen, carbon dioxide
facilitated diffusion (through a protein). eg larger charged particles like ions insoluble in lipids
active transport, energy in the form of ATP is required. moving against a conc. gradient, a variety of substance go through active transport
endocytosis, vesicle forms and takes in whatever is outside the cell. pinocytosis is a type of endocytosis which is non selective
receptor-mediated endocytosis, it is selective, substances bind to protein receptors and take them into the cell
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exocytosis, membrane-bound vesicle migrates towards the plasma membrane, proteins from the vesicle fuse with proteins in the plasma membrane and opens a pore to release the content of the vesicle.
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organelles
ribosomes, dense particles free or attached to rough endoplasmic reticulum. site for protein synthesis
endoplasmic reticulum, smooth has no ribosomes, rough has ribosomes attached. makes proteins and membranes, site for drug detoxification, lipid and hormone synthesis.
Golgi apparatus, a stuck of smooth membranes close to the endoplasmic reticulum (ER). it receives proteins from ER, modifies, sorts and package them for export, plasma membrane growth and creation of lysosomes
lysosomes, spherical, membrane-walled sacs containing enzymes that break up biological materials
mitochondria, rodlike, double membrane. synthesis ATP
peroxisomes, are membrane-walled sacs that resemble small lysosomes. they are responsible for toxic waste removal from the cell. they break down long chains of fatty acids in lipid metabolism
cytoskeleton
are extensive network of rods running through the cyotosol. there are three types, microfilaments, intermediate filaments, and microtubles
microfilaments contains a protein actin, help change the shape of the cell. not permanent, they build up and break down
intermediate filament, fibrous, ropelike connected to desmosomes. they are permanent
microtubles, lumen shaped and transport of vesicles through it
nucleus
it is the control center of the cell and directs the activities of the cell. it is made up of nuclear envelope, nucleolus and chromatin and chromosomes
nuclear envelope, it surrounds the nucleus, consist of parallel membranes separated by a fluid filled space. it encloses a jellylike fluid called nucleoplasm in which the chromatin and nucleolus are suspended. it separates the nucleoplasm rom cytoplasm and regulates passage of substances to and from the nucleus
nucleolus, is the dark staining body of the cell nucleus.it serves as the site where large and small sub units of ribosomes are assembled
chromatin and chromosomes, DNA molecules and proteins form chromatin. a chromosome contains a single very long DNA molecule. there are 23 pairs of chromosomes in a human cell. they contain genetic information which is passed on to offsprings
cytoplasm
cytosol, jellylike fluid substance without the organelles. it consist of water, ions and enzymes. it makes up about half of the volume of the cytoplasm.
lies internal to the cell membrane and outside the nucleus, many cell activities occur there, it consist of three elements, cytosol, organelles, and inclusions
inclusions are temporary structures in the cytoplasm that may not be present in a giving cell. these are pigments, crystals of protein and food stores