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3-movement in and out of cells - Coggle Diagram
3-movement in and out of cells
movement and states of matter
temperature influences the speed at which particles move
the more kinetic energy they have, the faster they move
in a liquid, particles can move more freely but they still are in contact with one another
in a solid substance, particles cannot move very far
they can only vibrate around a fixed position
in a gas,particles can move even freer since they do not have any attractive force to keep them in place
in thi state, they tend to spread out evenly
diffusion
when they can, particles that can move freely tend to occupy all the space they have got, even though their movement is random
after some time, all the molecules will be spread evenly: this is the "net movement"
they will move from their starting point, which has a high concentration of molecules, to other points with a lower concentration
this can be represented as a slope, where the top of the slope is the point with the high concentration and the bottom of the slope are the points with low concentration
a synonim for slope is "gradient"; hence, we can say that molecules move down the concentration gradient
it is employed by living organisms, too
carbon dioxide diffuses into leaves and oxygen out of leaves
it is present in gas exchange for respiration in animals and plants, since oxygen and carbon dyoxide can easily diffuse in and out of cells thanks to the cell membranes
it is also employed in the diffusion of solutes (substances diluted in a liquid, called "solvent"). This is the case with glucose molecules and sodium ions in cytoplasms
osmosis
it can be intended as an another type of diffusion, regarding water molecules
it takes place when there are different quantities of substances diluted in water inside and outside cells
over time there will be a net movement of water molecules from the area with more water molecules to those with a lesser concentration of such molecules (the molecules move down the concentration gradient
a dilute solution has a high water potential, while a concentrated solution has a low water potential
the water molecules move through a partially permeable membrane, which blocks other bigger molecules
it takes place in both animal and plant cells
animal cells
if it is put in pure water, water enters the cell by osmosis, which swells and then bursts
if it is put in a concentrated solution, water leaves the cell by osmosis, which shrinks
plant cells
if it is put in pure water, water enters the cell by osmosis, and the cell, the cytoplasm and the vacuole swell
however, thanks to the cell wall, the cell will not burst
the plant cells are costantly in this state and are said to be turgid
this helps to keep plants upright
the water pressure pressing outwards is called "turgor pressure"
if it is put in a concentrated solution, water leaves the cell by osmosis; the cytoplasm and the vacuole shrink and the cell membrane moves away from the cell wall
if a plant cell loses water, then the interior of the cell does not push outwards anymore, leading to the cell becoming "flaccid" (soft and floppy)
the plant loses its firmness and begins to wilt
if the cell membrane tears away from the cell wall, it can be damaged and the cell can become "plasmolysed"
active transport
a substance will be actively transported only if a cell urgently requires it
it requires energy in order to transport something up the gradient
this energy is obtained thanks to respiration
an example of this is provided by the existence of carrier proteins
these proteins need energy to change their shape so that nitrate ions can be introduced in root hair cells