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Cell membrane and types of transport, Exocytosis, as, because - Coggle…
Cell membrane and types of transport
Structure of the cell membrane
Is made up of a phospholipid bilayer
phosphate head
hydrophilic (attracted to water)
polar
has charge
go wherever the water is
tail
hydrophobic (repeals water)
non-polar
Also made up of proteins
Integral proteins
Enzymes= sites for chemical reactions
set up using both sides of the bilayer
Pumps= for active transport of molecules
Peripheral
Act as receptor
Any type of protein that only uses 1 side of the bilayer
Glycoproteins
important for cell recognition
has an oligosaccharide chain
glucose on the top
Cholesterol
regulates the
fluidity and flexibility of the membrane
Channel Protein
Carry molecules through the plasma membrane
Active Transport
Engulfing membrane
Endocytosis (active)
The taking in of external substances (like proteins that we don't have in our body)
by
inward punching of the plasma membrane
forming a
vesicle
(small spherical packages that bud off of the RER and the Golgi apparatus)
Carry proteins produced by ribosomes on the RER to the Golgi apparatus, where they are prepared for export from the cell via another vesicle
Types
Phagocytosis
"cell eating"
The plasma membrane ingests / engulf solid particles
Pinocytosis
"cell drinking"
Liquid droplets are ingested / absorbed by the plasma membrane
Receptor-mediated endocytosis
Vesicles form in areas of the plasma membrane where cell surface receptors are found
A clathrin coat forms around the vesicle
uses energy from the hydrolysis, in the form of ATP
to pump molecules against a concentration flow
using membrane protein pumps
The molecules cannot pass through the membrane, due to their properties
Active transport is key in homeostasis in organism, such as re-setting nerves after impulses have passed though, or absorbing glucose in the gut.
Passive Transport
substances cross the plasma membrane without any input of energy
the substances is moving from a higher concentration area to lower concentration area
they tend to move towards the region where they are few
Osmosis
the passage of water from a region of high concentration through a semi-permeable membrane to a region of low concentration
Water moves in or out of a cell until its concentration is the same on both sides of the plasma membrane.
uses transport protein (aquaporin)
Filtration
The removal of water from solid materials, usually for nutrients to be selectively absorbed into the body
Simple diffusion
the movement of particles from an area of greater concentration to an area of lesser concentration.
pass directly through the partially permeable membrane
allows SOME things to pass
small molecules
not charged (non-polar)
ex: oxygen
Facilitated diffusion
A process that occurs when molecules or ions pass through a cell membrane with the assistance of an integral protein.
big, polar molecules
ex: glucose
Characteristics of the cell membrane
Membrane fluidity
It is not determined if the membrane is liquid or solid
Head acts like a solid
Tail behaves as a liquid
It needs to be fluid, so things can move across the cell
but not too fluid as it also needs to be able to restrict some substances from passing
Role of cholesterol
Restricts the movement of molecules (fluidity)
Disrupts the packing of hydrocarbon tiles of phospholipid molecules (increases flexibility)
Reduces the permeability to hydrophilic/water soluble molecules and ions
Exocytosis
Types
Consecutive Secretion
occurs
continuously in cells, depending on their function
Regulated secretion
in
response to a trigger
example
the release of neurotransmitter
The release of substances
from
Cell secretion when a vesicle joins
with
cell's plasma membrane
as
because