Plasma Membrane Recap Flashcards
what 3 molecules does the plasma membrane have embedded in it
proteins, carbs and cholesterol
what do the embedded proteins of the plasma membrane assist in
cell signalling and act as receptors
plasma membrane is
selectively permeable
- separates intracellular and extracellular environments
- helps the cell maintain homeostasis
- ensures optimal function of organelles ( they require specific concentrations
of proteins, small molecules, and ions.)
main component of plasma membrane and how are they arranged
phospholipids
phospholipid bilayer
what do phospholipids contain and which is hydrophilic / hydrophobic
phosphate head (hydrophilic) and fatty acid tail (hydrophobic)
what is the function of proteins in plasma membrane
controlling what enters and exits the
cell
- speeding up chemical reactions
- communicating and receiving signals
via the cytoskeleton
- adhesion by
sticking to other cells, the extracellular
matrix, or the cytoskeleton.
what is the structure of proteins found in PM
integral - permanently anchored - called transmembrane proteins if they span the entire membrane
peripheral - temporarily anchored
function of carbs in PM
adhesion by
sticking to other cells, the extracellular
matrix, or the cytoskeleton.
structure of carbs in PM
Usually in chains that extend outside
the cell, rooted in the membrane
to lipids (glycolipids) or proteins
(glycoproteins).
function of cholesterol in PM
Regulates the fluidity of the membrane.
At higher temperatures, cholesterol keeps phospholipids bound together.
At lower temperatures, cholesterol
disrupts the fatty acid tails, stopping phospholipids from becoming a solid
boundary.
structure of cholesterol in PM
A lipid steroid that embeds itself between the fatty acid tails of the
phospholipid bilayer in animal cells.
glycolipid
a phospholipid bound
to a carbohydrate
glycoprotein
a protein bound to a
carbohydrate
which factors affect if and how a molecule passes through the PM
molecule in qs
size and shape
polarity
concentration gradient
what are the 2 and then 2 of each type of transport
passive - diffusion and osmosis
active - active transport and bulk transport
diffusion
the passive movement
of molecules from areas of
high concentration to areas of low concentration (down the concentration gradient)
what is the cause of diffusion
occurs as a result of the kinetic energy stored inside each molecule,
which causes them to randomly move around and bounce off each other. Over time,
this random movement leads to an even dispersion of particles in an area
explain the relation of polarity with passing through PM
Nonpolar or hydrophobic molecules can easily pass through the plasma membrane because its interior, made of fatty acid tails, is also hydrophobic.
Nonpolar molecules are attracted to each other, allowing them to move freely across the membrane.
Examples include oxygen (O₂), hydrogen (H₂), carbon dioxide (CO₂), and lipids.
explain the relation of size with passing through PM
Small molecules like water can pass through the phospholipid bilayer by slipping between the lipids, allowing them to diffuse freely.
However, highly charged molecules, like ions (e.g., H⁺, K⁺, Cl⁻), cannot cross the membrane this way. They need special protein channels to help them move across.
osmosis
the passive movement
of water from a region of high concentration of water molecules
to a region of lower concentration
of water molecules through a cell’s
semipermeable membrane
tonicity
a measure of the relative
concentration of solutes on either side of a semipermeable
membrane,
hypertonic
describes a solution
with a higher solute concentration
when compared to another
solution
isotonic
describes a solution with
the same solute concentration as
another solution
hypotonic
describes a solution
with a lower solute concentration
when compared to another
solution
turgid
describes plant cells that
are swollen and firm from water
uptake
plasmolysed
describes plant cells
with weak and sagging plasma
membranes from water loss
lyse
to cause a cell membrane to burst or break
facilitated diffusion
a type of
passive transport where molecules move through a phospholipid bilayer with the aid of a membrane
protein
protein channel
transmembrane protein embedded in the phospholipid bilayer that selectively allows large or polar molecules to pass through the membrane.
carrier protein
membrane-based protein that changes shape (undergoes a conformational change) to transport molecules across the membrane.
active transport
moving molecules against their concentration gradient from a region of low concentration of that molecule to a
region of high concentration. This process requires both energy and the assistance of protein pumps.
protein mediated active transport
a type of active
transport which involves using
membrane proteins to move
molecules across a membrane
against their concentration
gradient.
bulk transport
a type of active
transport that uses vesicles to move large molecules or groups of molecules into or out of the cell.
Also known as cytosis
exocytosis
Exocytosis is the process by which large molecules or large groups of molecules are
released from cells via vesicles.
endocytosis
transporting large molecules or large groups of molecules into the
cell.
