Module 10 Flashcards
Membrane Transport
What part of the bilayer is hydrophobic
interior
Hydrophilic part of bilayer
exterior
Cholersterol
Lipid
Thicker and impenetrable, but softer
What makes the membrane semipermeable
structure and mic of proteins and lipids included
How is membrane fluidity influenced
Types of lipids
Why is membrane fluidity important
for what system?
Allows membranes to break and reform for the movement of substance through the endomembrane system
What is the cell membrane a selective barrier to what
, polar, charged, and large molecules
Why can them membrane act as selective
combo of lipids and protiens
Interior of the bilayer prevents what from entering the cell
hydrophobic nonpolar
Charged ions and polar molecules
Large molecules
polysaccharides, proteins
Small gasses
o2, co2, n2
Transport proteins can facilitate movement of
water, ions, and nutrients
How do chemical reactions occur
as a result of interactions between molecules and cannot occur unless they bump into eachother
Concentration gradient
There are areas of higher and lower concentration
Diffusion’s net movement
area of high to low concentration
diffusion is a result of
random movement of molecules
Dynamic equalibrium
movement of molecules in both directions continues
Passive transport
Molecules move across the membrane by diffusion, as a result of concentration difference between the inside and outside the cell
What hydrophobic molecules can diffuse into the cell
why
steroids, lipids
the lippid bilayer is also hydrophobic
Transport protien
Transmembrane protein that spans the cell membrane and provides a route for substance to enter and exit the cell
Facilitated Diffusion
diffusion across a cell through a transport protein
high to low concentration
Channel protein
Type of transport protein
Provides opening between the inside and outside of the cell where certain molecules can pass, depending on shape and charge
Gated channel protiens
open in response to some sort of signal; chemical or electrical
Carrier Protein
Binds to and then transports specific molecules across the cell membrane
When binding happens, shape changes to allow molecule to move across the bilayer
Aquaporins
Water channels that allow water to enter and exit cell by FACILITATED DIFFUSION
REsult of ions moving across membrane
cell can have different amount of electrical charge than the outside
Membrane Potiental
CHARGE DIFFERENCES between the inside and outside of a cell due to differences in charged ions
Electrical signals
Membrane potential cause
Movement of ions across cell
Active transport
Requires an input of cellular energy
Primary active transport
Cell uses ATP directly
Break down of Adenosine triphosphate
Secondary active transport
Uses ATP indirectly to move molecules across the membrane
What do transport proteins do with energy
Use it to change shape and pumps molecules
Sodium potassium pump
A transmembrane protein that actively moves sodium ions out of the cell and potassium ions in
Uses energy from ATP bonds
AGAINST concentration gradients
Antiporters
One molecule moves into the cell, while another one moves out of the cell
Symporters
One transport protein that moves two molecules in the SAME direction
How do concentrations of ions build up on one side of the cell
Transport proteins pump ions into the cells
Concentration gradients in 2ndary transport
Stores energy that can be harnessed to drive the movement of other molecules across the membrane, against their concentration gradient.
Molecules the flow from areas of higher to lower concentration happen when
As ions move from areas of higher to lower concentration
2ndary transport
Movement of molecules is driven by the movement of ions, not atp directly
2ndary active transport
What drive secondary active transport
The energy stored in an electrochemical gradient
Proton pumps through active transport can cause what
The concentration of protons to build up on one side of the cell membrane.
A CONCENTRATION gradient
Concentration gradient movememnt
Favors movement of protons back to the other side
What blocks the movement of protons back to the otherside after primary transport
What does this cause
The lipid bilayer blocks movement
It stores the energy
Electrotrical Graident
Difference in charge of a membrane
Ions move from areas of like to unlike charge
Protons –> MORE NEGATIVE side
As protons move out, other molecules are pushed into the cell, 2ndary transport
Electrical chemical gradient
A gradient that has both a chemical and charge component
Why can transport proteins use the movement of protons down their gradient to drive the movement of other molecules against their concentration gradient
The electrochemical gradient` moves protons back.
Where do molecules end up with diffusion
The cytoplasam of the cell
Vessicles
Small spherical organelles that trabel between organelles of the ENDOMEMBRANE SYSTEM in eukaryotic cells
Where are contents released during endocytosis
outside the cell
exotysis
Where vesicle fuses with the cell membrane and releases its contents to the EXTRACELLULAR SPACE
what does exocytosis depend on
fluid and dynamic nature of the cell membrane
vesicles fuse with membrane
Exocytosis and waste
remove cytoplasmic waste, packed into vesicles and fused with the cell membrane, releasing waste outside the cell.
Exocytosis and neurotransmitters
neurotransmitters are packaged into vesicles by nerve cells, and released by exocytosis, travel through extracellular space, where they bind to receptors on surface of an adjacent nerve.
Exocytosis and protiens
Deliver proteins, embedded on rough endoplasmic reticulum as they are synthesized
Vesicles carry proteins that were associated with the membrane , and fuse them with surrounding membranes
Endocytosis
Vesicle buds off from the cell membrane towards towards the cell interior or INVAGINATES, enclosing materials from outside the cell, into the cell
Phagocytosis
Cells ingest large particles, microorganisms, and dead cells.
What part of the cell digests waste
lysosomes
Where do materials end up through endo and exocytosis
In and out of vessicels
Where do things end up in active and passive transport
in the cytosol of the cytoplasm
Where does endo and exocytosis uniquely occur in
Eukaryotes
Why is a dynamic cytoskeleton needed for in tranportation
Shuttle vesicles around the interior of the cell, directing their movement in endocytosis.
Consequence of accelerated pace of transportation
Eukaryotic cells are much larger.
