Diffusion🛝 Flashcards
What is dynamic equilibrium?
When there is no net movement but there is still a movement of particles as well as a balance on each side
So if a particles comes to one side then the particles in the other side one needs to come.
What is diffusion?
The net movement of molecules or ions from the region of high concentration to a low concentration area(passive) ATP is not required
Factors that affect the rate of diffusion
Concentration gradient:the greater the gradient the faster the rate of diffusion
Higher concentration is needed for faster rate of diffusion
S.A: larger the SA (doors)the faster the rate of diffusion as there are more membranes for particles to move to
Particle charge/size:the hydrophobic core in cell membrane,charge particle such as ions cant diffuse thru(big) to enter but water (polar)which is charged can because of how small it is via facilitated diffusion
But uncharged particles like oxygen can diffuse across rapidly
Size:larger don’t diffuse as faster as smaller particles.
Length of diffusion pathway:the thinner the an exchange surface the faster the rate of diffusion and the thicker (cystic fibrosis) where mucus is trapped in the lungs the slower is the rate of diffusion as there is more distance particles like oxygen which need to diffuse across.
Temperature:in warmer conditions particles have more kinetic energy and diffuse faster (mammals and birds is not an issues as there is a constant temperature kept)
What is ficks law:
State the rate of diffusion is proportional to both surface area and concentration differences and inversely proportional to the thickness of membrane
Rate of diffusion o< SAof diffusion * difference in concentration
/
Thickness of membrane
What is facilitated diffusion?
Is the transport of hydrophilic substances across a membrane from an area of high concentration to area of low concentration with the help of a intrinsic transport protein without interact with hydrophobic core using intrinsic protein because they expand across the cell membrane
-carrier protein
Have a binding site for specific Chemicals and when it binds it cause the tertiary structure of carrier protein to change and chemical goes across membrane and now is released
-channel protein
Protein with central pore which hydrophilic substances can pass through
Why do we need facilitated diffusion?
Polar molecules (slightly positive and the other end is slightly negative)can’t cross the bilayer of phospholipids (hydrophobic barrier)
So instead they travel via the facilitated diffusion.
Why can’t some come chemical diffuse through the cell membrane and other can’t?
The cell membrane is partially permeable and other can’t diffuse across needle different mechanisms for transport
Give some points of protein channel?
Channel:Selective for the chemical which can pass through
Carrier:protein Channels are open but some open due to a trigger e.g chemical binding to protein channel.
What is co-transport ?
It is a type of active transport
Is the coupled movement of substances across cell membrane via carrier protein.
(Involves facilitated diffusion and active transport.)
Give the epithelial cell co-transport example.
-Co-transport can be found in the cell surface membrane of epithelial cell lining the mammalian ileum
-involved in the absorption of glucose after digestion
-so in the epithelial cell sodium ions are transported into blood stream by active transport so ATP attached and it hydrolyses to ADP Pi causes carrier protein to change shape allowing them through,using a carrier protein which opens up by a trigger,and transports potassium in cell(anti port)
-reducing sodium ion concentration in the epithelial cell and so the high concentration of sodium ions in the lumen can now diffuse in the cell by facilitated diffusion into cell down concentration gradient via a carrier protein called
-Co transporter
-So either glucose or amino acids attach and are transported in the cell against their concentration gradient due to the facilitated diffusion stoped due to dynamic equilibrium of glucose so low to high now.
(1st sodium attaches and then glucose attaches enabling sodium to be released and then glucose is released)
This is symport
*they are transported together so it is called co-transport
-there is a glucose build up in epithelial cell so then it moves in the blood (capillaries) via facilitated diffusion using a different carrier protein from sodium.
Extra points of co transport
(Microvilli and blood,mitochondria)
-The concentration of glucose in blood in lower than in cell because of the constant movement carrying away glucose away
-microvilli on epithelial cell increase the S.A for co-transport proteins.
-epithelial cell have a large number of mitochondria this provides ATP needed for sodium-potassium pump which transports sodium in bloodstream and potassium in cell
What is the problem in the movement of glucose from lumen to cell and then to bloodstream?
-The rate of facilitated diffusion depends on size of concentration gradient of glucose and as it is transported in the epithelial cell it reduces so that means facilitated diffusion can’t absorb available glucose.
What is indirect transport?
refers to the movement of substances or molecules within an organism via a carrier or intermediary, such as through the bloodstream or via other specialized transport mechanisms.
What is co-transporter
It is a type of membrane protein or transporter that moves multiple substances across a cell membrane simultaneously.
