Module 2: Section 5- Biological membranes Flashcards
What is the cell membrane also known as and what is it
-also known as the plasma membrane
-the cell membrane is a semi-permeable area in a cell
that separates the interior components of the cell from the extracellular matrix.
what are the functions of the cell membrane
-Separation between the extracellular fluid and the internal components of the cell.
-Communication with other cells.
-Recognition of external substances.
-Structural support.
-Transport of materials.
why is the plasma membrane described as fluid mosaic model
-mosaic as there are proteins embedded in the membrane
-fluid as phospholipids can move freely in the phospholipid bilayer
what does cholesterol do in the plasma membrane
-makes membranes ridged , maintains fluidity and increases stability of the membrane
how is transport of materials
accomplished
Simple diffusion
facilitated diffusion
osmosis
active transport
co transport
what is a glycoprotein and glycolipid
-glycoprotein is a protein with a carbohydrate attached to it
-glycolipid is a lipid with a carbohydrate attached to it
what is the role of a glycoprotein and glycolipid
- glycoprotein: receptors for chemical signals
-glycolipids: play a role in makers/ antigens
what is the definition of simple diffusion
the net movement of very small molecules from an area of high concentration to an area of low concentration, by simply moving across the phospholipid bilayer
what types of molecules are transported via simple diffusion
small
mostly uncharged
what is facilitated diffusion
the net movement of large or charged molecules from an area of high concentration to low concentration via carrier or channel proteins
what type of molecules are transported via facilitated diffusion
large
charged
what is the definition of active transport
the net movement of molecules from an area of low concentration to high concentration, travelling through a carrier protein. This process also requires energy from the breakdown of ATP
what is the definition of osmosis
the net movement of water particles from an are of high water potential to low water potential, through a partially permeable membrane
what is the main difference between carrier and channel proteins
The main difference between carrier and channel proteins is carrier proteins are not
open readily to both intracellular and extracellular environments, while a channel protein is open to both.
can carrier proteins change shape
yes
Describe the structure of a plasma (cell surface) membrane.
-phospholipid bilayer containing proteins ;
-head / hydrophilic region, facing outwards
-tail / hydrophobic region, facing inwards ;
-ref to intrinsic and extrinsic (glyco)proteins
idea of: glycoproteins / glycolipids, sticking out (of
bilayer / membrane);
cholesterol, inside bilayer / between phospholipids ;
can channel proteins change shape
no
what is meant by cell signalling
communication between cells
Describe the effect of high temperature on the structure of the yeast cell membranes.
-phospholipids / (named) molecules, vibrate more / have more kinetic energy ;
-increases, size / number, of gaps, in membrane /
between phospholipids ;
-bilayer, becomes more fluid / melts ;
-proteins / glycoproteins, denatured ;
State two functions of membranes within cells.
-control what substances, enter / leave, organelles
-site of (named), processes / reactions ;
provides surface for attachment (of enzymes / ribosomes)
What is permeability in the cell membrane affected by
-temperature
-pH
-solvent type
-Solvent concentration
Why do cell need to use cell signalling
-to control processes in the body and to respond to changes in the environment
How does increasing the temp increase membrane permeability
-higher temps means the phospholipids have more kinetic energy
-when temps get above 45 degrees the phospholipids breakdown and the membrane becomes more permeable and water in the cell increases
How does changing solvents/ their concentration affect membrane permeability
- Solvents dissolve the lipids in a cell membrane , so it looses it structure
How would you investigate how temp affects beetroot membrane permeability
1) Cut 5 equal size beetroot and rinse them off to remove pigment released during cutting
2) Place the 5 pieces in different test tubes with 5cm3 of water
3) place each test tube in a water bath at different temps for the same amount of time
4) Remove the beetroot from the tubes and place it through a colourimeter
What factors affect the rate of diffusion
- concentration gradient
-thickness of exchange surfaces
-surface area
-temperature
How does temp affect rate of diffusion
- higher temp, particles have more kinetic energy so they move faster
How does concentration gradient affect the rate of diffusion
the higher the concentration gradient the faster the rate of diffusion
How does the thickness of the exchange surface increase the rate of diffusion
short diffusion pathway so a faster rate of diffusion
why do some molecules get transported via endocytosis rather than via channel or carrier proteins
they are too large
what is endocytosis
is the process where cells take in substances from outside the cell
what is exocytosis
is the process where cells secrete substances from inside the cell to outside of the cell
what are the types of endocytosis and what do they do
-phagocytosis: The cell engulfs solid particles (e.g., bacteria).
-Pinocytosis: The cell takes in liquid substances (e.g., fluids or dissolved molecules).
Give a brief description of the process of endocytosis
- the cells surrounds the substance with its plasma membrane and the membrane pinches off to form a vesicle which contains the ingested substance
Give a brief description of the process of exocytosis
- The vesicle pinches off the Golgi apparatus and fuses with the cell membrane releasing its contents
Does endo and exocytosis use ATP
yah
what is hypertonic
A hypertonic solution has a higher concentration of solutes compared to the inside of the cell. This causes water to move out of the cell, leading to shrinking or crenation of the cell.
What is a hypotonic solution?
A hypotonic solution has a lower concentration of solutes than the inside of the cell. Water moves into the cell, which can lead to swelling or even lysis (bursting) of the cell.
Why is an isotonic solution important for red blood cells?
An isotonic solution is important for red blood cells because it prevents them from shrinking (in a hypertonic solution) or bursting (in a hypotonic solution), maintaining their shape and function.
What experiment can you do to investigate water potential
1) Prepare different concentration sucrose solutions by doing a serial dilution
2) Use a cork borer to cut potatoes into the same sized pieces
3)measure the mass of each potatoes
4) Place each potato in each solution for the same amount of time
5) remove them and pat them dry
6) Weigh the potatoes and record your results, calculate the percentage change and plot your results in a graph
