Bilberries Vaccinium myrtillus, European blueberry, blaeberry, whortleberry, bulberry, whinberry, winberry, trackleberry, huckleberry, fraughan The bilberry plant is a close relative of the blueberry and is amongst the numerous species in the Ericaceae family. The bilberry has historical uses since the 16th century based upon both the dried berries and leaves of this shrub.
Next Steps How do we study cell membranes? Cell membranes are phospholipid bilayers that are usually visualised by the 'fluid mosaic model' consisting of proteins, carbohydrate polymers and glycoproteins that are able to move around relatively freely amongst the phospholipids.
These molecules have many functions, including acting as channels to allow movement of molecules into and out of the cell, as cell signalling apparatus or even enzymes involved in metabolism.
The phospholipids have polar heads which are hydrophilic, and nonpolar tails which are hydrophobic. The hydrophobic tails mean that it is difficult for polar molecules which includes many substances that easily dissolve in water to pass through the membrane without the help of channels or other cell membrane machinery.
There are factors that affect the fluidity of the cell membrane, and these can affect membrane permeability making it easier for us to influence what substances can go into or out of cells. A typical A Level membrane permeability experiment involves investigating the influence of a named variable on the membrane permeability of a vegetable such as beetroot Beta vulgaris.
Common variables to investigate are the effect of solvents or temperature because both of these factors can change the fluidity of the membrane.
Beetroot is a useful subject for this experiment because of the distinctive betalains pigment that the stem tuber contains. These pigments are a useful indicator of membrane fluidity as they are typically contained within the vacuole of intact beetroot cells.
An increase in membrane fluidity will cause the pigment to leak out of the cell, and the amount of pigment can be measured simply by using a colorimeter. Don't forget to wash your cores thoroughly before the experiment, as we are interested in the amount of pigment that will leave intact cells, not those that have been damaged by coring.
Why are researchers interested in cell membranes? What variables should we consider? Variables are something that you should always be conscious of when conducting any experiment.
Some are common to most experiments like temperature, pH, concentration and surface area to volume ratio. Others can be quite specific, such as the impact of solvents on membrane permeability or the intensity of light when using a potometer to measure transpiration rates. Here, we will discuss the potential variables that could impact results in the membrane permeability experiment, but every experiment that you do has a range of variables to consider.
So, what are the variables that could affect cell membrane experiments? We already know that the two named variables that we are likely to investigate are the impact of solvents or temperature on membrane permeability, so whichever of these you are investigating, be sure to control the for the other.
For example, if you are measuring solvent concentrations then there might be potential for your solvent to react exothermically with a part of your experiment, therefore increasing the temperature.
You could control for this by monitoring the temperature of your samples as you perfrom each test, or by setting up the practical in a fixed temperature water bath. Surface area is a variable that you are unlikely to be investigating in this experiment, but is something that needs to be controlled during your experimental procedure.
All of the beetroot cores should be cut with the same corer and cut precisely to the desired length to ensure that they have the same mass and same surface area.
The power of the surface area affect can be massive.
Consider how much paint you would need to fully cover an entire football pitch. Probably a fair few tins? If your paint particles were only 1 nanometre thick and nanotechnology is starting to become available in paints then you would only need 1 cubic centimetre about a teaspoon of paint to cover your football pitch entirely!
In some practicals there may be a pH difference between the reactant and the product. For example, when measuring the effect of catalase concentration on hydrogen peroxide decomposition, the reactant, hydrogen peroxide, is acidic and the product, water plus oxygen gasis neutral.
Therefore this pH change could be affecting the reaction in addition to your experimental variable. A buffer solution can be used in such experiments to control small changes in pH, which will help to ensure the variable of interest is having the measured effect, rather than the pH.
In this episode we look at sampling techniques in fieldwork and the safe and ethical use of organisms in experiments. Why are membranes so important? The results of this experiment helps us to better understand the function and structure of cell membranes.
Once we understand the factors that can affect membrane permeability, we are then able to better understand the transport of molecules into and out of the cell. Cell membranes can also be highly specialised for very particular tasks, such as the villi of the epithelial cells in the small intestine, or the axon of a neurone, so understanding their typical function allows us to appreciate the way that these specialised cells are adept at carrying out their particular roles.
Currently, the most important aspect of transport across cell membranes for researchers is the rise of antibiotic resistance.
There are two main strategies that bacteria have when they develop resistance - either to prevent the antibiotic reaching its target, or to modify or bypass the target. There can be implications to membrane structure and function as part of both of these strategies.
Efflux pumps a kind of active transport that remove antibiotics and enzymes that modify or destroy them which can be extrinsic membrane proteins are ways that the membrane can be involved in resistance.
Resistance can be developed by the bacteria altering this peptidogylcan layer or the penicillin binding protein.
Some bacteria are also able to make their cell membranes less permeable to antibiotics as a method of resistance.“Can you keep a secret?” one of the marketing & brand organizers asked us. (Us being a three strong T(n)S Catering team located at Go Compare, Newport Wales.).
Effects of Temperature on Beetroot Cell Membranes Background Information: A cell membranes is a thin structure that surrounds the whole cell.
It contains the cytoplasm of a cell. The cell membrane is made up of hydrophilic region and a hydrophobic region. Lessons on cells and tissues for high schools, including leaves, roots, stems, plants in dry environments, phloem and xylem. RESOURCES FOR QUEENSLAND STUDENTS & TEACHERS DEADLY EEI IDEAS Ideas for Year 11 and 12 Biology Extended Experimental Investigations.
From Dr Richard Walding, BAppSc, MSc, MPhil, PhD, FAIP, FRACI, CChem, Griffith University, Australia. A website mainly aimed at students studying A-Level Biology - covers genetics, cells, biochemistry, enzymes, ecology, environment, photosynthesis, respiration, heart.
The aim of this practical is to use beetroot to examine the effect of temperature or alcohol on cell membranes and relate the effects observed to membrane structure.
To function correctly a cell needs to be able to control transport across the partially permeable cell membrane.