- Summary list for topic 1.3 Membrane structure
- Mindmaps
- Skills video tutorial
- Model answer
- Model answer:
- Multiple choice quiz
- 1.3 Membrane structure 1/1
The first models of membranes included protein and phospholipids but not in the same structure as we see them today. In this topic the components of cell membranes are investigated and the structure of the membranes as fluid and dynamic structures is outlined.Learn and test your biological vocabulary for Membrane structure 1.3 using these flash cards
Summary list for topic 1.3 Membrane structure
- Phospholipids form bilayers in water due to the amphipathic properties of phospholipid molecules.
- Membrane proteins are diverse in terms of structure, position in the membrane and function.
- Cholesterol is a component of animal cell membranes.
- Application: Cholesterol in mammalian membranes reduces membrane fluidity and permeability to some solutes.
- Can you draw a diagram of the fluid mosaic model.
- Can you explain how evidence from electron microscopy led to the proposal of the Davson-Danielli model.
- Can you outline the evidence which led to the falsification of the Davson-Danielli model and support of the Singer-Nicolson model.
Mindmaps
This diagram summaries the main sections of topic 1.3 about membrane structure.
Test if you can draw your own list or concept map from memory.
Skills video tutorial
Explaining plasma membrane structure and the structure and function of the molecules in the membrane is an important skill in this topic. This video tutorial explains how to draw a simple 2D diagram of a cell membrane, and label it for an IB Biology exam.
How to draw a membrane diagram in an exam from David Faure on Vimeo.
Describe three functions of membrane proteins. (4)
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Hint: Membrane proteins can have several functions. In an answer to a 'describe' question don't just list the functions, describe that function too, giving an example if possible.
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This question requires knowledge of phospholipids and how they form the bilayer structure of the plasma membrane.
Explain the role of phospholipids in plasma membrane structure. (5 marks).
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Examiners hint: for Explain questions, give a description and a reason or cause.
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Multiple choice quiz
This quiz contains a set of multiple choice questions covering the membrane structure topic. Explanations of each answer are displayed after you click to check the answer(s).
START QUIZ!
Which property of phospholipid molecules describes the fact that they have both hydrophobic and hydrophilic parts?
Phospholipids form bilayers in water due to the amphipathic properties of phospholipid molecules. The hydrophobic tails attract each other and the hydrophilic phosphates are attracted to the water.
Amphoteric substances may behave either as an acid or a base depending on the environment. Amino acids are said to be amphoteric because they both have a basic group (amine: NH2/NH3+) and an acid group (carboxylic acid) but this doesn't help them form bilayers.
Which of the following is true of peripheral proteins in cell membranes?
Membrane proteins are diverse in terms of structure, position in the membrane and function.
Peripheral proteins are attached to the membrane but found on its surface.
What effect does reducing the amount of cholesterol in a cell membrane have on its properties?
Cholesterol is a component of animal cell membranes. Application: Cholesterol in mammalian membranes reduces membrane fluidity and permeability to some solutes.
The photograph is from an electron microscope image of a membranes.
Parallel dark lines are clearly seen.
In electron micrography, heavy metal stains are often used to enhance contrast. DNA and Proteins often show as dark areas because these molecules can attach to the stain.
Which of the following interpretations is most similar to the proposal of the Daveson-Danielli model of membranes?
Students are expected to know how to use evidence from electron microscopy to support an idea about membranes. One illustration of this is the proposal of the Davson-Danielli model.
Further evidence lead to the falsification of the Davson-Danielli model and the proposal of the fluid mozaic model.
The illustration shown below is of a protein (green) attached to a membrane.
What is the most likely function of this membrane protein?
This protein is found in the human liver, where the hormone adrenaline indirectly stimulates it to mobilise stored energy inside liver cells in the "fight or flight" response.
The fact that it is a transmembrane protein is essential for this function.
It is interesting to note that this protein is also secreted by Anthrax bacteria as a toxin.
It upsets the metabolism of host cells when it enters them.
What is the name given to the type of molecule found in membranes which is made from carbohydrate and protein.
Glycoproteins have many functions in the human body, many involve interactions between cells.
Interestingly the hormones, FSH and LH are also glycoproteins.
Drag and drop activities
Test your construction of biological explanations using the drag and drop questions below.
The structure of cholesterol and its role in membrane structure.
Drag and drop the correct term into the gap to describe the structure and role of cholesterol in the plasma membrane.
fluid rigidity rigid hydrophilic water-soluble permeability anchoring amphipathic hydrophobic tails vesicles
Cholesterol is an lipid which gives to the cell membrane by binding in-between the of the phospholipid molecules in the bilayer close to the heads of the phospholipids.
This allows the membrane to be but to retain a definite structure such as in the formation of .
The more cholesterol present, the more the membrane.
As it is a lipid, it also reduces to molecules.
It aids in proteins to the bilayer.
Explanation/Examiner hint. Structure and role means both must be in your response to gain full marks.
Just for fun
If you want to review key terminology and have some fun with your revision try this. It will help you remember the terms through repetition. Membrane structure card match game.
Alternatively this choice of Arcade games will help you to practise the basics while having fun. Arcade game "Membrane structure".
How much of Membrane structure 1.3 have you understood?
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