Essential idea: Membranes control the composition of cells by active and passive transport.
The image above is a piece of artwork inspired by the complexity of an E. Coli. Complexity in cell structure is much greater in Eukaryotes and this only possible through the compartmentalisation and the selective transport membranes allow.
Understandings, applications and skills:
|1.4.U1||Particles move across membranes by simple diffusion, facilitated diffusion, osmosis and active transport.|
|1.4.U2||The fluidity of membranes allows materials to be taken into cells by endocytosis or released by exocytosis.|
|1.4.U3||Vesicles move materials within cells.|
|1.4.A1||Structure and function of sodium–potassium pumps for active transport and potassium channels for facilitated diffusion in axons.|
|1.4.A2||Tissues or organs to be used in medical procedures must be bathed in a solution with the same osmolarity as the cytoplasm to prevent osmosis.|
|1.4.S1||Estimation of osmolarity in tissues by bathing samples in hypotonic and hypertonic solutions. (Practical 2) [Osmosis experiments are a useful opportunity to stress the need for accurate mass and volume measurements in scientific experiments.]|
[Text in square brackets indicates guidance notes]
A fast paced introduction to membrane transport by Hank Green from Crash Course
A rap by Mr W to introduce you to how water moves in and out of cells
Presentation and notes
The presentation is designed to help your understanding. The notes outline is intended to be used as a framework for the development of student notes to aid revision.
Correct use of terminology is a key skill in Biology. It is essential to use key terms correctly when communicating your understanding, particularly in assessments. Use the quizlet flashcards or other tools such as learn, scatter, space race, speller and test to help you master the vocabulary.
Bubbles - modelling membranes
Investigate membranes structure and transport using bubbles from Ms Purdy.
Extension: can you use your equipment to model endosymbiosis and exocytosis?
Observing plasmolysis and turgor in plant cells by Practical Biology
1.4.S1 Estimation of osmolarity in tissues by bathing samples in hypotonic and hypertonic solutions. (Practical 2) - ideas and links given in the presentation
Quick quiz Use the BioK Quick Quiz on 1.4 Membrane transport (as directed) to check your understanding of the topic.
Nature of science:
Experimental design—accurate quantitative measurement in osmosis experiments are essential. (3.1) (covered by the practical and processing of data)
Video on vesicles move materials within cells by Stephanie Castle
Video on Endocytosis and Exocytosis by Stephanie Castle
Membrane transport by Wisconsin online
Cellular transport by Interactive concepts in biochemistry
Cell transport tutorials and notes by National Louis University
Membrane Structure and Transport and Membrane Dynamics & Communication plus quizzes to test your learning by Biocoach
Molecules move across the cell membrane by Sunamas Inc.
Diffusion, osmosis and facilitated diffusion
The cell: passive transport diffusion by Wisconsin online
How diffusion works by McGraw and Hill
Passive transport: filtration and facilitated diffusion by Wisconsin online
How osmosis works by McGraw Hill
Osmosis animation by St. Olaf College
Isotonic equilibrium by Carnegie Mellon
Facilitated diffusion by St. Olaf College
Facilitated diffusion by Northland Community and Technical College
Passive transport by W H Freeman Lifewire
Cotransport by McGraw and Hill
Sodium-potassium exchange pump by McGraw and Hill
Proton pump by McGraw and Hill
Examples of active transport, uniports, symports, antiports (e.g. resting potential in neurones) by St. Olaf College
Macromolecules by Lifewire from W H Freeman
Endoplasmic reticulum and Golgi apparatus by W H Freeman Lifewire
Vesicle budding and fusing by Sunamas Inc
Lysosomes by McGraw and Hill
Endocytosis and exocytosis by McGraw and Hill
Phagocytosis (endocytosis) by McGraw and Hill
Endocytosis of LDL by Candlelight productions
Directing Traffic: How Vesicles Transport Cargo - learn more about vesicles and see them in action on this learn.genetics tutorial
Protein synthesis and exocytosis by St. Olaf College
Plasmolysis of red onion epidermis as seen under a light microscope
Liposomes are artificial vesicles which are used to transport drugs around the body and deliver them to specific cells. To find out more about this medical use of membranes use the links below:
Liposomes tutorial and animation
Video introduction from Encapsula Nanosciences (below)
Fun and clever rap from the Stanford Biologists
Play a game
Against the gradient uses your knowledge of the different modes of membrane transport to solve puzzles