Cell Membrane
The cell membrane, also known as the plasma membrane, is a semipermeable barrier that separates the interior of a cell from the external environment. It is primarily composed of lipids, proteins, and carbohydrates.
Structure
The cell membrane is composed of a double layer of phospholipid molecules. Each phospholipid molecule has a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) tails. This arrangement forms a lipid bilayer in which the hydrophobic tails face inward and the hydrophilic heads face outward.
Function
The main functions of the cell membrane include:
- Selective Permeability: The cell membrane allows certain substances to pass through while restricting the passage of others. This helps in maintaining the internal environment of the cell.
- Cell Signaling: The membrane contains proteins that facilitate communication between the cell and its external environment.
- Cell Recognition: Carbohydrates attached to the proteins and lipids on the outer surface of the membrane help in cell recognition and identification.
Study Guide
Here are some key points to remember about the cell membrane:
- Describe the structure of the cell membrane, including the arrangement of phospholipid molecules.
- Explain the concept of selective permeability and give examples of molecules that can pass through the membrane.
- Discuss the role of proteins and carbohydrates in the function of the cell membrane.
- Explain the significance of the cell membrane in maintaining the internal environment of the cell.
- Describe how the cell membrane is involved in cell signaling and recognition.
◂Chemistry Worksheets and Study Guides High School. The Science of Chemistry
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The Science of Chemistry 
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The Science of Chemistry Worksheet/Answer key
The Science of Chemistry
Worksheet/Answer keyWorksheet/Answer keyThe resources above cover the following skills:
Nature of Science
The Practice of Science - A: Scientific inquiry is a multifaceted activity; The processes of science include the formulation of scientifically investigable questions, construction of investigations into those questions, the collection of appropriate data, the evaluation of the meaning of those data, and the communication of this evaluation. B: The processes of science frequently do not correspond to the traditional portrayal of ''the scientific method.'' C: Scientific argumentation is a necessary part of scientific inquiry and plays an important role in the generation and validation of scientific knowledge. D: Scientific knowledge is based on observation and inference; it is important to recognize that these are very different things. Not only does science require creativity in its methods and processes, but also in its questions and explanations.
Define a problem based on a specific body of knowledge, for example: biology, chemistry, physics, and earth/space science, and do the following:
Use tools to gather, analyze, and interpret data (this includes the use of measurement in metric and other systems, and also the generation and interpretation of graphical representations of data, including data tables and graphs)