5 Questions
Explain the functions of the cell membrane.
The functions of the cell membrane include acting as a semi-permeable barrier, maintaining the difference in composition of intracellular fluid (ICF), extracellular fluid (ECF), and fluid in various organelles, protecting the cell from toxic substances, excreting waste products, transporting nutrients, receiving chemical and electrical signals from the outside, and serving as a site for attachment to neighboring cells.
What is the importance of cell transport, and what are the mechanisms involved?
Cell transport is important for facilitating the transport of materials from the outside to the inside of the cells, or vice-versa. It is necessary for the survival of the cell. The mechanisms involved in cell transport include passive transport (movement of materials across the cell membrane without using cellular energy) and active transport (movement of materials across the cell membrane using cellular energy).
What is passive transport, and why is it important for cells?
Passive transport is the movement of materials across the cell membrane without using cellular energy. It is important for cells because it allows the movement of molecules from areas of high concentration to areas of low concentration, helping in the uptake of nutrients and removal of waste products without the need for cellular energy.
How does the cell membrane control the amount of substances that go into or out of the cell?
The cell membrane controls the amount of substances that go into or out of the cell through the processes of passive and active transport. Passive transport allows the movement of substances across the membrane without using cellular energy, while active transport uses cellular energy to move substances across the membrane.
What is the significance of the cell membrane in receiving signals from the outside?
The cell membrane plays a significant role in receiving chemical and electrical signals from the outside, which are important for various cellular processes and communication with other cells.
Study Notes
Cell Membrane Structure
- The cell membrane surrounds the entire cell and cell organelles, and is fluid in nature, allowing for the movement of molecules.
- The cell membrane is composed of a phospholipid bilayer, with a polar/hydrophilic head and a nonpolar/hydrophobic tail.
- There are two types of proteins in the cell membrane: integral proteins (carrier and channel proteins) and peripheral proteins (receptors and antigens).
Fluid Mosaic Model
- The fluid mosaic model describes the cell membrane as a fluid structure with proteins floating in a sea of phospholipids that also move.
- The movement of phospholipids and proteins allows for the fluidity of the membrane.
- Long chained and saturated fatty acids make the membrane stiff, while unsaturated fatty acids have more kinks, making the membrane more fluid.
- Cholesterol helps to maintain fluidity over a wide range of temperatures.
Membrane Asymmetry
- Regional asymmetry of the membrane exists, with different regions having different functions.
- Transverse asymmetry also occurs, where the two sides of the membrane have different compositions and functions.
Learning Objectives
- Define a concentration gradient and its importance in cell membrane transport.
- Understand the concept of tonicity and differentiate between isotonic, hypertonic, and hypotonic solutions.
- Know the different ways in which molecules move across the cell membrane, including passive and active transport.
- Compare the different types of cell transport, including diffusion, osmosis, and facilitated transport.
Test your knowledge on membrane transport, concentration gradients, tonicity, and the movement of molecules across the cell membrane.
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