A cell membrane is kind of like the guard that watches over the cell. It is a thin layer that surrounds the cell’s organelles and cytoplasm, and it ensures that only approved materials can enter and exit the cell.
Keeping the cell healthy is the main job of the cell membrane and to allow materials in and out it has small openings or doorways.
This ability is called being “permeable” and it lets those materials leave that are supposed to (such as waste), approved materials enter when they are supposed to (such as food); and it blocks anything that could be toxic to the health of the cell.
The cell membrane is often compared to a kind of “plastic bag” that has small holes and surrounds the cell.
Most of the structure of the membrane is made up of phospholipids, which make of the “bag”, and proteins that are found inside and outside of the holes to assist in moving materials in an out of the cell.
Sometimes called the “plasma membrane”, it’s so small (10 mm thick), that it can barely be seen using a transmission electronic microscope. Although both animal-like cells and plant-like cells have cell membranes, each type is different.
Cell Membranes in Animals:
Animal cell membranes differ from plant cell membranes because they have a harder membrane due containing a substance called cholesterol.
Unlike plant cell membranes, animal cell membranes have a single outside membrane that accomplishes all of the functions.
Cell Membranes in Plants:
Plant-like cells have a cell wall as the first layer of protection and the structure of this wall is very rigid.
The membrane as a secondary protection area and it’s found inside the cell wall. Since plant cell membranes have the sturdy wall, they don’t need the cholesterol that animal cell membranes use.
The plant cell membrane is a lot softer than animal cell membranes.
Fluid Mosaic:
Since the membrane is a kind of two-dimension flow, scientists refer to cell membranes as “fluid mosaic”. This is mainly because of the job that they do.
The plasma membrane is made up of the same materials that surround the organelles on the inside of the cell. Different species have different cell and membrane sizes, depending upon the purpose of the cell.
Membrane Transportation:
The term “membrane transportation” is a scientific name for the molecules that are allowed to enter and leave using the membrane access. There are two types of transportation:
Passive transport, which is the allowance of molecules to flow across the membrane from an area where they have a high population to one that has a low population.
This is also called the process of “diffusion” and we can see this happen to our fingers and toes when we are in the water for a long time. Diffusion is what lets water in and makes our fingers and toes wrinkly.
Active transport is the exact opposite, moving molecules from a low concentration to a higher one.
Fun Cell Membrane Facts
- Cell membranes are beyond small! – Cell membranes are so small that you would have to pack over 10,000 cell membranes on top of each other just to get something as thick as a piece of paper.
- The human body has a lot of cell membranes – If you add up all of the cell membranes in your body it would equal enough to cover four American football fields or 300,000 square feet.
- Cell membranes are like a data libraries – Cell membranes direct the traffic in and out of the cell through a complex design of information that it contains.
- Cell membranes are choosy – The cell membrane makes the decisions on what is ok to enter and what needs to leave a cell. This makes the cell membrane extremely selective.
- Carbohydrates are like name tags for cell membranes – Molecules make use of carbohydrates to form glycolipids and these are a kind of name tag announcement for the cell membrane. The glycolipids tell each cell and cell membrane what its job is and that of its neighbor so that the cells can all work together to get things done.
Interesting Facts about Biology
- The famous French chemist and microbiologist, Louis Pasteur, invented “pasteurization.” This process gets rid of the microorganisms in our food that can cause disease without affect the food quality. The milk that you drink has most likely been “pasteurized.”
- Termites are pesky insects, but unlike many insect types, the queen termite can have a very long life, often living to be as old as fifty years.
- Your brain controls both sides of your body, but in opposite ways that you might think. Your right side of the brain controls the left side of the body and the right side of your body is controlled by the left side of your brain.
- Saliva is what lets you “taste” your food. Some that suffer from lack of or low saliva never have the ability to truly taste what they are eating.
- You might think that being tickled is funny, but in reality, it is your body’s way of panicking. Your brain is telling you that there is a potential bug on you.
- Humans can’t swallow and breathe at the same time.
Cell Membrane Quiz
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