Cell Walls, Membranes, Cytoplasm, and Cytoskeleton
The Cell Wall "the fence"
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Cell walls are like a protective fence that protects and maintains the shape of a cell. Cell walls are found in all cells but animal cells. It's made up of polysaccharides and found outside the membrane. In small cells, cell walls can be bendy, but in large plants like trees the cell walls are hard and sturdy. There are two types of cell walls. There is a primary cell wall, which forms outside of the membrane. It's thin and found in all plant cells and is mostly made up of cellulose. Another wall can form after it called the secondary cell wall, which is between the membrane and the primary wall. It is thick and not elastic, unlike the primary wall. It is made up of hemicelluloses, lignin, and pectin. Together, they provide a very durable and strong barrier.
The Plasma Membrane
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The cell membrane is a thin barrier that surrounds the cell and is also essential to the cell. It is selectively permeable, meaning it only allows certain substances to come in or out. It is composed of mostly phospholipids, cholesterol, proteins, and carbohydrates. Some organelles have a membrane of their own, like the nucleus. A fluid mosaic model is used to show you the structure of the membrane. In the model, you can see the phospholipids have a head and a tail. The heads are hydrophilic, meaning they like water. The tails are hydrophobic, meaning they don't like the water. The tails face each other to avoid the water, and the heads face outward. This created a lipid bilayer in the membrane. The proteins in the membrane have their own specific jobs, like some proteins are transport proteins which transport molecules through the membrane.
The Cytoplasm "the air"
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The gel-like fluid that fills the cell is called the cytoplasm. It's compared to the air because it fills the empty space of everything. The cytosol is the actual "soup" of it and all the organelles live in it. It is about 70-80% water, but theres many molecules that are found in the cytoplasm, such as fatty acids, enzymes, sugars, and amino acids.
The Cytoskeleton "the INFRASTRUCTURE"
The cytoskeleton is the infrastructure of the cell. It provides shape and structure and contain three different parts: the microtubules, microfilaments, and intermediate filaments.
Microtubules
The microtubules are long and straight cylinders with a diameter of 25-30 nanometers. They are made up of tubulins, specifically beta and alpha tubulins. Microtubules aid in moving organelles around the cell like vesicles.
Microfilaments
Microfilaments are also called actin filaments because they are made up of the polymers of actin. They are the smallest filaments in the cytoskeleton, being only 8 nm in diameter. They form a band below the membrane to provide strength and movement. They can be found in muscle tissues.
Intermediate Filaments
Intermediate filaments are about 8-12 nm in diameter and are made up of different types of proteins. They are important in providing structure and support for the membrane.
Microtubules
The microtubules are long and straight cylinders with a diameter of 25-30 nanometers. They are made up of tubulins, specifically beta and alpha tubulins. Microtubules aid in moving organelles around the cell like vesicles.
Microfilaments
Microfilaments are also called actin filaments because they are made up of the polymers of actin. They are the smallest filaments in the cytoskeleton, being only 8 nm in diameter. They form a band below the membrane to provide strength and movement. They can be found in muscle tissues.
Intermediate Filaments
Intermediate filaments are about 8-12 nm in diameter and are made up of different types of proteins. They are important in providing structure and support for the membrane.