This is part two of the study of eukaryotes. This part two will consist of the study of the external structures of eukaryotes, the cytoplasmic membrane, which is the interface between the inner and the outer environment of the cell and the cytoplasm. Here's a brief overview of part two, we will look at the external structures of eukaryotes starting with the appendages or auxiliary organelles, which are the flagella and the cilia. Next, we will study the capsule and the cell wall, then the cytoplasmic membrane and finally, the cytoplasm. We will mainly focus on structure, composition and function for each of these items. The flagella is located within the cytoplasmic membrane And it is an extension of the cytoplasm.
The actual name shown here as one in width is the inner core Seidel skeletal structure. The shaft has tubulin protein, the shaft is shown in a cross section in five, and the tubulin protein in yellow, and the shape of it is in the form of microtubules. Nine pairs of chewable surround to chew balls in the center making a nine plus two structure in the shaft. The basal body shown as four in blue has nine triplets of microtubules and nano In the center, shown here as six and this structure is very similar to that of centrioles. Now, no hook connects the basal body and the shaft contrary to the prokaryotes, which have a hook in their flagella in terms of their function flagella are responsible for locomotion. Shown here are the details of the flagella structure and electron micrograph of the cross section of flagella at the levels of the shaft in red and the basal body in blue at the level of the shaft There are nine pairs Have microtubules surrounding two central microtubules whereas at the level of the basal body there are nine triplets of microtubules with none in the middle.
Interestingly, the basal body is structurally identical to that offer. century all. Examples of organisms that have flagella are grd alum Leah trichomonas, Virgin Alice, and creepin on Soma cruzi. The senior our hair like structures that extend the surface of the cell. They are shorter and more numerous than the flagella. The Celia also has a nine plus two structure of acronym at the level of the shaft As shown in this electron micrograph there are usually hundreds or thousands in number.
They beat with rhythm similar to a swimmer doing a butterfly stroke, the senior aide with clearance of mucus or dirt and they function by propulsion. Examples of microorganisms with cilia and of cells with cilia are epithelial tissue, which is shown in this top left image. staining in which you can see clearly the cilia at the top layer of the cell. to the top right is an SEM image of the nasal passage showing cilia. Then a typical micro organism that has Celia is the paramecium shown at the bottom left is a light microscopy image. And here is a diagram of the same with details of the internal structures such as the field vacuole.
Mouth for the macro nucleus and the micro nucleus contractile vacuole and Deanna pore. The capsule is a sticky structure anchored to the cell membrane via Koval and bonds. It has several functions. The main functions are to anchor one cell to another to strengthen the cell surface to provide protection against dehydration and for cell to cell recognition. capsules are absent in eukaryotes that have us A wall that is in plants and fungi shown in this electron micrograph is the glyco calyx that is the capsule of an amoeba glyco calyx is being shown as GL the cell membrane as M over here and then these dark structures are dense arrangement of dense material. So, once again shown here is the glyco calyx.
Now that we have studied the external structures let us focus on the cell membrane. I'm sorry, the cell wall. The cell wall is composed of various polysaccharides in plants the capsule is made up of cellulose in fungi It is made up of cellulose kit in our gluco mana in our game, it is made up of cellulose auger origin our SIS silicates. Again in plants the cell wall is made up of cellulose in fungi of cellulose, cotton or blue Camana in algae, cellulose, auger, Alden or silicates. The function of the cell wall is to provide shape and support against osmotic pressure. Shown here is a diagram of the plant cell wall.
It shows the cellulose micro fibrils in blue among other structures such as spectin and like now that we have studied the external structures we'll focus on the cell membrane. The eukaryotic cell membrane is a fluid mosaic of phospholipids and proteins. It is a bio layer containing steroid lipids, cholesterol in particular, fatty acid chains and Ester linkages. membrane grafts are unique feature of eukaryotes where small distinct regions of lipid and protein molecules that do not mix with other molecules. The membrane drafts serve in cell signaling, protein sorting and cell movement. The cell membrane has several functions such as passive and active transport endocytosis, phagocytosis and exocytosis.
Endocytosis involves engulfment of molecules such as proteins phagocytosis is ingestion of cell fragments microorganisms or foreign particles and exocytosis is a process by which the contents of the cell vacuole are released to the exterior. In this diagram of cell membrane the main characteristics to observe are the phospholipid bilayer, shown here on either side. The presence of glycol lipids and glyco proteins, shown here in green and blue. The presence of proteins such as the integral proteins, which span The whole membrane the peripheral proteins that are on either side of the membrane, as shown here 30 fro and the protein channels shown here that are pore forming proteins that allow ions and molecules to cross in and out by cell diffusion. The eukaryotic cell contains cholesterol shown here in the cell membrane eukaryotic cell membrane contain fatty acids that are unbranched. When these side chains of fatty acids are added to the glycerol, the organism uses Ester linkages in which one oxygen molecule is used to form the link with glycerol while the other is produced to the side.
And finally, in terms of striker metric is a de Esser all that is used in eukaryotic membranes. The cytoplasm consists of the cytosol and the organelles. the cytosol can also be known as intracellular fluid or cytoplasmic matrix. the cytosol is thus the liquid found inside the cells but not inside the organelles. It is also considered to be the complex mixture of substances dissolved in water including ions, minerals, amino acids and nucleotides, the cytosol within the cell membrane, and within the cytosol cell metabolism takes place. organelles are internal structures that are either members or non members.
They include examples such as mitochondria, Golgi, and micro filaments. Many of the organelles carry out metabolic reactions. One important concept to note is that the cytoplasm does not include the cell nucleus. Shown here at the top is a comparison of cytoplasm and cytosol. As you can see from this diagram, the cytoplasm includes everything inside the plasma membrane except the nucleus whereas the cytosol and compasses all that is inside the plasma memory Brain except the nucleus and the organelles. At the bottom left, you can see all that a cell consists of all of the cell membrane cytoplasm and nucleus.
At the bottom right you can see that the cytosol is included in is all that is included in the semi fluid liquid found inside the cell but not inside the nucleus and not inside the organelles. So, in summary, we have seen that the flagella and cilia are appendages of the cell that help with locomotion the flagella are long and few the Celia are short and many the capsule has several forms. functions including avoiding desiccation. It is absent in organisms that have a cell wall. A cell wall is mainly composed of cellulose. It can be found in plants, fungi, and alga only.
The cell membrane is a fluid mosaic model. It contains cholesterol and membrane graft.