Hi, and welcome to the part two of the study of prokaryotes. In part one, we had looked at the characteristics of prokaryotes, the taxa a few examples and the external structures of the prokaryotes. So now we will look at the cytoplasmic membrane, which is the interface between the outer and the inner environment of the cell, and then the cytoplasm And finally, the internal structures of the cell. We will briefly look at the schematic overview of a prokaryotic cell. For that purpose we'll focus on the structure of bacteria. In this schematic, we can notice the plasma membrane In this dark blue line surrounding the cytoplasm, the cytoplasm in this light blue color, the internal structure such as the ribosomes shown here in red, and the inclusion bodies shown in purple, as we have studied before, the nucleoid region where the DNA is located and the plasmid is an extra chromosomal DNA present in some bacteria.

Now, we will focus on the cytoplasmic membrane, we will look at its composition and function and at the differences between bacterial and archaeal cell membranes. bacterial cytoplasmic membranes are made up of phospholipids and proteins. It has a phospholipid by layer structure in which the phosphate has shown here in yellow are hydrophilic or water loving and hydrocarbon. canes are hydrophobic or water fearing facing each other on each side of the by layer membrane. And here they're shown in green. The proteins found in the membrane can be integral protein spanning all Through the full layer of the bilateral membrane, or they can be on each side of the membrane known as peripheral protein.

The main aspect of the cell membrane to note is that it has a fluid mosaic model. This means that the membrane is dynamic with the movement of proteins from one place to another within the membrane, and with the flip flop movement of the proteins as well. The function of the bacterial cell membrane is similar to that of all biological membranes. They include selective permeability, concentration gradient, electrical or electrochemical gradients. Also the cell membranes aid in the transport of solids and solvents through passive or active transport. Shown here are examples of hydrogen ion gradient, in which there is a higher concentration of hydrogen ions on the outside of the cell compared to the inside of the cell.

This concentration gradient is maintained by an ATP enzyme that is present on the membrane. The next example is that of diffusion in diffusion. So, new such as ions diffuse from a higher to a lower concentration gradients examples are the chloride ions shown here in green And the sodium ions shown in blue, moving from the outside of the cell to the inside of the cell, and potassium ion shown in purple moving from the inside of the cell to the outside of the cell. What needs to be noticed also is that there is a net positive charge on the outside of the cell over here, and a net negative charge on the inside of the cell. This is known as electrochemical gradient. In osmosis, water moves from an area of less solutes oops, excuse me.

Going back, off less solid to an area of more solids, trying to actually break the water concentration on each side. Finally, one special function of the cytoplasmic membrane in prokaryotes is that of energy metabolism. We had looked at differences in the bacterial and archaeal cell walls. Now we will look at differences between bacterial and archaeal cell membranes wildly while bacteria and actually you carrier. Use fatty acids as their side chains in the phospholipids archaea use the fingernail side chains which are branched as you can see here by these projections. Why bacteria and archaea as well have a bio layer as shown over here, two layers on each side.

Archaea have a mono layer cell membrane shown as one layer. Also, the linkages that bacteria and archaea use are the Ester linkages. Whereas the archaea use the ether linkages shown here as CEO. Whereas for Esther it is co summarized here are the same observations archaeal cell membranes have branch fitter nails side chains. Instead of fatty acids. The fiddle chains are connected to the glycerol by ether linkages into of Ester linkages, the limitations of the archaea are longer and form a mono layer instead of the bio layer.

This has particular advantage for the archaea that are hyper thermal files, since it prevents easy peeling of the membrane, which could easily happen for the typical bio layer of the bacteria. In this part, we will focus on the cytoplasm which is composed of the cytosol and the bacterial sub compartments also known as the internal structures. The cytoplasm is the gelatinous material found inside the cell and enclosed by the cell membrane. It consists of the cytosol and the bacterial sub compartments. So, if you remove all the sub compartment within the cell, all that remains is the cytosol. the cytosol is the semi fluid mass of proteins, amino acids, sugars, nucleotides, salts, what vitamins, and ions all of these dissolved in water.

The sub compartments are mainly inclusions and spores and non membranous organelles. inclusions are reserved deposits of nutrients or compounds. So, these are structures that store nutrients such as lipids and starch and compounds such as nitrogen, phosphate, and sulfur. These nutrients and compounds are taken up in abundance when needed and used when there are scars in the environment. And the spores are tough, dormant non reproductive structures used as a defensive strategy Against hostile or unfavorable conditions as when there is a drought or in extreme heat. They are also capable of causing disease example of bacteria that have no spores are bacillus and Clostridium.

Finally non membranous organelles include ribosomes and cytoskeleton. Since bacterial compartments are the internal structures of a bacteria, let us study those in detail. We'll start with endless fours and inclusions, and then with ribosomes and cytoskeleton, emphasizing structure and function. Fingers A and B in the top panel referred to no sports in the top panel figure a is a staining of endo spores, as you can see them over here. In these circles figure B is a schematic of the process of formation of intersperse, it starts with a vegetative cell. that divides unequally the smaller part develops a spore code, which then thickens until it finally becomes a free end of spore.

And as far as are resistant to heat desiccation and radiation, however, they can be destroyed by burning or autoclaving. This C and D in the bottom panel relate to inclusion bodies finger see, on the left, you see a differential interference contrast image are the other b i see image and on the left you see a fluorescence microscopy image, the dark spots in the DRC and the blue highlighted spots in the fluorescence microscopy image and the green spots are all inclusion bodies within the precariat. Figure D is showing the staining of bacteria. The inset image is showing the outline in yellow. of two bacteria within which are metal chromatic granules stained in dark blue. Meta chromatic granules are also examples of inclusion bodies.

Let me cells have thousands of ribosomes. The size of a ribosome is expressed in swedberg units and it is determined by the sedimentation rate. In prokaryotes ribosomes are 70 s. All ribosomes are made up of two subunits. In prokaryotes, the subunits are a smaller 30 s subunit and a larger 50 s subunit. The subunits are made up of polypeptides and ribosomal RNA, because the sedimentation rate depends not only on the size and mass but also on the shape. The addition of a 30 s subunit with a 50 s subunit does not add up directly to 80 s but to a 70 s ribosome as shown over here decided skeleton of prokaryotes is the collective name for all structural filaments.

It is the internal network of fibers. The cytoskeleton provides shape and movement. Now finally, a summary of prokaryotes, part two, and prokaryotes in general. It is part two of the study of prokaryotes. We looked at the prokaryotic cell membrane, which is a phospholipid by layer with a fluid mosaic Model Model. We saw the three main differences between the bacterial and archaeal cell membranes.

We studied that the cytoplasm is composed of the cytosol and sub compartments also known as internal structures. They internal structures include the endless force inclusion bodies, ribosomes, and cytoskeleton. As a recap, by definition, the word pro means before and carry out means nucleus. prokaryotes are those organisms that existed before there was a nucleus. Therefore, these micro organisms do not have a nuclear membrane surrounding their genetic material. Instead, the DNA is falling in a region which is known as a nuclear void.

Prokaryotes also have no membrane bound organelles in their cytoplasm. Or in other words, they lack a number of internal structures that are bound With a phospholipid membrane. The chromosome of prokaryotes is small and circular, double stranded DNA. Some prokaryotes also have plasmids that are separate from the chromosome and replicate independently from the chromosome. Overall, prokaryotes are small and simple organisms when compared to eukaryotes. This concludes the study of prokaryotes.