Prokaryotes Vs Eukaryotes

Cells were first observed by Robert Hooke in 1665. The word “cell” was first coined by Hooke who got the term from monks who were very simple and their living quarters were called cells. There are two types of cells; prokaryote and eukaryote. The latin root “pro” is translated to primitive or before. Prokaryotes were the first cells and they contain no membrane bound organelles. Prokaryotes contain ribosomes, cytoplasm, DNA, and a plasma membrane, another key difference is that prokaryotes are much smaller than eukaryotes. Eukaryotes evolved much later and are also much larger. The latin root for “eu” is translated to true. Eukaryotes do contain membrane bound organelles.

Cells are small because cells work together and take on different tasks.

Cells also have to stay small enough for a surface-to-volume ratio that will allow adequate exchange with the environment. While cells are small, they must be large enough to have DNA and proteins.
All cells have a cytoskeleton. This gives cells shape, support, and structure. Cyto is the latin root for cell. Cytoskeletons are made of 2 categories of proteins: microtubules, which are fatter, and microfilaments, which are thinner. Cells also have cilia, short little hairs that aid in locomotion. One organelle not related to any endomembrane structures is peroxisome. Peroxisome breaks down the hydrogen peroxide in the cell.
Cells are about 70% water. In plant cells, the water will go straight to the central vacuole. The central vacuole is found only in plants cells and stores water, sugars, and wastes. Plant cells have cell walls. These cell walls do not let the cell burst. When full, the central vacuole can take up about 90% of the cell. This is called a turgid cell. An almost empty central vacuole is called a flaccid cell. A cell wall is made of cellulose, a sugar that humans cannot digest. Only some bacteria can digest it, which live in the stomach. The cell wall’s function is to give plant cells support and protection.
Another organelle that is only found in plant cells is chloroplast. Photosynthesis takes place in chloroplast. Chloroplast has stroma, which is located within the inner membrane of chloroplasts, between the grana. Grana is membranous sacs, each disk of granum is a thylakoid and each is green. Chlorophyll is a green pigment found in thylakoid. Chlorophyll is vital for photosynthesis because it makes energy in the form of sugar for the plant cell. This organelle is one of the three that have a double membrane. Chloroplast also contains DNA, and because of this scientist have developed a theory called the Endosymbiont theory. It’s the theory that mitochondria and chloroplast were once living creatures because they have double membrane and DNA, but they were somehow combined to live in mutualism.
Mitochondria are one of the three with a double membrane, and their main function is cellular respiration. Mitochondria have an inner and outer membrane, matrix and loops. The loops are called cristae. This is for efficiency, the cristae makes it that the mitochondria can convert oxygen to produce even more adenosine triphosphate (ATP). The matrix contains maternal DNA. The mitochondria is the powerhouse of the cell. The chemical reactions happen on the inner membrane. Brain cells, muscle cells, liver cells, and nerve cells use a lot of oxygen and have a lot of energy, which means these cells have a lot of mitochondria. Red blood cells have no mitochondria, and skin cells and fat cells have little to none mitochondria.
In eukaryotes there is the endomembrane system, which is composed of the different membranes that are in the cytoplasm within the cell. In eukaryotes the organelles of the endomembrane system include: the nuclear envelope, the endoplasmic reticulum, the Golgi apparatus, lysosomes, vacuoles, vesicles, and the cell membrane. The endomembrane system does not include the membranes of mitochondria or chloroplasts.
All cells have cell membranes, another name for cell membrane is plasma membrane. Cell membranes are made up of a kind of lipid called phospholipids. Lipids are fats and the phospholipids create a lipid bilayer. A part of the lipid is called the head, the head is always polar. The head is attracted to water because it is hydrophilic. Under the head is the tail, the tail is scared of water because it is hydrophobic. The tail is made of carbons, and for every carbon, there is a hydrogen attached. Tails can also be different lengths and can bend at the double bond part of the tail. Membranes also use cholesterol, and the cholesterol is used to stabilize the plasma membrane. Only certain things can pass through the plasma membrane. Water moves in and out easily through aquaporin channels. While water goes mostly in, carbon dioxide travels mostly out, these these can pass in and out easily because they are nonpolar. things like sodium and calcium need help getting through, because they are polar.
The nucleus is surrounded by a nuclear envelope, a double membrane that contains pores. These pores are too small for the DNA to go out of them. DNA is in the form of chromatin, thin strands of DNA wrapped around proteins. Even though the DNA never leaves the nucleus, RNA does. The nucleus is where ribosomes are made as well as ribosomal DNA. Inside the nucleus is the nucleolus and nuclear sap.
Lysosomes are also part of the endomembrane system.

The name lysosome derives from the Greek words ‘lysis’, which means dissolution or destruction, and ‘soma’, which means body. They have earned the nickname the suicide sac because of its role in autolysis, or the destruction of a cell through the action of its own enzymes. Lysosomes are smallish organelles filled with digestive enzymes. They go around the cell and looks for things to digest, they then fuse with organelle/vesicle or surround it to digest. Since certain cells are only supposed to live for a certain amount of time, lysosomes help with programed cell

death.
Another important organelle that is a part of the endomembrane system is the Golgi Apparatus, or the Golgi Bodies.

They look like several flatten sacs, stacked one on top of another and it’s function is to modify, package, and ship proteins for export from cell. Golgi Bodies have a shipping and receiving side; they receive things from the “cis” side and export things from the “trans” side. Vesicles are made from the Golgi Apparatus or plasma membrane and their function is to strictly to package the molecules in a cell.

Eukaryotic cells contain both smooth endoplasmic reticulum (SER) and rough endoplasmic reticulum (RER). The SER stores calcium, makes lipids, and detoxifies poisons. If you take a lot of medicine, you will end up having more SER in your liver, and if you take the same medicine over and over again, you could build up an immunity to it. The RER is where the plasma membrane is made, and where ribosomes are attached.

Ribosomes are smallest organelle and most numerous organelle. A ribosome nave no membrane, so Prokaryotes can have ribosomes. Ribosomes are made of ribosomal RNA (rRNA) and protein. Its function is to make proteins. Ribosomes are actually made in the nucleolus. There are free-floating ribosomes that make proteins that stay inside the cell, and there’s bound ribosomes on RER that make proteins that are exported out of

cell.