Explain The Intracellular Compartments Of A Cell

[4] – Frank Schluenzen et al, Structure of Functionally Active Small Ribosomal Subunit at 3.3A Resolution

Mitochondria and chloroplasts have two membranes that surround them. The inner membrane is probably from the engulfed bacterium and this is supported by that the enzymes and proteins are most like their counterparts in prokaryotes. The outer membrane is formed from the plasma membrane or endoplasmic reticulum of the host cell. The electron transport enzymes and the H+ ATPase are only found in the mitochondria and chloroplasts of the eukaryotic cell. (2)

Analyze the anatomical structure of ten different organelles in the cell and their respective functions.

▪ Know the functions of the various organelles, e.g., glyoxysomes, peroxisomes, ribosomes, chloroplasts, mitochondria, rough and smooth ER, Golgi, etc.

The cell membrane consists of eight distinctive parts that each have their own unique structure and function. The phospholipid bilayer is an integral part of the cell membrane because it is the external layer of the cell membrane and composes the barriers that isolate the internal cell components and organelles from the extracellular environment. It is composed of a series of phospholipids that have a hydrophobic region and a hydrophilic region. These regions are composed of the hydrophilic heads and the hydrophobic tails of the phospholipids, this organization of the polar heads and nonpolar tails allows the heads of the cell to form hydrogen bonds with water molecules while the tails are able to avoid water. The phospholipid bilayer also has many important functions within the cell, it gives the cell shape, provides protection, and it is selectively permeable which allows it to only let very specific molecules pass through its surface. The phospholipid bilayer is an important structure because it prevents harmful and unwanted molecules from entering the cell and isolates organelles which helps to maintain the internal environmental homeostasis of the cell.

Introduction: Cell membranes contain many different types of molecules which have different roles in the overall structure of the membrane. Phospholipids form a bilayer, which is the basic structure of the membrane. Their non-polar tails form a barrier to most water soluble substances. Membrane proteins serves as channels for transport of metabolites, some act as enzymes or carriers, while some are receptors. Lastly carbohydrate molecules of the membrane are relatively short-chain polysaccharides, which has multiple functions, for example, cell-cell recognition and acting as receptor sites for chemical signals.

All cells have a cell membrane. The structure of membranes is formed from a double layer of phospholipids with proteins floating in it. The proteins are embedded on the surface and inside or bridge the double layers of phospholipids. This structure is called a mosaic model. The main function of cell membranes is to provide protection and support for the cell and they also control what enter and exit the cell to maintain internal balance, called homeostasis. There are two types of a membrane protein: integral proteins and peripheral proteins. The integral membrane proteins are

Membranes and Their Functions Membranes form boundaries both around the cell (the plasma membrane) and around distinct sub cellular compartments (e.g. nucleus, mitochondria, lysosomes, etc.). They act as selectively permeable barriers allowing the inside environment of the cell or the organelle to differ from that outside. Membranes are involved in signaling processes; they contain specified receptors for external stimuli and are involved in both chemical and electrical signal generation. All membranes contain two basic components: lipids (mainly phospholipids) and proteins. Some membranes also contain carbohydrate.

P1 – Describe the microstructure of a typical animal cell and the functions of the main cell components. A typical animal cell is seen as a tiny, three dimensional sac which is in fact made up of many components, each as important as the other. The microstructure of an animal cell was in fact uncovered mainly through the use of both cell fractionation and electron microscopy. Each main component has its own, individual function which helps a cell to function and maintains the cell membrane. The components that I will be describing include the cell membrane, nucleus, cytoplasm, mitochondria, lysosomes, Golgi bodies, centrioles, endoplasmic reticulum (both smooth and rough) and ribosomes.

A mitochondrion is a rod-shaped organelle that generates power. In a eukaryotic cell, the mitochondria act as ATP factories. Which helps release energy for the cells to carry out their jobs. They have an outer membrane made from phospholipid bilayers with embedded proteins. to help regulate the organelle They have proteins within them. In the outer membrane Porins are found. “Porins are beta barrel proteins that cross a cellular membrane and act as a pore, through which molecules can diffuse.” Porins allow Passive diffusion because they are large enough to pass through unlike other membrane transport proteins. For example, they act as channels that are specific

The cell membrane is made of phospholipids and proteins, like eukaryotic membranes, and controls the entry and exit of substances into and out of the cell. The mesosome is a tightly folded region of the cell membrane containing all the membrane-bound proteins required for respiration and photosynthesis. The flagellum is a rigid rotating helical-shaped tail used for propulsion. The motor is embedded in the cell membrane and is driven by a H+ gradient across the membrane. A clockwise rotation drives the cell forwards, while an anticlockwise rotation causes a chaotic spin.

Structurally mitochondria are made up of an outer and inner membrane; which are separated by the intermembrane space. The outer membrane is composed of about a 1:1 ratio by weight of protein to phospholipid lipid, similar to the eukaryotic plasma membrane. The outer membrane contains integral membrane proteins called porins that greatly increase the permeability of the membrane by allowing passage of high molecular weight molecules. The inner membrane is composed of a very high ratio of protein to phospholipid (3:1 by weight), a much higher proportion of protein than found in other eukaryotic membranes. The inner membrane is much less permeable and most molecules require special membrane-spanning transport proteins to enter or exit the matrix

These compartments allow the chemicals involved in a particular process in the cell, such as photosynthesis or respiration to be kept separate from the rest of the cytoplasm. This cell structure and high degree of internal organisation optimizes essential chemical reactions, and allows the processes within the cell to function. The fluid that occupies the space between the organelles is called the cytosol, a solution containing a complex mixture of enzymes, amino acids and waste materials.

Then the second part of the secretory pathway takes place by sending these modified proteins to the Golgi complex by packing them into anterograde vesicles. These vesicles bind to the cis-cisternae of the Golgi, then through the process of cisternal maturation, move across the medial Golgi, to reach the trans-Golgi. As a protein moves through the Golgi complex before it reaches the trans-golgi, further modifications can occur. (Specifically the carbohydrates that were attached to the proteins in the ER can get further modified by glycosyl transferases. The Golgi can also perform O-linked glycosylation like the ER).

The cytoplasm is a semifluid in the plasma membrane. It is in all eukaryotic cells. In prokaryotes, this is where the chemical processes of the cell take place. In eukaryotic cells, this is where organelles perform their functions. Cellular respiration also takes place here. One of stages of cellular respiration is glycolysis. Glycolysis is when glucose breaks down to form two pyruvates and 4 ATP. Its net result of 2 ATP is important for another process called the Krebs Cycle. This process is important because it begins cellular respiration. The cytoplasm also gives the cell its shape; without it, the cell would be “deflated” and substances would not be able to move throughout the cell. Organelles would have difficulty functioning too. It has been misunderstood that organelles float freely in the cytoplasm even