Thing to Know about Ribosomes

If you’d like to learn about the different cell structures, ribosomes should never be discounted. Ribosomes serve significant functions that are very essential in plant life and processes. It pays to know these details to better appreciate plant life down to its cellular level.

What Is a Ribosome?

The ribosome is a very important aspect of any cellular structure, particularly for the plant even if it is only a very small and dense organelle found in plant cell structures. They play a big role in assembling proteins. A ribosome can reach a measurement of 20 nanometers in diameter. Each one is composed of RNA and RNP. The ribosomal RNA comprises 65 percent of the organelle while 35 percent of it are the RNP or Ribonucleoprotein that serve as the proteins for the substance. Because of the presence of the proteins in ribosomes, many thought of it as an enzyme. It may be seen as a giant enzyme. However, the presence of the active RNA in this organelle sets it apart. They now have their own classification regarded as the ribozymes.

What Are the Components of a Ribosome?

It is important to understand the structure of ribosomes to grasp better its components and mechanisms. For plant cell structures, the ribosomes are located in the mitochondria of eukaryotes and in chloroplasts. These are organelles that are distinct to the plant life. However, there are studies that showed to share similar characteristics and subunits of prokaryotes, the ones found in most bacteria.

These ribosomes have their own structures with same components as others. The only way one may vary to the other is in the difference of sizes. Each one will contain a number of ribonucleic acid or RNA and other proteins. Every activity inside the membrane of the ribosome and the movement of the ribosomes itself depend on the RNA. The proteins ensure the stability of the organelle.

Functions of Ribosomes

Ribosomes mainly function to make proteins. They are even regarded as the workhorses in cellular structures because they are very significant in protein biosynthesis. It undertakes the process of translating RNA to proteins.

The biosynthetic process of making proteins takes certain steps. The roles of mRNA and tRNA come into play. The production of protein depends on the instructed genetic data in the RNA to be carried by the mRNA. The mRNA or messenger RNA is composed of a series of codons that carry the genetic expressions that dictate the sequences of amino acids essential for making proteins.

There are also the Transfer RNA or tRNA that delivers amino acids to the body of the ribosome. The molecules of the tRNA are utilized to pair the right type of amino acid with the codons in the mRNA template. Through this, the ribosome will be able to go through each codon until the proper pair is achieved. The translated expression from the mRNA and the amino acids from the tRNA will then be built into a polypeptide chain like the protein.

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Plastids 101: Cell Structures Education

There are life forms in this world that people can barely appreciate because of their very small structures but seemingly significant role in biological processes. Plastids are such structures that need to be comprehended more to appreciate plant life and processes down to its cellular level.

What Are Plastids?

Plastids are specialized structures that can be found in the cells of plants, algae and protista Among the living cells, these are the ones that can be clearly seen under the microscope. One will need to make use of a light microscope to be able to see them clearly. There are classes among plastids. There are the leucoplasts. These are colorless. They are useful in the storage of food molecules. Take for example the starch plastids called amyloplasts that are commonly found in the cell structures of potatoes. The colored plastids are called the chromoplasts. Among green plants, the colored plastids in action are the chloroplasts.

The Components of Plastids

To be able to further appreciate the components of plastids, particularly the ones found in plants, it is important to take note from where these organelles are derived. The origins of plastids are claimed to be from the endosymbiotic cyanobacteria. These will then grow into 1500 mya. In plants structures, it is important to look at the meristematic regions. These regions have proplastids or those components that are formerly known as the eoplasts. Proplastids contain one nucleoid and it can be found at the core of these regions. These are crucial to ensure the oxygen production of the eukaryotes. The plastids that are able to evolve in the plant structures are known as the chloroplasts.

The chloroplasts plastids can be specifically located in the cytoplasmic matrix area for the plant cells. They are very small with their ovoid or sometimes spherical shapes. These chloroplasts have double membranes. The inner membranes of these plastids are rich in protein substance called the stroma. These stromas then form a series that is called the granal network.

Granal networks are distinguishable because of their three-dimensional formation of cavities. When these cavities or vesicles are formed, they become known as the thylakoids. These thylakoids are responsible for storing green chlorophyll a and b. These are the elements that factor in to make the photosynthetic process possible.

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Mitochondrion: Components, Origin, Functions and Observation Techniques

In plant cell biology, the mitochondrion is an organelle that is found in nearly every eukaryotic organism. Shaped like a rod and enclosed by a double membrane (also called the phospholipids bi-layer), mitochondrion or its plural form, mitochondria, are sometimes referred to as the cell’s power plants because they are the source of the plant’s chemical energy. Mitochondria, which comes from the Greek words ‘mitos’ meaning thread and ‘khondrion’ meaning granule, contain the enzymes responsible for converting oxygen and carbohydrate, protein and fat metabolism products into ATP or adenosine triphosphate. ATP is the energy source that helps the cell perform its functions.

Components of the mitochondria
The mitochondria are considerably larger than many of the organelles contained within a plant cell. In fact, they are the second largest of the organelles that carry their own unique genetic material. The number of mitochondria that a single plant cell can contain varies, although cells that require higher levels of metabolic requirements typically have more. A mitochondrion measures about 5-10 micrometers long and about 0.5-1.0 micrometer wide. The outer membrane is smooth while the second, inner membrane is highly folded. The projections in this membrane are called cristae.

Most of the ATP that a mitochondrion will produce is found on the inner membrane, which is the ideal space for storage because of its surface area. Due to the fact that a mitochondrion has two membranes, it actually has three other compartments – 1) the intermembrane, which divides the inner and outer membranes, 2) the matrix, which is a liquid-filled compartment that contains enzymes that are necessary for aerobic respiration and 3) the folded membrane or cristae space where ATP is synthesized. The cristae also contain enzymes and transport proteins. These proteins carry molecules to the matrix after they are filtered by the inner membrane. Although a cell’s DNA is found mostly in the nucleus, each mitochondrion possesses its own genetic material, so it is capable of producing its own proteins and RNAs.

Mitochondria are not evenly distributed within the plant cell’s cytoplasm. Instead, they have been shown to clump together. They also exhibit evidence of a dynamic structure, capable of shifting positions and changing shape – from spherical to oval to bean-shaped to worm-like. Despite their common functions across plant species, mitochondria do not always appear in the same shape or size.

How mitochondria are formed

Mitochondria are formed when other mitochondria divide, which makes them acceptable as originating from endosymbiotic prokaryotes, primitive cells that do not contain a nucleus. Mitochondiral DNA and ribosomes are similar to that of prokaryotes. Since mitochondria have their own set of DNA, they can only develop through mitochondrial fission.

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Plant Cell Structures: The cell membrane and cell wallPlant cells are the fundamental unit of structure in most plants. And two of the most vital cell structures are the cell membrane and cell wall.The Cell Membrane

The cell membrane, also referred to as plasma membrane, is a semi-permeable lipid membrane. It contains lipids, biological molecules and proteins which help in the cellular processes.

The cell membrane acts as a separator or a skin that separates the extracellular environment from the intracellular components. The skin-like membrane can regulate substances that enter and exit the cell. Substances can move through the membrane passively (no cellular energy required) or actively (requiring cellular energy).

Certain proteins within the cell membrane function as signals to allow cells to interact. All throughout the cell membrane, protein receptors are found and function as signal receptors from other cells and from the environment. Other proteins on the cell membrane’s surface function as markers.

Cell membrane structure:

Integral membrane proteins are found all throughout the cell membrane surface. These can be viewed by an electron microscope or fluorescence microscope. These proteins include desmosomes, caveolaes, clathrin-coated pits, synapses and other structures that are vital for cell adhesion.

The cell membrane contains a cytoskeleton that also serves as an anchor for forming organelles and other proteins. The cytoskeleton can form limb-like organelles that develop from the cell’s surface are covered by the cell membrane. These limb-like extensions of the cell are called microvilli and they increase the cell’s surface area which in turn increases nutrient absorption.

The fluid mosaic model of Singer and Nicholson states that biological membranes could be made up of two-dimensional fluid where protein and lipid molecules can diffuse less or more freely. But plasma membranes contain various structures such as protein complexes, actin-based cytoskeleton, lipid drafts and either desmosomes or synapses.

The cell membrane is composed of three types of amphipathic lipids namely phospholipids, steroids and glycolipids. Composition of each type vary from one cell type to another, but in most cases the phospholipids are more predominant.

Fatty acid chains found in glycolipids and phospholipids normally equal in number, around 14 to 24. These fatty acids may be unsaturated or saturated. Unsaturation degree and length usually affects the fluidity of the membranes.

Hydrophobic tails which held the entire cell membrane is quite fluid. The fluidity of the cell membrane is attributed to the phospholipids molecules allows it to freely diffuse.

The protein content of a typical cell membrane is about 50%. Proteins are quite vital for cell development and function. There are three membrane proteins namely integral proteins, lipid anchor proteins and peripheral proteins.

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The Cell Nucleus

The nucleus is the most prominent feature of a eukaryotic cell – cells that have nuclei. It is quite easy to recognize the nucleus when you look at a cell through microscope as it is an organelle that is enclosed by a membrane, forming a very distinct “center” in the cellular structure. The nucleus houses majority of the genetic material of the cell, particularly the molecules of DNA that are responsible for the control of the cell’s general activity, which in turn expresses the organism’s identity. It is the nucleus that maintains the expression of genes by managing the cell’s activities based on the genetic plan imprinted in the organism.

Components of the Nucleus

The nucleus is comprised of the nuclear envelope, the cytoskeleton, chromosomes, the nucleolus, and sub-nuclear bodies.

1. The Nuclear Envelope – this serves as the container that keeps materials within the nucleus, allowing just some items to pass through and from by means of little holes. The nuclear envelope is comprised of two cell membranes that act as parallel walls. The little holes are called nuclear pores and act as a regulatory system of the nucleus so that only water-soluble substances are allowed to enter and exit.

2. Cytoskeleton – this provides mechanical support in animal cells. The cytoskeleton is actually a web of intermediate filaments that both give the nuclear envelope structural support and the chromosomes anchoring sites. The cytoskeleton is made of nuclear lamina, which are comprised of proteins called lamins.

3. Chromosomes – these are structures that contains most of the genetic material of the cell in the form of several molecules of DNA. For majority of the cell’s cycle, chromosomes are organized in a complex of DNA-proteins known as chromatin but when the cell divides, the chromosomes become well defined and are seen as pairs of rods that line up to be split.

4. The Nucleolus – when you look closely at a nucleus, you might observe a dense structure that seems to be a “nucleus” of the nucleus. This is the a concentration of genetic material. However, the nucleolus is not enveloped by a membrane like the nucleus. It is where several strands of DNA, rDNA, and RNA congregate.

5. Subnuclear bodies – there are other distinct components of the nucleus that, like the nucleolus, are not delineated by a membrane. These include the Cajal bodies or gems, PTF and PIKA domains, promyelocytic leukaemia bodies, paraspeckles, splicing speckles. These subnuclear bodies contribute to the genetic function of the nucleus.

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