Parts Of The Cell And Its Function – Have you ever heard the saying “form follows function”? This is a philosophy that guides many industries. In architecture, this means that buildings should be constructed to support the activities that will take place inside them. For example, a skyscraper should contain several elevators. The hospital should have an easily accessible emergency department.

Our natural world also uses the principle that form follows function, especially in cell biology, which will become clear as we study eukaryotic cells (figure). Unlike prokaryotic cells, eukaryotic cells have: 1) a nucleus surrounded by a membrane; 2) numerous membrane-bound organelles such as the endoplasmic reticulum, Golgi apparatus, chloroplasts, mitochondria, and others; and 3) several rod-shaped chromosomes. Because the membrane surrounds the nucleus of a eukaryotic cell, it has a “true nucleus”. The word “organelle” means “small organ” and, as we have already mentioned, organelles have specialized cellular functions, just as the organs in your body have specialized functions.

Parts Of The Cell And Its Function

At this point, it should be clear to you that eukaryotic cells have a more complex structure than prokaryotic cells. Organelles allow different functions to be divided into different areas of the cell. Before we move on to organelles, let’s first look at two important components of the cell: the cell membrane and the cytoplasm.

What Are The 3 Main Parts Of A Cell And Their Function?

These figures depict the major organelles and other cellular components of (a) a typical animal cell and (b) a typical eukaryotic plant cell. A plant cell has a cell wall, chloroplasts, plastids and a central vacuole – structures that do not occur in animal cells. Most cells do not have lysosomes or centrosomes.

If the nucleolus were unable to perform its function, what other cellular organelles would be affected? Have you ever heard the expression “form follows function?” This is a philosophy practiced in many industries. In architecture, this means that buildings should be constructed to support the activities that will take place inside them. For example, a skyscraper should be built with several elevators; the hospital should be built so that its emergency room is easily accessible.

The principle that form follows function has originated in our natural world, especially in cell biology, and this will become clear as we study eukaryotic cells. Unlike prokaryotic cells, eukaryotic cells have: (1) a membrane-bound nucleus; (2) numerous membrane-bound organelles – such as the endoplasmic reticulum, Golgi apparatus, chloroplasts, mitochondria, and others; and (3) several rod-shaped chromosomes. Because the nucleus of a eukaryotic cell is surrounded by a membrane, it is often said to have a “true nucleus”. The word “organelle” means “small organ” and, as already mentioned, organelles have specialized cellular functions, just as the organs of your body have specialized functions.

Figure 1. These figures show the major organelles and other cellular components of (a) a typical animal cell and (b) a typical eukaryotic plant cell. A plant cell has a cell wall, chloroplasts, plastids and a central vacuole – structures that are not found in animal cells. Plant cells do not have lysosomes or centrosomes.

Cell Structure And Function All Cells Show Some Similarities In Their Str

Before we start looking at individual organelles, we need to briefly discuss the matrix in which they are found: the cytoplasm. The part of the cell called the cytoplasm is slightly different in eukaryotes and prokaryotes. In eukaryotic cells that have a nucleus, the cytoplasm is everything between the plasma membrane and the nuclear envelope. In prokaryotes, which do not have a nucleus, cytoplasm simply means everything inside the cell membrane.

One of the main components of the cytoplasm in both prokaryotes and eukaryotes is the gel-like cytosol, a water-based solution containing ions, small molecules, and macromolecules. In eukaryotes, the cytoplasm also contains membrane-bound organelles that are suspended in the cytosol. The cytoskeleton, the network of fibers that supports the cell and gives it shape, is also part of the cytoplasm and helps organize cellular components.

Even though the cytosol is composed mainly of water, it has a semi-solid, jelly-like consistency due to the many proteins suspended in it. The cytosol contains a rich broth of macromolecules and smaller organic molecules, including glucose and other simple sugars, polysaccharides, amino acids, nucleic acids, and fatty acids. The cytosol also contains ions of sodium, potassium, calcium and other elements. Many metabolic reactions take place in this part of the cell, including protein synthesis.

Figure 2. The nucleus stores chromatin (DNA and proteins) in a gel-like substance called the nucleoplasm. The nucleolus is a condensed area of ​​chromatin where ribosome synthesis takes place. The boundary of the nucleus is called the nuclear envelope. It consists of two phospholipid bilayers: an outer membrane and an inner membrane. The nuclear membrane is continuous with the endoplasmic reticulum. Nuclear pores allow substances to enter and exit the nucleus.

Biology 2e, The Cell, Cell Structure, Eukaryotic Cells

) houses the cell’s DNA and directs the synthesis of ribosomes and proteins. Let’s look at this in more detail (Figure 2).

The nuclear envelope is a double-membrane structure that constitutes the outermost part of the nucleus (Figure 2). Both the inner and outer membranes of the nuclear envelope are phospholipid bilayers.

The nuclear envelope is punctuated by pores that control the flow of ions, molecules, and RNA between the nucleoplasm and cytoplasm. The nucleoplasm is the semisolid fluid inside the nucleus, which contains the chromatin and nucleolus.

To understand chromatin, it is helpful to first consider chromosomes. Chromosomes are structures in the nucleus made of DNA, the hereditary material. In prokaryotes, DNA is organized into a single circular chromosome. In eukaryotes, chromosomes are linear structures. Each eukaryotic species has a specific number of chromosomes in the nuclei of its body cells. For example, humans have 46 chromosomes, while fruit flies have eight. Chromosomes are visible and distinguishable from each other only when the cell is preparing to divide. When a cell is in the growth phase and maintaining its life cycle, proteins that resemble an unrolled, confused bundle of threads are attached to chromosomes. These unfolded protein-chromosome complexes are called chromatin (Fig. 3); chromatin describes the material that makes up chromosomes both after condensation and after decondensation. We will focus in more detail on chromatin and chromosomes later.

Cell Cycle Phases And Checkpoints

Figure 3. (a) This image shows different levels of chromatin organization (DNA and protein). (b) This image shows paired chromosomes. (credit b: modification of work by NIH; scale bar data from Matt Russell)

We already know that the nucleus directs ribosome synthesis, but how does it do it? Some chromosomes have stretches of DNA that encode ribosomal RNA. A dark colored area in the nucleus, called the nucleolus (plural = nucleoli), aggregates ribosomal RNA with associated proteins to form ribosomal subunits, which are then transported through pores in the nuclear envelope into the cytoplasm.

Figure 4. Ribosomes consist of a large subunit (top) and a small subunit (bottom). During protein synthesis, ribosomes combine amino acids into proteins.

Ribosomes are cellular structures responsible for protein synthesis. When viewed through an electron microscope, ribosomes appear either as clusters (polyribosomes) or as individual, tiny dots that float freely in the cytoplasm. They may be attached to the cytoplasmic side of the cell membrane or the cytoplasmic side of the endoplasmic reticulum and the outer membrane of the nuclear envelope. Electron microscopy has shown us that ribosomes, which are large complexes of protein and RNA, are composed of two subunits, aptly called large and small (Figure 4). Ribosomes receive “orders” to synthesize proteins from the nucleus, where DNA is transcribed into messenger RNA (mRNA). The mRNA travels to ribosomes, which translate the code provided by the sequence of nitrogenous bases in the mRNA into a specific order of amino acids in the protein. Amino acids are the building blocks of proteins.

Prokaryotic Cells: Structure, Function, And Definition

Because protein synthesis is the primary function of all cells, ribosomes are found in virtually every cell. Ribosomes are especially abundant in cells that synthesize large amounts of protein. For example, the pancreas is responsible for producing several digestive enzymes, and the cells that produce these enzymes contain many ribosomes. So we see another example of form following function.

) are often called the “power plants” or “energy factories” of the cell because they are responsible for producing adenosine triphosphate (ATP), the main energy-transmitting molecule in the cell. ATP represents the short-term stored energy of the cell. Cellular respiration is the process of producing ATP using the chemical energy contained in glucose and other nutrients. In the mitochondria, this process uses oxygen and produces carbon dioxide as a waste product. In fact, the carbon dioxide exhaled with each breath comes from cellular reactions that produce carbon dioxide as a byproduct.

In keeping with our theme of form following function, it is important to emphasize that muscle cells have a very high concentration of ATP-producing mitochondria. Muscle cells need a lot of energy to keep the body moving. When your cells don’t get enough oxygen, they don’t produce much ATP. Instead, the small amount of ATP they produce in the absence of oxygen is accompanied by the production of lactic acid.

Figure 5. This electron microscope image shows a mitochondrion viewed under a transmission electron microscope. This organelle has an outer membrane and an inner membrane. The inner membrane contains folds called cristae that increase in size

Solution: Parts Of Cell, Their Main Characteristics And Chief Functions.

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