Question

What are the structures of Eukaryotic and prokaryotic cells and their functions

Answer 1

Prokaryotes and eukaryotes have a structure outside the cell membrane known as cell wall. All prokaryotes have thick, rigid cell walls, which provides their shape. Cell walls are not identical in these organisms. In fungi, the cell wall contains a polysaccharide known as chitin. Plant cell walls are composed of the polysaccharide cellulose. Cell walls provide support and help cells resist mechanical pressures.

All prokaryote and eukaryote cells have plasma membranes. The plasma membrane is the outermost cell surface, which separates the cell from the external surroundings. The plasma membrane is composed of proteins and lipids, especially phospholipids.

All prokaryote and eukaryote cells also have cytoplasm. It is a semi liquid substance, which composes the volume of a cell. It is the gel-like material enclosed by the plasma membrane. Within the cytoplasm of eukaryote cells are a number of membrane-bound bodies called organelles, which provide a specialized function within the cell.

PROKARYOTIC CELL STRUCTURE AND FUNCTION

There are two major kinds of prokaryotes: Bacteria and Archaea. There are four main structures shared by all prokaryotic cells:

• Plasma membrane: Prokaryotic cells can have multiple plasma membranes. The plasma membrane is responsible for controlling what gets into and out of the cell. Proteins stuck in the membrane acts as a communicating channel with the surrounding environment. The communication include sending and receiving chemical signals from other bacteria and interacting with the cells during the process of infection.
• Cytoplasm: The cytoplasm is a gel-like fluid in which all of the other cellular components are suspended. It does not contain organelles.
• Ribosomes: Ribosomes have a slightly different shape and composition than those found in eukaryotic cells. Bacterial ribosomes, for instance, have about half of the amount of ribosomal RNA (rRNA) and 53 ribosomal proteins. Ribosomes build proteins by translating messages sent from DNA.
• Genetic material (DNA and RNA): All prokaryotic cells contain large quantities of genetic material in the form of DNA and RNA. As prokaryotic cells do not have a nucleus, it has single large circular strand of DNA which contains most of the genes needed for cell growth, survival, and reproduction is found in the cytoplasm. DNA is spread throughout the entire cell and is readily accessible to be transcribed into mRNA.

EUKARYOTIC CELL STRUCTURE AND FUNCTION

Eukaryotic cell has a true membrane-bound nucleus and also other membranous organelles, which permit for compartmentalization of functions.

There are three main structures in Eukaryotic cells

• Nucleus: Nucleus is the most prominent organelle in the cell. Eukaryotic cells have a true nucleus, that shows the cell’s DNA is surrounded by a membrane. Therefore, the nucleus helps in synthesis of proteins and ribosomes. It is responsible for protein synthesis. The nuclear envelope is a double-membrane structure, which constitutes the outermost portion of the nucleus. Both the inner and outer membranes of the nuclear envelope are phospholipid bilayers. The nuclear envelope is disrupted with pores, which control the passage of ions, molecules, and RNA between the nucleoplasm and cytoplasm. The nucleoplasm is the semi-solid fluid inside the nucleus where the chromatin and the nucleolus are present.
• Membrane-bound organelles: Mitochondria are oval-shaped, double membrane organelles, which have their own ribosomes and DNA. These organelles are known as the “energy factories” of a cell because they are responsible for formation of ATP. ATP is the cell’s main energy-carrying molecule, by conducting of cellular respiration process. The endoplasmic reticulum modifies proteins and synthesizes lipids, while the golgi apparatus is where the sorting, tagging, packaging, and distribution of lipids and proteins takes place. Peroxisomes are small, round organelles enclosed by single membranes; they carry out oxidation reactions, which break down fatty acids and amino acids. Peroxisomes also acts as detoxify many poisons, which enter the body. Vesicles and vacuoles are membrane-bound sacs . It helps in the storage and transport. The chloroplasts contain a green pigment known as chlorophyll, which captures the light energy that forces the reactions of photosynthesis. Chloroplasts are plant cell organelles that carry out photosynthesis. Photosynthesis is the series of reactions that use carbon dioxide, water, and light energy to make glucose and oxygen.
• Chromosomes: Chromosomes are the thread-like structure found in the nuclei of both animal and plant cells. These structures are present within the nucleus, which are made up of DNA, the genetic material. A chromosome is a DNA molecule with part or all of the genetic material of an organism. They are made of protein and one molecule of DNA. During the cell division, DNA intact and keeps its even distribution throughout the cells. The structure of chromosomes and chromatin varies through the cell cycle. They are even more condensed than chromatin and are an necessary unit for cellular division. They must be replicated, divided, and passed successfully to their daughter cells so as to ensure the genetic diversity and survival of their progeny.