Cell structures and function

• Cells are the basic units of life and are very small in size, ranging from approximately 1 to 100 micrometers.
• There are two major types of cells: eukaryotic and prokaryotic
• A cell's nucleoid region or nucleus contains the cell's DNA(deoxyribonucle ic acid) which contains the cell's encoded genetic information.
• Prokaryotic single-celled organisms were the earliest and most primitive forms of life on Earth
• There are more bacterial cells in the body than human cells
• Cells have varying life spans and can commit suicide
• A prokaryote is a simple, single-celled (unicellular) organism that lacks an organized nucleus or any other membrane-bound organelle.
• They are microscopic, measuring from 0.1 to 5.0 μm
• Measuring over a centimetre long, Thiomargarita magnifica is over 5000 times bigger than the average microbe
• The world's largest bacterium has been discovered amongst the mangroves of the Caribbean island of Guadeloupe.
• Cyanobacteria, also known as bluegreen algae, are a group of photosynthetic bacteria that play a crucial role in the Earth's ecosystems
• Some prokaryotic cells have a protective outer layer called a capsule, which is a slimy, gel-like coating. The capsule can help protect the cell from the host's immune system.
• The cell wall is a protective layer that surrounds some cells and gives them shape and rigidity. The major component of bacterial cell walls is called peptidoglycan.
• Cytoplasm is a gel-like substance that fills the cell and contains various cellular structures.
• A plasmid is a small, circular, doublestranded DNA molecule that exists independently of the chromosomal DNA in the bacterial cell.
• Nucleoid is a region within the cytoplasm where the circular DNA molecule is located.
• Ribosomes - Cellular structures responsible for protein synthesis.
• Flagellum - Whip-like appendages that extend from the cell surface, enabling the cell to move. Not all prokaryotic cells have this
• FIMBRIAE - Bristle-like-fibers that are shorter than pili. It is primarily used for bacterial attachment
• PILI - Short, hair-like structures on the cell surface that aid in adherence to surfaces or other cells. it can also be involved in the transfer of genetic material during a process called conjugation
• A eukaryotic cell is a type of cell that possesses a true nucleus and membrane-bound organelles
• A typical eukaryotic cell measures 10 to 100 μm in diameter
• PLASMA MEMBRANE (Gatekeeper of the Cell) - also called the cell membrane, is the membrane found in all cells that separates the interior of the cell from the outside environment.
• . In bacterial and plant cells, a cell wall is attached to the plasma membrane on its outside surface. The plasma membrane consists of a lipid bilayer that is semipermeable. The plasma membrane regulates the transport of materials entering and exiting the cell
• The cytoplasm is the interior of the cell that surrounds the nucleus. It includes the organelles and a jelly-like fluid called the cytosol. Cellular processes, such as metabolism and protein synthesis, occur in the cytoplasm
• The nucleus is the control center of the cell. It is the largest organelle in the cell and it contains the DNA of the cell.
• ENDOPLASMIC RETICULUM (Highway of the Cell) The endoplasmic reticulum is a network of membranes involved in the synthesis of lipids and proteins
• The rough endoplasmic reticulum is where most protein synthesis occurs in the cell.
• The function of the smooth endoplasmic reticulum is to synthesize lipids in the cell. The smooth ER also helps in the detoxification of harmful substances in the cell.
• GOLGI APPARATUS (Packaging center of the cell) - Also called Golgi complex. This organelle was named after an Italian physician, Camillo Golgi. He was the first person to describe this organelle in the cell
• Golgi complex - cell organelle primarily responsible for transporting, modifying, and packaging proteins and lipids to target destinations.
• A vesicle is a small, membrane-bound sac that can transport and store substances within a cell.
• Lysosomes are membrane-bound vesicles containing enzymes that break down and digest cellular waste materials, old organelles, and foreign substances
• Peroxisomes are organelles involved in various metabolic processes, particularly those related to lipid metabolism and detoxification
• MITOCHONDRIA (Powerhouse of the Cell) - are organelles that play a crucial role in cellular respiration, producing energy (in the form of ATP) for the cell.
• Mitochondria - have their own circular DNA and replicate independently of the cell
• A vacuole is a membrane-bound organelle found in the cells of plants, animals fungi, and some protists.
• Vacuole plays crucial roles in maintaining cell turgor pressure, storing nutrients and waste products, and participating in various cellular processes.
• A chloroplast is a membrane-bound organelle found in the cells of plants, algae, and some protists. Chloroplasts are the sites of photosynthesis, a process that converts light energy into chemical energy in the form of glucose, ultimately providing energy for the organism. These organelles contain pigments, including chlorophyll, which give them a green color.
• Ribosomes are cellular organelle involved in protein synthesis, translating genetic information from mRNA (messenger RNA) into functional proteins