Cell Structures and Functions

• 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 (deoxyribonucleic acid) which contains the cell's encoded genetic information.
• Cells don't reproduce by different methods.

  False
• Cells are too small to be seen without magnification.

  True
• Prokaryotic single-celled organisms were the earliest and most primitive forms of life on Earth.

  True
• There are more human cells in the body than bacterial cells.

  False
• Cells don't contain the genetic material

  False
• Cells don't have varying life spans

  False
• Cells commit suicide

  True
• It is when your cell is programmed to die to prevent abnormalities. (Cell Death)

  Apoptosis
• A prokaryote is a simple, single-celled (unicellular) organism that lacks an organized nucleus or any other membrane-bound organelle.
• These are microscopic cells, measuring from 0.1 to 5.0 μm.


  Prokaryotic cells
• The world's largest bacterium has been discovered amongst the mangroves of the Caribbean island of Guadeloupe.
• Measuring over a centimetre long, Thiomargarita magnifica is over 5000 times bigger than the average microbe.
• Cyanobacteria

  Also known as blue-green algae, these are a group of photosynthetic bacteria that play a crucial role in the Earth's ecosystems.
• Cell Wall

  It is a protective layer that surrounds some cells and gives them shape and rigidity.
• The major component of bacterial cell walls is called peptidoglycan.
• Plasma Membrane


  It is a thin lipid bilayer that completely surrounds the cell and separates the inside from the outside.
• Capsule


  Some prokaryotic cells have a protective outer layer which is a slimy, gel-like coating. This can help protect the cell from the host's immune system
• Cytoplasm


  A gel-like substance that fills the cell and contains various cellular structures.
• Plasmid


  A small, circular, double-stranded DNA molecule that exists independently of the chromosomal DNA in the bacterial cell.
• Nucleoid


  A region within the cytoplasm where the circular DNA molecule is located.
• Ribosome

  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. Pili 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 (Cell Membrane)

  Known as the gatekeeper of the cell, is found in all cells that separate the interior of the cell from the outside environment. It also regulates the transport of materials entering and exiting the cell.
• Cytoplasm

  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.
• Nucleus

  Known as the control center of the cell, it is also the largest organelle and contains the DNA.
• Endoplasmic Reticulum

  Known as the 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 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

  Known as the Packaging center of the cell.
• Golgi Apparatus

  This organelle was named after an Italian physician, Camillo Golgi as he was the first person to describe this organelle in the cell. This organelle is primarily responsible for transporting, modifying, and packaging proteins and lipids to target destinations.
• Vesicles


  A small, membrane-bound sac that can transport and store substances within a cell. These are involved in various cellular processes, including intracellular transport, secretion, and storage of cellular materials.