Cell Structure and Function

• Cell is the smallest unit of living matters.
• Cells range in size from 1 millimeter (mm) down to 1 micrometer (μm) in diameter.
• All organisms are composed of cells.
• Cells are the basic units of structure and function in organisms.
• Cells come only from preexisting cells because cells are self-producing.
• The surface‑area‑to‑volume ratio requires that cells be small.
• Large cells – surface area relative to volume decreases, which also decreases the efficiency of transporting materials in and out of the cell.
• As cell size decreases the surface-area-to-volume ratio increase.
• Small cells – larger surface-area-to-volume ratio is advantageous for exchanging molecules.
• Area = length x width x # of sides
• Volume = length x width x height
• Smaller cells can transport substances more easily.
• Diffusion is inefficient over longer distances.
• The cytoskeleton transportation network becomes less efficient for a cell if the distance to travel becomes too large.
• Cellular communication is more efficient in smaller cells.
• What are the two different types of cells that exist in nature?

  Prokaryotic cells and Eukaryotic cells
• prokaryotic cells lack a nucleus and other membrane-bound organelles
• Eukaryotic cells possess a nucleus
• Which domains are classified as prokaryotic cells?

  Eubacteria and Archaea
• Archaea lives in extreme habitats
• To which domain are all eukaryotic cells assigned?

  Domain Eukarya
• an average size of a prokaryotic cell is 1.1-1.5 µm wide and 2.0-6.0 µm long
• The three main shapes of prokaryotes are cocci (spherical), bacilli (rod-shaped), and spirilla (spiral-shaped).
• the cell envelope include the plasma membrane, the cell wall, and the glycocalyx.
• The plasma membrane has the important function of regulating the entrance and exit of substances into and out of the cytoplasm.
• In prokaryotes,the plasma membrane can form internal pouches called mesosomes, which increase surface area.
• the Plasma membrane is a phospholipids by layers with embedded protein.
• Cell wall helps maintains the shape of the cell
• the cell wall is strengthened by peptidoglycan.
• Glycocalyx is a layer of polysaccharides that lies outside the cell wall in some bacterias.
• If the glycocalyx is well-organized and attached firmly, it forms a capsule
• If the glycocalyx is loosely organized, it forms a slime layer
• The cytoplasm is a semifluid solution composed of water, inorganic and organic molecules, and enzymes.
• The cytoplasm is enclosed by the plasma membrane.
• the Nucleoid is a region that contains the single, circular DNA molecule.
• Plasmids are small accessory (extrachromosomal) rings of DNA.
• Ribosomes are tiny structures in the cytoplasm that synthesize proteins.
• prokaryotic ribosomes are smaller than eukaryotic ribosomes but are similar in shape and function.
• Cyanobacteria are a form of bacteria that are capable of photosynthesis in the same manner as plants.
• Cyanobacteria are also called the blue-green bacteria.