A2.2 - Cell Structure

• Single cells are known as unicellular
• Many celled organisms are multicellular
• Cell theory:

  1. Cells can only be made from pre-existing cells
  2. Living organisms are made of cells (smallest units of life)
  3. Organisms of only one cell carry out all functions of life in the cell
• I/A = M
• Resolution is the ability to separate visually small objects that are very close together
• A cell consists of a nucleus surrounded by cytoplasm (which is mostly made of water), contains within the cell membrane made of lipids
• Differentiation: growing cell divides into 2 cells (often restricted to unspecialized cells)
• Tiny structure in cytoplasm called organelles (most of the common in plants and animals) - discrete structure in a cell with a specific function
• Prokaryotes - very small, the size of an organelle in eukaryotes
• Prokaryotes have no nucleus, just a loop of DNA called a nucleoid
• Prokaryotes have 70S ribosomes
• Eukaryotes are reactions of life - metabolism
• Eukaryotes have 80S ribosomes
• Chromosomes in eukaryotes are linear
• Prokaryotes and eukaryotes both have cytoplasm, a cell membrane, and ribosomes (ribosomes are just different size)
• Nucleus: Stores genetic material (DNA) and coordinates the cell's activites like growth, metabolism, and reproduction
• Mitochondria: Produces energy (ATP) through cellular respiration
• Endoplasmic reticulum (rough): Synthesizes and processes proteins (has ribosomes on its surface)
• Endoplasmic reticulum (smooth): Synthesizes lipids (lacks ribosomes)
• Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for transport to other parts of the cell or for secretion
• Lysosome: Contains digestive enzymes to break down waste materials. cellular debris, and pathogens (single layered)
• Cytoskeleton: Provides structural support for the cell, aiding in cell shape, transport, and movement
• Ribosomes: Synthesizes proteins by translating messenger RNA (mRNA). Ribosomes can be free-floating or attached to the rough endoplasmic reticulum.
• Plasma Membrane: Protects cell by controlling the movement of substances in and out of the cell
• Chloroplast: Conducts photosynthesis, converting light energy into chemical energy stored in glucose
• Vacuole: Stores nutrient, waste products, and helps maintain turgor pressure
• Centrosome/Centrioles: Organizes microtubules and aids in cell division by forming the mitotic spindle
• The Golgi Complex does final modifications on proteins before they’re functional, produces lysosomes, and does final modifications to lipids from SER, like the ones essential for cell membrane structure.
• Maximum magnification of an optical microscope is x1500
• In optical microscopes, you can't see in between objects that are closer than half the light wavelength
• Electron microscopes use electrons to form images
• A beam of electrons has a much smaller wavelength than light, so an electron microscope distinguish between two objects that are extremely close together
• Maximum useful magnification of an electron microscope is x1500000
• Transmission Electron Microscope has tissue sections and an objective lens while a Scanning Electron Microscope has a scanning coil (beam deflector) and a condenser lens
• Transmission Electron Microscope has maximum magnification of x500000
• Scanning Electron Microscope has maximum magnification of x250000
• Smooth endoplasmic reticulum stores calcium
• Aside from energy production, the mitochondria regulate calcium, synthesize steroid hormones, provide heat protection, and have its own DNA
• Lysosomes are bound by a single-layered membrane
• The vacuole is like the warehouse of the cell. It can store nutrients, pigments, citotoxic compounds, anti-bacterial compounds, and water.