Cell transportation notes

• The cell membrane is made up of a phospholipid bilayer
• Phospholipid head is hydrophilic and polar, while the tail is hydrophobic and nonpolar
• The tail of the phospholipid bilayer allows nonpolar hydrophobic substances to cross without protein helpers
• Substances that can cross without protein helpers include small gases, uncharged molecules, lipids, and water (slowly)
• Substances that need protein helpers for crossing the cell membrane include polar molecules, hydrophilic substances, ions, glucose, polar amino acids, and water with aquaporins
• Passive transport moves substances from high to low concentration without using energy, relying on the concentration gradient
• Diffusion rate is affected by the steepness of the gradient; the steeper it is, the faster the diffusion occurs
• Osmosis rate of diffusion is also affected by the steepness of the gradient; the steeper it is, the faster osmosis occurs
• Facilitated diffusion uses proteins to help substances cross the cell membrane
• Channel proteins' rate is affected by the gradient and whether gated channels are open or closed, requiring energy
• Carrier proteins' rate is affected by the steepness of the gradient and whether the carrier is available or saturated
• Osmosis is based on the movement of water across a membrane
• Simple diffusion occurs when substances are uncharged and do not need a protein to cross the membrane
• Facilitated diffusion involves substances passing through the phospholipid bilayer with the help of proteins
• Carrier proteins require substances to be larger than 3 to pass through, while channel proteins require energy
• Water movement through aquaporins is essential for osmosis
• Sodium Pump process involves forcing molecules from an area of low to high concentration, expelling sodium ions out while potassium ions try to enter the cell
• Iodine can diffuse from an area of high to low concentration; when it moves into a solution with starch, it turns black
• Passive transport moves substances from high to low concentration without using energy
• Active transport involves moving substances from low to high concentration using ATP
• Water molecules can travel in large quantities using aquaporins
• Hypertonic solutions have a higher solute concentration, while hypotonic solutions have a lower solute concentration
• Isotonic solutions have an equal concentration of solutes
• Endocytosis brings substances into the cell, while exocytosis pushes substances outside of the cell
• Phagocytosis involves ingesting large or whole particles, while pinocytosis ingests solutes or fluids
• Cells have resting potentials, usually negative inside the cell, which can change in response to stimuli
• Sodium-potassium pump requires ATP energy input to help maintain a resting membrane potential
• Protein channels are involved in facilitated diffusion and active transport processes
• Ions can enter cells through ion channels and protein pumps, with channels being passive and pumps being active
• Endocytosis and exocytosis are forms of bulk transport in cells
• Membrane invagination occurs when the cell membrane folds inwards to form a cavity around particles
• Exocytosis can push out secreted proteins from the Golgi apparatus
• Low-density lipoproteins are transported across the membrane by receptor-mediated endocytosis
• Permeable - it is allowed to pass through
• Semi permeable: allows some molecules to pass through the membrane but not all
• Non permeable: A material that does not allow water to pass through it.
• Osmosis goes thrugh a semi permeable membrane
• Phagocytosis - Cell eating, solids
• Pinocytosis - cell drinking, fluids
• Bulk transport - Brings in larger solids, uses vesicles and the plasma membrane, endocytosis and exocytosis