Cell Structure (Ch. 3) Flashcards
- Boundary of the cell
- Phospholipid bilayer
- Described by “Fluid Mosaic Model”
- Selectively permeable
- Includes proteins + lipids + carbohydrates
Plasma membrane
“Inside the cell”
Intracellular
“Outside the cell”
Extracellular
The intracellular environment made up of cytosol and organelles
Cytoplasm
Fluid between cells in the body
Interstitial fluid
Site for binding of a chemical messenger on the plasma membrane; “docking station”
Receptor molecules
Allow for cell recognition; important for the immune system to recognize invaders
Marker molecules
- Proteins and lipids with carbohydrates (sugars) stuck to them
- Act as receptor and marker molecules in the plasma membrane
Glycoproteins and glycolipids
- Any kind of movement through a plasma membrane that uses no energy
Passive transport
- Any kind of movement through a cell membrane that requires energy (ATP)
- May move solutes against their concentration gradient (i.e. from low to high)
Active transport
Dissolved substance in a solution
Solute
Liquid in a solution
Solvent
From higher to lower concentration
Concentration gradient
Net movement of a substance along its concentration gradient
Diffusion
- Diffusion of a dissolved substance (solute) along its concentration gradient;
- Occurs when membrane is permeable to the solute
Dialysis
- Diffusion of water along its concentration gradient
- Occurs when membrane is NOT permeable to the solute
Osmosis
- Equal (balanced) concentration of solutes between two solutions (i.e. between intracellular and extracellular)
- No net movement occurs
Isotonic
- A solution that contains a higher concentration of solutes (in comparison)
- A cell put in this solution with SHRINK (if its membrane is not permeable to the solute)
Hypertonic
- A solution that contains a lower concentration of solutes (in comparison)
- A cell put in this solution may burst or LYSE (if its membrane is not permeable to the solute)
Hypotonic
- A type of passive transport in which a moving stream of liquid (e.g. the blood stream) flows over a membrane, and only particles small enough to fit through tiny holes in the membrane get through.
Filtration
A type of passive transport in which substances diffuse, but with the help of “carrier” molecules
Facilitated diffusion
A tiny “bubble” of membrane, filled with material for transport.
Vesicle
- Extracellular material pushes up against the plasma membrane of a cell until part of the membrane caves in and surrounds it
- Allows for particles too large to fit through the plasma membrane to enter the cell in the form of vesicles
Endocytosis
- A cell wraps itself around something solid, like an invading bacteria, until the invader becomes completely surrounded (“eaten”)
Phagocytosis
- A cell wraps itself around a drop of solution, like digested food sloshing around in the intestines, and “drinks” it inside of itself
Pinocytosis
- Vesicles formed inside the cell fuse with the plasma membrane and dump their contents outside of the cell boundary
Exocytosis
- Gooey stuff organelles float around in
- Includes: Fluid (A solution of dissolved ions and a colloid of suspended molecules) and cytoplasmic inclusions
Cytosol
Maintains cell shape and allows certain cells to move (e.g. sperm)
Cytoskeleton
- Temporary additions to the cell (e.g. nutrients not yet used up or waste products not yet expelled)
Cytoplasmic inclusions
- Organelle bound by a double membrane
- Glucose is broken down to create ATP
Mitochondria
- The folds in the inner membrane of the mitochondria
- Contain enzymes for the Electron Transport System
Cristae
- The space between the folds of the inner membrane of a mitochondria
- Contains enzymes for the Citric Acid Cycle
Matrix
- Organelles with NO membrane of their own
- Composed of two small “sub-units” joined together
- Synthesize proteins
- May be either free-floating (make proteins for use by the cell) or attached to the RER (make proteins for export)
Ribosomes
- A series of membrane-bound channels and sacs directly connected to the cell nucleus
- Synthesizes lipids such as phospholipids to replace lost plasma membrane
Smooth endoplasmic reticulum (SER)
- Membrane-bound channels and sacs that are “studded” with ribosomes
- Manufactures proteins for out-of-cell use
Rough endoplasmic reticulum (RER)
- Organelle that modifies, packages, and distributes lipids and proteins inside of vesicles meant for exocytosis from the cell
- A stack of flattened, membranous sacs that recieves lipids and proteins from the SER and RER and prepares them for export.
Golgi apparatus
- Membrane-bound organelles produced by the golgi apparatus
- Filled with digestive enzymes
- Used to break down food, and also to commit “suicide” in an old or defective cell
Lysosome
- A large centrally located membrane-bound organelle
- Contains DNA
- The site of RNA synthesis
- Contains a nucleolus
Nucleus
- A dense patch of the nucleus made up of RNA
- Synthesizes the “sub-units” that eventually make up ribosomes
Nucleolus
