Basic, living, structural and functional unit of the body
Cellular Level
Level with compartmentalization of chemical reactions within specialized structures
Cellular Level
Another name for the Cell membrane
Plasma membrane
Genetic material of a cell
Nucleus
everything between the membrane and the nucleus
Cytoplasm
Name for the intracellular fluid in the cytoplasm
Cytosol
Name for the subcellular structures with specific functions (in the cytoplasm)
Organelles
Flexible but sturdy barrier that surrounds cytoplasm of cell and separates the external and internal environments of the cell
Plasma Membrane
Important for regulating the movement of substances into and out of the cell
selective permeability
Important for communication with other cells and substances
plasma membrane
True or false: most cells have a common overall structure
True
What does the plasma membrane consist of?
lipids
proteins
carbohydrates
What model describes the structure of the plasma membrane?
Fluid mosaic model
Describe the fluid mosaic model
Sea of lipids in which proteins float like icebergs
lipid is barrier to entry or exit of polar substances
proteins are "gatekeepers" -- regulate traffic
carbohydrates provide attachment points and protection
Comprises most of the lipids
Phospholipids
2 parallel layers of phospholipid molecules
phospholipid bilayer
True or false: Polar parts (heads) of phospholipids are hyrophobic
False.
Polar parts (heads) are hydrophilic and face on both surfaces of a watery environment
True or false: nonpolar parts (heads) are hydrophobic
True.
Nonpolar parts line up next to each other in the interior
Where do carbohydrate groups attach to the cell membrane?
Carbohydrate groups attach to the polar heads on hte side of the membrane facing the extracellular fluid
What are carbohydrate groups important?
They are important for cell adhesion and cell recognition (forms part of the glocoalyx-protective sugar coating)
Where can you find cholesterol in the cell membrane?
Interspersed among the other lipids in both layers
Why is cholesterol important within the cell membrane?
Important for strengthening the cell membrane and making it flexible.
What are they?
Usually extend completely across the cell membrane
Form a small protein channel for transport of substances
Integral Proteins
What are they?
Attached to either inner or outer surface cell membrane and are easily removved from it
Peripheral proteins
What are they?
Sugars attached to proteins
Glyoprotein
Why are glycoproteins important? (3 reasons)
Have the sugar portion facing the extracellular fluid to form a glycocalyx
Gives cell "uniqueness", protects it from being digested
Creates a stickiness to hold it to other cells and forms part of a glycocalyx
Which Membrane Proteins:
Name for the passageway to allow specific substance to pass through (especially non-liped soluble substane)
Channel
Which Membrane Proteins:
Binds a specific substance, changes their shape and movies it across the membrane
Transporter Proteins
Which Membrane Proteins:
Cellular recognition site
Binds to substance
Receptor Proteins
Which Membrane Proteins:
Allows cell to recognize other similar cells
Cell Identity Marker
Which Membrane Proteins:
Anchor proteins in cell membrane or to other cells
Cell shape and structure
Cytoskeleton
Which Membrane Proteins:
Speed up reactions
Act as Enzyme
Permeable to nonplar, uncharged molecules -- oxygen, CO2, steroids
Permeable to water which flows through gaps that form in hydrophobic core of membrane as phospholipids move about
Lipid bilayer (selective permeability)
True or false: Transmembrane proteins act as specific channels.
True, for small and medium polar & charged particles
How do macromolecules pass through the membrane?
Vesicular transport
Moves substances down their concentration gradietn with only their kinetic energy
Passive Transport
Uses ATP to drive substances against their concentration gradient or to move large molecules across the membrane
Active Transport
What are the principles of diffusion?
1. Random mixing of particles in a solution as a result of the particle's kinetic energy
----aka more molecules move away from an area of high concentration to an area of low concentration
2. when the molecules are evenly distributed, equilibrium has been reached
Why is diffusion important?
Important for absorption of nutrients and excretion of wastes
What type of molecules diffuse?
Nonpolar, hydrophobic molecules:
oxygen, carbon dioxide, nitrogen, fatty acids, steroids, small alcohols, ammonia and fat-soluble vitamins (A, E, D and K)
Which type of transport across the plasma membrane:
1. Substance binds to specific transporter protein
2. Tranporter protein moves substance across cell membrane.
3. Only occurs down concentration gradient --if no concentration difference exists, no net movement occurs
Facilitated Diffusion
Explain how glucose would enter a cell
1.Glucose binds to transport protein
2.Transport protein changes shape
3. Glucose moves across cell membrane (only down concentration gradient)
Net movement of water through a selectively permeable membrant from an area of high water concentration to an area of lower water concentration
--diffusion through lipid bilayer
Osmosis
What type of solution:
Water concentration the same inside and outside of cell results in no net movement of water across the cell membrane
Isotonic Solution
What type of solution:
Higher concentration of water ouside of cell reults in hemolysis
Hypotonic Solution
What type of solution:
Lower concentration of water outside of cell cause crenation
Hypertonic Solution
A process in which substances move across a plasma membrane down a pressure gradient
Filtration
Movement of charged substances, large substances and nonlipid substances against their concentration gradient mainly through protein channels
-energy-requiring process (energy from hydrolysis of ATP)
Active Tranport
Examples of actively transported molecules
Na+, K+, H+, Ca+2, I-, Cl-, amino acids and monosaccharides
Vesicular Transport:
Bringing something into a cell
Endocytosis
Cell eating by macrophages & WBC
(whole bacteria or viruses are engulfed and later digested)
Phagocytosis
Cell drinking
Pinocytosis
Selective input
Substance binds to receptor on cell membrane before being ingested (ie hormones)
Receptor-mediated endocytosis
Release something from cell
-Vesicles form inside cell, fuse to cell membrance
-Release their contents
Exocytosis
What do vesicles release from exocytosis?
Digestive enzymes
hormones
neurotransmitters or
waste products
What is the difference between pinocytosis and phagocytosis in regards to structure:
Pinocytosis: no pseudopods form & nonselective drinking of extracellular fluid
Phagocytosis: pseudopods extend to form phagosome & lysosome joins it
Why is there receptor-mediated endocytosis?
Mechanism for uptake of specific substances -- ligands
Desired substance binds to receptor protein in clathrin-coated pit region of cell membrane causing membrane to fold inward
Ligands are digested by lysosomal enzymes or transported across cell - epithelial cell crossing accomplished