A&P Chapter 3: Cells Living Unit
voltage-sensitive proteins
Because some plasma membrane proteins are involved in electrical signaling (by responding to changes in the membrane potential), these channels will oprn or close depending on changes in the voltage and polarity of the membrane. (Usually found in neural and muscle tissues!!!)
They are all different sizes!
Briefly describe cell diversity:
phagocytosis
"big eater"; the cell engulfs a large particle by forming projecting pseudopods around it and enclosing it within a membrane sac called a phagosome.
pinocytosis
"small eater"; the cell "gulps" drops of extracellular fluid containing solutes into tiny vesciles; a small portion of the plasma membrane surrounds a small volume of interstitial fluid and fuses with an endosome
2 ; in
How many K+ slots are in the carrier for the Na+/K+ pump? Do they go in or out?
3 ; out
How many Na+ slots are in the carrier for the Na+/K+ pump? Do they do in or out?
50-100 trillion
How many cells are in the human body (approx.)?
No pump, no transport
In active transport, if there is no pump, what happens?
isotonic
When cells retain their normal size and shape in isotonic solutions (concentration on the outside of the cell is the same as the inside of the cell)
What is the concentration?
When looking for tonicity, what are we really looking for? What are we asking?
vesicular trafficking
When vesicles pinch off of organelles and travel to other organelles to unload their contents
Because it helps make the bilayer more fluid, mobile, and flexible.
Why is these cholesterol in the lipid bilayer?
glycocalyx
a collection of glycoproteins and glycolipids that form a thick "sugary" coat to the extracellular surface of the cell; helps cells identify other cells (ex: sperm to egg!)
gap junctions
a nexus bond that allows cells to communicate with one another, making a channel that is selective to the molecule it will allow to pass between cells
centrosome
a region near the nucleus that attaches to microtubules
desmosomes
anchoring junctions that form a plaque with linker proteins that connect two cells, distributing tension to continuous internal support structures
facilitated diffusion
assisted diffusion of glucose, amino acids, or ions through membrane channels or carriers
centrioles
barrel-shaped organelles within the centrosome that are ivnolved in organizing the mitotic spindle during cell division and are the bases of cilia and flagella; in 90 degree angles of one another
endocytosis
bringing molecules into the cell
exocytosis
bringing molecules out of the cell
hypertonic
cells lose water by osmosis and shrink (water goes OUT of the cell to balance the concentrations out, which then DEHYDRATES the cell and it shrink)
hypotonic
cells take on water by osmosis until they become bloated and burst (lyse) in a hypotonic solution (which contains a lower concentration of solutes than are present inside cells)
carriers
facilitated diffusion through a trans-membrane integral protein that is specific for that substance (amino acids or glucose)
channels
facilitated diffusion through a transmembrane integral protein that is specific for that substance (ions or small molecules)
tight junctions
integral proteins that fuse together between adjoining cells, forming an impermeable junction that prevents molecules from entering the extracellular space between cells
second messengers
intracellular messengers that typically activate protein kinase enzymes (that then activate a series of enzymes)
flagella
long but small in number, these propel the cell itself forward or backward
ribosomes
made of proteins and RNA, they float in cytoplasm and bind to ER, and also produce proteins
peroxisomes
membranous sacs that contain oxidases and catalases; can neutralize free radicals like alcohol and formaldehyde
microvilli
minute, finger-like projections of the plasma membrane that increase the cell surface area for better absorption
membranous organelles
organelles which have membrane which include mitochondria, peroxisomes, lysosomes, ER, and golgi apparatus
non-membranous organelles
organelles which lack membranes and include cytoskeleton, centrioles, and ribosomes
glycoproteins
proteins that abut the extracelluar fluid that have sugar groups attached
osmosis
simple diffusion of a solvent (water) through the cell membrane
microfilaments
strandes made of spherical protein and subunits called actin; involved in cell motility and changes in shape
rough ER
studded with ribosomes, this produces proteins secreted from the cell
lysosomes
suicide sacs, which contain digestive enzymes that assist with the digestion of bacteria and cellular debris; also can degrade the cell itself
contact signaling
the actual coming together and touching of cells to allow cells to recognize one another; the contact between cells tell other cells they're not needed anymore
chemical signaling
the binding of plasma membrane receptors to ligans, which activate some downstream effect
cytoplasm
the cellular material between the plasma membrane and the nucleus
inclusions
the chemical substances that are present in specific cell types; not a true organelle, but located in the cell
For movement, shape of the cell, and to know where the organelles will be.
What are the three types of rods used for?
NO, cAMP, and CA++
What are the three types of second messengers?
active and vesicular
What are the two main modes of transport for active processes?
diffusion and filtration
What are the two main modes of transport for passive processes?
primary active transport' secondary active transport
What are the two main types of transports?
The movements of ions across the membrane; K+ channels let K+ leak from inside to the outside of the cell
What creates the electrical charge of the plasma membrane potential?
It opens the pump to either the Na or K sides of the pump
What does the phosphate do for the Na/K pump?
The Na/K pump
What helps maintain both the membrane potential and the osmotic balance?
The exchange ot the ions going back and forth through the NaK pump
What helps maintain the plasma membrane potential?
electrochemical gradient
What ions diffuse according to:
bacteria/amoeba
What is an example of a one-celled organism?
plants/animals
What is an example of multicellular organisms?
It is selectively permeable.
What is it about the plasma membrane which only allows certain things in and certain things out?
A cell is the basic structural and functional unit of living organisms.
What is the cell theory?
Made out of phospholiids, cholesterol, and glycolipids. Proteins are also found in and around the lipid bilayer.
What is the lipid bilayer made out of? What is also found either immersed or laying right on the surface of the bilayer?
-50 to -100 mV
What is the resting membrane potential? (the range, so numbers!!!)
ATP
What is the source of energy for primary active transport?
solute pumps
What moves solutes against the concentration gradient?
When a membrane is permeable to solutes
When can both water and solutes diffuse freely? What causes this?
Parts of the cytoskeleton may anchor the proteins, which may help maintain the cell shape and fix the location of certain membrane proteins. Also may help join some cells together.
Describe the attachment to cytoskeleton and extracellular matrix role of membrane proteins.
Some glycoproteins may serve as identification tags that are specifically recognized by other cells.
Describe the cell-cell recognition role of membrane proteins.
The protein may be enzymatic with its active site exposed to the substances in the adjacent solution.
Describe the enzymatic activity role of membrane proteins.
Membrane proteins of adjacent cells may hook together to join cells, and even use these as channels to migrate contents of the two cells from one to the other.
Describe the intercellular joining role of membrane proteins.
May have a binding site at surface of protein to outside to a chemical messenger, which can then change the shape of the protein that may then initiate a chain of chemical reactions in the cell.
Describe the receptors for signaling transduction role of membrane proteins.
They may span entire membrane, providing a channel across the membrane which is selectively permeable. Some may be transports using ATP.
Describe the transport role of membrane proteins.
Nope
Does secondary active transport use ATP?
No, the concentration is higher
Is the concentration of the K+ lower on the inside?
When a membrane is impermeable to solutes. So, since the solutes couldn't move, the water did.
When can only water diffuse freely? What causes this? Why?
microtubules
These are large in diameter, made of tubulin, and determines the shape of the cell and organelle distribution; they are constantly assembling and dissassembling
lipid rafts
These are made of tightly packed saturated phospholipids which act in cellular signaling.
glycolipids
These are phospholipids with attached sugar groups
caveolin-coated vesicles
These capture specific molecules and participate in some forms of transcytosis; involved in cellular signaling and cross-talk.
CAMs
These help hold cells together
integral proteins
These type of membrane proteins are firmly inserted into the lipid bilayer, is transmembranous, with hydrophilic and hydrophobic regions in order to act as carriers or channels for substances to travel into or out of the cell. May even act as a receptor for hormones as second messengers.
peripheral proteins
These type of membrane proteins are not embedded in the lipid bilayer, though can be attached to integral proteins. They usually assist in the support of intracellular filaments, as well as provide an anchor transport of cellular vesicles, cell division, or muscle contraction.
Na+/K+ pump
This maintains a high concentration of K+ inside the cell, while keeping a low concentration of Na+ inside the cell
clathrin
This protein collects within the plasma membrane, deforming the membrane and interacting with interstitial fluid substances.
secondary active transport
This type of transport is driven indirectly by energy stored in ionic gradients; a coupled system, it moves several substances at one time, and helps bring additional substances into the cell
1.) transport 2.) receptors for signaling 3.) attachment to cytoskeleton and extracellular matrix 4.) Enzymatic activity 5.) Intercellular joining 6.) Cell-cell recognition
What are the six roles of membrane proteins? (What do they do?)
1.) cell adhesion molecules (CAMs) 2.) Membrane receptors 3.) Voltage-sensitive channel proteins
What are the three main types of cell-environment interaction
microtubules microfilaments intermediate filaments
What are the three main types of rods in the cytoskeleton?
cytosol sytoplasmic organelles inclusions
What are the three parts of cytoplasm?
Plasma Membrane Cytoplasm and Organelles and Nucleus
What are the three parts of the cell?
cytoplasmic organelles
the metabolic machinery of the cell
mitochondria
the powerplant of the cell, providing ATP, which controls the environment with 2 layers; also has its own DNA and RNA so they can replicate themselves; also makes its own proteins
filtration
the process that forces water and solutes through a membrane or capillary wall by hydrostatic pressure (high pressure to low pressure)
cells
the structural units of all living things
diffusion
the tendency of molecules to scatter evenly throughout the environment, when the molecules moves from a higher concentration to lower concentration until it is all balanced out; ends when we reach equilibrium
vesicular transport
the transport of large particles, macromolecules, and fluids across plasma and intracelluolar membranes; allows for exocytosis, endocytosis, and transcytosis. Requires ATP.GTP energy, since it transfers BIG molecules.
cytosol
the viscous, semitransparent fluid that supports the other cytoplasmic elements; the fluid in the cell, made mostly of water
G protein receptors
these bind cells together, also binding the receptors, and activiates second messengers which then release kinase to enzymes to start different chemical effects and changes within the cell
smooth ER
this communicates with its rough version and synthesizes steroids and lipids; also makes cholesterol
plasma membrane
this is a flexible barrier that separates the intracellular fluid from the extra cellular fluid
golgi apparatus
this is like the post office of the cell, which sorts out all of the materials within the cell and then brings it to the right location; pretty much it packages and transports proteins for export
phosphorylate
this transfers phosphate ATP to the pump
intermediate filaments
tough, insoluble protein fibers constructed like woven ropes
simple diffusion
unassisted diffusion of lipid-soluble or very small particles
active transport
when cells use energy in ATPto move solutes across the membrane; requires carrier proteins that combine specifically and reversibly with the transported substances
receptor-mediated endocytosis
when extracellular substances bind to specific receptor proteins in regions of coated pits, enabling the cell to ingest and concentrate specific substances in protein-coated vesicles. Receptors within are recycled to the plasma membrane in vesicles.