Chapter 2 - Cells Flashcards
plasma membrane
forms the cells flexible outer surface; it separates the cells internal environment and its external environment
3 principal parts of a cell
plasma membrane, cytoplasm, and __________
cytoplasm
all the cellular contents between the plasma membrane and the nucleus
2 components of cytoplasm
cytosol, organelles
cytosol
the fluid portion of cytoplasm, contains water, dissolves solutes and the suspended particles
organelles
each organelle has a characteristic shape and special function
lipid bilayer
2 back-to-back layers made of 3 types of lipid molecules
3 types of lipid molecules
phospholipids (75% of membrane lipids)
cholesterol molecules (20% of membrane lipids)
glycolipids (5% of membrane lipids)
integral proteins
entend into or through the lipid bilayer and are firmlyembedded in it
transmembrane proteins
integral proteins that span the entire lipid bilayer and protrude into both the cytosol and extracellular fluid.
peripheral proteins
integral proteins not as firmly embedded in the membrane and are attached to membrane lipids or integral proteins at the inner or outer surface of the membrane.
glycoproteins
proteins w/ carbohydrate groups attached to the ends that protrude into the ecf
glycocoloyx
the carbohydrate portions of glycolipids and glycoproteins that form an extensive sugary coating; acts like a molecular “signature” that enables cells to recognize one another.
ion channels
pores or holes through which specific ions, such as K+ ions, can flow through to gain entry or leave the cell
carriers/transporters
selectively moving a polar substance or ions from one side of the membranne to the other
receptors
serve as cellular recognition sites; each type of receptor recognizes and binds a specific type of molecule
ligand
specific molecule that binds to a receptor
enzymes
integral proteins that catalyze specific chemical reactions at the inside or outside surface of cell
linkers
proteins that anchor the plasma membranes of neighboring cells to one another or to protein filaments inside and outside the cell (integral and peripheral proteins can be linkers)
cell identity markers
enabling a cell to 1)recognize other cells of the same kind during tissue formation and 2) recognize and respond to potentially dangerous foreign cells. ex: blood type markers; often membrane glycoproteins and glycolipids serve as cell identity markers
intracellular fluid
inside cell, cytosol
extracellular fluids
outside cell; found in several places: interstitial fluid and plasma; circulatory vessels -> lymphatic -> between tissue and capillaries.
interstitial fluid
filling microscopic spaces b/w tissues
plasma
ecf in blood vessels
lymph
ecf in lymphatic vessels
passive process
substance moves down it’s concentration gradient or electrical gradient to cross the membrane using only its own kinetic energy
active processes
cellular energy expended to move the substance into an area of higher concentration gradient/electrical gradient.
adenosine phosphate (ATP)
cellular energy used for active processes
ways materials may cross plasma membranes
1) kinetic energy
2) transporter proteins
3) vessicles
processes that rely on kinetic energy to pass through a plasma membrane
diffusion and osmosis
diffusion
passive process in which the net movement of a substance is from a region of higher concentration to an area of lower concentration; continues until equilibrium.
osmosis
passive process; net movement of water molecules through a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration
aquaporins
pores made of integral proteins, and b/w neighboring phospholipid molecules in the membrane, an movement continues until equilibrium is reached
facilitated diffussion
a passive process that is accomplished w/ the assistance of transmembrane proteins functioning as carriers; allows some molecules too large to fit through the protein pores and others that are too insoluble in lipids to pass through the plasma membrane. ex: glucose
active transport
substances transported across plasma membranes with the expenditure of energy by the cell, typically from an area of lower concentration to an area of higher concentration
vessicle
small, spherical, membranous sac formed by the biudding off from an existing membrane; transport substances from one structure to another within cells, take in substances from ecf, or release substances into ecf
endocytosis
materials move into a cell in a vesicle formed from the plasma membrane; active processes
exocytosis
materials move out of a cell in a vesicle formed inside a cell with the plasma membrane; active transport
endocytosis
3 types: receptor-mediated endocytosis, phagocytosis, and bulk-phase endocytosis
receptor-mediated endocytosis
binding->vesicle formation->uncoating->fusion with endosome->recycling of receptors to plasma membrane->degradation in lysosomes
phagocytosis
cell engulf large solid particles including worn-out cells, whole bacteria, or viruses
phagocytes
body cells that carry out phagocytosis; 2 types: macrophages and neutrophils
macrophages
located in many body tissues, type of phagocyte
neutrophils
type of white blood cell
pseudopods (false feet)
projections of its plasma membrane and cytoplasm; surround outside of cell, and the membranes fuse to form a vessicle calles phagosome
phagosome
enters cytoplasm; fuses with one or more lysosomes, and lysosomal enzymes break down the ingested material
2 types of cels where exocytosis is very important
1) secretory cells that liberate digestive enzymes, hormones, or other secretions.
2) nerve cells that release neurotransmitters
trancytosis
active processes; vessicles undergo endocytosis on one end of the cell, then undergo exocytosis on te opposite side; occurs most often through the epithelial cells that line blood vessels and is a means for material to move b/w blood plasma and interstitial fluid.
bulk-phage endocytosis
“cell drinking”; movement of ecf into a cell by infolding of plasma membrane to form a vesicle
2 components of cytoplasm
cytosol and organelles
cytosol
fluid portion of cytoplasm that surrounds organelles
cytoskeleton
network of protein filaments that extend through the cytosol; microfilaments, intermediate filaments and microtubules
microfilaments
thinnest elements of cytoskeleton; mechanical support responsible for basic strength and shape of cells
microvilli
core of parallel microfilaments w/in a microvillus supports it and attaches is to other parts of the cytoplasm
intermediate filaments
found in parts of cells subject to mechanical stress, they help anchor organelles such as the nucleus and attach cells to one another
microtubules
long, unbranched hollow tubes composed of mainly a protein called tubulin; helps determine cell shape and function in the intracellular transport of organelles.
centrosome
located near the nucleus, consists of 2 components: a pair of centrisoles and pericentriolar material
centrioles
cylindrical structures, each composed of 9 clusters of 3 microtubules arranged in a circular pattern
cilia
numerous, short, hairlike projections that extend from the surface of the cell; anchored to a basal body.
