Chapter 4 Flashcards
nucleus
only in eukaryotes ; DNA can only be the in the nucleus
nuclear envelope
wraps the nucleus
nucleolus
where rRNA is transcribed and the subunits of ribosomes are assembled
endocytosis
how cells can acquire substances from the extracellular environment
phagocytosis
a few cells are capable of this , proteins binding on the particular matter to protein receptors on the phagocytotic cell
pinocytosis
ECF engulfed by small invaginations of the cell membrane, performed by most cell and it is a random process
receptor mediated endocytosis
specifiic uptake of macromolecules, ligand binds to a receptro protein on the cell membrane and is then moved to a clathrin coated pit, the pit invaginates to form a coated vesicle, this process absorbs the ligands
exocytosis
reverse of endocytosis
phospholipid bilayer
membrane invaginates and forms individual membrane bound organelles
ER
separates the cytosol from the ER lumen, in many places it is contiguous in places with the space between the double bilayer of the nuclear envelope
rough ER
ER near the nucleus that has ribsomes attached,
Golgi appartus
series of flattened membrane bound sacs, transport vescicles bud off from the ER and carry the proteins from the ER to the Golgi appartus, organizes and concentrates the proteins as they shuttled by tansport vesicles progressively outward from compartment or cisterna of the Golgi to the next. Golgi may change proteins chemically by glycosylation or by removing AA. end product is a vesicle full of proteins. can be released to mature into proteins or transported to other parts of the cell, secretory vesicles form the protein filled vesicles are expelled from the cell,
secretory vesicles
may contain enzymes, growth factors, or ECF matrix components , release contents through exocytosis, supply membrane with its integral proteins and lipids and as the mechanism for membrane expansion. regulated secretion–only release in response to a certain stimulus, some proteins are activated within the secretory vesicles
lysosomes
contain acid hydrolases–can break down every major type of macromolecule, have interior pH of 5 , fuse with endocytotic vesicles and digest their contents, any material not degraded by lysosomes is ejected by the cell. Autolysis– lysosome bursts and kills the cell
smooth ER
resembles flattened sacs, contains glucose-6-phosphate which is hydrolyzed to glucose. triglycerides are produced in smooth ER and stored in fat droplets, phospholipids are orginially synthesized there
adipocytes
cells contains predominately fat droplets
peroxisomes
vesicles in the cytosol, grow by incorporating lipds and proteins from the cytosol, self -replicate, produce and breakdown hydrogen peroxide , inactivate toxic substances, regulate ocygen concentration, play a role in the synthesis of breakdown of lipids, and in tthe metabolism of nitrogenous bases and carbohydrates
cytoskeleton
structure and motility of a cell is determined by a network of filaments
microtubles and microfilaments
microtubules are larger than microfilaments;rigid hollow tubes from a protein called tubulin; 13 of these filaments lie alongside each other to form the tube
mitotic spindle
made from microtubules
flagella and cilia
specialized structures also made from microtubules
axoneme
the major portion of each flagella and cilium, contains 9 pairs of microtubules forming a circle around 2 lone microtubules in an arrangement 9+2
crossbridges
made from dynein connect each of the outer pairs of microtubules to their neighbor,cause microtubule pairs slidge along their neighbors creating a whip action in cilia causing fluid to move laterally, or a wiggle action in flagella causing fluid to move directly away from the cell
MTOC in animal cells
centrosome
centrioles
function in the production of flagella and cilia
Actin
major component of microfilaments
microfilaments
contracting force in muscle as wll as being active in cytoplamic streaming (responsible for amoeba-like movement), phagocytosis and microvilli movement
tight junctions
form a watertight seal from cell to cell that can block water, ions and other molecules from moving around and past cells, –complete fluid barrier, hold together epithelial tissue in organs , barrier to protein movement between the apical and the basolateral surface of a cell
desmosomes
two cells at single point, attach directly to the cytosketeleton, don’t provent fluid from circulating, found in tissues that normally experience a lot of stress
gap junctions
small tunnels connecting cells, allow small molecules and ions to move between cels, in cardiac muscle provide for the spread of the action potential from cell to cell
mitochondria
own circular DNA that replicates independently from the eukaryotic cell, no histones or nucleosomes genes in mitochondrial DNA code for mitochondrial RNA that is distnct from the RNA in the rest of the cell, DNA passed maternally even in organisms whose male gamete contributes to the cytoplasm
endosymbiont theory
mitochondria may have evolved from a symbiotic relationship between ancient prokaryotes and eukaryotes
mitochondria
surrounded by 2 phospholipid bilayers; inner membrane – invaginates to form cristae, inner membrane that holds the electron transport chain, between inner and outer membrane in the intermembrane space
Tissue
cells that work together for a common purpose– epithelial tissue, muscle tissue, connective tissue and nervous tissue
Extracellular Matrix
constitute most of the tissue as in bone, surrounds the cell and that is formed by the cell itself
