nucleus
contains nuclear envelope, DNA (spread out w/in this as the threadlike matrix chromatin)
Ribosome
manufactured in the nucleus; consists
... [Show More] of RNA molecs and proteins; in the cytoplasm, this assists in the assembly of amino acids into proteins
Endoplasmic Reticulum (ER)
stacks of flattened sacs involved in the production of various materials; appear as a series of maze-like channels in cross section; when ribosomes are present, it creates glycoproteins
Smooth ER
without ribosomes; responsible for various activities, including the synthesis of lipids andhormones
Golgi Apparatus
group of flattened sacs arranged like a stack of bowls; modify and package proteins and lipids into vesicles; vesicles often migrate to and merge with the plasma membrane
Vesicles
small, sphericaly shaped sacs that bud from the outside surface of the Golgi apparatus; often migrate to and merge with the plasma membrane, releasing their contens to the outside of the cell
Lysosomes
vesicles from a Golgi apparatus that contain digestive enzymes; break down food, cellular debris, and foreign invaders such as bacteria; a low pH is favorable;do NOT occur in PLANT cells
Peroxisomes
break down various substances, including hydrogen peroxide (H202), fatty acids, and amino acids; common in liver and kidney cells; in plant cells, these modify by-products of photorespiration
Mitochondria
carry out aerobic respiration (energy-in the form of ATP- is obtained from carbohydrates)
Chloroplasts
carry out photosynthesis
Microtubules
made of protein tubulin; provide support and motility for cellular activites; found in the spindle apparatus
Intermediate filaments
provide support for maintaining the shape of the cell
Microfilaments
made of the protein actin; involved in cell motility; found in muscles cells and in cells that move by changing shapes, such as phagocytes (WBCs attacking bacteria)
Flagella
structures that protrude from the cell membrane; long, few, move in a snakelike motion; 9+2 array; Ex: propels sperm
Cilia
structures that protrude from the cell membrane; short, many, move with a back and forth movement; 9+2 array; Ex: line the resp. tract and sweep away debris
9+2 arrangement
nine pairs (doublets) of microtubulesarranged in a circle surrounding a pair of microtubules
Centrioles
microtubule organizing centers; pair (enclosed in a centrosome) are located outside the nuclear envelope, gives rise to the microtubules that make up the spindle apparatus used during cell division; nine triples of microtubules arranged in a circle; PLANTS LACK THESE
Basal bodies
microtubule organizing centers; at the base of each flagellum and cillium and appear to organize their development; 9 triplets of microtubules arranged in a circle; lower plants (mosses and ferns) with MOTILE sperm have these
transport vesicles
move materials b/w organelles or between organelles and the plasma membrane
food vacuoles
temporary receptacles of nutrients; often merge with lysosomes, whose digesitve enzymes break down the food
Storage vacuoles
in plants store starch, pigments, and toxic substances
central vacuoles
large bodies occupying most of the interior of certain plant cells; when fully filled, they exert turgor pressure on the cell walls, thus maintaining the rigidity in the cell; store nutrients and carry out functions otherwise assumed by lysosomes in animal cells
contracile vacuoles
specialized organelles in single-celled organisms that collect and pump excess water out of the cell
cell walls
found in plants, fungi, protists, and bacteria; develop outside the plasma membrane and provide support for the cell; in plants, it consists mainly of cellulose
extracellular matrix
found in animals in the area b/w adjacent cells; occupied by fibrous structural proteins, adhesion proteins, and polysaccharides; provides mechanical support and helps bind adjacent cells together
anchoring junctions
protein attachments between adjacent ANIMAL cells
Desmosome
kind of anchoring junction; consists of proteins that bind adjacent cells together, providing mech. stability to tissues; associated w/protein filaments that extend into the interior of the cell and serve to hold cellular strucures together
tight junctions
tightly stitched seams b/w ANIMAL cells; completely encircles each cell, producing a seal that prevents the passage of materials b/w cells
Communicating junctions
passageways b/w cells that allow the transfer of chemical or electrical signals
gap junctions
narrow tunnels between ANIMAL cells; consist of connexins (proteins); prevent the cytoplasms of each cell from mixing but allow the passage of ions and small molecs; allow communication b/w cells thru exchange of materials or thru the tranismission of elec. impulses; essentially channel proteins of two adjacents cells that are closely aligned
Plasmodesmata
narrow channels between PLANT cells; a narrow tube of ER surrounded by cytoplasm and the plasma membrane passes thru the channel; material exhange occurs thru the cytoplasm surrounding the demotubule
Selectively permeable membrane
allows onliy specific substances to pass
hypertonic
when there is a higher concentration of solutes
hypotonic
when there is a lower concentration of solutes
isotonic
when there is an equal concentration of solutes
Bulk flow
collective movement of substances in the same direction in response to a force or pressure; Ex: blood moving through a blood vessel
Passive Transport
movement of substances from region sof higher to lower concentrations (DOWN a concentration gradient) and do not require expenditure of energy
Diffusion
net movement of substances from an area of higher concentration to an area of lower concentration; this movment occurs as a result of the random and constant motion characteristic of all molecules, motion that is independent from the motion of other molecs; a state of equilibrium is attained where molecs are uniformly distributed but continue to move randomly [Show Less]