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Terms in this set (82)
the study of cells
75 trillion cells
how many cells does the adult human have?
characteristics of cells
functions to sustain life. obtain nutrients and other materials from surrounding fluids. cells must dispose of the waste. the shape and integrity of the cell is maintained by both its internal content and surrounding membrane. undergo cell division to make more cells
generalized cell that shows the basics of several different types of cells. almost all mature cells share the same 3 basic constituents
3 constituents of mature cells
plasma membrane, cytoplasm, nucleus
forms outer barrier which separates internal contents from external material (skin)
general term for everything located between the plasma membrane and nucleus
3 components of the cytoplasm
cytosol, organelles, and inclusions
tiny structures that perform specific cellular function
non-functional, temporary structures that store cellular products
cells control center
function of nucleus
controls protein synthesis, therefore, it directs functional and structural characteristics of the cell
forms the thin outer border of the cell, separates the internal components of a cell from the external environment and extracellular materials. functions as the "gate keeper" to regulate passage of gases, nutrients and waste between the internal and external environments
fluid build up around the lungs vs. CHF = fluid build up in the lungs
external carbohydrate coat
plasma membrane is composed of
equal mixtures of lipids and proteins (which forms a fluid matrix)
form the main structure of the plasma membrane
determines the main function of the plasma membrane
materials that are insoluble in water and ensures the plasma membrane will not dissolve if it comes in contact with water
3 types of lipids in plasma membrane
phospholipids, cholesterol, glycolipids
are the most abundant in plasma membrane and contain phosphate. have water soluble and water insoluble regions. are polar (unequal charge)
phospholipid bilayer head
polar, hydrophilic (loves water)
non-polar, hydrophobic (hates water)
type of liquid called a steroid. 20% of membrane liquids. scattered in the hydrophobic regions of the phospholipid bilayer where is strengthens the membrane and stabilizes it at extreme temperature
a lipid with attached carbohydrate group. 5-10% of membrane lipids. located only on the outer layer of the membrane where they are exposed to extracellular fluid.
carbohydrate portion of glycolipids. helps the molecule to participate in cell to ell recognition, adhesion and communication
composed of chains of smaller amino acids. perform various structural and functional activities with the cell and the body. make up about half of the plasma membrane by weight. determine most of the membranes functions
embedded within and extend across the phospholipid bilayer. some act as membrane channels providing a hole for specific substances to pass. receptors serve as binding sites for molecules outside of the cell.
are not embedded in the phospholipid bilayer. loosely attached to the external and internal surfaces of the membrane. often attach to the exposed parts of the integral protein. can "float" and move around in the bilayer like a beach ball
enzymes or catalyst
integral and peripheral membrane proteins may serve as these. important for functional or metabolic activities within the cell. can change the rate of a reaction
functions of the plasma membrane
protective barrier around the cell. permits the entry of oxygen, sugars, amino acids and other nutrients. facilitate the disposal of carbon dioxide and metabolic wastes before the accumulate, regulate the movement of other molecules across the membrane
substances move across a plasma membrane without expending energy. materials moved along the concentration gradient. (higher to lower concentration) no ATP needed
examples of passive transport
simple diffusion, osmosis, facilitated diffusion, and bulk filteration
when substances move across membranes unaided because they are either small or nonpolar or both. move from high to low concentration
water diffuses from one side of selectively permeable membrane to the other. from a region of high water concentration to low concentration until equilibrium is established
requires participation of specific proteins that help specific substances or molecules move across the plasma membrane. molecule binds to the transport protein in the membrane. binding helps alter the shape of the protein and the molecule which allows it to pass through. specific substances are either large molecules or molecules that are insoluble in lipids
diffusion of both solvents and solutes together across the membrane.
liquids that have substances, called solutes dissolved in them.
the movement of a substance across a plasma membrane against a concentration gradient. materials moved from an area of low concentration to high concentration. requires cellular energy ATP and sometimes a transport protein. ATP synthesized by the mitochondria.
2 active transport systems
ion pumps and bulk movement
active transport system that moves ions across the membrane. major factor in a cell's ability to maintain its internal concentrations of small molecules or ions.
"exchange pump" moves one ion into the cell while simultaneously removing another type of ion. (humans have higher concentration of potassium ions and much lower of sodium ions. plasma membrane maintains these differences by continuously excluding sodium ions from the cell and moving potassium ions into the cell)
active processes that move larger molecules across the membrane are exocytosis and endocytosis
large molecules are secreted from the cell. large proteins that cannot just pass through. material is packaged within intracellular transport vesicles. membranes fuse (requires ATP) vesicle contents are released. (observed in pancreas where cells release digestive enzymes into a pancreatic duct for transport to the small intestine)
cellular uptake of large substances. extracellular macromolecules are packaged into vesicle. small area of plasma membrane folds inward to form a pocket (invagination) which deepens and pinches off as the lipid layer fuses. fusion of lipids is the energy expending step. new intracellular vesicle is formed containing new material
3 types of endocytosis
phagocytosis, pinocytosis, receptor-mediated endocytosis
"cellular eating" occurs when a cell engulfs or captures a large particle external to the cell by forming membrane extensions called pseudopodia to surround the particle. (ex: when a WBC engulfs and digests a bacterium)
"cellular drinking" occurs when the cell internalizes a very small droplet of extracellular fluid into tiny vesicles. (ex: cells that line a capillary wall, where vessels fill with small fluid droplets containing small solutes from the blood, carry this droplet to the other side of the cell and expel its contents outside the opposite capillary wall.
movement of specific molecules from the extracellular environment into a cell by way of newly formed vesicle.
3 parts of cytoplasm
cytosol, organelles and inclusions
cytoplasmic matrix or intracellular fluid. syrup like fluid in the cytoplasm. its carbohydrates and lipids serve as an energy source for the cell. many small molecules in this are the building blocks of large macromolecules (ext: amino acids are small molecules dissolved in the cytosol that the cell uses to synthesize new proteins)
2 categories of organelles
membrane bound and non membrane bound
membrane bound organelles (membranous organelles)
the membrane separates the oranelle's contents from the cytosol so that the specific activities of th organelle can proceed without disrupting other cellular activities.
examples of membrane bound organelles
endoplasmic reticulum, golgi apparattus, lysosomes, peroxisomes and mitochondria
extensive cellular network thoughout the cytoplasm that is invilved in the syntheses, transport and storage of macromolecules, along with the detoxification of drugs and alcohol
rough ER is responsible for
responsible for transporting, producing and storing proteins to be exported outside the cell. responsible for proteins to be incorporated into the plasma membrane, enzymes that are housed with lysosomes, and consists of profiles of parallel membrane enclosing spaces called cisternae
small structures attached to the cytoplasmic sides of membranes. synthesize the proteins targeted for cell export, membrane insertion or inclusion within a lysosomes as a catalyst. they form the rough ER
no ribosomes are attached. resembles multiple interconnected branches of tubules. function in diverse metabolic procsses including synthesis, transport and storage of lipids, metabolism of carbs, and detoxification of drugs, alcohol, and poisoning. Liver contains abundant amounts of this in order to process digested nutrients and detoxify drugs and alcohol
center for modifying, packaging and sorting materials that arrive from the ERE in transport vesicles. extensive and active in cells specialized for secretion. composed primarily of a series of cisternae which are arranged in a stack. inhibits distinct polarity. the membranes of th ecisternae at opposite ends of a stack differ in thickness and molecular composition. these two poles are called the receiving region and the shipping region. diameter of the flattened sac is larger in the receiving region than in the shipping region. products of the RER move throuhg this via transport vesicles
materials pass through the golgi apparatus as follows:
newly synthesized proteins in the RER are sequestered into a transport vesicle. the vesicle pinches off the ER and travels to the Golgi apparatus. Newly arrived transport vesicles fuse with the receiving region of the Golgi apparatus. protein modification occurs as the proteins are moved by transport vesicles sequentially through the golgi apparatus cisternae from the receiving region to the shipping region. modified proteins are packaged in secretory vesicles. some secretory vesicles undergo exovytosis to discharge their contents into the extracellular fluid, while other secretory vesicles remain in the cell and become lysosomes. vesicles that become lysosomes contain proteins called digestive enzymes.
membrane sac formed by the Golgi apparatus. contain enzymes used by the cell to digest waster products. enzymes break down large molecules (proteins, fats, polysaccharides, nucleic acids) into smaller molecules.
old organelles are removed by lysosomes
rapid digestion of the entire cell itself
membrane enclosed sacs that are usually smaller than lysosomes. formed by pinching off vesicles from the RER. responsible for detoxifying specific harmful substances that are produced by the cell or taken in by the cell. are able to do this because it contains an enzyme called catalase that converts hydrogen peroxide into water before it can damage the cell. most abundant in liver cells
organelles with a double membrane that are involved in producing large amounts of the cells energy (ATP) powerhouses. completely surrounded by an outer membrane, while a second or inner membrane is folded internally into the space at the center of the organelle. inner membrane proteins are on the cristae. can self replicate. (ex: muscle cells with a high rate of energy usage have a large number of mitochondria in their cytoplasm.) also contain a small fragment of DNA
non-membrane bound organelles
organelles that are always in direct contact with the cytosol.
ex of non membrane bound organelles
ribosomes, cytoskeleton, centrosome, centrioles, cilia, flagella, microvilla
very small. responsible for protein production. small and large subunit. subunits are formed in the nucleus and assembled in the cytosol.
once units are assembled, these float freely in the cytosol. responsible for the synthesis of proteins that remain within the cytosol of the cell
produce proteins that are exported outside the cell, incorporated into the plasma membrane, or housed as enzymes in a new lysosome
for stability. composed of protein subunits as filaments or hollow tubes.
3 components of cytoskeleton
microfilaments, intermediate filaments, and microtubules
smallest components of cytoskeleton. composed of thin actin proteins. help maintain cell shape, support changes in shape, muscle contraction, separate two cells formed during division, facilitate cytoplasmic streaming.
more rigid. support cells and stabilize junctions between cells.
hollow tubules. composed of long chains of tubulin protein radiate out of the centrosome. are not permanent. help hold organelles in place, maintain cell shape and rigidy, direct organelle movement bw different regions, provide means of cell motility using cilia and flagella, move chromosomes during cell division
growth and elongation of microtubules
responsible for organizing microtubules
move material. transport system.
longer, move cell around
thin, extend from the surface of the plasma membrane. function to increase surface area of the plasma membrane.
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