Flashcards
Cells: Living Units
Cards in this deck (139)
- 1CellStructural unit of all living things
- 2Cell theorya) a cell is a basic structural and functional unit of organisms. Cell properties= properties of life.
b)the activity of an organism depends on both the individual and combined activities of its cells
c) biochemical activity of cells are di - 3cell's 3 main parts:PLASMA MEMBRANE: the outer boundary of the cell which acts as a selective permeable barrier.
CYTOPLASM: intracellular fluid packed with organelles (small structures that perform specific functions)
NUCLEUS: Organelle that controls cellular - 4Extracellular FluidsSUBSTANCES CONTRIBUTING TO BODY MASS FOUND OUTSIDE OF CELLS
- 5Body FluidsInclude INTERSTITIAL FLUID, BLOOD PLASMA, and CEREBROSPINAL FLUID.
- 6INTERSTITIAL FLUIDFLUID IN TISSUES THAT BATHES ALL OUR CELLS. CONTAINS AMINO ACIDS, SUGARS FATTY ACIDS, REUGULATORY SUBSTANES AND WASTES.
CELLS EXTRACT FROM THIS FLUID TH SUBSTANCES IT NEEDS DEPENDING ON THE PRESENT CONDITIONS. - 7CELLULAR SECRETIONSSubstances that aid in digestion: intestinal and gastric fluids, and act as lubricants: saliva, mucus and serous fluids.
- 8Extracellular Matrixabundant extracellular material, especially in connective tissues, ranging from soft to hard rock. jellylike substance composed of proteins and polysaccharides.
Cell glue: holds body cells together. Self assembled molecules into organized m - 9PLASMA MEMBRANESeparates 2 of the body's major fluid compartments: Intracellular and extracellular fluids.
plays dynamic role in cellular activities. - 10PLasma membrane structurethin (7-10 nm) structure composed of a double layer or bilayer of lipid molecules with protein molecules dispersed into it.
- 11Membrane lipidsforms the basic fabric of the membrane. constructed largely of phospholipids, with smaller amounts of glycolipids and cholesterol.
- 12PHOSPHOLIPIDSLollipop-shaped molecule with a polar head that is charged ad hydrophilic and an uncharged nonpolar tail, that is made with 2 fatty acid chains, and is hydrophobic.The heads lie on the inner and outer surfaces of the membrane.
- 13GLYCOLIPIDSLipids with attached sugar groups. only on the outer plasma membrane surface, they account for about 5% of total membrane lipids. Their sugar groups make the end of the molecule polar.
- 14CHOLESTEROL20% of membrane lipids. has a polar region (hydroxyl group) and non polar region (fused ring system). Its platelike hydrocarbon rings stabilize the membrane, while decreasing the mobility of the phospholipids and the fluidity of the membran
- 15Membrane proteinsallow the cell to communicate with its environment. make up 1/2 of plasma membrane by mass. responsible for for most of the membrane specialized functions. some float freely, some are tethered to intra or extracellular structures and are re
- 16INTEGRAL PROTEINSfirmly inserted into the lipid bilayer. most are transmembrane proteins that protrude on both sides. Have hydrophilic and hydrophobic regions, allowing them to interact with nonpolar lipid tails and water inside and outside the cell.
- 17Membrane proteins tasks-Transport
-receptors for signal transduction
-attachment to the cytoskeleton and extracellular matrix
-Enzymatic activity
-Intercellular joining
-Cell-cell recognition - 18Membrane proteins tasks: TRANSPORTProvides hydrophilic channel across the membrane that is selective for a particular solute.
Hydrolyzes ATP as an energy source to actively pump substances across the membrane. - 19Membrane proteins task: Receptor for signal transductionMembrane protein exposed to the outside of cell may have a binding site that fits the shape of a specific chemical messenger, such as a hormone.
When bound, the chemical messenger may cause a change in shape in the protein that initiates a - 20Membrane proteins task: Attachment to cytoskeleton and extracellular matrixElements of the cytoskeleton (cell's internal support) and the extracellular matrix (fibers and other substances outside the cell) may anchor to membrane proteins, which helps maintain cell shape and fix the location of certain membrane pro
- 21Membrane proteins task: Enzymatic activityMembrane protein may be an enzyme with its active site exposed to substances in the adjacent solution.
A team of several enzymes in a membrane may catalyze sequential steps of a metabolic pathway. - 22Membrane protein task: INTECELLULAR JOININGMembrane protein of adjacent cells may be hooked together in various kinds of intercellular junctions.
Some membrane proteins (cell adhesion molecules or CAMs) of this group provide temporary binding sites that guide cell migration and oth - 23Membrane proteins task: CELL-CELL RECOGNITIONSome glycoproteins (proteins bonded to short chains of sugars which help to make the glycocalyx) serve as identification tags that are specifically recognized by other cells.
- 24Signal transductionrelaying of chemical messages to the cell interior.
- 25Peripheral proteinsNot imbedded in the lipid layer. Attached loosely to integral proteins and are easily removed without disrupting the membrane. Include network of filaments that help support the membrane from its cytoplasmic side. Some are enzymes. Some are
- 26THE GlycocalyxGlycoproteins and glycolipids secreted by the cell that form a fuzzy, sticky, carb rich area at the cell surface.
Provides highly specific biological markers by which approaching cells recognize each other. ex sperm recognizes ovum egg. - 27FACTORS FOR CELL BINDINGGlycoproteins in the glycocalyx act as an adhesive.
Wavy contours of the membranes of adjacent cells fit together in a tongue in groove fashion.
special cell junctions form. - 28TIGHT JUNCTIONSSeries of integral protein molecules in the plasma membrane of adjacent cells fuse together, forming an impermeable junction that encircles the cell.Prevents molecules from passing through the extracellular space between adjacent cells.
- 29DesmosomesBinding bodies. Serve as anchoring junctions. Mechanical couplings scattered like rivets along the sides of adjacent cells to prevent their separation
- 30plaquebutton-like thickening on the cytoplasmic face of each plasma membrane.
- 31cadherinsthin linker protein filaments.
they extend from the plaque and fit together like the teeth of a zipper in the intercellular space. - 32Intermediate filamentsthicker keratin filaments.
form part of the cytoskeleton.
extend form the cytoplasmic side of the plaque across the width of the cell to anchor to the plaque on the cell's opposite side. - 33Gap junctionAKA Nexus. communicating junction between adjacent cells.
Present in excitable tissues such as the heart and smooth muscle, to help synchronize their electrical activity and contraction - 34connexonshollow cylinders composed of transmembrane proteins connecting cells at gap junctions.
- 35PASSIVE PROCESSESSubstances cross the membrane without any energy input from the cell.
- 36Active processesThe cell provides the metabolic energy (usually ATP) needed to move substances across the membrane.
- 37DIFFUSIONTendency of molecules or ions to move from an area where they are in higher concentration to an area where they are in lower concentration, that is, down or along their concentration gradient.
The system reaches equilibrium with molecules m - 38Speed of diffusioninfluenced by size= the smaller,
the faster
by temperature= the warmer, the faster - 39Molecule will diffuse through the membrane if:-the molecule or ion is lipid soluble
-small enough to pass through the membrane channels
-assisted by a carrier molecule - 40Simple diffusionunassisted diffusion of lipid soluble or very small particles.
nonpolar and lipid soluble substances diffuse directly though the lipid bilayer. ex oxygen through the blood into the cells - 41Facilitated diffusionThe transported substance either 1) binds to protein carriers in the membrane and is ferried across or 2) moves through water-filled protein channels.
- 42Carrier-mediated facilitated diffusionvia protein carrier specific for one chemical; binding of substrate causes transport protein to change shape
- 43Channel-mediated facilitated diffusionthrough a channel protein; mostly ions selected on the basis of size and charge.
- 44OSMOSISDiffusion of a solvent such as water through a specific channel protein (aquaporin) or through the lipid bilayer.
- 45OSMOLARITYThe total concentration of all solute particles in a solution
- 46Hudrostatic pressurethe back pressure exerted by water against the membrane.
pushing water out.
(plant cells) - 47Osmotic pressure-the tendency of water to move into the cell by osmosis.
-the higher the amnt of nonpenetrating solutes in a cell, the higher the osmotic pressure.
pulling water in. (plant cells) - 48Tonicityability of a solution to change the shape or tone of a cell by altering the cell's internal water volume
- 49Isotonic solutionssame concentration of nonpenetrating solutes as those found in cells. Cells exposed to ISOTONIC solutions retain their normal shape and exhibit no net loss or gain of water.
ex: extracellular fluids and intravenous solutions are ISOTONIC. - 50Hypertonic SolutionsHigher concentration of nonpenetrating solutes than seen in the cell. ex strong saline solution.
Cells immersed in HYPERTONIC solutions lose water and shrink, or CRENATE. - 51Hypotonic solutionsMore dilute (contain lower concentration of non penetrating solutes) than cells. Cells placed in a HYPOTONIC solution plump up rapidly as water rushes into themDistilled water represent the most extreme example of hypotonicity. It contains
- 52—HYPER, ISO, HYPO-TONIC SOLUTIONS
- 53Active processcell uses energy to move solutes across the membrane. Substances moved actively across the plasma membrane are usually unable to pass in the necessary direction by passive transport processes.
- 54Active transportrequires carrier proteins that combine specifically and reversibly with the transported substances.
- 55Active tranporterssolute pumps, they move solutes, most importantly ions uphill against a concentration gradient. CELLS EXPEND ENERGY.
- 56PRIMARY ACTIVE TRANSPORTProcess in which solutes are moved across cell membranes against electrochemical gradients using energy supplied directly by ATP
- 57SECONDARY ACTIVE TRANSPORTTransport is driven indirectly by energy stored in concentration gradients of ions created by primary active transport pumps. Coupled systems: moving more than one substance at a time.
- 58SYMPORT SYSTEMSubstances are "dragged along" or cotransported by carrier proteins moving specific solutes, such as sodium
- 59VESICULAR TRANSPORTFluids containing large particles and macromolecules are transported across cellular membranes inside bubble-like membranous sacs called vesicles.
- 60ENDOCYTOSIS1) coated pit ingests substance.
2)protein-coated vesicle detaches
3)coat proteins are recycled to plasma membrane.
4)uncoated vesicle fuses with a sorting vesicle called an endosome
5)transport vesicle containing membrane components moves - 61Phagocytosis (cell eating)The cell engulfs a large particle (ex clump of bacteria) by forming projecting pseudopods around it and enclosing it within a membrane sac called phagosome, which combines with a lysosome. Undigested content remains in the vesicle (now call
- 62Pinocytosis (cell drinking)/ fluid-phase endocytosisThe cell gulps a drop of extracellular fluid containing solutes into tiny vesicles. No receptors are used so the process is non specific. Most vesicles are protein-coated.
- 63RECEPTOR MEDIATED ENDOCYTOSISExtracellular substances bind to specific receptor proteins enabling the cell to ingest and concentrate specific substances (ligands) in protein coated vesicles. Ligands may simply be released inside the cell, or combined w a lysosome to di
- 64Lysosomespecialized cell structure containing digestive enzymes where the ingested substance is degraded or released
- 65Amoeboid motioncytoplasm flows into temporary extensions that allows the cell to creep along ( ex macrophage)
- 66clathrinBristle-like protein coating found on cytoplasmic face of the pit.
- 67caveolae (little caves)tubular or flask shaped inpocketings of the plasma membrane seen in many cell types. Captures specific molecules, LIKE clathrin. UNLIKE CLATHRIN COATED VESICLEs, CAVEOLAE are smaller and their cage-like protein coat is thinner. Plays Signif
- 68exocytosis1) the membrane-bound vesicle migrates to the plasma membrane.
2) there, proteins at the vesicle surface (v-snares) bind with t-snares (plasma membrane proteins)
3) the vesicle and plasma membrane fuse and a pore opens up
4) vesicle content - 69Membrane potentialVoltage
- 70resting membrane potential of plasma membrane-50 to -100 millivolts (mV)
- 71Cell Adhesion Molecules (CAMs)Sticky glycoproteins found in almost every cell in the human body, Key roles in embryonic dev., wound repair and immunity. Cadherins and integrins.
- 72Roles of CAMs-Molecular velcro used by anchor cells to anchor themselves to molecule in the the extracellular space and to each other.
- arms that migrating cells use to haul themselves past one another
-SOS signals sticking out from the blood vessel l - 73Contact signalingcells come together and touch, means by which cells recognize each other.
- 74Ligandschemicals that bind specifically to plasma membrane receptors. include neurotransmitters and paracrines ( chemicals that act locally and are rapidly destroyed.)
- 75G proteinsmiddlemen, relays between extracellular first messengers and intracellular second messenger (intracellular chemical signals) that cause responses within the cell
- 76Cytoplasmcellular material between the plasma membrane and the nucleus. Site of most cellular activities. 3 major elements: cytosol, organelles, inclusions.
- 77cytosolviscous semitransparent fluid in which the other cytoplasmic elements are suspended. Mixture of colloid and true solution. Contains sugars, salts and other solutes.
- 78INclusionschemical substances that may or may not be present depending on cell type. ex stored nutrients
- 79organellesmetabolic machinery of the cell. each type carry out a specific function for the cell
- 80Mitochondriatypically threadlike or lozenge shaped membranous organelles. Squirm, elongate and change shapes continuously.
Provide most of cell's ATP supply.
Cluster where the action is. - 81Structure of mitochondrionEnclosed by 2 membranes each the general structure of the plasma membrane.
Outer membrane: smooth and featureless
inner membrane: folds inward forming shelf like cristae (crests) that protrude into the matrix (gel-like substance within the - 82RibosomesSmall, dark-staining granules composed of proteins and a variety of RNA's called ribosomal RNAs.
Each has 2 globular subunit that fit together like the body and cap of an acorn.
Sites of protein synthesis
Can switch back and forth between t - 83Free ribosomesFloat freely in the cytosol. MAKE SOLUBLE PROTEINS THAT function in the cytosol, as well as those imported in the mitochondria and some other organelles.
- 84Membrane-bound ribosomesattached to membranes forming a complex called rough endoplasmic reticulum. Synthesize proteins either destined for incorporation into cell membrane or lysosomes, or for export from the cell.
- 85Endoplasmic reticulumextensive system of interconnected tubes and parallel membranes enclosing fluid filled cavities or cisterns. Coils and twists through the cytosol, continuous with the outer nuclear membrane and accounts for half of the cell's membrane. 2 ty
- 86ROUGH ER-external surface studded with ribosomes (rough)
-proteins assembled on ribosomes thread into fluid filled ER cisterns
- New proteins are enclosed in vesicles to head to the golgi apparatus for further processing - 87Functions of rough ER-Its ribosomes manufacture all proteins secreted from cells.
-Abundant in secretory cells, immune cells, and liver cells.
Membrane factory, manufacturing phospholipids and integral proteins.
-Active sites of enzymes that catalyze lipid sy - 88Smooth ER-Continuous with the rough ER and consists of tubules arranged in a looping network.
- 89Role of smooth ER enzymes-Metabolize lipids, synthesize phospholipids and cholesterol, synthesize the lipid component of lipoproteins
-Synthesize steroid based hormones ex testosterone
-Absorb synthesize and transport fat
-Detoxify drugs, pesticides and cancer cau - 90GOLGI APPARATUSStacked and flattened membranous sacs, shaped like hollow dinner plates, assoc. w. tiny membranous vesicles.
Traffic director for cellular proteins - 91Function of Golgi ApparatusModify, concentrate and package proteins and lipids made at the rough er DESTINED FOR export from the cell.
- 92Peroxisomesresembling small lysosomes, they are spherical membranous sacs containing a variety of powerful enzymes such as oxydases and catalases.
Formed when pinched in half. Most formed by by budding off the ER - 93Oxidasesuse molecular oxygen to detoxify harmful substances including alcohol and formaldehude.
Neutralize free radicals. - 94Free radicalshighly reactive chemicals with unpaired electrons that can scramble the structure of biological molecules.
Are converted to hydrogen peroxide by oxydases. - 95Lysosomesspherical membranous organelles containing activated digestive enzymes.
Large and abundant in phagocytes. Its enzymes can digest almost all kinds of biological molecules.
Called acid hydrolases because they work best in acidic conditions. - 96Lysosome functionsCell demolition: digest particles taken in by endocytosis
Degrading dead or stressed cells and non functioning organelles (autophagy - self eating)
Metabolic functions like glycogen breakdown
breaking down bone to release calcium into the blood - 97AutolysisWhen lysosomes rupture, the cell digest itself
- 98Endomembrane systemSystem of organelles that work together to 1) produce, degrade, store, and export biological molecules and 2) degrade potentially harmful substances.
Includes: the golgi apparatus, the ER, the secretory vesicles, lysosomes, and nuclear membrane - 99CytoskeletonElaborate network of rods running through the cytosol and hundreds of accessory proteins that link these rods to other cell structures.
Acts as cell's bone, ligament and muscles.
3 types of rods: microfilaments, intermediate filaments, and microtubules. - 100Microfilamentsthinnest elements of the cytoskeleton
semiflexible strands of the protein actin.
Unique arrangement in each cell
Involved in cell motility or changes in the cell shape - 101Intermediate filamentsTough insoluble protein fibers constructed like woven ropes composed of tetramer fibrils
- 102Microtubuleshollow tubes of spherical protein subunits called tubulin
- 103Centrosomecell center
microtubule organizing center - 104centriolessmall barrel-shaped organelles oriented at right angles to each other.
consist of a pinwheel array of 9 triplets of microtubules
form the base of cilia and flagella - 105Ciliawhiplike motile cellular extensions. occur in large numbers on the exposed surface of certain cells. Ciliary action moves substances in one direction across cell surfaces.
- 106Flagellaformed by projections formed by centrioles but are longer than cilia.
ex sperm
tail called flagellum
Propels the cell itself - 107Basal bodiescentrioles forming the the bases of cilia and flagella
- 108Microvilliminute finger like extensions of the plasma membrane that project from an exposed cell surface
they increase the plasma membrane surface. ex intestines and kidney tubule cells - 109Nucleuscontrol center, contains the gene.
contains intruction to build all the body proteins - 110Multinucleatemany nuclei
- 111Nucelar envelopedouble membrane barrier separated by a fluid filled space. continuous with the rough EROF THE CYTOPLASM and is studded with ribosomes on its external face. lined by nuclear lamina that maintain the shape of the nucleus and acts as a scaffoldto organize DNA in the nucleous. (lamins: rod shaped proteins that assemble to form intermediate filaments)
Selectively permeable - 112Nucleolidark staining spherical bodies where the ribosomal subunits are assembled
- 113Chromatinfine, unevenly stained network, bumpy threads weaving through the nucleoplasm.
Compose of 30% DNA
60% GLOBULAR HISTONE PROTEINS
10% RNS chains - 114nucleosomesflattened disc shaped cores or clusters of 8 histone proteins connected like beads on a string
- 115Cell cycle: INTERPHASEPeriod from cell formation to cell division.
Metabolic or growth phase.
Divided into G1, S, G2 Subphases (G - GAPS; S- Synthetic) - 116Interphase: G1-Cell is metabolically active, synthesizing proteins and growing rapidly
- most variable in length of time, fr a few minute to years
G0 phase: cells permanently stop dividing.
As G1 ends, centrioles begin replicating in prep for cell division - 117Interphase: S phaseDNA REPILCATES, ENSURING 2 FUTURE CELLS RECEIVE IDENT. COPIES OF GENETIC MATERIAL.
New histones are made and assembled into chromatin
Sphase nec. to correct mitotic phase - 118Interphase: G2 (gap 2 subphase)-Final phase of interphase
-Enzymes and division proteins are synthesized and moved to sites.
-Centriole replication complete
- If all DNA is replicated, cell ready to divide. - 119DNA REPLICATION1-Uncoiling: enzymes unwind DNA molecule, forming replication bubble.
2- Separation: 2 DNA strands separate as hydrogen bonds are broken, unzips at replication fork
3 Assembly: old strands acts as template. Enzyme DNA polymerase positions complementary free nucleotides along the templates strands, forming 2 new strands. 2 new strands are synthesize in the opposite direction. 2 new daughter molecules result fr 1 parental. (semiconservative replication: each new molecule is half new, half old.
4- Restoration: Ligaze enzymes splice short segment of DNA together, restoring the dbl helix structure. - 120CELL DIVISIONEssential to body growth and tissue repair.
Called the Mitotic (M) phase.
involves mitosis and cytokinesis - 121Mitosisprocess of nuclear division in which the chromosomes are distributed to 2 daughter nuclei. Together with cytokinesis it produces 2 daughter cells
-4 phases: prophase, metaphase anaphase, telophase. Last about 1 hr in human cells - 122Mitosis: Early prophase-chromatins coils and condenses, forms barlike chromosomes
-each chromosome= 2 ident. threads-> sister chromatidsheld tog at the centromere(ctr)
-chromosomes appear, nucleoli disappears, 2 centrosome separate fr each other
-centrosomes: focal pts for growth of microtubule called mitotic spindle. As microtubules lengthen, they propel centrosomes to poles of cell.
- microtubules callesd asters extend from centrosome matrix - 123Mitosis: Late prophase-Nuclear envelope breaks up allowing spindle to interact w chromosomes
-growing spindles attache to kinetochores ( special protein structures at each chromosome centromere -> kinetochore microtubules
-remaining spindle microtubules (non-kinetochore microtubules_ slide past each other forcing poles apart
-kinetochore microtubules pull on each chromosome to draw each to the center of the cell - 124Mitosis: Metaphase- 2 Centrosomes at opp poles of of cell
-chromosomes cluster in midline of cell, w centromeres align at spindle equator. (metaphase plate)
-at the end, enzymes will act to separate the chromatids fr each other are triggered - 125Mitosis Anaphase-Shortest phase of mitosis, begins abruptly at centromeres of chromosomes split simultaneously. Each chromatid becomes a chromosome
-kinetochore microtubules pull each chromosome toward the pole it faces
-nonkinetochore microtubules push the poles of the cell apart
-V shaped moving chromosomes. centromeres lead, chromosomal arms dangle behind
- short, compact chromosomes help moving and separating - 126Mitosis: Telophase-Prophase in reverse
- Identical sets of chromosomes at the opposite poles of cell begin to uncoil and resume threadlike chromatin form
- New nuclear envelope forms around each chromatin mass, nucleoli reappear within the nuclei, and the spindle breaks down and disappear
-Mitosis is ended. for a brief moment cell is binucleate and each new nucleus is identical to the mother nucleus. - 127CytokinesisBegins during late anaphase and continues through and beyond telophase. A contractile ring of microfilaments forms the cleavage furrow and pinches the cell apart.
- 128Transcriptiontransfer info from a DNA base sequence to the complementary base sequence of an mRNA molecule.
DNA info encode in mRNA - 129Genesegment of a DNA molecule that carries instructions for creating one polypeptide chain.
- 4 nucleotide bases: A,G,T,C. Each sequence of 3 bases is a triplet, can be thought of as a "word" that specify a particular aminoacid - 130exoninformational sequence of DNA. separated by INtrons
- 131Intronnoncoding often repetitive segment of DNA, reservoir or scrapyard for ready to use DNA segments, as well as a rich source of RNA molecules.
- 132Messenger RNAmRNA: long nucleotide resembling half dna molecules
carries coded info to cytoplasm, where protein synthesis occurs - 133Ribosomal RNArRNA: form the ribosomes along w proteins
consist of 2 subunits, oe large one small - 134Transfer RNAtRNA: SMALL l SHAPED MOLECULES THAT FERRY amino acids to the ribosomes. decode mRna's message for amino acids sequence in the polypeptide to be built
- 135Translationgenetic info carried by mRNA is decoded in the ribosome to form a particular polypeptide. Translators are tRNA molecules and that recognize and bind both to an mRNA and an amino acid
- 136Transcription phasesInitiation: RNA polymerase pull apart the dna dbl helix so transcription begins at start pt in promoter
elongation: RNA Polymeras align incoming nucleotides w complementary dna BASES ON THE TEMPLATE STRANDS and link them together
termination: polymerase reaches termination signal, mRNA separates fr DNA template. - 137Genetic coderules by which the base sequence of a gene is translated into an amino acid
- 138codoncorresponding 3 base sequence on mRna for each triplet or 3 base sequence on DNA
- 139Micro RNAS