Chapter 6 : A Tour of the Cell
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95 terms
Sundanese | English |
|---|---|
| light microscope |  a microscope in which visible light ia passed through the specimen and then through glass lenses; can magnify effectively to 1000 times; lenses refract light so that the image of the specimen is magnified as it is projected |
| magnification | the ratio of an object's image size to its real size |
| resolution | a measure of the clarity of the image; the minimum distance two points can be separated and be distinguished as two points |
| Robert Hooke | Who first saw cell walls? |
| Anton van Leeuwenhoek | Who was the first to see living cells? |
| contrast | a measure of the accentuation of differences in a sample's parts |
| organelles | membrane-enclosed compartments within a cell; too small to be seen with a light microscope |
| electron microscope | a microscope that focuses a beam of electrons through the specimen or onto its surface |
| cell ultrastructure | the cellular anatomy revealed by an electron microscope |
| scanning electron microscope | a microscope that is especially useful for the detailed study of the surface of a specimen; electron beams scan the surface of the sample, which is usually coated with a thin film of gold, allowing electrons on the surface to be deleted and translated into an image; result is a 3D topographic image |
| transmission electron microscope | a microscope that is used to study the internal ultrastructure of cells; aims an electron beam through a thin section of specimen that is coated with atoms of heavy metals, allowing open space to result in an image of transmitted electrons; lenses are electromagnets |
| cytology | the study of cell structure |
| cell fractionation | a technique for studying cell structure and function that takes cells apart and separates major organelles and other subcellular structures from one another; enables researchers to prepare specific cell components in bulk and identify |
| cytosol | a semifluid, jelly-like substance enclosed by the membrane; contains all organelles and other components |
| plasma membrane | a selective barrier that allows sufficient passage of oxygen, nutrients, and wastes to service the entire cell |
| nucleus | organelle that contains most of the DNA; is the largest organelle |
| nuclear envelope | organelle that encloses the nucleus, separating it from the cytoplasm; composed of two phospholipid bilayer membranes; perforated by pore structures, each of which has continuous membrane surrounding it |
| pore complex | lines the nuclear envelope to regulate the entry and exit of proteins, RNA, and some large complexes of macromolecules |
| nuclear lamina | a netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope |
| nuclear matrix | a network of fibers that extends throughout the nuclear interior; adds extra support |
| chromosomes | structures that carry genetic information; technically exists only when cells are dividing |
| chromatin | the functioning form of DNA (chromosomes), a complex structure including DNA and proteins; |
| nucleolus | a structure within the nondividing nucleus that synthesizes rRNA from instructions in DNA; also constructs ribosomal units from rRNA and protein; number depends on species and life stage of cell |
| ribosomes | complexes made of ribosomal RNA and proteins that carry out protein synthesis |
| free ribosomes | ribosomes that float in the cytosol to make the proteins that are used there |
| bound ribosomes | ribosomes that are attached to the endoplasmic reticulum to make proteins to be exported, to be embedded in membranes, and to be shipped elsewhere within the cell |
| endomembrane system | collection of different membranes within cell that carries out a variety of tasks within it; responsible for synthesis and transport of proteins, metabolism, movement of lipids, and detoxification of poisons |
| vesicles | sacs made of membrane that transfer membrane segments within the cell |
| endoplasmic reticulum | an extensive network of membranes that accounts for more than half of total membranes in cells |
| smooth endoplasmic reticulum | endoplasmic reticulum whose outer surface lacks ribosomes; functions in diverse metabolic processes (lipid synthesis, metabolism of carbs, detox of poisons, production of hormones, stores calcium ions) |
| rough endoplasmic reticulum | endoplasmic reticulum whose outer surface has ribosomes, which secrete proteins; as proteins grow, they are threaded into ER lumen through a pore formed by a protein complex in the ER membrane; as protein enters, it is folded into shape |
| glycoproteins | proteins that have carbohydrates covalently bonded to them |
| Golgi apparatus | organelle that modifies and stores products of the endoplasmic reticulum, such as proteins, before sending them to other parts of the cell; has a distinct structural polarity with two opposing poles (cis face and trans face) which act as receiving and shipping centers; sorts molecules according to final destination |
| cisternal maturation model | model that explains that Golgi's cisternae progress from the cis face to the trans face, carrying and modifying cargo as they move |
| lysosome | a membranous sac of hydrolytic enzymes that an animal cell uses to digest macromolecules; acidic environment is prime for these; responsible for intracellular digestion, such as phagocytosis |
| phagocytosis | the occurrence in which protists eat by engulfing smaller organisms or other food particles; the resulting food vacuole fuses with the lysosome, whose enzymes digest it--products then pass into cytosol as nutrients for the cell |
| food vacuoles | vacuoles that are formed by phagocytosis |
| contractile vacuoles | vacuoles that pump excess water out of the cell to maintain the proper concentration of ions and molecules |
| central vacuoles | vacuoles that develop from the culmination of smaller vacuoles originating from the ER and the Golgi apparatus; an integral part of plant cells because it selects transporting solutes (can take up to 90% of cell's volume); holds plants' proteins, inorganic ions, disposes dangerous metabolic by-products, contains color pigments, enables growth, protects from poison |
| mitochondria | the site of cellular respiration; made of two membranes: a smooth outer, and a rough inner |
| chloroplasts | the site of photosynthesis; made of two membranes, both smooth; |
| cristae | the folds of a mitochondrion's inner membrane; stores the enzyme that helps make ATP |
| grana | stacked membranous compartments within the chloroplast |
| thylakoid | singular membranous compartment within the chloroplast |
| stroma | fluid inside of chloroplast; contains DNA, ribosomes, and enzymes |
| peroxisome | an oxidative organelle that is not part of the endomembrane system; imports proteins primarily from cytosol; helps detoxify hydrogen peroxide; use asexual reproduction |
| mitochondrial matrix | a matrix enclosed by membrane mitochondria; contains enzymes, DNA, and ribosomes; catalyzes part of cellular respiration |
| glyoxysomes | specialized peroxisomes found in fat-storing tissues of plant seeds that have enzymes which convert fatty acids to sugars; used for energy until photosynthesis occurs to produce its own sugar |
| cytoskeleton | a network of fibers extending throughout the cytoplasm; organizes structures and activities within the cell; has three main components: microtubules, intermediate filaments, and microfilaments |
| microtubules | hollow rods constructed from globular protein, tubulin, which consists of two polypeptide chains: an alpha tubulin and a beta tubulin; function: shape and support the cell, serve as tracks for transport for motor proteins, separate chromosomes during cell division |
| centrosome | a region located near the nucleus that organizes microtubules that specialize in resisting compression from the cytoskeleton |
| centriole | part of the centrosome; composed of nine fused sets of triplet microtubules arranged in a ring; they replicate before an animal cell divides |
| cilia | microtubule-containing extensions of a cell that project it; lie perpendicular to the axis of motion; usually hundreds or thousands of these per cell |
| flagella | microtubule-containing extensions of a cell that project it; lie in the same axis of motion; usually 1-3 per cell (humans only have these on sperm cells) |
| basal body | the microtubule assembly of cilium or flagellum anchors to the cell based on structure that is identical to centriole |
| dyneins | a large motor protein on the outer doublets of cilia and flagella that provides bending movement for microtubules; performs movements by conformational changes, which ATP causes with energy |
| microfilaments | solid thread-like structures that are responsible for structure and support, amoeboid movement, and muscle contractions |
| actin | the globular protein that makes up microfilaments |
| pseudopodia | the part of a cell that is responsible for the conversion of cytoplasm from fluidy sol to a gel; this part functions due to localized contractions through actin and myosin movement |
| cytoplasmic streaming | a circular flow of cytoplasm within cells that results from actin-myosin interactions; speeds distribution of materials within cell; occurs a lot around the central vacuole of plant cells |
| intermediate filaments | an organelle specialized for bearing tension; associated with the keratin family of proteins; even after cell death, this part remains; responsible for fixing the positioning of organelles and stabilizing the cell's shape |
| cell wall | an extracellular structure of plant cells that serves as a means of protection, maintenance of shape, and balance of water intake; holds plants against gravity (some prokaryotes, fungi, and protists have this, but animals never do) |
| primary cell wall | the initial stage of a plant's extracellular structure; formed when microtubules in the cell cortex guide cellulose synthase as it deposits fibrils to aid in growth |
| cortex | the outer cytoplasmic layer of a cell; has a semisolid consistency of a gel |
| middle lamella | a structure that is situated between the primary cell walls of adjacent cells; has a layer with sticky polysaccharides, which glues adjacent cells together |
| secondary cell wall | a structure within plants that lies between the plasma membrane and the primary cell wall to add more strength to the overall structure |
| extracellular matrix | a structure outside of animal cells that contains glycoproteins, most of which are collagens, that create a web outside of the cell |
| collagen | a protein that accounts for about 40% of all protein in the human body; it is embedded in networks woven from proteoglycans, which consist of small core proteins with many carbohydrate chains covalently attached |
| fibronectin | a protein of the extracellular matrix that connects it to the cell by binding to integrin |
| integrin | a receptor protein built into the cell's membrane that aids fibronectin's connection to the cell from the extracellular matrix |
| tight junction | a cellular junction formed by plasma membranes of adjacent cells pressed tightly against each other and bound by proteins; they form continuous seals to prevent leakage of extracellular fluid |
| desmosomes | a cellular junction that fastens cells together into strong sheets |
| gap junction | a cellular junction that provides cytoplasmic channels from one cell to another (similar to plasmodesmata in plants); it allows for the passing of small molecules and is necessary for communication between cells in different tissues |
| compartmentalization | The following are benefits of what within the eukaryotic cell? 1) individualized microenvironments, 2) membranes in membrane-bound organelles provide more surface area, 3) can store waste that would otherwise be harmful, 4) allows for space for poisons |
| mimicry | taking on the appearance of another organism for self-defense |
| Batesian | the type of mimicry in which an organism appears to be more dangerous than it actually is; the mimic is harmless while the model is dangerous |
| Mullerian | the type of mimicry in which the mimic and the model are dangerous |
| replication | the process DNA goes through when it copies itself |
| transcription | the process that occurs when enzymes separate the two strands of DNA and replace one strand with messenger RNA, and then re-bind both strands |
| translation | the process that occurs when protein synthesis ensues; going from RNA to a protein |
| triplet | a sequence of DNA nucleotides that codes for an amino acid |
| codon | a sequence of RNA nucleotides that codes for an amino acid |
| leader sequence | a sequence of nucleotides on every messenger RNA region that merely regulates where to start the translation process |
| plasmodesmata | narrow threads of cytoplasm that pass through the cell walls of adjacent plant cells, allowing for communication between them |
| aminoacyl tRNA synthetases | the 64 different enzymes, each of which corresponds to a unique amino acid |
| anti-codon | the complementary nucleotide sequence on transfer RNA that is physically positioned across from each codon on mRNA |
| nucleolar organizers | structures within a cell that put ribosomal RNA and proteins together to form ribosomal subunits |
| endosymbiotic theory | a theory that proposed that both mitochondria and chloroplasts were once free-living bacteria; at one point, a eukaryotic cell engulfed bacteria, and lysosomes did not come to function--bacteria are now codependent on the cell |
| green | color that chloroplasts give |
| colored | color that chromoplasts give |
| colorless | color that amyloplasts give |
| protein pair | an element of the cytoskeleton plus a motor protein (track + engine--actin + myosin) |
| 9+2 structure | the structure of cilia and flagella cross sections |
| radial spokes | the proteins that extend from the fused doublets to the unfused central tubule within cilia and flagella; these never move--they keep the cell in tact and attached, which causes bending when other proteins move |
| myofibril | the individual muscle strand within each muscular fiber that runs its entire length; contains microfilaments and the functioning space of muslce |
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