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_____ is the basic structural and functional unit of living organisms.
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_____ the intracellular fluid that is packed with organelles, small structures that perform specific cell functions.
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Bio 2401 chapter 3
Chapter 3-cells
| Question | Answer |
|---|---|
| _____ is the basic structural and functional unit of living organisms. | cell |
| _____ the intracellular fluid that is packed with organelles, small structures that perform specific cell functions. | cytoplasm |
| _____ controls cellular activities and typically it lies near the cell's center. | nucleus |
| The _____ of membrane structure depicts the plasma membrane as an exceedingly thin (7-10nm) structure composed of a double layer, or bilayer, of lipid molecules with protein molecules "plugged into" or dispersed in it. | fluid mosaic model |
| Each lollipop-shaped phospholipid molecule has a polar "head" that is charged and is ______. | hydrophilic |
| An uncharged, nonpolar "tail" that is made of two fatty acid chains and is _____. | hydrophobic |
| ______ are lipids with attached sugar groups. They are found only on the outer plasma membrane surface and account for about 5% of the total membrane lipid. | Glycolipids |
| About 20% of the outer membrane surface contains _____, dynamic assemblies of saturated phospholipids associated with unique lipids sphingolipids and lots of cholesterol. | lipid rafts |
| There are two distinct populations of membrane proteins ______ and _____. | integral and peripheral. |
| _____ are firmly inserted into the lipid bilayer. | integral proteins |
| ______ span the entire width of the membrane and protrude on both sides. | transmembrane protein |
| _____ are not embedded in the lipid. Instead, they attach rather loosely only to integral proteins and are easily removed without disrupting the membrane. | peripheral proteins |
| _____ is used to describe the fuzzy, sticky, carbohydrate-rich area at the cell surface. | glycocalyx |
| _____, a series of integral proteins molecules (including occludins and claudins) in the plasma membranes of adjacent cells fuse together, forming an _____ that encircles the cell. | tight junction; impermeable junction |
| _____ are anchoring junctions - mechanical couplings scattered like rivets along the sides of abutting cells that prevent their separation. | Desmosomes |
| On the cytoplasmic face of each plasma membrane is a buttonlike thickening called a _____. | plaque |
| A _____, or nexus, is a communicating junction between adjacent cells. | gap junction |
| At gap junctions the adjacent plasma membranes are very close, and the cells are connected by hollow cylinders called _____. | connexons |
| Our cells are bathed in an extracellular fluid called _____. | interstitial fluid |
| Although there is continuous traffic across the plasma membrane, it is a ____, or _____, ____ barrier, meaning that it allows some substances to pass while excluding others. | selectively, or differentially, permeable |
| In____, substances cross the membrane without any energy input from the cell. | passive processes |
| In_____, the cell provides the metabolic energy (ATP) needed to move substances across the membrane. | active processes |
| The two main types of passive transport are _____ and ____. | diffusion and filtration |
| _____ is the tendency 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 _____. | Diffusion; concentration gradient |
| In ____, nonpolar and lipid-soluble substances diffuse directly through the lipid bilayer. | simple diffusion |
| ______ in which the transported substance either binds to protein carriers in the membrane and is ferried across or moves through water-filled protein channels. | facilitated diffusion |
| ______ are transmembrane integral proteins that show specificity for molecules of a certain polar substance or class of substances that are too large to pass through membrane channels, such as sugars and amino acids. | carriers |
| _____ are transmembrane proteins that serve to transport substances, usually ions or water, through aqueous channels from one side of the membrane to the other. | channels |
| the so-called ____ are always open and simply allow ion or water fluxes according to concentration gradients. | leakage channels |
| The diffusion of a solvent, such as water, through a selectively permeable membrane is _____. | Osmosis |
| Water also moves freely and reversibly through water-specific channels constructed by transmembrane proteins called ______. | aquaporins (AQPs) |
| The total concentration of all solute particles in a solution is referred to as the solution's _____. | osmolarity |
| As water diffuses into the cell, the point is finally reached where the _____ (the back pressure exerted by water against the membrane) within the cell is equal to its _____ (the tendency of water to move into the cell by osmosis). | hydrostatic pressure; osmotic pressure. |
| The ability of a solution to change the shape or tone of cells by altering their internal water volume is called _____. | tonicity |
| Solutions with the same concentrations of nonpenetrating solutes as those found in cells are _____. | isotonic |
| Solutions with a higher concentration of nonpenetrating solutes that seen in the cell are ______. | hypertonic |
| solutions that are more dilute (contain a lower concentration of nonpenetrating solutes) than cells are called _____. | hypotonic |
| _____, like carrier-mediated facilitated diffusion, requires carrier proteins that combine specifically and reversibly with the transported substances. | active transport |
| In _____, the energy to do work comes directly from hydrolysis of ATP. | primary active transport |
| In _____, transport is driven directly by energy stored in ionic gradients created by operation of primary active transport pumps. | secondary active transport |
| If the two transported substances are moved in the same direction, the system is a _____. | symport system |
| If the transported substances "wave to each other" as they cross the membrane in opposite directions, the system is called ____. | antiport system |
| In _____, hydrolysis of ATP results in the phosphorylation of the transport protein. This step causes the protein to change its shape in such a manner that it "pumps" the bound solute across the membrane. | primary active transport |
| The most investigated example of a primary active transport system is the operation of the _____, for which the carrier, or "pump" is an enzyme called ____. | sodium-potassium pump; Na+-K+ ATphase |
| In _____, fluids containing large particles and macromolecules are transported across cellular membranes inside membranous sacs called ____. | Vesicular transport; vesicles |
| Vesicular transport processes that eject substances from the cell interior into the extracellular fluid are called _____. | exocytosis |
| Those in which the cell ingests small patches of the plasma membrane and moves substances from the cell exterior to the cell interior are called ____. | endocytosis |
| Vesicular transport is also used for combination processes such as _____, moving substances into, across, and the out of the cell, and ____, or ____, _____, moving substances from one area (or organelle) in the cell to another. | transcytosis; substance, or vesicular, trafficking |
| The substance to be taken into the cell by endocytosis is progressively enclosed by an infolding portion of the plasma membrane called ____. | coated pit |
| The coating is most often the bristlelike _____ protein coating found on the cytoplasmic face to the pit. | clathrin |
| The uncoated vesicle then typically fuses with a processing and sorting vesicle called an _____. | endosome |
| _____, a specialized cell structure containing digestive enzymes, where the ingested substance is degraded or release (if iron or cholesterol), or be transported completely across the cell and released by exocytosis on the opposite side (trancytosis). | lysosome |
| ______ is common in the endothelial cells lining blood vessels because it provides a quick means to get substances from the blood to the interstital fluid. | Transcytosis |
| ____ is the type of endocytosis in which the cell engulfs some relatively large or solid material, such as clump of bacteria, cell debris, or inanimate particles (asbestos fibers or glass for example). | Phagocytosis |
| When a particle binds to receptors on the cell's surface, cytoplasmic extensions called pseudopods for and flow around the particle and engulf it. This endocytotic vesicle formed in this way is called a _____. | Phagosome |
| _____ cells help police and protect the body by ingesting and disposing of bacteria, other foreign substancs, and dead tissue cells. | phagocytes |
| Most phagocytes move about by ____ that is, the flowing of their cytoplasm into temporary pseudopods allows them to creep along. | amoeboid motion |
| In ____ ("cell drinking") also called fluid-phase endocytosis, a bit of infolding plasma membrane (which begins as a clathrin-coated pit) sorrounds a very small volume of extra cellular fluid containing dissolved molecules. | pinocytosis |
| ____ is the main mechanism for the specific endocytosis and transcytosis of most macromolecules by body cells, and it is exquisitely selective. | receptor-mediated endocytosis |
| _____, tubular or flask shaped inpocketings of the plasma membrane seen in many cells types, are involve in unique kind of receptor-mediated endocytosis called ____. | Caveolae; potosis |
| The process of ____, typically stimulated by a cell-surface signal such as binding of a hormone to a membrane receptor or a change in membrane voltage, accounts for hormone secretion, neurotransmitter release, mucus secretion, and ejection of wastes. | Exocytosis |
| The substance to be removed from the cell is first enclosed in a protein-coated membranous sac called a ____. | vesicle |
| ____ is electrical potential energy resulting from the separation of oppositely charged particles. | voltage |
| An equally important result is the generation of a ____, or voltage, across the membrane. | potential membrane |
| All body cells exhibit a _____ that typically ranges from -50 to -100 millivolts depending on cell type. For this reason, all cells are said to be ____. | resting membrane potential; polarized |
| Ion diffuse according to _____, thereby recognizing the effect of both electrical and concentration (chemical) forces. | electrochemical gradeints |
| ____ are found on almost every cell in the body. They play key roles in embryonic development and wound repair and in immunity. | cell adhesion molecules |
| A huge diverse of integral proteins and glycoproteins that serve as binding sites are collectively known as ____. | membrane receptors |
| _____ is the actual coming together and touching of cells, and it is the means by which cells recognize one another. | contact signaling |
| Most plasma membrane receptors are involved in ______. | chemical signaling |
| signaling chemicals that bind specifically to plasma membrane receptors are called ____. | ligands |
| _____ acts as a middleman or relay to activate or inactivate a membrane-bound enzyme or ion channel. | G protein |
| one or more intracellular chemical signals commonly called ____, are generated and connect plasma membrane events to the internal metabolic machinery of the cell. | second messengers |
| Two very important second messengers are ____ and ____, both of which typically activate protein kinase enzyme. | cyclic AMP and Ionic calcium |
| ____ transfer phospate groups from ATP to other proteins. | protein kinase enzymes |
| ____ one of nature's simples molecules, is made of a single atom of nitrogen and oxygen. | nitric oxide |
| In the process known as ____, certain plasma membrane proteins are channel proteins hat respond to changes in membrane potential by opening or closing the channel. | electrical signaling |
| ____ is the cellular material between the plasma membrane and the nucleus. | cytoplasm |
| ___ is the site where most cellular activities are accomplished. | cytoplasm |
| Three major elements of cytoplasm. | cytosol, organelles, and inclusions |
| ____, is the viscous, semitransparent fluid in which the other cytoplasmic elements are suspended. | cytosol |
| ___ are the metabolic machinery of the cell. | organelles |
| ____ are chemical substances that may or may not be present, depending on cell type. | inclusions |
| What are the nonmembranous organelles? | cytoskeleton, centrioles, and ribosomes |
| What are the membranous organelles? | mitochondria, peroxisomes, lysosomes, endoplasmic reticulum, and Golgi apparatus. |
| _____ are threadlike or lozenge-shaped membranous organelles. They are the power plants of a cell, providing most of its ATP supply. | Mitochondria |
| ____ are small, dark-staining granules composed of proteins and a variety of RNAs called _____. | Ribosomes; ribosomal RNAs |
| Some ribosomes float freely in the cytoplasm. Others are attached to membranes, forming a complex called the ____. | rough endoplasmic reticulum |
| ____ make soluble proteins that function in the cytosol, as well as those imported into mitochondria and some other organelles. | Free ribosomes |
| ____ synthesize proteins destined either for incorporation into cell membranes or for export from the cell. | membrane-bound ribosomes |
| _____ is an extensive system of interconnected tubes and parallel membranes enclosing fluid-filled cavities, or cisternae. | endoplasmic reticulum |
| Its ribosomes manufacture all proteins secreted from cells. | Rough endoplasmic reticulum |
| ____ is continuous with the rough ER and consists of tubules arranged in a looping network. Its enzymes play no role in protein synthesis. | smooth endoplasmic reticulum |
| ___ consists of stacked and flattened membranous sacs, shaped like hollow dinner plates, associated with swarms of tiny membranous vesicles. | Golgi apparatus |
| Vesicles containing proteins destined for export pinch off from the trans face as ____, or ___, which migrate to the plasma membrane and discharge their contents from the cell by exocytosis. | secretory vesicles or granules |
| ____ are spherical membranous organelles containing activated digestive enzymes. | lysosomes |
| Lysosomal enzymes digest almost all kinds of biological molecules. They work best in acidic conditions and so are called ____. | acid hydrolases |
| ____ is a system of organelles that work together mainly to produce, store and export biological molecules, and to degrade potentially harmful substances. | endomembrane system |
| ____ are membranous sacs containing a variety of powerful enzymes, the most important of which are oxidases and catalases. | peroxisomes |
| ___ is an elaborate network of rods running through the cytosol. It acts as cell's "bones", "muscles", and "ligaments" by supporting cellular structures providing the machinery to generate various cell movements. | cytoskeleton |
| The thee types of rods in order of increasng size in the cytoskeleton are ____, ____ and ____. | microfilaments, intermediate filaments, and microtubules. |
| ____, the elements with the largest diameter, are hollow tubes made of spherical protein subunits called ____. | microtubules; tubulins |
| Most microtubules radiate from a small region of cytoplasm near the nucleus called the ____ or ____. | centrosome or cell center |
| Mitochondria, lysosomes, and secretory vesicles attach to the microtubules like ornaments hanging from tree branches. They are continually moved along the microtubules and repositioned by tiny protein machines called ____or ____. | motor proteins or motor molecules. |
| _____, the thinnest elements of the cytoskeleton, are strands of the protein actin. | microfilaments. |
| ____ are tough, insoluble protein fibers that have a diameter between those of microfilaments and microtubules. | intermediate filaments |
| The centrosome acts as a _____. it has few distinguising marks other than a granular-looking matrix that contains paired ____, small, barrel-shaped organelles oriented at right angles at each other. | microtubule organizing center; centrioles |
| ____ are whiplike, motile cellular extensions that occur, typically in large numbers, on the exposed surfaces of certain cells. | Cilia |
| When the projections formed by centrioles are substantially longer, they are called ____. | flagella |
| Centrioles forming the bases of cilia and flagella are commonly referred to as ____. | basal bodies |
| ____ are minute, fingerlike extensions of the plasma membrane that project from a free, or exposed, cell surface. | microvilli |
| Most cells have only one nucleus, but some, including skeletal muscle cells, bone destruction cells, and some liver cells, are ___, that is, they have many nuclei. | multinucleate |
| The nucleus has three recognizable regions or structures: the _____, ____ and ___. | nuclear envelope, nucleoli, and chromatin |
| ____, a double membrane barrier separated by a fluid-filled space. | nuclear envelope |
| The nuclear enevelope encloses a jellylike fluid called ____ in which other nuclear elements are suspended. | nucleoplasm |
| ___ are the dark-staining spherical bodies found within the nucleus. | nucleoli |
| Nucleoli are associated with ____, which contain the DNA that issues genetic instructions for synthesizing ribosomal RNA (rRNA). | nucleolar organizer regions |
| ____ a fine, unevenly stained network, but special techniques reveal it as a system of bumpy threads waving their way through the nucleoplasm. | chromatin |
| The fundamental units of chromatin are ____, which consist of flattened disc-shaped cores or clusters of eight histone proteins connected like beads on a string by a DNA molecule. | nucleosomes |
| When a cell is preparing to divide, the chromatin threads coil and condense enormously to form short, barlike bodies called ____. | chromosomes |
| ____ is the series of changes a cell goes through from the time it is formed until it reproduces. | cell life cycle |
| ____ is the period from cell formation to cell division. | interphase |
| During the ____, DNA is replicated, ensuring that the two future cells being created will receive identical copies of the genetic material. | S phase |
| ____ is essential for body growth and tissue repair. | cell division |
| ____ division of the nucleus | mitosis |
| ____ division of the cytoplasm | cytokinesis |
| ____ is the series of events that parcel out the replicated DNA of the mother cell to two daughter cells. | mitosis |
| four phases of mitosis. | prophase, metaphase, anaphase and telophase |
| ___ begins during the late anaphase and is completed after mitosis ends. | cytokinesis |
| The plasma membrane over the center of the cell (the spindle equator) is drawn inward to form a ____ by the activity of a contractile ring made of actin filaments. | cleavage furrow |
| The chromatin condenses, forming barlike chromosomes that are visible with a light microscope. | Early prophase |
| The centrosomes acts as focal points for growth of a microtubule assemble called the ____. | mitotic spindle |
| While the centrosomes are still moving apart, the nuclear envelope fragments, allowing the spindle to interact with the chromosomes. | late prophase |
| ___ is the second phase of mitosis. The two centrosomes are at the opposite poles of the cell. | metaphase |
| ____ is the third and shortest phase of mitosis. It begins abruptly as the centromeres of the chromosomes split simultaneously. Each chromatid now becomes chromosome in its own right. | Anaphase |
| ____ begins as soon as chromosomal movement stops. This final phase is like prophase in reverse. | Telophase |
| ___ completes the division of the cell into two identical daughter cells. | cytokinesis |
| ____ is a segment of a DNA molecule that carries instructions for creating one polypeptide chain. | gene |
| Most genes of higher organisms contain ___, which are amino acid-specifying informational sequence. | exons |
| ___, relatively long nucleotide strands resembling "half DNA" molecules (one of the two strands of a DNA molecule coding for protein structure). | Messenger RNA (mRNA) |
| ____ part of the ribosomes. | Ribosomal RNA (rRNA) |
| ___, small, roughly L-shaped molecules | Transfer RNA (tRNA) |
| Essential, polypeptide synthesis involves two major steps: ____, in which DNA's information is encoded in mRNA, and ___, in which the information carried by mRNA is decoded and used to assemble polypeptides. | transcription; translation |
| Essentially, three basic steps are involved in transcription: ____, ___, and ___. | initiation, elongation, and termination |
| ____ is a special DNA sequence that contains the start point (beginning of the structural gene to be transcribed.) | promoter |
| ___, the enzymes that oversees the synthesis of mRNA, correctly at the promoter. | RNA polymerase |
| Once bound with the help of the transcription factors, RNA polymerase pulls apart the strands of the DNA double helix so that transcription can begin at the start point in the promoter. | initiation |
| Using the incoming RNA nucleotides as substrates, the RNA polymerase aligns them with complementary DNA bases on the template strand and then links them together. | Elongation |
| When the polymerase reaches a special base sequence called a _____, transcription ends and the newly formed mRNA pulls of the DNA template. | Termination; Termination signal |
| In the ___ step of protein synthesis, the language of nucleic acids (base sequence) is translated into the language of proteins (amino acids sequence). | translation |
| The rules by which the base sequence of a gene is translated into an amino acid sequence are called the _____. | genetic code |
| The corresponding three-base sequence on mRNA is called a ___. | codon |
| ____ is a three-base sequence complementary to the mRNA codon calling for the amino acid carried by that particular tRNA. | anticodon |
| ____ are any substances contributing to body mass that are found outside the cells. | extracellular materials |
| ____ are also extracellular materials and include substances that aid in digestion and some that act as lubricants. | cellular secretions |
| The most abundant extracellular material is the ____. | extracellular matrix |
| The development of specific and distinctive features in cells is called ______. | cell differentiation |
| ____, a decrease in size of an organ or body tissue, can result from loss of normal stimulation. | atrophy |
| ____ are strings of nucleotides that cap the ends of chromosomes, protecting them from fraying or fusing with other chromosomes. | Telomeres |
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