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What is the idea that all organisms are composed of cells called?
cell theory
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What is the term for the fact that as cell size increases, volume grows much more rapidly than surface area?
surface-to-volume ratio
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What small "fingerlike" projections increase the surface area of a cell?
microvilli
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What semifluid matrix fills the interior of the cell?
cytoplasm
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What is defined as the minimum distance two points can be apart and still be distinguished as two separated points?
resolution
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What are microscopes that magnify in stages using several lenses called?
compound microscopes
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What are microscopes in which the electrons used to visualize the specimens are transmitted through the material?
transmission electron microscopes
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What kind of microscope beams the electrons onto the surface of the specimen?
scanning electron microscope
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What is the delicate sheet of molecules that encases all living cells called?
plasma membrane
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What are microscopes in which light is simply transmitted through a specimen in a culture, giving little contrast called?
bright-field microscopes
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What are microscopes in which light is directed at an angle toward the specimen; a condenser lens transmits only light reflected off the specimen called?
dark-field microscopes
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What are microscopes in which components of the microscope bring light waves out of phase, which produces differences in contrast and brightness when the light waves recombine called?
phase-contrast microscopes
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What are microscopes in which out-of-phase light waves to produce differences in contrast are combined with two beams of light travelling close together, which create even more contrast, especially at the edges of structures called?
differential-interference-contrast microscopes
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What are microscopes in which a set of filters transmits only light that is emitted by fluorescently stained molecules or tissues called?
fluorescence microscopes
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What are microscopes in which light from a laser is focused to a point and scanned across the specimen in two directions called?
confocal microscopes
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All plasma membranes have the same basic structure of proteins embedded in a sheet of lipids, which is called what?
fluid mosaic model
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The lipid layer that forms the foundation of a plasma membrane is composed of what modified fat molecules?
phospholipids
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What is the basic foundation of all biological membranes called?
lipid bilayer
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Plasma membranes contain what zones that are heavily enforced in cholesterol and therefore more tightly packed than the surrounding membrane?
lipid rafts
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What is the second major component of every biological membrane that float within the lipid bilayer?
membrane proteins
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What act as markers to identify particular types of cells or as beacons to bind specific hormones or proteins to the cell?
cell surface proteins
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What proteins extend all the way across the bilayer, and provide channels across which polar ions and molecules can pass into and out of the cell?
transmembrane proteins
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What is a fatal disease in which the body cells of affected individuals secrete a thick mucus that clogs the airways of the lungs?
cystic fibrosis
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What kind of cell has a relatively uniform cytoplasm that is not subdivided by interior membranes into separate compartments?
prokaryotes
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What is the framework of carbohydrates cross-linked into a rigid structure called?
cell wall
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In some bacteria, what other layer encloses the cell wall?
capsule
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What are the sites where proteins are made called?
ribosomes
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The DNA is found in what region of the cytoplasm?
nucleoid region
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What are long, threadlike structures projecting from the surface of a cell called?
flagella
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What are other hairlike structures that occur on the cells of some prokaryotes called?
pili
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What are specialized structues within which particular cell processes occur called?
organelles
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Inside the nucleus, the DNA is wound tightly around proteins and packaged into what compact units?
chromosomes
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What are all cells with nuclei called?
eukaryotes
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What weaves through the cell interior, creating organelles and a variety of vesicles?
endomembrane system
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What are small membrane-bounded sacs that store and transport materials called?
vesicles
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All eukaryotic cells are supported within by what internal protein scaffold?
cytoskeleton
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What is the command and control center of the cell called?
nucleus
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What is the special kind of membrane in which the surface of the nucleus is bound?
nuclear envelope
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Scattered over the surface of the nuclear envelope are what selective openings?
nuclear pores
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After cell division, eukaryotic chromosomes uncoil and fully extend into what threadlike strands that can no longer be distinguished individually with a light microscope within the nucleoplasm?
chromatin
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What is the region of the nucleus that appears darker than the rest?
nucleolus
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What is the extensive system of internal membranes called? It creates a series of channels and interconnections.
endoplasmic reticulum
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What is the surface of those regions of the ER devoted to the synthesis of such transported proteins that is heavily studded with ribosomes called?
rough ER
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What are regions in which ER-bounded ribosomes are relatively scarce called?
smooth ER
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As new molecules are made on the surface of the ER, they are passed from the ER to what flattened stacks of membranes?
Golgi bodies
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What are Golgi bodies collectively referred to as?
Golgi complex
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What are the membranous folds of the Golgi bodies called?
cisternae
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What organelles arise from the Golgi complex and contain a concentrated mix of the powerful enzymes that break down macromolecules?
lysosomes
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What are vesicles that contain two sets of enzymes and that are about the same size are lysosomes called?
peroxisomes
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Eukaryotic organisms extract energy from organic molecules in what complex series of chemical reactions?
oxidative metabolism
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What are the sausage-shaped organelles about the size of a bacterial cell called?
mitochondria
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The inner membrane of mitochondria is bent into what numerous folds?
cristae
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The cristae partition the mitochondria into two compartments: an outer compartment and an inner what?
matrix
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All photosynthesis in plants and algae takes place within what bacteria-like organelle?
chloroplast
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The inner membranes of chloroplasts are fused to form what stacks of closed vesicles?
thylakoids
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Thylakoids are stacked on top of one another to form what column?
granum
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What is the semiliquid substance that bathes the interior of a chloroplast?
stroma
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The theory of _______ proposes that some of today's eukaryotic organelles evolved by a symbiosis in which one cell of a prokaryotic species was engulfed by and lived inside the cell of another species of prokaryote that was a precursor to eukaryotes.
endosymbiosis
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What is the dense network of protein fibers that is the first thing you would encounter in a eukaryotic cell?
cytoskeleton
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What kind of protein fiber is long, slender, and made of the protein actin?
microfilaments
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What kind of protein fiber are hollow tubes made of the protein tubulin?
microtubules
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What kind of protein fiber are thick ropes of intertwined protein?
intermediate filaments
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What are the complex structures that assemble microtubules from tubulin subunits in the cells of animals and most protists called?
centrioles
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Each flagellum arises from what structure?
basal body
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What is a fundamental feature of eukaryotes and apparently evolved early in their history? It deals with how many microtubules pair up.
9 + 2 arrangement
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If flagella are numerous and organized in dense rows, what are they called?
cilia
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What motor protein uses ATP to power its movement toward the cell periphery?
kinesin
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What motor protein directs movement in the opposite direction, inward toward the cell's center?
dynein
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What are storage compartments that are not membrane-bounded called?
vacuoles
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What is the center of a plant cell called? It is a large, apparently empty space.
central vacuole
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What is located near the cell surface and accumulates excess water?
contractile vacuole
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What is the term for the thing that protects and supports the cells of plants, fungi, and many protists?
cell wall
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What part of a cell is laid down when the cell is still growing?
primary walls
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What is the sticky substance found between the walls of adjacent cells called?
middle lamella
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Some plant cells produce strong ______, which are deposited inside the primary walls of fully expanded cells.
secondary walls
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What are proteins with short chains of sugars attached to them called?
glycoproteins
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Animal cells secrete an elaborate mixture of glycoproteins into the space around them, forming what?
extracellular matrix (ECM)
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The ECM is attached to the plasma molecule by what third kind of glycoprotein?
fibronectin
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Fibronectin molecules bind not only to ECM glycoproteins, but also to what kind of proteins that are an integral part of the plasma membrane?
intergrins
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What is the concentration difference of a substance as a function of its molecules in one region to another called?
concentration gradient
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What is the net movement of molecules down a concentration gradient toward regions of lower concentration as a result of random motion called?
diffusion
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What is the term for where there is no net movement toward any particular direction?
equilibrium
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What is the term for when water passes into and out of a cell down its concentration gradient?
osmosis
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What is the term for the molecules dissolved in a solution?
solute
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If two solutions have unequal osmotic concentrations, the solution with the higher solute concentration is said to be what?
hypertonic
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If two solutions have unequal osmotic concentrations, the solution with the lower solute concentration is said to be what?
hypotonic
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If the osmotic concentrations of two solutions are equal, the solutions are what?
isotonic
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Movement of water into a cell by osmosis creates what kind of pressure that can cause a cell to swell and burst?
osmotic pressure
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What is the process by which the membrane engulfs the particles and forms a vesicle called?
endocytosis
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What is the process of discharging material from vesicles at the cell surface?
exocytosis
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What is it called if the material a cell takes in is particulate (made up of discrete particles)?
phagocytosis
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What is it called if the material the cell takes in is liquid?
pinocytosis
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Specific molecules are often transported into eukaryotic cells through _______.
receptor-mediated endocytosis
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What is the cell's ability to control what enters and leaves called?
selective permeability
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What is the mechanism of transport in which diffusion tends to equalize the concentration of such molecules on both sides of the membrane, with the molecules moving toward the side where they are scarcest called?
selective diffusion
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What is the mechanism of transport in which the net movement always occurs from high concentration to low, just as it does in simple diffusion, but the process is facilitated by the carriers called?
facilitated diffusion
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What is the movement of molecules across a membrane to a region of higher concentration by the expenditure of energy called?
active transport
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What expends metabolic energy to actively pump sodium ions in one direction, out of cells, and potassium ions, in one directions, into cells?
sodium-potassium pump
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Sugars and other actively transported molecules enter the cell via what?
coupled channels
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What is a complex channel that expends metabolic energy to pump protons across membranes?
proton pump
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What is the cellular process responsible for almost all of the adenosine triphosphate harvested from food and for all the ATP produced by photosynthesis called?
chemiosmosis
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Cells sense chemical information by means of what cell surface proteins that project from their plasma membranes?
receptor proteins
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What are chemical signals that your body uses called?
hormones
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What is a transmembrane pathway for an ion that is opened or closed by a change in the voltage, or charge difference, across the cell membrane called?
voltage-gated channel
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