Glossary of AP Bio Midterm - Chapter 7

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Image of a specimen magnified
Light Microscopes (LM)
Beam of electrons focused through the specimen or onto the surfaces; resolving power related to the wavelength of radiation
Electron Microscopes (EM)
Used to study internal ultrastructure of cells - electron beam using electromagnets
Transmission Electron Microscopes (TEM)
used for daily study on the surface of the specimen - surfaced coated with thin film of gold; appears 3-D
Scanning Electron Microscope (SEM)
Semifluid substance where organelles are found
DNA is in a nucleoid
Prokaryotic cell
Entire region between the nucleus and the plasma membrane; interior or prokaryotic cell
Selective barrier that allows sufficient passage of oxygen, nutrients, and wastes to service the entire volume of the cell
Plasma membrane
Most of the genes - nuclear envelope encloses it (double membrane) with intricate pore complex that regulates the entry and exit of large macromolecules and particles
Netlike array of protein filaments that maintains the shape of the nucleus
Nuclear lamina
Organizes DNA along with proteins
Chromatin fibers that are separate when a cell divides - 46 human, 23 in sex cells
Adjoins part of the chromatin - ribosomal RNA synthesized and assembled and proteins import it to ribosomal subunits
Particles of ribosomal RNA and protein - carry out protein synthesis - 2 subunits - build proteins in two cytoplasmic locales
Suspended in the cytosol - proteins function with the cytosol
Free Ribosomes
Attatched to the outside of the endoplasmic reticulum or nuclear envelope - proteins for insertion into membranes for packaging or for exporting
Bound Ribosomes
Different membranes of the eurkaryotic cell
Endomembrane system
Sacs made of membrane - direct physical continuity or by transfer of membrane segments
Labyrinth of tubules and sacs (cisternae) - separates the internal compartment of the ER (citernal space) from the cytosol
Endoplasmic Reticulum (ER)
Cytoplasmic surface lacks proteins - synthesis of lipids, metabolism of carbohydrates and detoxification of drugs and poisons and increases tolerance on drugs
Smooth ER
Ribosomes stud the cytoplasmic surface of the membrane
Rough ER
Covalently bonded to carbohydrates - secretory protein - keeps them separate from the proteins wrapped in transitional ER
Vesicles in transit from one part of the cell to another
Transport Vesicles
Center of manufactoring, warehousing, sorting and sihpping - products of the ER modified, stored, and sent to other destinations - specialized for secretion - has "cis" and "trans" faces
Golgi Apparatus
Membrane-bounded sac of hydrolytic enzymes that the cell uses to digest macromolecules - work best at pH5 - pumps hydrogen ions from the cytosol - made by Rough ER
Eating by engulfing smaller organisms or other food particles
Formed by phagocytosis
Food vacuoles
Pump excess water out of the cell (freshwater protists)
Contractile vacuoles
Enclosed by tonoplast-selective in transporting solutes - hold reserves of important organic compounds and main repository of inorganic ions, etc.
Central vacuole
Sites of cellular respiration - generates ATP
Sites of photosynthesis - convert solar energy to chemical energy
Inner membrane to the cell's level of metabolic activity
Flattened sacs - stacks called granum - fluid outside is the stroma - with DNA, ribosomes, and many enzymes - divides the chloroplast into two compartments
Bounded by single membrane; contain enzymes that transfer hydrogen from various substrates to oxygen as a by-product - toxic, but the organelle contains an enzyme to convert H202 to water
Network of fibers extending throughout the cytoplasm - organizes structures and activities of the cell
Thickest of microfilaments (actin filaments)
Located near the nucleus - compression-resisting girders
9 sets of triple microtubules as a ring - replicate before a cell divides - not essential for most plants
Locomotor appendages - move fluid over the surface of the tissue - 9 doublets of microtubules in a ring and two single microtubules
Flagella and cilia
Anchors the microtubule assembly - structurally identical to a centriole
Basal body
Solid rods, built from actin (globular protein) - twisted double chain of actin subunits - bears tension (pulling forces)
Acts as a motor molecule by means of projections (arms) that "walk" along the actin filaments
Cell crawls along a surface by extending and flowing into these cellular extensions - extend and contract through reversible assembly - extends until the actin reassembles into a network
Protects the plant cell, maintains shape, and prevents excessive uptake of water
Cell wall
Plant cell walls perforated with these where cytosol passes through and connects the living contents of adjacent cells - unifies into one living continuum
Membranes of neighboring cells are fused - prevent leakage of extracellular fluid across a layer of epithelial cells
Tight junctions
Like rivets, fastening cells together into strong sheets
Provide cytoplasmic channels between adjacent animal cells - special membrane proteins surround each pore - common in animal embryos
Gap junctions

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