Glossary of AP Biology- Chapter 7

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Light Microscopes
Used by the first scientists, visible light is passed through the specimen and then through glass lenses. The lenses refract (bend) the light in such a way that the image o the specimen I magnified as it is projected into the eye, onto photograph film, or onto a video screen.
The ratio of an object’s image to its real size.
Resolving Power
A measure of the clarity of the image, it is the minimum distance two points can be separated and still be distinguished as two separate points.
Subcellular structures, usually too small to be resolved by a light microscope.
Electron Microscope
Instead of light, a beam of electrons is focused through the specimen or onto its surface. The resolving power is inversely related to the wavelength of radiation used, and electrons have wavelengths much shorter than the wavelengths of visible light.
Transmission Electron Microscope
Used to study the internal ultrastructure of cells by aiming an electron beam through a thin section of the specimen, but it uses electromagnets as lenses (instead of glass) to focus and magnify the image by blending the paths of the electrons.
Scanning Electron Microscope
Used to study, in detail, the surface of the specimen. The electron beam scans the surface of the sample, which is usually coated with a thin piece of gold. The beam excites electrons on the sample’s surface, and these secondary electrons are collected and focused onto a screen. The image appears to be three-dimensional.
The study of cell structure.
The study of the molecules and chemical processes of metabolism.
Cell Fractionation
To take cells apart, separating the major organelles so that their functions can be studied.
Powerful instruments used to fractionate cells, a merry-go-round for test tubes that can spin at various speeds.
The disruption of cells, cells are broken apart without damage being done to their organelles.
Plasma Membrane
A basic feature of all cells, the membrane that bounds them and functions as a selective barrier that allows sufficient passage of oxygen, nutrients, and wastes to service the entire volume of the cell.
The semifluid substance within the plasma membrane, it is found in all cells.
Prokaryotic Cell
A type of cell where the DNA is concentrated in a region called the nucleoid, but no membrane separates this region from the rest of the cell.
An organelle in prokaryotic cells where the DNA is concentrated, it is separated from the rest of the cell.
Eukaryotic Cell
A type of cell that has a true nucleus, bounded by a membranous nuclear envelope.
The entire region (in all cells) between the nucleus and the plasma membrane. Where the organelles are suspended, in eukaryotic cells.
Contains most the genes in the eukaryotic cell and is enclosed by a nucleus envelope, separating it from the cytoplasm.
Nuclear Envelope
A double membrane, each a lipid bilayer with associated proteins. At the edges, the inner and outer membranes are fused. It regulates the entry and exit of certain large macromolecules and particles.
Nuclear Lamina
A netlike array of protein filaments that maintain the shape of the nucleus.
A fibrous material that DNA is organized along with proteins.
Chromatic fibers that have coiled up into thick structures that can be discerned.
The part of the nucleus where RNA is synthesized and assembled with proteins imported from the cytoplasm into the main compartments of ribosomes, called ribosomal subunits.
Particles made of RNA and protein, the organelles that carry out protein synthesis, each is composed of two subunits.
Free Ribosomes
Ribosomes suspended in the cytosol. They make proteins that function within the cytosol, such as enzymes that catalyze the breakdown of sugar.
Bound Ribosomes
Ribosomes that are attached to the outside of the endoplasmic reticulum or nuclear envelope. They make proteins that are destined either for insertion in membranes, for packaging within certain organelles such as lysosomes, or for export form the cell (secretion).
Endomembrane System
The collection of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles.
Sacs made of membrane.
Endoplasmic Reticulum
An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions.
Smooth ER
That portion of the endoplasmic reticulum that is free of ribosomes. It synthesizes lipids, metabolism of carbohydrates, and the detoxification of drugs.
Rough ER
That portion of the endoplasmic reticulum studded with ribosomes.
Proteins covalently attached to a carbohydrate.
v. Transport Vesicle- A tiny membranous sac in a cell's cytoplasm carrying molecules produced by the cell.
Golgi Apparatus
An organelle in eukaryotic cells consisting of stacks of flat membranous sacs that modify, store, and route products of the endoplasmic reticulum. It has a distinct polarity, with the membranes of the cisternae at opposite ends of the stack differing in thickness and molecular composition. It manufactures certain macromolecules.
A membrane-enclosed bag of hydrolytic enzymes found in the cytoplasm of eukaryotic cells. It can hydrolyze proteins, polysaccharides, fats and nucleic acids. It maintains a low pH of around 5.
A type of endocytosis involving large, particulate substances.
A process where lysosomes use their hydrolytic enzymes to recycle the cell’s own organic material.
Contractile Valcuoles
Found in freshwater protests, they pump excess water out of the cell.
Organelles in eukaryotic cells that serve as the site of cellular respiration, the catabolic process that generates ATP by extracting energy from sugars, fats, and other fuels with the help of oxygen.
Found only in plants and algae, they are the sites of photosynthesis and convert solar energy to chemical energy.
An infolding of the inner membrane of a mitochondrion that houses the electron transport chain and the enzyme catalyzing the synthesis of ATP.
Mitochondrial Matrix
The compartment of the mitochondrion enclosed by the inner membrane and containing enzymes and substrates for the Krebs cycle.
One of a family of closely related plant organelles, including chloroplasts, chromoplasts, and amyloplasts.
Flattened sacs found inside chloroplasts that tend to be stacked.

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