Terms For Bio. Test # 3

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A basic unit of living matter separated from its enviornment by a plasma membrane; the fundamental strctural unit of life.

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Cell

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A short appendage that propels some protists through the water and moves fluids across the surface of many tissue cells in animals.

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Cilium (plural, cilia)

In common with eukaryotic flagella, cilia have a 9 + 2 arrangement of microtubles covered by the cell's plasma membrane.

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A protective layer exernal to the plasma membrane in plant cells, bacteria, fungi, and some protists; protects the cell and helps maintain its shape.

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Cell wall

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A structure in an animal cell composed of microtubule triplets arranged in a 9 + 0 pattern.

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Centriole

An animal cell usually has a pair of centrioles within each of its centosomes.

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An organelle found in plants and photosynthetic protists. Enclosed by two concentrated membrane, it absorbs sunlight and uses it to power the synthesis of organic food molecules (sugars).

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Chloroplast

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The combination of DNA and proteins that constitutes chromosomes; often used to refer to the diffuse, very extended form taken by the chromosomes when a eukaryotic cell is not dividing.

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Chromatin

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A threadlike, gene-carrying structure found in the nucleus of a eukaryotic cell and the most visible during mitosis and meiosis; also, the main gene-carrying structure of a prokaryotic cell.

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Chromosome

Chromosomes consist of chromatin.

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An increase or decrease in the density of a chemical substance in an area.

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Concentration gradient

Cells often maintain concentration gradients of ions across their membranes.

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A meshwork of fine fibers in the cytoplasm of a eukaryotic cell, includes microfilaments, intermediate filaments, and microtubules.

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Cytoskeleton

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Everything inside a cell between the plasma membrane and the nucleus; consists of a semifluid medium and organelles.

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Cytoplasm

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An organism with eukaryotic cells.

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Eukaryote

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A type of cell that has a membrane-enclosed nucleus and other membrane-enclosed organelles. All organisms except bacteria and archaea are composed of these.

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Eukaryotic cells

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The domain of eukaryotes, organisms made of eukaryotic cells' includes all of the protists, plants, fungi, and animals.

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Eukarya

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An extensive membranous network in a eukaryotic cell, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and riblsome-free (smooth) regions.

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Endoplasmic Reticulum (ER)

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A network of interconnected membranous sacs in a eukaryotic cell's cytoplasm.

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Rough endoplasmic reticulum (rough ER)

Rough ER membranes are studded with riblsomes that make membrane proteins and secretory proteins. The rough ER constructs membrane from phospholipids and proteins.

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A network of interconnected membranous tubules in a eukaryotic cell's cytoplasm.

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Smooth endoplasmic reticulum (smooth ER)

Smooth ER lacks ribosomes. Enzymes embedded in the smooth ER membrane function in the synthesis of certain kinds of molecules, such as lipids.

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A substance in which the cells of an animal tissue are embedded, consists of protein and polysaccharides.

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Extracellular matrix

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The movement of materials out of the cytoplasm of a cell via membranous vescles or vacuoles.

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Exocytosis

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The movement of materials into the cytoplasm of a cell via membranous vesicles or vacuoles.

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Endocytosis

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A description of membrane structure, depicting a cellular membrane as a mosaic of diverse protein molecules embedded in a fluid bilayer made of phospholipid molecules.

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Fluid mosaic

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The passage of a substance across a biological membrane down its concentration gradient, aided by specific transport proteins.

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Facilitated diffusion

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An organelle in eukaryotic cells consisting of stacks of membranous sacs that modify, store, and ship products of the endoplasmic reticulum.

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Golgi apparatus

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A digestive organelle in eukarytoic cells; contains hydrolytic enzymes that digest the cell's food and wastes.

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Lysosome

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An organelle in eukaryotic cells where cellular respiration occurs. Enclosed by two concentric membranes, it is where most of the cell's ATP is made.

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Mitochondrion (plural, mitochondria)

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(1) An atom's central core, containing protons and neutrons. (2) The genetic control center of a eukaryotic cell.

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Nucleus (plural, nuclei)

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A structure within the nucleus of a eukaryotic cell where the ribosomal RNA is made and assembled with proteins to make ribosomal subunits; consists of parts of the chromatin DNA, RNA transcribed from the DNA, and proteins imported from the cytoplasm.

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Nucleolus (plural, nucleoli)

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A double membrane, perforated with pores, that encloses the nucleus and separates it from the rest of the eukaryotic cell.

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Nuclear envelope

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The diffusion of a substance across a biological membrane, without any input of energy.

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Passive transport

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The process by which plants, autotrophic protists, and some bacteria use light energy to make sugars and other organic food molecules from carbon dioxide and water.

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Photosynthesis

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Cellular "eating"; a type of endocytosis whereby a cell engulfs macromolecules, other cells, or particles into its cytoplasm.

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Phagocytosis

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Cellular "drinking"; a type of endocytosis in which the cell takes fluid and dissolved solutes into small membranous vesicles.

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Pinocytosis

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The thin layer of lipids and proteins that sets a cell off from its surroundings and acts as a selective barrier to the passage of ions and molecules into and out of the cell; consists of a phospholipid bilayer in which are embedded molecules of protein and cholesterol.

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Plasma (cell) membrane

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A temporary extension of an amoeboid cell.

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Pseudopodium (plural, pseudopodia)

Pseudopodia function in moving cells and engulfing food.

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A structure with a specialized function within a cell.

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Organelle

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The diffusion of water across a selectively permeable membrane.

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Osmosis

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The control of the gain and loss of water and dissolved solutes in an organism.

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Osmoregulation

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A cell organelle consisting of RNA and protein organized into two subunits and functioning as the site of protein synthesis in the cytoplasm.

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Ribosome

The ribosomal subunits are constructed in the nucleolus.

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The type of ribonuleic acid that, together with proteins, makes up ribosomes; the most abundant type of RNA.

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Ribosomal RNA (rRNA)

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On or in a cell, a specific protein molecule whose shape fits that of a specific molecular messenger, such as a hormone.

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Receptor

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A property of biological membranes that allows some substances to cross more easily than others and blocks the passage of other substances altogether.

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Selective permeability

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The spontaneous movement of particles of any kind from where they are more concentrated to where they are less concentrated.

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Diffusion (simple)

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A membrane protein that transports sodium ions out of, and potassium ions into, a cell against their concentration gradients. The process is powered by ATP.

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Sodium-potassium (Na+ -K+) pump.

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(1) The discharge of molecules synthesized by a cell. (2) In the vertebrate kidney, the discharge of wastes from the blood into the filtrate from the nephron tubules.

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Secretion

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The ability of a solution to cause a cell within it to gain or lose water.

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Tonicity

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In comparing two solutions, the one with the lower concentration of solutes.

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Hypotonic solution

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In comparing two solutions, the one with the greater concentration of solutes.

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Hypertonic solution

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A solution having the same solute concentration as another solution.

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Isotonic solution

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A membrane-enclosed sac, part of the endomembrane system of a eukaryotic cell, having diverse functions.

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Vacuole

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The movement of a substance across a biological membrane against its concentration gradient, aided by specific transport proteins and requiring input of energy (often as ATP)

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Active transport

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The thickest of three main kinds of fibers making up the cytoskeleton of a eukaryotic cell; a straight, hollow tube made of globular proteins called tubulins.

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Microtubule

Microtubules form the basis of the structure and movement of the cilia and flagella.

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A phenomenon that occurs in plants in a hypertonic solution. The cell loses water and shrivels, and its plasma membrane pulls away from the cell wall, usually killing the cell.

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Plasmolysis

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Meaning "nucleus-like" in a prokaryotic cell.

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Nucleoid

A prokaryotic cell lacks a nucleus (its name comes from the Greek pro meaning before, and karyon, meaning kernel- referring to the nucleus. So prokaryotic means before there was a nucleus.

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The region in a prokeryotic cell consisting of a concentrated mass of DNA that is NOT membrane bound!

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Nucleoid region

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A long surface projection that propels a prokaryotic cell through its liquid enviornment.

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Prokaryotic flagellum (plural, flagella)

It is completely different from the flagellum of a eukaryotic cell.

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A short projection on the surface of a prokaryotic cell that helps the prokaryote attach to other surfaces.

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Pilus (plural, pili)

Specialized sex pili are used in conjugation to hold the mating cells together.