Biology Chapter 4 Terms

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using oxygen.

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aerobic

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not using oxygen.

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anaerobic

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one of life’s three domains; consists of prokaryotes that are only distantly related to members of the domain Bacteria.

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Archaea

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one of life’s three domains; consists of prokaryotes that are only distantly related to members of the domain Archaea.

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Bacteria

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a structure resembling a centriole that produces a cilium or flagellum and anchors this structure within the plasma membrane.

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basal body

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a large, fluid-filled vacuole occupying most of the volume of many plant cells; performs several functions, including maintaining turgor pressure.

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central vacuole

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in animal cells, a short, barrel-shaped ring consisting of nine microtubule triplets; a microtubule-containing structure at the base of each cilium and flagellum; gives rise to the microtubules of cilia and flagella and is involved in spindle formation during cell division.

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centriole

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a pigment found in chloroplasts that captures light energy during photosynthesis; absorbs violet, blue, and red light but reflects green light.

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chlorophyll

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the organelle in plants and plantlike protists that is the site of photosynthesis; surrounded by a double membrane and containing an extensive internal membrane system that bears chlorophyll.

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chloroplast

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the complex of DNA and proteins that makes up eukaryotic chromosomes.

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chromatin

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a single DNA double helix together with proteins that help to organize the DNA.

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chromosome

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a short, hairlike projection from the surface of certain eukaryotic cells that contains microtubules in a 9 + 2 arrangement. The movement of may propel cells through a fluid medium or move fluids over a stationary surface layer of cells.

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cilium pl. cilia

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a fluid-filled vacuole in certain protists that takes up water from the cytoplasm, contracts, and expels the water outside the cell through a pore in the plasma membrane.

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contractile vacuole

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the material contained within the plasma membrane of a cell, exclusive of the nucleus.

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cytoplasm

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a network of protein fibers in the cytoplasm that gives shape to a cell, holds and moves organelles, and is typically involved in cell movement.

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cytoskeleton

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a molecule composed of deoxyribose nucleotides; contains the genetic information of all living cells.

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deoxyribonucleic acid

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a system of membranous tubes and channels in eukaryotic cells; the site of most protein and lipid syntheses.

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endoplasmic reticulum (ER)

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the hypothesis that certain organelles, especially chloroplasts and mitochondria, arose as mutually beneficial associations between the ancestors of eukaryotic cells and captured bacteria that lived within the cytoplasm of the pre-eukaryotic cell.

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endosymbiont hypothesis

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referring to cells of organisms of the domain Eukarya (plants, animals, fungi, and protists). ---------- cells have genetic material enclosed within a membrane-bound nucleus and contain other membrane-bound organelles.

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eukaryotic

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a long, hairlike extension of the plasma membrane; in eukaryotic cells, it contains microtubules arranged in a 9 + 2 pattern. The movement of ----------- propel some cells through fluids.

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flagellum

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a membranous sac, within a single cell, in which food is enclosed. Digestive enzymes are released into the vacuole, where intracellular digestion occurs.

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food vacuole

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a stack of membranous sacs, found in most eukaryotic cells, that is the site of processing and separation of membrane components and secretory materials.

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golgi apparatus

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part of the cytoskeleton of eukaryotic cells that probably functions mainly for support and is composed of several types of proteins.

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intermediate filament

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a membrane-bound organelle containing intracellular digestive enzymes.

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lysosome

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part of the cytoskeleton of eukaryotic cells that is composed of the proteins actin and (in some cases) myosin; functions in the movement of cell organelles and in locomotion by extension of the plasma membrane.

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microfilament

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a hollow, cylindrical strand, found in eukaryotic cells, that is composed of the protein tubulin; part of the cytoskeleton used in the movement of organelles, cell growth, and the construction of cilia and flagella.

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microtubule

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an organelle, bounded by two membranes, that is the site of the reactions of aerobic metabolism.

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mitochondrion

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the double-membrane system surrounding the nucleus of eukaryotic cells; the outer membrane is typically continuous with the endoplasmic reticulum.

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nuclear envelope

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the location of the genetic material in prokaryotic cells; not membrane-enclosed.

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nucleoid

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the region of the eukaryotic nucleus that is engaged in ribosome synthesis; consists of the genes encoding ribosomal RNA, newly synthesized ribosomal RNA, and ribosomal proteins.

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nucleolus

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the membrane-bound organelle of eukaryotic cells that contains the cell’s genetic material.

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nucleus (cellular)

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a structure, found in the cytoplasm of eukaryotic cells, that performs a specific function; sometimes refers specifically to membrane-bound structures, such as the nucleus or endoplasmic reticulum.

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organelle

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the outer membrane of a cell, composed of a bilayer of phospholipids in which proteins are embedded.

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plasma membrane

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in plant cells, an organelle bounded by two membranes that may be involved in photosynthesis (chloroplasts), pigment storage, or food storage.

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plastid

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referring to cells of the domains Bacteria or Archaea. ----------- cells have genetic material that is not enclosed in a membrane-bound nucleus; they also lack other membrane-bound organelles.

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prokaryotic

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a molecule composed of ribose nucleotides, each of which consists of a phosphate group, the sugar ribose, and one of the bases adenine, cytosine, guanine, or uracil; involved in converting the information in DNA into protein; also the genetic material of some viruses.

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ribonucleic acid

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an organelle consisting of two subunits, each composed of ribosomal RNA and protein; the site of protein synthesis, during which the sequence of bases of messenger RNA is translated into the sequence of amino acids in a protein.

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ribosome

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a vesicle that is typically large and consists of a single membrane enclosing a fluid-filled space.

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vacuole

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a small, membrane-bound sac within the cytoplasm.

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vesicle