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Biology chapt 4

Biology chapter 4

TermDefinition
cell The smallest unit of life that displays all the properties of life; composed of cytoplasm surrounded by a plasma membrane.
cell theory One of the major theories of biology, which states that all organisms are made up of cells; cells are capable of self-reproduction and come only from preexisting cells.
surface-area-to-volume ratio Ratio of a cell’s outside area to its internal volume; the relationship limits the maximum size of a cell.
prokaryotic cell Cells that generally lack a membrane-bound nucleus and organelles; the cell type within the domains Bacteria and Archaea.
eukaryotic cell (eukaryote) Type of cell that has a membrane-bound nucleus and membranous organelles; found in organisms within the domain Eukarya.
bacillus A rod-shaped bacterium; also a genus of bacteria, Bacillus.
coccus A spherical-shaped bacterium.
spirillum (pl., spirilla) Long, rod-shaped bacterium that is twisted into a rigid spiral; if the spiral is flexible rather than rigid, it is called a spirochete.
cell envelope In a prokaryotic cell, the portion composed of the plasma membrane, the cell wall, and the glycocalyx.
plasma membrane Membrane surrounding the cytoplasm that consists of a phospholipid bilayer with embedded proteins; functions to regulate the entrance and exit of molecules from cell.
cell wall Cellular structure that surrounds a plant, protistan, fungal, or bacterial cell and maintains the cell’s shape and rigidity; composed of polysaccharides.
glycocalyx Gel-like coating outside the cell wall of a bacterium. If compact, it is called a capsule; if diffuse, it is called a slime layer.
capsule A form of glycocalyx that consists of a gelatinous layer; found in blue-green algae and certain bacteria.
cytoplasm Region of a cell between the nucleus, or the nucleoid region of a bacterium, and the plasma membrane; contains the organelles of the cell.
nucleoid Region of prokaryotic cells where DNA is located; it is not bound by a nuclear envelope.
plasmid Extrachromosomal ring of accessory DNA in the cytoplasm of prokaryotes.
ribosome Site of protein synthesis in a cell; composed of proteins and ribosomal RNA (rRNA).
cyanobacterium (pl., cyanobacteria) Photosynthetic bacterium that contains chlorophyll and releases oxygen; formerly called a blue-green alga.
thylakoid Flattened sac within a granum of a chloroplast; membrane contains chlorophyll; location where the light reactions of photosynthesis occur.
flagellum (pl., flagella) Long, slender extension used for locomotion by some bacteria, protozoans, and sperm.
fimbria (pl., fimbriae) Small, bristlelike fiber on the surface of a bacterial cell, which attaches bacteria to a surface; also fingerlike extension from the oviduct near the ovary.
conjugation pilus (pl., conjugation pili) In a bacterium, elongated, hollow appendage used to transfer DNA to other cells.
organelle Small, membranous structures in the cytoplasm having a specific structure and function.
endosymbiotic theory Explanation of the evolution of eukaryotic organelles by phagocytosis of prokaryotes.
vesicle Small, membrane-bound sac that stores substances within a cell.
cytoskeleton Internal framework of the cell, consisting of microtubules, actin filaments, and intermediate filaments.
Nucleus Command center of cell
Nuclear envelope Double membrane with nuclear pores that encloses nucleus.
Chromatin Diffuse threads containing DNA and protein
Nucleolus Region that produces subunits of ribosomes.
Endoplasmic reticulum Protein and lipid metabolism.
Rough ER studded with ribosomes that synthesize proteins.
Smooth ER Lacks ribosomes, synthesize lipid molecules.
Peroxisome Vesicle that is involved in fatty acid metabolism.
Ribosomes Particles that carry out protein synthesis.
Polyribosomes Stiring of ribosomes simultaneously synthesizing same protein.
Mitochondrion Organelle that carries out cellular respiration producing ATP molecules.
Golgi Apparatus Processes, packages, and secretes modifies proteins.
Cytoplasm Semifluid matrix outside nucleus that contains organelles.
Lysosome Vesicle that digests macromolecules and even cell parts.
Centrosome Microtubule orgaizing center that contains a pair of centrioles.
Centrioles Short cylinders of microtubules.
Actin Filaments Protein fibers that play a role in cell division and shape.
Intermediate Filaments Protein fibers that provide stability of shape.
Microtubules Protein cylinders that move organelles.
Cytoskeleton Maintains cell shape and assists movement of cell parts.
Plasma Membrane Outer surface that regulates entrance and exit of molecules.
Nuclear Pore Permits passage of proteins into nucleus and ribosomal subunits out of nucleus.
Centrosome (plant) Microtubule organizing center (lacks centroioles).
cell wall Outer surface that shapes, supports, and protects cell.
Plasma Membrane (plant) Surrounds cytoplasm, and regulates entrance and exit of molecules.
Chloroplast Carries out photosynthesis, producing sugars.
Central Vacuole Large, fluid-filled sac that stores metaboties and helps maintain tugor pressure.
nucleus Membrane-bound organelle within a eukaryotic cell that contains chromosomes and controls the structure and function of the cell.
nucleoplasm Semifluid medium of the nucleus containing chromatin.
chromatin Network of DNA strands and associated proteins observed within a nucleus of a cell.
Chromosomes The structure that transmits the genetic material from one generation to the next; composed of condensed chromatin; each species has a particular number of chromosomes that is passed on to the next generation.
gene Unit of heredity existing as alleles on the chromosomes; in diploid organisms, typically two alleles are inherited—one from each parent.
nucleolus Dark-staining, spherical body in the nucleus that produces ribosomal subunits.
nuclear envelope Double membrane that surrounds the nucleus in eukaryotic cells and is connected to the endoplasmic reticulum; has pores that allow substances to pass between the nucleus and the cytoplasm.
nuclear pore Opening in the nuclear envelope that permits the passage of proteins into the nucleus and ribosomal subunits out of the nucleus.
ribosome Site of protein synthesis in a cell; composed of proteins and ribosomal RNA (rRNA).
polyribosome String of ribosomes simultaneously translating regions of the same mRNA strand during protein synthesis.
endomembrane system Cellular system that consists of the nuclear envelope, endoplasmic reticulum, Golgi apparatus, and vesicles.
endoplasmic reticulum (ER) System of membranous saccules and channels in the cytoplasm, often with attached ribosomes.
rough ER (endoplasmic reticulum) Membranous system of tubules, vesicles, and sacs in cells; has attached ribosomes.
smooth ER (endoplasmic reticulum) Membranous system of tubules, vesicles, and sacs in eukaryotic cells; site of lipid synthesis; lacks attached ribosomes
golgi apparatus Organelle consisting of sacs and vesicles that processes, packages, and distributes molecules about or from the cell.
lysosome Membrane-bound vesicle that contains hydrolytic enzymes for digesting macromolecules and bacteria; used to recycle worn-out cellular organelles. Tay-Sachs disease
peroxisome peroxisome Enzyme-filled vesicle in which fatty acids and amino acids are metabolized to hydrogen peroxide that is broken down to harmless products.
vacuole Membrane-bound sac, larger than a vesicle; usually functions in storage and can contain a variety of substances. In plants, the central vacuole fills much of the interior of the cell.
central vacuole In a plant cell, a large, fluid-filled sac that stores metabolites. During growth, it enlarges, forcing the primary cell wall to expand and the cell surface-area-to-volume ratio to increase.
chloroplast Membrane-bound organelle in algae and plants with chlorophyll-containing membranous thylakoids; where photosynthesis takes place.
mitochondria (sing., mitochondrion) Membrane-bound organelle in which ATP molecules are produced during the process of cellular respiration.
stroma Region within a chloroplast that surrounds the grana; contains enzymes involved in the synthesis of carbohydrates during the Calvin cycle of photosynthesis.
thylakoid Flattened sac within a granum of a chloroplast; membrane contains chlorophyll; location where the light reactions of photosynthesis occur.
granum (pl., grana) Stack of chlorophyll-containing thylakoids in a chloroplast.
plastid Organelle of plants and algae that is bound by a double membrane and contains internal membranes and/or vesicles (i.e., chloroplasts, chromoplasts, leucoplasts).
cristae (sing., crista) Short, fingerlike projections formed by the folding of the inner membrane of mitochondria.
matrix Unstructured, semifluid substance that fills the space between cells in connective tissues or inside organelles.
actin filament Component of the cytoskeleton; plays a role in the movement of the cell and its organelles; a protein filament in a sarcomere of a muscle, its movement shortens the sarcomere, yielding muscle contraction.
Intermediate filaments Ropelike assemblies of fibrous polypeptides in the cytoskeleton that provide support and strength to cells; so called because they are intermediate in size between actin filaments and microtubules.
microtubule Small, cylindrical organelle composed of tubulin protein around an empty central core; present in the cytoplasm, centrioles, cilia, and flagella.
centrosome Central microtubule organizing center of cells. In animal cells, it contains two centrioles.
centriole Cell structure, existing in pairs, that occurs in the centrosome and may help organize a mitotic spindle for chromosome movement during animal cell division.
cilia (sing., cilium) Short, hairlike projections from the plasma membrane, occurring usually in larger numbers.
flagellum (pl., flagella) Long, slender extension used for locomotion by some bacteria, protozoans, and sperm.
Created by: Haleyannestes