56 terms

Essential Cell Biology: Chapter 1

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Cells
The basic unit from which a living organism is made; consists of an aqueous solution of organic molecules enclosed by a membrane.
Cell Biology
The study of cells and their structure, function and behavior.
Cilium (cilia)
Hairlike structure made of microtubules found on the surface of many eukaryotic cells; when present in large numbers, its rhythmic beating can drive the movement of fluid over the cell surface, as in the epithelium of lungs.
DNA
Double-stranded polynucleotide formed from two separate chains of covalently linked deoxyribonucleotide units. It serves as the cell's store of genetic information that is transmitted from generation to generation.
RNA
Molecule produced by the transcription DNA; usually single-stranded , it is a polynucleotide composed of covalently linked ribonucleotide subunits. Serves a variety of structural, catalytic and regulatory functions as well.
Protein
Polymer built from amino acids that provides cells with their shape and structure and performs most of their activities.
Central Dogma
Th principle that genetic information flows from DNA to RNA to protein.
Amino Acids
Small organic molecule containing both an amino group and a carboxylic group; it serves as the building block of proteins.
Conformation
Precise, three-dimensional shape of a protein or other macromolecule, based on the spatial location of its atoms in relation to one another.
Mutations
A randomly produced, permanent change in the nucleotide sequence of DNA.
Evolution
Process of gradual modification and adaptation that occurs in living organisms over generations.
Genome
The total genetic information carried by all the chromosomes of a cell or organism.
Microscope
Instrument for viewing extremely small objects.
Light Microscope
Uses a focused beam of visible light and is used to examine cells and organelles.
Electron Microscope
Instrument that illuminates a specimen using beams of electrons to reveal and magnify the structures of very small objects, such as organelles and large molecules.
Cell Theory
All living cells are formed by the growth and division of existing cells.
Extracellular Matrix
Complex network of polysaccharides and proteins secreted by cells. A structural component of tissues that also influences their development and physiology.
Nucleus
The prominent, rounded structure that contains the DNA of a eukaryotic cell.
Cytoplasm
Contents of a cell that are contained within its plasma membrane but, in the case of eukaryotic cells, contained outside the nucleus.
Fluorescence Microscopes
Instrument used to visualize a specimen that has been labeled with a fluorescent dye; samples are illuminated with a wavelength of light that excites the dye, causing it to fluoresce.
Ribosome
Large macromolecular complex, composed of ribosomal RNAs and ribosomal proteins, that translates messenger RNA into protein.
Fixed
When tissue is preserved by pickling in a reactive chemical solution.
Organelles
A discrete structure or subcompartment of a eukaryotic cell that is specialized to carry out a particular function.
Plasma Membrane
The protein -containing lipid bilayer that surrounds a living cell.
Internal Membranes
The membranes surrounding organelles.
Eukaryotes
An organism whose cells have a distinct nucleus and cytoplasm.
Prokaryotes
Major category of living cells distinguished by the absence of a nucleus. Include archaea and bacteria.
Bacteria
One of the two divisions of prokaryotes; some species cause disease. The term is sometimes used to refer to any prokaryotic microorganism, although the world of prokaryotes also includes archaea, which are only distantly related.
Archaea
One of the two divisions of prokaryotes, often found in hostile environments such as hot springs or concentrated brine.
Mitochondria
Membrane-enclosed organelle, about the size of a bacterium, that carries out oxidative phosphorylation and produces most of the ATP in eukaryotic cells.
Photosynthesis
The process by which plants, algae and some bacteria use the energy of sunlight to drive the synthesis of organic molecules form carbon dioxide and water.
Chloroplasts
Specialized organelle in algae and plants that contains chlorophyll and serves as the site in which photosynthesis takes place.
Nuclear Envelope
Double membrane surrounding the nucleus. Consists of outer and inner membranes, perforated by nuclear pores.
Chromosomes
Long, threadlike structure composed of DNA and proteins that carries the genetic information of an organism; becomes visible as a distinct entity when a plant or animal cell prepares to divide.
ATP
Molecule that serves as the principle carrier of energy in cells; this nucleoside triphosphate is composed of adenine, ribose, and three phosphates.
Symbiosis
Intimate association between two organisms of different species from which both derive a long-term selective advantage.
Chlorophyll
Light-absorbing green pigment that plays a central part in photosynthesis.
Endoplasmic Reticulum
Labyrinthine membrane-enclosed compartment in the cytoplasm of eukaryotic cells where lipids and proteins are made.
Golgi Apparatus
Membrane-enclosed organelle in eukaryotic cells that modifies the proteins and lipids made in the ER and sorts them for transport to other sites.
Lysosomes
Membrane-enclosed organelle that breaks down worn-out proteins and organelles and other waste materials, as well as molecules taken up by endocytosis; contains digestive enzymes that are typically most active at the acid pH found inside these organelles.
Peroxisomes
Small membrane-enclosed organelle that contains enzymes that degrade lipids and destroy toxins.
Endocytosis
Process by which cells take in materials through an invagination of the plasma membrane, which surrounds the ingested material in the membrane-enclosed vesicle.
Exocytosis
Process by which most molecules are secreted from a eukaryotic cell. These molecules are packaged in membrane-enclosed vesicles that fuse with the plasma membrane, releasing their contents to the outside.
Cytosol
Contents of the main compartment of the cytoplasm, excluding the membrane-enclosed organelles such as ER and mitochondria. The cell fraction remaining after membranes, cytoskeletal components, and other organelles have been removed.
Cytoskeleton
System of protein filaments in the cytoplasm of a eukaryotic cell that gives the cell shape and the capacity for directed movement. Its most abundant components are actin filaments, microtubules and intermediate filaments.
Actin Filaments
Thin, flexible protein filament made from a chain of globular actin molecules; a major constituent of all eukaryotic cells, this cytoskeletal element is essential for cell movement and for the contraction of muscle cells.
Microtubules
Long, stiff, cylindrical structure composed of the protein tubulin. Used by eukaryotic cells to organize their cytoplasm and guide the intracellular transport of macromolecules and organelles.
Intermediate Filaments
Fibrous cytoskeletal element, about 10 nm in diameter, that forms ropelike networks in animal cells; helps cells resist tension applied from outside.
Motor Proteins
Protein such as myosin or kinesin that uses energy derived from ATP hydrolysis to propel itself along a protein filament or polymeric molecule.
Protozoans
A free-living, non photosynthetic, single-celled, motile eukaryote.
Model Organisms
A living thing selected for intensive study as a representative for a large group of species.
E. coli
Rodlike bacterium normally found in the colon of humans and other mammals and widely used in biomedical research.
Apoptosis
A tightly controlled form of programmed cell death that allows cells that are unneeded or unwanted to be eliminated from an adult or developing organism.
In Vitro
Term used by biochemists to describe a process that takes place in an isolated cell-free extract. Also used by cell biologists to refer to cells growing in culture, as opposed to in an organism.
In Vivo
In an intact cell or organism.
Homologous
Describes genes, chromosomes, or any structures that are similar because of their common evolutionary origin. Can also refer to similarities between protein sequences or nucleic acid sequences.