Exam 1 Flashcards
Biology
The science of life
Cell Theory
The scientific theory that the cell is the basic unit of life, of which all living things are composed, and that all cells are derived from pre-existing cells.
Systematics
The scientific study of the diversity of organisms and their evolutionary relationships. Taxonomy is an aspect of systematics. See taxonomy.
Pathogens
An organism, usually a microorganism, capable of producing disease.
Protists
One of a vast informal group of eukaryotic organisms, primarily unicellular or simple multicellular; mostly aquatic.
Evolution.
Any cumulative genetic changes in a population from generation to generation. Leads to differences in populations and explains the origin of all the organisms that exist today or have ever existed.
Homeostasis
The balanced internal environment of the body; the automatic tendency of an organism to maintain such a steady state.
Biological diversity or biodiversity
The variety of living organisms considered at three levels: genetic diversity, species diversity, and ecosystem diversity.
Prokaryotes
A cell that lacks a nucleus and other membrane-enclosed organelles; includes the bacteria and archaea (kingdoms Bacteria and Archaea). Compare with eukaryote.
Colonies
An association of loosely connected cells or individuals of the same species.
Cells
Vary greatly in size and appearance, basic unit that all organisms consist of.
Plasma Membrane
The selectively permeable surface membrane that encloses the cell contents and through which all materials entering or leaving the cell must pass.
Evolution
Any cumulative genetic changes in a population from generation to generation. Evolution leads to diff erences in populations and explains the origin of all the organisms that exist today or have ever existed.
coccus (pl., cocci)
A bacterium with a spherical shape. Compare with bacillus, spirillum, vibrio, and spirochete.
Coenocytic
An organism consisting of a multinucleate cell, i.e., the nuclei are not separated from one another by septa.
Unicellular organisms
Some of the simplest life-forms, each consists of a single cell.
Multicellular organisms
May consist of billions of cells specialized to perform specific functions.
Plasma membrane
Every cell is enveloped by a protective plasma membrane that separates it from the surroundings external environment.Regulates passage of material between the cell and its environment.
Organelles
One of the specialized structures within the cell, such as the mitochondria, Golgi complex, ribosomes, or contractile vacuole; many organelles are membrane-enclosed.
Microvilli
(sing., microvillus) Minute projections of the plasma membrane that increase the surface area of the cell; found mainly in cells concerned with absorption or secretion, such as those lining the intestine or the kidney tubules.
Light microscope (LM)
consists of a tube with glass lenses at each end. Because it contains several lenses, the modern light microscope is referred to as a compound microscope. Visible light passes through the specimen being observed and through the lenses. Light is refracted (bent) by the lenses, magnifying the image. Images obtained with light microscopes are referred to as light micrographs, or LMs.
Taxonomy
The science of naming, describing, and classifying organisms; see systematics.
Classification
arranging organisms into groups based on similarities that reflect evolutionary relationships among lineages.
Binomial system of nomenclature
System of naming a species by the combination of the genus name and a specific epithet.
bacillus (pl., bacilli)
A rod-shaped bacterium. Compare with coccus, spirillum, vibrio, and spirochete.
spirochete
A long, flexible, helical bacterium. Compare with spirillum, vibrio, bacillus, and coccus.
spirillum (pl., spirilla)
A long, rigid, helical bacterium. Compare with spirochete, vibrio, bacillus, and coccus.
Mutualism
In ecology, a symbiotic relationship in which both partners benefi t from the association. Compare with parasitism and commensalism.
Commensalism
A type of symbiosis in which one organism benefi ts and the other one is neither harmed nor helped. Compare with mutualism and parasitism.
Deoxyribonucleic acid, DNA
Double-stranded nucleic acid; contains genetic information coded in specific sequences of its constituent nucleotides.
Magnification
the ratio of the size of the image seen with the microscope to the actual size of the object.
genus (pl., genera)
A taxonomic category made up of related species.
vibrio.
A spirillum (spiral-shaped bacterium) that is shaped like a comma. Compare with spirillum, spirochete, bacillus, and coccus.
Parasitism
A symbiotic relationship in which one member (the parasite) benefi ts and the other (the host) is adversely affected. Compare with commensalism and mutualism.
Organelles
Internal structure of cells that are specialized to perform specific functions.
Resolution aka resolving power
The ability of a microscope to show fine detail, defined as the minimum distance between two points at which they are seen as separate images.
specific epithet
The second part of the name of a species designates a specific species belonging to that genus.
nuclear area, also referred to as the nucleoid,
Region of a prokaryotic cell that contains DNA; not enclosed by a membrane. Also called nucleoid.
Plankton
Free-floating, mainly microscopic aquatic organisms found in the upper layers of the water; consisting of phytoplankton and zooplankton. Compare with nekton.
Prokaryotic cells
Exclusive to bacteria and to microscopic organisms called archaea.Do not have a nucleus or other membrane-enclosed organelles.
Electron microscope (EM)
A microscope capable of producing highresolution, highly magnified images through the use of an electron beam (rather than light). Transmission electron microscopes (TEMs) produce images of thin sections; scanning electron microscopes (SEMs) produce images of surfaces.
Family
A taxonomic category made up of related genera.
Cell wall
The structure outside the plasma membrane of certain cells; may contain cellulose (plant cells), chitin (most fungal cells), peptidoglycan and/or lipopolysaccharide (most bacterial cells), or other material.
serial endosymbiosis
The hypothesis that certain organelles such as mitochondria and chloroplasts originated as symbiotic prokaryotes that lived inside other, free-living prokaryotic cells.
Eukaryotic cells
Typically contains a variety of organelles enclosed by membranes, including a nucleus, which houses DNA
Nucleus
Houses DNA (1) The central reason of an atom that contains the protons and neutrons. (2) A cell organelle in Eukaryotes that contain the DNA and serves as the control center of the cell. (3) A mass of nerve cell bodies in the central nervous system.
Biological growth
Involves an increase in the size of individual cells of an organism, in the number of cells, or in both.
Development
All the progressive changes that take place throughout the life of an organism.
Ultrastructure
Fine details of cells obtained by the electron microscope
Cell fractionation
The technique used to separate the components of cells by subjecting them to centrifugal force. See differential centrifugation and density gradient centrifugation
orders
A taxonomic category made up of related families.
classes
A taxonomic category made up of related orders.
phylum (pl., phyla)
A taxonomic grouping of related, similar classes; a category beneath the kingdom and above the class.
kingdoms
A broad taxonomic category made up of related phyla; many biologists currently assign living organisms to five kingdoms and several “supergroups”.
peptidoglycan
A modified protein or peptide having an attached carbohydrate; component of the bacterial cell wall.
Gram-positive
A thick layer of peptidoglycan molecules is held together by amino acids. Contain peptidoglycan.
Gram-negative
A thin layer of peptidoglycan is covered by an outer membrane.
Capsule or slime layer
(1) The portion of the moss sporophyte that contains spores. (2) A simple, dry, dehiscent fruit that develops from two or more fused carpels and opens along many sutures or pores to release seeds. (3) A gelatinous coat that surrounds some bacteria.
Monophylectic
A group of organisms that includes a recent common ancestor and all its descendants; a clade. Compare with polyphyletic group and paraphyletic group.
Paraphyletic group
A group of organisms made up of a common ancestor and some, but not all, of its descendants. Compare with monophyletic group and polyphyletic group.
Excavates
A diverse group of unicellular protists with flagella. These protists are so named because many have a deep, or excavated, oral groove. Unlike other protists, excavates have atypical, greatly modified mitochondria. Many excavates are endosymbionts and live in anoxic (without oxygen) environments. These excavates do not carry out aerobic respiration; they obtain energy by the anaerobic pathway of glycolysis (presumably by fermentation.
Metabolism
The sum of all the chemical activities of the organisms
Homeostasis
an appropriate, balanced internal environment.
Stimuli
Physical or chemical changes in their internal or external environment.
Cilia (pl.) (cilium, sing.)
One of many short, hairlike structures that project from the surface of some eukaryotic cells and are used for locomotion or movement of materials across the cell surface.
Centrifuge
A device used to separate cells or their components by subjecting them to centrifugal force.
differential centrifugation
Separation of cell particles according to their mass, size, or density. In differential centrifugation, the supernatant is spun at successively higher revolutions per minute.
density gradient centrifugation
Procedure in which cell components are placed in a layer on top of a density gradient, usually a sucrose solution and water. Cell structures migrate during centrifugation, forming a band at the position in the gradient where their own density equals that of the sucrose solution.
Prokaryotic cell
One of the two basic type of cells, bacteria and archaea are prokaryotic cells.
domains
(1) A structural and functional region of a protein. (2) The broadest taxonomic category; each domain includes one or more kingdoms.
taxon (pl., taxa)
A formal taxonomic group at any level, e.g., phylum or genus.
Plantae
One of two kingdoms for organisms.
Animalia
One of two kingdoms for organisms.
Pili (sing., pilus)
Hairlike structures on the surface of many bacteria; function in conjugation or attachment.
fimbriae (sing., fi mbria).
Hairlike structures that project from the cell surface of some prokaryotes; help bacteria to adhere to one another and to attach to the surfaces of cells they infect.
Endospores
A resting cell formed by certain bacteria; highly resistant to heat, radiation, and disinfectants.
Flagella
A long, whiplike structure extending from certain cells and used in locomotion. (1) Eukaryote flagella consist of two central, single microtubules surrounded by nine double microtubules (9 + 2 structure), all covered by a plasma membrane. (2) Prokaryote flagella are filaments rotated by special structures located in the plasma membrane and cell wall.
Diplomonads
Small, mostly parasitic zooflagellates with one or two nuclei, no functional mitochondria, and 2 or more flagella
Parabasalids
Anaerobic, flagellated excavates that often live in animals; examples include trichonymphs and trichomonads.
Trichonymphs
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trichomonad
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Cell theory
The scientific theory that the cell is the basic unit of life, of which all living things are composed, and that all cells are derived from pre-existing cells.
Nuclear area or nucleoid
Region of a prokaryotic cell that contains DNA; not enclosed by a membrane. Also called nucleoid.
Protista
Ernst Haeckel, proposed that a third kingdom, Protista, be established to accommodate bacteria and other microorganisms. However, biologists largely ignore this suggestion.
Chemotaxis
movement in response to chemicals in the environment.
euglenoids
A group of mostly freshwater, flagellate, unicellular algae that move by means of an anterior flagellum and are usually photosynthetic.
Flagella (pl.) flagellum (sing.)
A long, whiplike structure extending from certain cells and used in locomotion. (1) Eukaryote flagella consists of two central, single micro tubules surrounded by nine double microtubules (9+2 structure), all covered by a plasma membrane. (2) Prokaryote flagella are filaments rotated by special structures located in the plasma membrane and cell wall.
Sessile
Permanently attached to one location, e.g., coral animals.
Flagella (sing. Flagellum)
A long, whiplike structure extending from certain cells and used in locomotion. (1) Eukaryote flagella consist of two central, single microtubules surrounded by nine double microtubules (9 + 2 structure), all covered by a plasma membrane. (2) Prokaryote flagella are filaments rotated by special structures located in the plasma membrane and cell wall.
Fungi (sing. fungus)
A heterotrophic eukaryote with chitinous cell walls and a body usually in the form of a mycelium of branched, threadlike hyphae. Most fungi are decomposers; some are parasitic.
Bacteria
Prokaryotic organisms that have peptidoglycan in their cell walls; most are decomposers, but some are parasites and others are autotrophs. Bacteria is the name of one of the two prokaryotic domains. Compare with archaea.
Plasmids
Small, circular, double-stranded DNA molecule that carries genes separate from those in the main DNA of a cell.
Binary fission
Equal division of a prokaryotic cell into two; a type of asexual reproduction.
phagocytosis
Literally, “cell eating”; a type of endocytosis by which certain cells engulf food particles, microorganisms, foreign matter, or other cells.
Pellicle
A flexible outer covering consisting of protein; characteristic of certain protists, e.g., ciliates and euglenoids.
Asexual reproduction
Reproduction in which there is no fusion of gametes and in which the genetic makeup of parent and of offspring is usually identical.
Sexual reproduction
A type of reproduction in which two gametes (usually but not necessarily, contributed by two different parents) fuse to form a zygote.
Adaptations
Inherited characteristics that enhance an organism’s ability to survive in a particular environment.
Ribosomes
Organelles that are part of the protein synthesis machinery of both prokaryotic and eukaryotic cells; consist of a larger and smaller subunit, each composed of ribosomal RNA (rRNA) and ribosomal proteins.
Cytoplasm
The plasma membrane and cell contents with the exception of the nucleus.
Nucleoplasm
The contents of the cell nucleus.the part of the cell within the nucleus is nucleoplasm.
Archaea
Prokaryotic organisms with a number of features, such as the absence of peptidoglycan in their cell walls, that set them apart from the bacteria. Archaea is the name of one of the two prokaryotic domains. Compare with bacteria.
Eukarya
*One of the three domains.
Clade
A group of organisms containing a common ancestor and all its descendants; a monophyletic group.
Gene transfer
Exchange of genes
Horizontal gene transfer
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Trypanosomes
excavates with a single mitochondrion that has an organized deposit of DNA called a kinetoplastid.
kinetoplastid
A single mitochondrion with an organized deposit of DNA; characteristic of trypanosomes.
chromalveolates
A supergroup composed of diverse protists with few shared characters; most are photosynthetic, and heterotrophic chromalveolates, such as the water molds and ciliates, probably descended from autotrophic ancestors. Divided into two main groups, alveolates and stramenopiles.
Reductionism
Learning about a structure by studying its parts.
Emergent properties
Characteristics of an object, process, or behavior that could not be predicted from its component parts; can be identified at each level as we move up the hierarchy of biological organization.
Cytosol
The fluid component of the cytoplasm in which the organelles are suspended.
Endomembrane system
A protein that is tightly associated with the lipid bilayer of a biological membrane; a transmembrane integral protein spans the bilayer. Compare with peripheral membrane protein.
PhyloCode
An approach to classification known as phyloCode in which organisms are grouped into Clades based on evolutionary relationships.
Phylogenetic tree
A branching diagram that shows lines of descent among a group of related species.
Conjugation
(1) A sexual process in ciliate protists that involves exchange of haploid nuclei with another cell. (2) A mechanism for DNA exchange in bacteria that involves cellto-cell contact.
Sex pili
long, hairlike extensions that project from the cell surface.
alveolates
Protists that have alveoli, flattened vesicles located just inside the plasma membrane; include the dinoflagellates, apicomplexans, and ciliates. See chromalveolates.
alveolus (pl., alveoli)
(1) An air sac of the lung through which gas exchange with the blood takes place. (2) Saclike unit of some glands, e.g., mammary glands. (3) One of several flattened vesicles located just inside the plasma membrane in certain protists.
Atom
The smallest unit of a chemical element that retains the characteristic properties of that element.
Vesicles
Any small sac, especially a small, spherical, membrane-enclosed compartment, within the cytoplasm.
Cladogram
A branching diagram that illustrates taxonomic relationships based on the principles of cladistics.
Autotrophs
An organism that synthesizes complex organic compounds from simple inorganic raw materials; also called producer or primary producer. Compare with heterotroph. See chemoautotroph and photoautotroph.
stramenopiles
Protists that have motile cells with two flagella, one of which has tiny hairlike projections off the shaft ; include water molds, diatoms, golden algae, and brown algae. See chromalveolates.
Molecule
The smallest particle of a covalently bonded elements or compound; two or more atoms joined by covalent bonds.
Nucleus (pl. nuclei)
1) The central region of an atom that contains the protons and neutrons. (2) A cell organelle in eukaryotes that contains the DNA and serves as the control center of the cell. (3) A mass of nerve cell bodies in the central nervous system. Compare with ganglion.
Branch
Each branch in a cladogram represents a clade, a group of organisms with a common ancestor. Each branching point, referred to as a node (depicted by a circle), represents the divergence, or splitting, of two or more new groups from a common ancestor.
Heterotrophs
An organism that cannot synthesize its own food from inorganic raw materials and therefore must obtain energy and body-building materials from other organisms. Also called consumer. Compare with autotroph. See chemoheterotroph and photoheterotroph.
Dinoflagellates
A unicellular, biflagellate, typically marine protist that is an important component of plankton; usually photosynthetic.
Tissues
A group of closely associated, similar cells that work together to carry out specific functions.
Organs
A specialized structure, such as the heart or liver, made up of tissues and adapted to perform a specific function or group of functions.
Organ system
An organized group of tissues and organs that work together to perform a specialized set of functions, e.g., the digestive system or circulatory system.
Nuclear envelope
The double membrane system that encloses the cell nucleus of eukaryotes.
Nuclear pores
Structures in the nuclear envelope that allow passage of certain materials between the cell nucleus and the cytoplasm.
Root
The root, or node at the base of the cladogram, represents the most recent common ancestor of all of the clades depicted in the tree.
Vertical gene transfer
which genes are transmitted from parent to off spring within the same species.
Chemotrophs
Organism that uses organic compounds or inorganic substances, such as iron, nitrate, ammonia, or sulfur, as sources of energy. Compare with phototroph. See chemoautotroph and chemoheterotroph.
Phototrophs
Organism that uses light as a source of energy. Compare with chemotroph. See photoautotroph and photoheterotroph.
Photoautotrophs
An organism that obtains energy from light and synthesizes organic compounds from inorganic raw materials; includes plants, algae, and some bacteria. Compare with photoheterotroph, chemoautotroph, and chemoheterotroph.
zooxanthellae (sing., zooxanthella)
Endosymbiotic, photosynthetic dinofl agellates found in certain marine invertebrates; their mutualistic relationship with corals enhances the corals’ reef-building ability.
Red tides
A red or brown coloration of ocean water caused by a population explosion, or bloom, of dinoflagellates.
Apicomplexans
A group of parasitic protists that lack structures for locomotion and that produce sporozoites as infective agents; malaria is caused by an apicomplexan.
Organism
Any living system consisting of one or more cells.
Population
A group of organisms of the same species that live in a defined geographic area at the same time.
Nuclear lamina
A fibrous network of protein filaments, called the nuclear lamina, forms an inner lining for the nuclear envelope.
(DNA) Replication
The process by which DNA is duplicated; ordinarily a semiconservative process in which a double helix gives rise to two double helices, each with an “old” strand and a newly synthesized strand.
Horizontal gene transfer or lateral gene transfer.
In this process, genes move from one species to another species in the same generation.
Phylogeny
The complete evolutionary history of a group of organisms.
Chemoautotrophs
Organism that obtains energy from inorganic compounds and synthesizes organic compounds from inorganic raw materials; includes some bacteria and many archaea. Compare with photoautotroph, photoheterotroph, and chemoheterotroph.
Photoheterotrophs
An organism that can carry out photosynthesis to obtain energy but cannot fix carbon dioxide and therefore requires organic compounds as a carbon source; includes some bacteria and archaea. Compare with photoautotroph, chemoautotroph, and chemoheterotroph.
sporozoites
The infective sporelike state in apicomplexans.
Ciliates
A unicellular protist covered by many short cilia.
Community
An association of populations of different species living together in a defined habitat with some degree of interdependence.
Genes
A segment of DNA that serves as a unit of hereditary information; includes a transcribable DNA sequence (plus associated sequences regulating its transcription) that yields a protein or RNA product with a specific function.
Population
A group of organisms of the same species that live in a defined geographic area at the same time.
Chemoheterotrophs
Organism that uses organic compounds as a source of energy and carbon; includes animals, fungi, many bacteria, and a few archaea. Compare with photoautotroph, photoheterotroph, and chemoautotroph.
Cilia
Fine short hairlike, extend through the pores in the pellicle to facilitate movement.
Ecosystem
The interacting system that encompasses a community and it’s nonliving, physical environment.
Biosphere
All of Earth’s living organisms, collectively.
Messenger RNA (mRNA)
RNA that specifies the amino acid sequence of a protein; transcribed from DNA.
Chromatin
The complex of DNA and protein that makes up eukaryotic chromosomes
Homology
Similarity in different species that results from their derivation from a common ancestor. The features that exhibit such similarity are called homologous features. Compare with homoplasy.
Convergent evolution
The independent evolution of structural or functional similarity in two or more distantly related species, usually as a result of adaptations to similar environments.
Decomposers
Microbial heterotrophs that break down dead organic material and use the decomposition products as a source of energy. Also called saprotrophs or saprobes.
Aerobic
Growing or metabolizing only in the presence of molecular oxygen. Compare with anaerobic.
Micronuclei
One or more smaller nuclei found, along with the macronucleus, in ciliates. The micronucleus is involved in sexual reproduction. Compare with macronucleus.
Macronucleus
A large nucleus found, along with one or several micro nuclei, in ciliates. The macronucleus regulates metabolism and growth. Compare with micronucleus.
Ecology
A discipline of biology that studies the interrelations among living things and their environments.
Chromosomes
Structures in the cell nucleus that consist of chromatin and contain the genes. The chromosomes become visible under the microscope as distinct structures during cell division.
Reversal
in which a trait reverts to its ancestral state. A reversal removes a similarity that had evolved.
facultative anaerobes
An organism capable of carrying out aerobic respiration but able to switch to fermentation when oxygen is unavailable, e.g., yeast. Compare with obligate anaerobe.
Conjugation
(1) A sexual process in ciliate protists that involves exchange of haploid nuclei with another cell. (2) A mechanism for DNA exchange in bacteria that involves cellto-cell contact.
Genes
A segment of DNA that serves as a unit of hereditary information; includes a transcribable DNA sequence (plus associated sequences regulating its transcription) that yields a protein or RNA product with a specific function.
nucleoli (sing., nucleolus).
Specialized structure in the cell nucleus formed from regions of several chromosomes; site of assembly of the ribosomal subunits.
Homoplasy
Similarity in the characters in different species that is due to convergent evolution, not common descent. Characters that exhibit such similarity are called homoplastic features. Compare with homology.
Obligate anaerobes
Bacteria that carry out anaerobic respiration; they respire with terminal electron acceptors other than oxygen. (sulfate, nitrate, or iron)
zoosporangium
A thick-walled sporangium containing a zygospore.
Nucleotides
A molecule consisting of one or more phosphate groups, a five-carbon sugar (ribose or deoxyribose), and a nitrogenous base (purine or pyrimidine).
Nucleolar organizer
Each nucleolus contains a nucleolar organizer, made up of chromosomal regions containing instructions for making the type of RNA in ribosomes.
Shared ancestral character
Traits that were present in an ancestral species that have remained essentially unchanged; suggest a distant common ancestor. Also called plesiomorphic characters. Compare with shared derived characters.
Nitrogen fixation
The conversion of atmospheric nitrogen (N2) to ammonia (NH3) by certain bacteria; part of the nitrogen cycle.
Oospores
A thick-walled, resistant spore formed from a zygote during sexual reproduction in water molds.
Proteins
A large, complex organic compound composed of covalently linked amino acid subunits; contains carbon, hydrogen, oxygen, nitrogen, and sulfur.
Ribosomal RNA (rRNA)
A family of single-stranded nucleic acids that function mainly in protein synthesis
Shared derived characters
Homologous traits found in two or more taxa that are present in their most recent common ancestor but not in earlier common ancestors. Also called synapomorphic characters. Compare with shared ancestral characters.
Nitrification
The conversion of ammonia (NH3) to nitrate (NO3−) by certain bacteria (nitrifying bacteria) in the soil; part of the nitrogen cycle.
Diatoms
A usually unicellular alga that is covered by an ornate, siliceous shell consisting of two overlapping halves; an important component of plankton in both marine and fresh waters.
Hormones
A chemical messenger, often produced in one region of the body of a multicellular organism and transported to another region where it signals cells to alter some aspect of growth, development, or metabolism.
Ribosomes
Organelles that are part of the protein synthesis machinery of both prokaryotic and eukaryotic cells; consist of a larger and smaller subunit, each composed of ribosomal RNA (rRNA) and ribosomal proteins.
Barcode
The molecular sequence selected can be used as a genetic marker, or barcode, to identify organisms, much like the barcodes on grocery store items. This method can be used to distinguish among species that look alike.
Signature sequences
regions of SSU rRNA that have unique nucleotide sequences.
Plankton
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Cell signaling
Mechanisms of communication between cells. Cells signal one another with secreted signaling molecules, or a signaling molecule on one cell combines with a receptor on another cell. See signal transduction.
Endoplasmic reticulum (ER)
An interconnected network of internal membranes in eukaryotic cells enclosing a compartment, the ER lumen. Rough ER has ribosomes attached to the cytosolic surface; smooth ER, a site of lipid biosynthesis, lacks ribosomes.
Molecular systematics
The science of molecular systematics focuses on molecular structure to clarify evolutionary relationships. DNA, RNA, and amino acid sequencing are used to compare the macromolecules of organisms being studied.
Archaea
Prokaryotic organisms with a number of features, such as the absence of peptidoglycan in their cell walls, that set them apart from the bacteria. Archaea is the name of one of the two prokaryotic domains. Compare with bacteria.
Brown alga
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Neurotransmitters
A chemical signal used by neurons to transmit impulses across a synapse.
ER lumen
The internal space the membranes enclose is called the ER lumen. In most cells the ER lumen forms a single internal compartment that is continuous with the compartment formed between the outer and inner membranes of the nuclear envelope.
Molecular clocks
A comparison of the DNA nucleotide sequences of related organisms to estimate when they diverged from one another during the course of evolution.
Bacteria
Prokaryotic organisms that have peptidoglycan in their cell walls; most are decomposers, but some are parasites and others are autotrophs. Bacteria is the name of one of the two prokaryotic domains. Compare with archaea.
Blades
(1) The thin, expanded part of a leaf. (2) The flat, leaflike structure of certain multicellular algae.
Cellular respiration
The process by which cells generate ATP through a series of redox reactions. In aerobic respiration the terminal electron acceptor is molecular oxygen; in anaerobic respiration the terminal acceptor is an inorganic molecule other than oxygen.
Smooth ER
a site of lipid biosynthesis, lacks ribosomes
Monophyletic group
A group of organisms that includes a recent common ancestor and all its descendants; a clade. Compare with polyphyletic group and paraphyletic group.
Crenarchaeota
Consists mainly of extreme thermophiles, archaea that are require a very high temperature or very low temperature for growth.
Stipes
A short stalk or stemlike structure that is a part of the body of certain multicellular algae.
Autotrophs
An organism that synthesizes complex organic compounds from simple inorganic raw materials; also called producer or primary consumer.
Rough ER
The outer surface of the rough ER is studded with ribosomes that appear as dark granules. The ribosomes attached to the rough ER are known as bound ribosomes; free ribosomes are suspended in the cytosol. The rough ER plays a central role in the synthesis and assembly of proteins.
Sister taxa
Groups of organisms that share a more recent common ancestor with one another than either taxon does with any other group shown on a cladogram.
Euryarchaeota
Include many archaea that exhibit extreme environments.
Holdfast
The basal structure for att achment to solid surfaces found in multicellular algae.
Photosynthesis
The biological process that captures light energy and transforms it into the chemical energy of organic molecules (e.g., carbohydrates), which are manufactured from carbon dioxide and water.
Molecular chaperones
Proteins that help other proteins fold properly. Although not dictating the folding pattern, chaperones make the process more efficient.
Paraphyletic group
A group of organisms made up of a common ancestor and some, but not all, of its descendants. Compare with monophyletic group and polyphyletic group.
Methanogens
a large, diverse group that inhabit oxygen-free environments in sewage, swamps, and the digestive tracts of humans and other animals. They are obligate anaerobes that produce methane gas from simple carbon compounds.
Alternation of generations
A type of life cycle characteristic of plants and a few algae and fungi in which they spend part of their life in a multicellular n gametophyte stage and part in a multicellular 2n sporophyte stage
Consumers
An organism that cannot synthesize its own food from inorganic raw materials and therefore must obtain energy and body-building materials from other organisms.
Proteasomes
protein complexes in the cytosol that direct the destruction of defective proteins.
Polyphyletic group
A group made up of organisms that evolved from two or more different ancestors. Compare with monophyletic group and paraphyletic group.
Extreme halophiles
heterotrophs that require large amounts of Na+ for their growth. They live in saturated brine solutions such as salt ponds, the Dead Sea, and Great Salt Lake.
Golden algae
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Heterotrophs
An organism that cannot synthesize its own food from inorganic raw materials and therefore must obtain energy and body-building materials from other organisms.
Transport vesicles
Small cytoplasmic vesicles that move substances from one membrane system to another.
Phenetic approach
An approach to classification based on measurable similarities in phenotypic characters without consideration of homology or other evolutionary relationships. Compare with cladistics and evolutionary systematics.
Nanoarchaeum
a very small (400 nm) anaerobic, extreme thermophile that is now classifi ed as a euryarchaeote.
Zoospores
A flagellated motile spore produced asexually by chytrids, certain algae, water molds, and other protists.
Primary consumers
An animal that feeds on plants or algae.
Golgi complex
Organelle composed of stacks of flattened, membranous sacs. Mainly responsible for modifying, packaging, and sorting proteins that will be secreted or targeted to other organelles of the internal membrane system or to the plasma membrane; also called Golgi body or Golgi apparatus.
Cladistics (also known as phylogenetic systematics)
An approach to classification based on recency of common ancestry rather than degree of structural similarity. Also called phylogenetic systematics. Compare with phenetics and evolutionary systematics.
Rickettsias
very small, rod-shaped bacteria.
Nanoplankton
Extremely minute (<10 μm in length) algae that are major producers in the ocean because of their great abundance; part of phytoplankton
Secondary consumers
An animal that feeds on other animals; flesh eater; also called carnivore or tertiary consumer. Secondary consumers eat primarily consumers (herbivores), whereas tertiary consumers eat secondary consumers.
Cisternae (sing. cisterna)
Stacks of flattened membranous sacs that make up the Golgi complex.
Evolutionary systematic approach
An approach to classification that considers both evolutionary relationships and the extent of divergence that has occurred since a group branched from an ancestral group. Compare with cladistics and phenetics.
enterobacteria
decomposers that live on decaying plant matter, pathogens, and a variety of bacteria that inhabit humans.
coccolithophorids
H
Decomposers
Microbial heterotrophs that break down dead organic material and use the decomposition products as a source of energy.
Lysosomes
Intracellular organelles present in many animal cells; contain a variety of hydrolytic enzymes.
Outgroup analysis
A research method for estimating which att ributes are shared derived characters in a given group of organisms.
Vibrios
Vibrios are mainly marine; some are bioluminescent. Vibrio cholerae causes cholera.
Rhizarians
A diverse supergroup of amoeboid cells that often have hard outer shells, called tests, through which cytoplasmic projections extend; include forams, actinopods, and certain shell-less amoebas.
Systematics
The scientific study of the diversity of organisms and their evolutionary relationships. Taxonomy is an aspect of systematics. See taxonomy
Vacuole
A fluid-filled, membrane-enclosed sac found within the cytoplasm; may function in storage, digestion, or water elimination.
Ingroup
the members of the group under study
Pseudomonads
heterotrophs that produce nonphotosynthetic pigments; cause disease in plants and animals, including humans.
Tests
R
Taxonomy
The science of naming, describing, and classifying organisms; see systematics.
Tonoplast
The membrane surrounding a vacuole. The membrane of the vacuole, part of the endomembrane system.
Outgroup
In cladistics, a taxon that represents an approximation of the ancestral condition; the outgroup is related to the ingroup (the members of the group under study) but separated from the ingroup lineage before they diversified.
Purple sulfur bacteria
Purple sulfur bacteria are photoautotrophs that do not produce oxygen
foraminiferans (forams)
A marine protist that produces a shell, or test, that encloses an amoeboid body. Also called foram. See rhizarians.
Species
According to the biological species concept, one or more populations whose members are capable of interbreeding in nature to produce fertile off spring and do not interbreed with members of other species. Compare with phylogenetic species concept.
Food vacuoles
Most protozoa have food vacuoles, which fuse with lysosomes that digest the food.
Maximum likelihood
Maximum likelihood is a statistical method that depends on probability, for example, the probability that nucleotide sequences in DNA and RNA change at a constant rate over time.
myxobacteria
*(slime bacteria), which secrete slime and glide or creep along.
Index fossils
Fossils restricted to a narrow period of geologic time and found in the same sedimentary layers in different geographic areas.
Gene pool
All the alleles of all the genes present in a freely interbreeding population.
Contractile vacuoles
A membrane-enclosed organelle found in certain freshwater protists, such as Paramecium; appears to have an osmoregulatory function.
Prokaryotae
A kingdom to accommodate the bacteria
Cyanobacteria
Prokaryotic photosynthetic microorganisms that possess chlorophyll and produce oxygen during photosynthesis.
Actinopods
Protists characterized by axopods that protrude through pores in their shells. See rhizarians.
Genus (pl., genera)
A taxonomic category made up of related species.
Peroxisomes
In eukaryotic cells, membraneenclosed organelles containing enzymes that produce or degrade hydrogen peroxide.
Parsimony
Choose simplest explanation to interpret data.
Actinomycetes
Superficially resemble fungi. Contain peptidoglycan in their cell walls, lack nuclear envelopes, have other prokaryotic characteristics.
Axopads
Long, filamentous, cytoplasmic projections characteristic of actinopods.
Binomial systems of nomenclature
System of naming a species by the combination of the genus name and a specific epithet.
Serial endosymbiosis
The hypothesis that certain organelles such as mitochondria and chloroplasts originated as symbiotic prokaryotes that lived inside other, free-living prokaryotic cells.
Lactic acid bacteria
ferment sugar, producing lactic acid as the main end product. Inhabit decomposing plant material, milk, and other dairy products; responsible for the characteristic taste of yogurt, pickles, sauerkraut, and green olives. Among the normal inhabitants of the human mouth and vagina.
radiolarians
Those actinopods that secrete elaborate shells of silica (glass).
Specific epithet
The second part of the name of a species; designates a specific species belonging to that genus.
Mitochondria (sing. Mitochondrion)
Intracellular organelles that are the sites of oxidative phosphorylation in eukaryotes; include an outer membrane and an inner membrane.
Mycobacteria
slender, irregular rods; contain a waxy substance in their cell walls. One species causes tuberculosis; another causes leprosy.
archaeplastids
A monophyletic supergroup of eukaryotes with chloroplasts bounded by outer and inner membranes; include red algae, green algae, and land plants.
Family
A taxonomic category made up of related genera.
Aerobic respiration
(1) Cellular respiration is the process by which cells generate ATP through a series of redox reactions. In aerobic respiration the terminal electron acceptor is molecular oxygen; in anaerobic respiration the terminal acceptor is an inorganic molecule other than oxygen. (2) Organismic respiration is the process of gas exchange between a complex animal and its environment, generally through a specialized respiratory surface, such as a lung or gill.
Streptococci
inhabit the mouth and digestive tract of humans and some other animals. Among the harmful species are those that cause “strep throat,” dental caries, a form of pneumonia, scarlet fever, and rheumatic fever (see chapter opener).
Red algae
G
Order
A taxonomic category made up of related families.
Intermembrane space
The intermembrane space is the compartment formed between the outer and inner mitochondrial membranes.
Clostridia
anaerobic. One species causes tetanus; another causes gas gangrene. Clostridium botulinum can cause botulism, an often fatal type of food poisoning
Green algae
G
Class
A taxonomic category made up of related orders.
Matrix
(1) In cell biology, the interior of the compartment enclosed by the inner mitochondrial membrane. (2) In zoology, nonliving material secreted by and surrounding connective tissue cells; contains a network of microscopic fibers.
mycoplasmas
are a group of very small bacteria that lack cell walls. They may have evolved from bacteria with gram-positive cell walls. They inhabit soil and sewage; some are parasitic on plants or animals. Some inhabit human mucous membranes but do not generally cause disease; one species causes a mild type of bacterial pneumonia in humans.
Unicellular Gametangia (sing., gametangium),
F
Phyla (sing., phylum)
A taxonomic grouping of related, similar classes; a category beneath the kingdom and above the class.
Outer mitochondrial membrane
The outer mitochondrial membrane is smooth and allows many small molecules to pass through it.
Chlamydias
lack peptidoglycan in their cell walls. They are energy parasites, completely dependent on their hosts for ATP. Infect almost every species of bird and mammal. A strain of Chlamydia causes trachoma, the leading cause of blindness in the world. Sexually transmitted chlamydias are the major cause of pelvic infl ammatory disease (PID) in women.
Unikonts
One of two main clades of all eukaryotes that had a common ancestor with a single posterior flagellum. Compare with bikonts.
Kingdoms
A broad taxonomic category made up of related phyla; many biologists currently assign living organisms to five kingdoms and several “supergroups”
Inner mitochondrial membrane
The inner mitochondrial membrane has numerous folds and strictly regulatesthe types of molecules that can move across it.
symbiosis.
An intimate relationship between two or more organisms of different species. See commensalism, mutualism, and parasitism.
opisthokonts
E
Domains
(1) A structural and functional region of a protein. (2) The broadest taxonomic category; each domain includes one or more kingdoms.
Cristae (sing. crista)
Shelflike or fingerlike inward projections of the inner membrane of a mitochondrion.
symbionts
The partners in a symbiotic relationship are called symbionts.
Triple gene fusion
The fusion of three separate genes into a single unit early in the course of eukaryote evolution; provides evidence of a bifurcation; characteristic of unikonts.
Taxon
A formal taxonomic group at any level, e.g., phylum or genus.
Apoptosis
Programmed cell death; apoptosis is a normal part of an organism’s development and maintenance. Compare with necrosis.
Mutualism
In ecology, a symbiotic relationship in which both partners benefit from the association. Compare with parasitism and commensalism.
Bikonts
One of two main clades of all eukaryotes that had a common ancestor with two flagella. Compare with unikonts.
Clade
A group of organisms containing a common ancestor and all its descendants; a monophyletic group.
Necrosis
Uncontrolled cell death that causes infl ammation and damages other cells. Compare with apoptosis.
commensalism
A type of symbiosis in which one organism benefi ts and the other one is neither harmed nor helped. Compare with mutualism and parasitism.
amoebozoa
J
Cladogram
A branching diagram that illustrates taxonomic relationships based on the principles of cladistics.
Caspas
Any of a group of proteolytic enzymes that are active in the early stages of apoptosis.
parasitism
A symbiotic relationship in which one member (the parasite) benefi ts and the other (the host) is adversely affected. Compare with commensalism and mutualism.
pseudopodia (sing., pseudopodium, meaning “false foot”)
A temporary extension of an amoeboid cell that is used for feeding and locomotion.
Prokaryotes
A cell that lacks a nucleus and other membrane-enclosed organelles; includes the bacteria and archaea (kingdoms Bacteria and Archaea). Compare with eukaryote.
Free radicals
Toxic, highly reactive compounds with unpaired electrons that bond with other compounds in the cell and interfere with normal function.
parasite
A heterotrophic organism that obtains nourishment from the living tissue of another organism (the host).
amoeba (pl., amoebas)
A unicellular protist that moves by means of pseudopodia.
Bacteria
Prokaryotic organisms that have peptidoglycan in their cell walls; most are decomposers, but some are parasites and others are autotrophs. Bacteria is the name of one of the two prokaryotic domains. Compare with archaea.
Photosynthesis
The biological process that captures light energy and transforms it into the chemical energy of organic molecules (e.g., carbohydrates), which are manufactured from carbon dioxide and water.
pathogens
An organism, usually a microorganism, capable of producing disease.
Cyst
T
Archaea
Prokaryotic organisms with a number of features, such as the absence of peptidoglycan in their cell walls, that set them apart from the bacteria. Archaea is the name of one of the two prokaryotic domains. Compare with bacteria.
Chloroplasts
Membranous organelles that are the sites of photosynthesis in eukaryotes; occur in some plant and algal cells.
Biofilms
An irregular layer of microorganisms embedded in the slime they secrete and concentrated at a solid or liquid surface.
plasmodial slime mold
A funguslike protist whose feeding stage consists of a plasmodium.
Eukaryotes
An organism whose cells have nuclei and other membrane-enclosed organelles. Includes protists, fungi, plants, and animals. Compare with prokaryote.
Chlorophyll
A group of light-trapping green pigments found in most photosynthetic organisms.
bioremediation
A method to clean up a hazardous waste site that uses microorganisms to break down toxic pollutants, or plants to selectively accumulate toxins.
plasmodium
A multinucleate mass of living matter that moves and feeds in an amoeboid fashion.
Protists
One of a vast informal group of eukaryotic organisms, primarily unicellular or simple multicellular; mostly aquatic.
Carotenoids
A group of yellow to orange plant pigments synthesized from isoprene subunits; include carotenes and xanthophylls.
microbiota
(also referred to as microflora)—harmless symbiotic prokaryotes.
sporangium (pl., sporangia)
A spore case, found in plants, certain protists, and fungi.
Fungus
(pl., fungi) A heterotrophic eukaryote with chitinous cell walls and a body usually in the form of a mycelium of branched, threadlike hyphae. Most fungi are decomposers; some are parasitic.
Stroma
A fl uid space of the chloroplast, enclosed by the chloroplast inner membrane and surrounding the thylakoids; site of the reactions of the Calvin cycle.
Koch’s postulates
A set of guidelines used to demonstrate that a specific pathogen causes specific disease symptoms.
Cellular slime molds
A group of funguslike protists whose feeding stage consists of unicellular, amoeboid organisms that aggregate to form a pseudoplasmodium during reproduction.
Mutations
Any change in DNA; may include a change in the nucleotide base pairs of a gene, a rearrangement of genes within the chromosomes so that their interactions produce different effects, or a change in the chromosomes themselves.
Thylakoids
An interconnected system of flattened, saclike, membranous structures inside the chloroplast.
Exotoxins
A poisonous substance released by certain bacteria. Compare with endotoxin.
Cell signaling
Mechanisms of communication between cells. Cells signal one another with secreted signaling molecules, or a signaling molecule on one cell combines with a receptor on another cell. See signal transduction.
Deductive reasoning
The reasoning that operates from generalities to specifics and can make relationships among data more apparent. Compare with inductive reasoning. See hypothetico-deductive approach.
Grana (sing. Granum)
A stack of thylakoids within a chloroplast.
Endotoxins
A poisonous substance in the cell walls of gram-negative bacteria. Compare with exotoxin.
Choanoflagellates
H
Inductive reasoning
The reasoning that uses specific examples to draw a general conclusion or discover a general principle. Compare with deductive reasoning. See hypothetico-inductive approach.
Thylakoid lumen
The thylakoid membrane encloses the innermost compartments within the chloroplast, the thylakoid lumen.
Rfactors
Plasmids that have genes for antibiotic resistance are called R factors.
Sessile
Permanently att ached to one location, e.g., coral animals.
Hypothesis
A testable statement about the nature of an observation or relationship. Compare with theory.
Plastids
A family of membrane-enclosed organelles occurring in photosynthetic eukaryotic cells; include chloroplasts, chromoplasts, and amyloplasts and other leukoplasts.
vancomycin-resistant Staphylococcus aureus, or VRSA
Methicillin-resistant Staphylococcus aureus (SA), referred to as MRSA, and vancomycin-resistant Staphylococcus aureus, or VRSA, have been directly linked to the horizontal transfer of antibiotic resistance genes by plasmids during conjugation
Control group
In a scientific experiment, a group in which the experimental variable is kept constant. The control provides a standard of comparison used to verify the results of the experiment.
Proplastids
Organelles that are plastid precursors; may mature into various specialized plastids, including chloroplasts, chromoplasts, or leukoplasts.
Methicillin-resistant Staphylococcus aureus (SA), referred to as MRSA,
Methicillin-resistant Staphylococcus aureus (SA), referred to as MRSA, and vancomycin-resistant Staphylococcus aureus, or VRSA, have been directly linked to the horizontal transfer of antibiotic resistance genes by plasmids during conjugation.
Natural selection
The mechanism of evolution proposed by Charles Darwin; the tendency of organisms that have favorable adaptations to their environment to survive and become the parents of the next generation. Evolution occurs when natural selection results in changes in allele frequencies in a population.
Chromoplasts
Pigment-containing plastids; found mainly in fl owers and fruits.
Spirochetes
spiral-shaped bacteria with fl exible cell walls; move by means of unique internal fl agella called axial fi laments. Some species are free-living, whereas others form symbiotic associations; a few are parasitic. The spirochete of greatest medical importance is Treponema pallidum, which causes syphilis.
Systems biology
A field of biology that synthesizes knowledge of many small parts to understand the whole. Also referred to as integrative biology or integrative systems biology.
Leukoplasts
Colorless plastids; include amyloplasts, which are used for starch storage in cells of roots and tubers.
Tree of life
A family tree showing proposed evolutionary relationships among organisms.
Amyloplasts
store starch in the cells of many seeds, roots, and tubers (such as white potatoes).
Eukarya
1 of 3 domains
Cytoskeleton
The dynamic internal network of protein fibers that includes microfilaments, intermediate filaments, and microtubules.
Plantae
Members of kingdom Plantae are complex multicellular organisms adapted to carry out photosynthesis.
Microtubules
Hollow, cylindrical fibers consisting of tubulin protein subunits; major components of the cytoskeleton and found in mitotic spindles, cilia, flagella, centrioles, and basal bodies.
Animalia
Kingdom Animalia is made up of multicellular organisms that obtain their nutrition by eating other organisms
Tubulin
Microtubules consist of two forms of proteins. These proteins combine to form a dimmer. Dimmers form the association of two simpler units, referred to as monomers.
Process of science
investigative, dynamic, and often controversial. The observations made, the range of questions asked, and the design of experiments depend on the creativity of the individual scientist.
Microtubule-associated proteins (MAPs)
Include structural proteins that help regulate microtubule assembly and cross-link microtubules to other cytoskeletal polymers; and motors, such as kinesin and dynein, that use ATP to produce movement.
Scientific method
involves a series of ordered steps. Using the scientific method, scientists make careful observations, ask critical questions, and develop hypotheses, which are tentative explanations.
Kinesin
One motor protein, kinesin, moves organelles toward the plus end of a microtubule
Data
information that they can analyze.
Dynein
Dynein, another motor protein,transports organelles in the opposite direction, toward the minusend. This dynein movement is referred to as retrograde transport.
Models
Increasingly in biology, hypotheses may be derived from models that scientists have developed to provide a comprehensive explanation for a large number of observations.
Microtubule-organizing centers (MTOCs)
The region of the cell from which microtubules are anchored and possibly assembled. The MTOCs of many organisms (including animals, but not flowering plants or most gymnosperms) contain a pair of centrioles.
Experimental group
Group being experimented on.Differs from a control group only with respect to the variable being studied.
Centrosome
An organelle in animal cells that is the main microtubule-organizing center; typically contains a pair of centrioles and is important in cell division.
Scientific theory
An integrated explanation of some aspect of the natural world that is based on a number of hypotheses, each supported by consistent results from many observations or experiments.
Centrioles
One of a pair of small, cylindrical organelles lying at right angles to each other near the nucleus in the cytoplasm of animal cells and certain protist and plant cells; each centriole is in the form of a cylinder composed of nine triplets of microtubules (9 × 3 structure).
Paradigm
A set of assumptions or concepts that constitute a way of thinking about reality.
Mitotic spindle
Structure consisting mainly of microtubules that provides the framework for chromosome movement during cell division.
Paradigm shift
Changed their view of reality to accommodate this new knowledge.
Cilia (sing. Cilium)
One of many short, hairlike structures that project from the surface of some eukaryotic cells and are used for locomotion or movement of materials across the cell surface.
Unfalsifiable hypothesis
Cannot be proven false
Basal body
Structure involved in the organization and anchorage of a cilium or fl agellum. Structurally similar to a centriole; each is in the form of a cylinder composed of nine triplets of microtubules (9 × 3 structure).
prediction
a deductive, logical consequence of a hypothesis
Primary cilium
a single cilium on the cell surface that serves as a cellular antenna.
Microfilaments aka actin filaments
Thin fibers consisting of actin protein subunits; form part of the cytoskeleton.
Actin
protein of which microfilaments consist. Actin, together with the protein myosin, is responsible for muscle contraction.
Cell cortex
In many cells, a network of microfilaments is visible just inside the plasma membrane, a region called the cell cortex.
Myosin
A protein that together with actin is responsible for muscle contraction.
pseudopodium (pl., pseudopodia)
A temporary extension of an amoeboid cell that is used for feeding and locomotion.
Glycocalyx or cell coat
A coating on the outside of an animal cell, formed by the polysaccharide portions of glycoproteins and glycolipids associated with the plasma membrane.
Extracellular matrix (ECM)
A network of proteins and carbohydrates that surrounds many animal cells.
Fibronectins
Glycoproteins of the extracellular matrix that bind to integrins (receptor proteins in the plasma membrane).
Integrins
Receptor proteins that bind to specific proteins in the extracellular matrix and to membrane proteins on adjacent cells; transmit signals into the cell from the extracellular matrix.
Cellulose
A structural polysaccharide consisting of beta glucose subunits; the main constituent of plant primary cell walls.
Middle lamella
The layer composed of pectin polysaccharides that serves to cement together the primary cell walls of adjacent plant cells.
Cell homogenate
Is subjected to centrifugal force by spinning in a centrifuge.
Eukaryotic cell
Eukaryotic cells have a membrane-enclosed nucleus, and their cytoplasm contains a variety of organelles; the fl uid component of the cytoplasm is the cytosol.
Regeneration
Common among simple organisms
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