BGYA01 - Key Terms

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Published on 29 Sep 2011
School
UTSC
Department
Biological Sciences
Course
BIOA01H3
Professor
Chapter 1 – Terms
atom - The smallest unit of a chemical element. Consists of a nucleus and one or more electrons.
Biosphere - All regions of Earth (terrestrial and aquatic) + Earth's atmosphere in which organisms can live.
ecosystem The organisms of a particular habitat, such as a pond or forest, together with the physical
environment in which they live.
community Any ecologically integrated group of species of microorganisms, plants, and animals inhabiting a
given area.
population Any group of organisms coexisting at the same time and in the same place and capable of
interbreeding with one another.
organism Any living entity.
organ system An interrelated and integrated group of tissues and organs that work together in a physiological
function.
organ A body part, such as the heart, liver, brain, root, or leaf. Organs are composed of different tissues
integrated to perform a distinct function. Organs are in turn often integrated into systems, such as the digestive or
reproductive system.
organelles Organized structures found in or on eukaryotic cells. Examples include ribosomes, nuclei,
mitochrondria, chloroplasts, cilia, and contractile vacuoles.
tissue A group of similar cells organized into a functional unit; usually integrated with other tissues to form part
of an organ.
molecule A particle made up of two or more atoms joined by covalent bonds or ionic attractions.
element A substance that cannot be converted to simpler substances by ordinary chemical means.
consumer An organism that eats the tissues of some other organism.
primary producer A photosynthetic or chemosynthetic organism that synthesizes complex organic molecules
from simple inorganic ones.
domain (1) Independent structural elements within proteins that affect the protein's function. Encoded by
recognizable nucleotide sequences, a domain often folds separately from the rest of the protein. Similar domains
can appear in a variety of different proteins across phylogenetic groups (e.g., "homeobox domain"; "calcium-
binding domain.") (2) In phylogenetics, the three monophyletic branches of Life. Members of the three domains
(Bacteria, Archaea, and Eukarya) are believed to have been evolving independently of each other for at least a
billion years.
Genus A group of related, similar species recognized by taxonomists with a distinct name used in binomial
nomenclature.
species The basic lower unit of classification, consisting of an ancestor–descendant lineage of populations of
closely related and similar organisms. The more narrowly defined "biological species" consists of individuals
capable of interbreeding freely with each other but not with members of other species.
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emergent property A property of a complex system that is not exhibited by its individual component parts.
Chapter 4 – Terms
cell wall A relatively rigid structure that encloses cells of plants, fungi, many protists, and most prokaryotes.
Gives these cells their shape and limits their expansion in hypotonic media
extracellular matrix In animal tissues, a material of heterogeneous composition surrounding cells and
performing many functions including adhesion of cells.
chloroplast An organelle bounded by a double membrane containing the enzymes and pigments that perform
photosynthesis. Chloroplasts occur only in eukaryotes.
granum (plural: grana) Within a chloroplast, a stack of thylakoids.
stroma The fluid contents of an organelle, such as a chloroplast.
thylakoid A flattened sac within a chloroplast. Thylakoid membranes contain all of the chlorophyll in a plant, in
addition to the electron carriers of photophosphorylation. Thylakoids stack to form grana.
plastid Organelle in plants that serves for food manufacture (by photosynthesis) or food storage; bounded by a
double membrane.
cilium Hairlike organelle used for locomotion by many unicellular organisms and for moving water and mucus
by many multicellular organisms. Generally shorter than a flagellum.
Flagellum Long, whiplike appendage that propels cells. Prokaryotic flagella differ sharply from those found in
eukaryotes.
pseudopod A temporary, soft extension of the cell body that is used in location, attachment to surfaces, or
engulfing particles.
cytoplasm The contents of the cell, excluding the nucleus.
cytosol The fluid portion of the cytoplasm, excluding organelles and other solids.
cytoskeleton The network of microtubules and microfilaments that gives a eukaryotic cell its shape and its
capacity to arrange its organelles and to move.
desmosome An adhering junction between animal cells.
gap junction A 2.7-nanometer gap between plasma membranes of two animal cells, spanned by protein
channels. Gap junctions allow chemical substances or electrical signals to pass from cell to cell.
tight junction A junction between epithelial cells, in which there is no gap whatever between the adjacent cells.
Materials may pass through a tight junction only by entering the epithelial cells themselves.
plasmodesma (plural: plasmodesmata) [Gk. plassein: to mold + desmos: band] A cytoplasmic strand connecting
two adjacent plant cells.
endomembrane system Endoplasmic reticulum plus Golgi apparatus; also lysosomes, when present. A system
of membranes that exchange material with one another.
endoplasmic reticulum (ER) A system of membranous tubes and flattened sacs found in the cytoplasm of
eukaryotes. Exists in two forms: rough ER, studded with ribosomes; and smooth ER, lacking ribosomes.
rough ER That portion of the endoplasmic reticulum whose outer surface has attached ribosomes.
ribosome A small organelle that is the site of protein synthesis.
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prokaryotes Organisms whose genetic material is not contained within a nucleus: the bacteria and archaea.
Considered an earlier stage in the evolution of life than the eukaryotes.
eukaryotes Organisms whose cells contain their genetic material inside a nucleus. Includes all life other than
the viruses, archaea, and bacteria.
Golgi apparatus A system of concentrically folded membranes found in the cytoplasm of eukaryotic cells;
functions in secretion from cell by exocytosis.
lysosome A membrane-enclosed organelle found in eukaryotic cells (other than plants). Lysosomes contain a
mixture of enzymes that can digest most of the macromolecules found in the rest of the cell.
peroxisome An organelle that houses reactions in which toxic peroxides are formed. The peroxisome isolates
these peroxides from the rest of the cell.
vesicle A membrane enclosed compartment within the cytoplasm.
microfilament Minute fibrous structure generally composed of actin found in the cytoplasm of eukaryotic cells.
They play a role in the motion of cells.
microtubules Minute tubular structures found in centrioles, spindle apparatus, cilia, flagella, and cytoskeleton of
eukaryotic cells. These tubules play roles in the motion and maintenance of shape of eukaryotic cells.
intermediate filaments Cytoskeletal component with diameters between the larger microtubules and smaller
microfilaments.
Mitochondrion An organelle in eukaryotic cells that contains the enzymes of the citric acid cycle, the
respiratory chain, and oxidative phosphorylation.
mitochondrial matrix The fluid interior of the mitochondrion, enclosed by the inner mitochondrial membrane.
crista (plural: cristae) A small, shelflike projection of the inner membrane of a mitochondrion; the site of
oxidative phosphorylation.
nuclear envelope The surface, consisting of two layers of membrane, that encloses the nucleus of eukaryotic
cells.
nuclear lamina A meshwork of fibers on the inner surface of the nuclear envelope.
nucleoid The region that harbors the chromosomes of a prokaryotic cell. Unlike the eukaryotic nucleus, it is not
bounded by a membrane.
nucleolus A small, generally spherical body found within the nucleus of eukaryotic cells. The site of synthesis of
ribosomal RNA.
nucleus (1) In cells, the centrally located compartment of eukaryotic cells that is bounded by a double
membrane and contains the chromosomes. (2) In the brain, an identifiable group of neurons that share common
characteristics or functions.
nucleoplasm The fluid material within the nuclear envelope of a cell, as opposed to the chromosomes, nucleoli,
and other particulate constituents.
organelles Organized structures found in or on eukaryotic cells. Examples include ribosomes, nuclei,
mitochrondria, chloroplasts, cilia, and contractile vacuoles.
phagocytosis Endocytosis by a cell of another cell or large particle.
plasma membrane The membrane that surrounds the cell, regulating the entry and exit of molecules and ions.
Every cell has a plasma membrane.
vacuole A liquid-filled, membrane-enclosed compartment in cytoplasm; may function as digestive chambers,
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