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steroid : (also, sterol) lipid compound composed of four hydrocarbon rings bonded to a variety of other atoms and molecules
https://openstax.org/books/anatomy-and-physiology-2e/pages/2-key-terms
substrate : reactant in an enzymatic reaction
https://openstax.org/books/anatomy-and-physiology-2e/pages/2-key-terms
suspension : liquid mixture in which particles distributed in the liquid settle out over time
https://openstax.org/books/anatomy-and-physiology-2e/pages/2-key-terms
synthesis reaction : type of anabolic reaction in which two or more atoms or molecules bond, resulting in the formation of a larger molecule
https://openstax.org/books/anatomy-and-physiology-2e/pages/2-key-terms
triglyceride : lipid compound composed of a glycerol molecule bonded with three fatty acid chains
https://openstax.org/books/anatomy-and-physiology-2e/pages/2-key-terms
valence shell : outermost electron shell of an atom
https://openstax.org/books/anatomy-and-physiology-2e/pages/2-key-terms
The cell membrane provides a barrier around the cell, separating its internal components from the extracellular environment. It is composed of a phospholipid bilayer, with hydrophobic internal lipid “tails” and hydrophilic external phosphate “heads.” Various membrane proteins are scattered throughout the bilaye...
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-chapter-review
The internal environment of a living cell is made up of a fluid, jelly-like substance called cytosol, which consists mainly of water, but also contains various dissolved nutrients and other molecules. The cell contains an array of cellular organelles, each one performing a unique function and helping to maintain the he...
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-chapter-review
Cells also contain mitochondria and peroxisomes, which are the organelles responsible for producing the cell’s energy supply and detoxifying certain chemicals, respectively. Biochemical reactions within mitochondria transform energy-carrying molecules into the usable form of cellular energy known as ATP. Peroxisomes ...
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-chapter-review
The nucleus is the command center of the cell, containing the genetic instructions for all of the materials a cell will make (and thus all of its functions it can perform). The nucleus is encased within a membrane of two interconnected lipid bilayers, side-by-side. This nuclear envelope is studded with protein-lined po...
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-chapter-review
There is a pool of cells constantly dividing within your body. The result is billions of new cells being created each day. Before any cell is ready to divide, it must replicate its DNA so that each new daughter cell will receive an exact copy of the organism’s genome. A variety of enzymes are enlisted during DNA repl...
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-chapter-review
DNA stores the information necessary for instructing the cell to perform all of its functions. Cells use the genetic code stored within DNA to build proteins, which ultimately determine the structure and function of the cell. This genetic code lies in the particular sequence of nucleotides that make up each gene along ...
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-chapter-review
The life of cell consists of stages that make up the cell cycle. After a cell is born, it passes through an interphase before it is ready to replicate itself and produce daughter cells. This interphase includes two gap phases (G1and G2), as well as an S phase, during which its DNA is replicated in preparation for cell ...
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-chapter-review
Once a cell has completed interphase and is ready for cell division, it proceeds through four separate stages of mitosis (prophase, metaphase, anaphase, and telophase). Telophase is followed by the division of the cytoplasm (cytokinesis), which generates two daughter cells. This process takes place in all normally divi...
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-chapter-review
One of the major areas of research in biology is that of how cells specialize to assume their unique structures and functions, since all cells essentially originate from a single fertilized egg. Cell differentiation is the process of cells becoming specialized as the body develops. A stem cell is an unspecialized cell ...
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-chapter-review
active transport : form of transport across the cell membrane that requires input of cellular energy
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
amphipathic : describes a molecule that exhibits a difference in polarity between its two ends, resulting in a difference in water solubility
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
anaphase : third stage of mitosis (and meiosis), during which sister chromatids separate into two new nuclear regions of a dividing cell
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
anticodon : consecutive sequence of three nucleotides on a tRNA molecule that is complementary to a specific codon on an mRNA molecule
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
autolysis : breakdown of cells by their own enzymatic action
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
autophagy : lysosomal breakdown of a cell’s own components
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
cell cycle : life cycle of a single cell, from its birth until its division into two new daughter cells
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
cell membrane : membrane surrounding all animal cells, composed of a lipid bilayer interspersed with various molecules; also known as plasma membrane
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
centriole : small, self-replicating organelle that provides the origin for microtubule growth and moves DNA during cell division
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
centromere : region of attachment for two sister chromatids
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
centrosome : cellular structure that organizes microtubules during cell division
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
channel protein : membrane-spanning protein that has an inner pore which allows the passage of one or more substances
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
checkpoint : progress point in the cell cycle during which certain conditions must be met in order for the cell to proceed to a subsequence phase
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
chromatin : substance consisting of DNA and associated proteins
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
chromosome : condensed version of chromatin
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
cilia : small appendage on certain cells formed by microtubules and modified for movement of materials across the cellular surface
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
cleavage furrow : contractile ring that forms around a cell during cytokinesis that pinches the cell into two halves
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
codon : consecutive sequence of three nucleotides on an mRNA molecule that corresponds to a specific amino acid
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
concentration gradient : difference in the concentration of a substance between two regions
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
cyclin : one of a group of proteins that function in the progression of the cell cycle
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
cyclin-dependent kinase (CDK) : one of a group of enzymes associated with cyclins that help them perform their functions
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
cytokinesis : final stage in cell division, where the cytoplasm divides to form two separate daughter cells
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
cytoplasm : internal material between the cell membrane and nucleus of a cell, mainly consisting of a water-based fluid called cytosol, within which are all the other organelles and cellular solute and suspended materials
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
cytoskeleton : “skeleton” of a cell; formed by rod-like proteins that support the cell’s shape and provide, among other functions, locomotive abilities
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
cytosol : clear, semi-fluid medium of the cytoplasm, made up mostly of water
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
diffusion : movement of a substance from an area of higher concentration to one of lower concentration
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
diploid : condition marked by the presence of a double complement of genetic material (two sets of chromosomes, one set inherited from each of two parents)
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
DNA polymerase : enzyme that functions in adding new nucleotides to a growing strand of DNA during DNA replication
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
DNA replication : process of duplicating a molecule of DNA
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
electrical gradient : difference in the electrical charge (potential) between two regions
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
endocytosis : import of material into the cell by formation of a membrane-bound vesicle
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
endoplasmic reticulum (ER) : cellular organelle that consists of interconnected membrane-bound tubules, which may or may not be associated with ribosomes (rough type or smooth type, respectively)
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
exocytosis : export of a substance out of a cell by formation of a membrane-bound vesicle
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
exon : one of the coding regions of an mRNA molecule that remain after splicing
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
extracellular fluid (ECF) : fluid exterior to cells; includes the interstitial fluid, blood plasma, and fluid found in other reservoirs in the body
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
facilitated diffusion : diffusion of a substance with the aid of a membrane protein
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
flagellum : appendage on certain cells formed by microtubules and modified for movement
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
G0phase : phase of the cell cycle, usually entered from the G1phase; characterized by long or permanent periods where the cell does not move forward into the DNA synthesis phase
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
G1phase : first phase of the cell cycle, after a new cell is born
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
G2phase : third phase of the cell cycle, after the DNA synthesis phase
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
gene : functional length of DNA that provides the genetic information necessary to build a protein
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
gene expression : active interpretation of the information coded in a gene to produce a functional gene product
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
genome : entire complement of an organism’s DNA; found within virtually every cell
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
glycocalyx : coating of sugar molecules that surrounds the cell membrane
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
glycoprotein : protein that has one or more carbohydrates attached
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
Golgi apparatus : cellular organelle formed by a series of flattened, membrane-bound sacs that functions in protein modification, tagging, packaging, and transport
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
helicase : enzyme that functions to separate the two DNA strands of a double helix during DNA replication
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
histone : family of proteins that associate with DNA in the nucleus to form chromatin
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
homologous : describes two copies of the same chromosome (not identical), one inherited from each parent
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
hydrophilic : describes a substance or structure attracted to water
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
hydrophobic : describes a substance or structure repelled by water
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
hypertonic : describes a solution concentration that is higher than a reference concentration
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
hypotonic : describes a solution concentration that is lower than a reference concentration
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
integral protein : membrane-associated protein that spans the entire width of the lipid bilayer
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
intermediate filament : type of cytoskeletal filament made of keratin, characterized by an intermediate thickness, and playing a role in resisting cellular tension
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
interphase : entire life cycle of a cell, excluding mitosis
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
interstitial fluid (IF) : fluid in the small spaces between cells not contained within blood vessels
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
intracellular fluid (ICF) : fluid in the cytosol of cells
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
intron : non-coding regions of a pre-mRNA transcript that may be removed during splicing
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
isotonic : describes a solution concentration that is the same as a reference concentration
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
kinetochore : region of a centromere where microtubules attach to a pair of sister chromatids
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
ligand : molecule that binds with specificity to a specific receptor molecule
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
lysosome : membrane-bound cellular organelle originating from the Golgi apparatus and containing digestive enzymes
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
messenger RNA (mRNA) : nucleotide molecule that serves as an intermediate in the genetic code between DNA and protein
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
metaphase : second stage of mitosis (and meiosis), characterized by the linear alignment of sister chromatids in the center of the cell
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
metaphase plate : linear alignment of sister chromatids in the center of the cell, which takes place during metaphase
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
microfilament : the thinnest of the cytoskeletal filaments; composed of actin subunits that function in muscle contraction and cellular structural support
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
microtubule : the thickest of the cytoskeletal filaments, composed of tubulin subunits that function in cellular movement and structural support
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
mitochondrion : one of the cellular organelles bound by a double lipid bilayer that function primarily in the production of cellular energy (ATP)
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
mitosis : division of genetic material, during which the cell nucleus breaks down and two new, fully functional, nuclei are formed
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
mitotic phase : phase of the cell cycle in which a cell undergoes mitosis
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
mitotic spindle : network of microtubules, originating from centrioles, that arranges and pulls apart chromosomes during mitosis
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
multipotent : describes the condition of being able to differentiate into different types of cells within a given cell lineage or small number of lineages, such as a red blood cell or white blood cell
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
mutation : change in the nucleotide sequence in a gene within a cell’s DNA
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
nuclear envelope : membrane that surrounds the nucleus; consisting of a double lipid-bilayer
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
nuclear pore : one of the small, protein-lined openings found scattered throughout the nuclear envelope
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
nucleolus : small region of the nucleus that functions in ribosome synthesis
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
nucleosome : unit of chromatin consisting of a DNA strand wrapped around histone proteins
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
nucleus : cell’s central organelle; contains the cell’s DNA
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
oligopotent : describes the condition of being more specialized than multipotency; the condition of being able to differentiate into one of a few possible cell types
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
organelle : any of several different types of membrane-enclosed specialized structures in the cell that perform specific functions for the cell
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
osmosis : diffusion of water molecules down their concentration gradient across a selectively permeable membrane
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
passive transport : form of transport across the cell membrane that does not require input of cellular energy
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
peripheral protein : membrane-associated protein that does not span the width of the lipid bilayer, but is attached peripherally to integral proteins, membrane lipids, or other components of the membrane
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms
peroxisome : membrane-bound organelle that contains enzymes primarily responsible for detoxifying harmful substances
https://openstax.org/books/anatomy-and-physiology-2e/pages/3-key-terms