- amphipathic
- describes a molecule that exhibits a difference in polarity between its two ends, resulting in a difference in water solubility
- anaphase
- third stage of mitosis (and meiosis), during which sister chromatids separate into two new nuclear regions of a dividing cell
- anticodon
- consecutive sequence of three nucleotides on a tRNA molecule that is complementary to a specific codon on an mRNA molecule
- autolysis
- breakdown of cells by their own enzymatic action
- autophagy
- lysosomal breakdown of a cell’s own components
- cell cycle
- life cycle of a single cell, from its birth until its division into two new daughter cells
- cell membrane
- membrane surrounding all animal cells, composed of a lipid bilayer interspersed with various molecules; also known as plasma membrane
- centriole
- small, self-replicating organelle that provides the origin for microtubule growth and moves DNA during cell division
- centromere
- region of attachment for two sister chromatids
- centrosome
- cellular structure that organizes microtubules during cell division
- channel protein
- membrane-spanning protein that has an inner pore which allows the passage of one or more substances
- 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
- chromatin
- substance consisting of DNA and associated proteins
- chromosome
- condensed version of chromatin
- cilia
- small appendage on certain cells formed by microtubules and modified for movement of materials across the cellular surface
- cleavage furrow
- contractile ring that forms around a cell during cytokinesis that pinches the cell into two halves
- codon
- consecutive sequence of three nucleotides on an mRNA molecule that corresponds to a specific amino acid
- concentration gradient
- difference in the concentration of a substance between two regions
- cyclin
- one of a group of proteins that function in the progression of the cell cycle
- cyclin-dependent kinase (CDK)
- one of a group of enzymes associated with cyclins that help them perform their functions
- cytokinesis
- final stage in cell division, where the cytoplasm divides to form two separate daughter cells
- 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
- cytoskeleton
- “skeleton” of a cell; formed by rod-like proteins that support the cell’s shape and provide, among other functions, locomotive abilities
- cytosol
- clear, semi-fluid medium of the cytoplasm, made up mostly of water
- diffusion
- movement of a substance from an area of higher concentration to one of lower concentration
- 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)
- DNA polymerase
- enzyme that functions in adding new nucleotides to a growing strand of DNA during DNA replication
- DNA replication
- process of duplicating a molecule of DNA
- electrical gradient
- difference in the electrical charge (potential) between two regions
- endocytosis
- import of material into the cell by formation of a membrane-bound vesicle
- 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)
- exocytosis
- export of a substance out of a cell by formation of a membrane-bound vesicle
- exon
- one of the coding regions of an mRNA molecule that remain after splicing
- extracellular fluid (ECF)
- fluid exterior to cells; includes the interstitial fluid, blood plasma, and fluid found in other reservoirs in the body
- facilitated diffusion
- diffusion of a substance with the aid of a membrane protein
- flagellum
- appendage on certain cells formed by microtubules and modified for movement
- G0 phase
- phase of the cell cycle, usually entered from the G1 phase; characterized by long or permanent periods where the cell does not move forward into the DNA synthesis phase
- G1 phase
- first phase of the cell cycle, after a new cell is born
- G2 phase
- third phase of the cell cycle, after the DNA synthesis phase
- gene
- functional length of DNA that provides the genetic information necessary to build a protein
- gene expression
- active interpretation of the information coded in a gene to produce a functional gene product
- genome
- entire complement of an organism’s DNA; found within virtually every cell
- glycocalyx
- coating of sugar molecules that surrounds the cell membrane
- glycoprotein
- protein that has one or more carbohydrates attached
- Golgi apparatus
- cellular organelle formed by a series of flattened, membrane-bound sacs that functions in protein modification, tagging, packaging, and transport
- helicase
- enzyme that functions to separate the two DNA strands of a double helix during DNA replication
- histone
- family of proteins that associate with DNA in the nucleus to form chromatin
- homologous
- describes two copies of the same chromosome (not identical), one inherited from each parent
- hydrophilic
- describes a substance or structure attracted to water
- hydrophobic
- describes a substance or structure repelled by water
- hypertonic
- describes a solution concentration that is higher than a reference concentration
- hypotonic
- describes a solution concentration that is lower than a reference concentration
- integral protein
- membrane-associated protein that spans the entire width of the lipid bilayer
- intermediate filament
- type of cytoskeletal filament made of keratin, characterized by an intermediate thickness, and playing a role in resisting cellular tension
- interphase
- entire life cycle of a cell, excluding mitosis
- interstitial fluid (IF)
- fluid in the small spaces between cells not contained within blood vessels
- intracellular fluid (ICF)
- fluid in the cytosol of cells
- intron
- non-coding regions of a pre-mRNA transcript that may be removed during splicing
- isotonic
- describes a solution concentration that is the same as a reference concentration
- kinetochore
- region of a centromere where microtubules attach to a pair of sister chromatids
- ligand
- molecule that binds with specificity to a specific receptor molecule
- lysosome
- membrane-bound cellular organelle originating from the Golgi apparatus and containing digestive enzymes
- messenger RNA (mRNA)
- nucleotide molecule that serves as an intermediate in the genetic code between DNA and protein
- metaphase
- second stage of mitosis (and meiosis), characterized by the linear alignment of sister chromatids in the center of the cell
- metaphase plate
- linear alignment of sister chromatids in the center of the cell, which takes place during metaphase
- microfilament
- the thinnest of the cytoskeletal filaments; composed of actin subunits that function in muscle contraction and cellular structural support
- microtubule
- the thickest of the cytoskeletal filaments, composed of tubulin subunits that function in cellular movement and structural support
- mitochondrion
- one of the cellular organelles bound by a double lipid bilayer that function primarily in the production of cellular energy (ATP)
- mitosis
- division of genetic material, during which the cell nucleus breaks down and two new, fully functional, nuclei are formed
- mitotic phase
- phase of the cell cycle in which a cell undergoes mitosis
- mitotic spindle
- network of microtubules, originating from centrioles, that arranges and pulls apart chromosomes during mitosis
- 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
- mutation
- change in the nucleotide sequence in a gene within a cell’s DNA
- nuclear envelope
- membrane that surrounds the nucleus; consisting of a double lipid-bilayer
- nuclear pore
- one of the small, protein-lined openings found scattered throughout the nuclear envelope
- nucleolus
- small region of the nucleus that functions in ribosome synthesis
- nucleosome
- unit of chromatin consisting of a DNA strand wrapped around histone proteins
- nucleus
- cell’s central organelle; contains the cell’s DNA
- 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
- organelle
- any of several different types of membrane-enclosed specialized structures in the cell that perform specific functions for the cell
- osmosis
- diffusion of water molecules down their concentration gradient across a selectively permeable membrane
- passive transport
- form of transport across the cell membrane that does not require input of cellular energy
- 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
- peroxisome
- membrane-bound organelle that contains enzymes primarily responsible for detoxifying harmful substances
- phagocytosis
- endocytosis of large particles
- pinocytosis
- endocytosis of fluid
- pluripotent
- describes the condition of being able to differentiate into a large variety of cell types
- polypeptide
- chain of amino acids linked by peptide bonds
- polyribosome
- simultaneous translation of a single mRNA transcript by multiple ribosomes
- promoter
- region of DNA that signals transcription to begin at that site within the gene
- prophase
- first stage of mitosis (and meiosis), characterized by breakdown of the nuclear envelope and condensing of the chromatin to form chromosomes
- proteome
- full complement of proteins produced by a cell (determined by the cell’s specific gene expression)
- reactive oxygen species (ROS)
- a group of extremely reactive peroxides and oxygen-containing radicals that may contribute to cellular damage
- receptor
- protein molecule that contains a binding site for another specific molecule (called a ligand)
- receptor-mediated endocytosis
- endocytosis of ligands attached to membrane-bound receptors
- ribosomal RNA (rRNA)
- RNA that makes up the subunits of a ribosome
- ribosome
- cellular organelle that functions in protein synthesis
- RNA polymerase
- enzyme that unwinds DNA and then adds new nucleotides to a growing strand of RNA for the transcription phase of protein synthesis
- S phase
- stage of the cell cycle during which DNA replication occurs
- selective permeability
- feature of any barrier that allows certain substances to cross but excludes others
- sister chromatid
- one of a pair of identical chromosomes, formed during DNA replication
- sodium-potassium pump
- (also, Na+/K+ ATP-ase) membrane-embedded protein pump that uses ATP to move Na+ out of a cell and K+ into the cell
- somatic cell
- all cells of the body excluding gamete cells
- spliceosome
- complex of enzymes that serves to splice out the introns of a pre-mRNA transcript
- splicing
- the process of modifying a pre-mRNA transcript by removing certain, typically non-coding, regions
- stem cell
- cell that is oligo-, multi-, or pleuripotent that has the ability to produce additional stem cells rather than becoming further specialized
- telophase
- final stage of mitosis (and meiosis), preceding cytokinesis, characterized by the formation of two new daughter nuclei
- totipotent
- embryonic cells that have the ability to differentiate into any type of cell and organ in the body
- transcription
- process of producing an mRNA molecule that is complementary to a particular gene of DNA
- transcription factor
- one of the proteins that regulate the transcription of genes
- transfer RNA (tRNA)
- molecules of RNA that serve to bring amino acids to a growing polypeptide strand and properly place them into the sequence
- translation
- process of producing a protein from the nucleotide sequence code of an mRNA transcript
- triplet
- consecutive sequence of three nucleotides on a DNA molecule that, when transcribed into an mRNA codon, corresponds to a particular amino acid
- unipotent
- describes the condition of being committed to a single specialized cell type
- vesicle
- membrane-bound structure that contains materials within or outside of the cell
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