Cell Biology Vocabulary

These flashcards cover essential vocabulary and definitions related to cell biology, organized by key terms and concepts relevant to the subject.

active transport

Form of transport across the cell membrane that requires input of cellular energy.

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 subsequent 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)

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.

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 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.

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 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 intermediate thickness.

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 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

Cellular organelle bound by a double lipid bilayer that functions 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.

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

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

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.

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.

peroxisome

Membrane-bound organelle that contains enzymes primarily responsible for detoxifying harmful substances.

phagocytosis

Endocytosis of large particles.

pinocytosis

Endocytosis of fluid.

pluripotent

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)

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 during transcription.

S phase

Stage of the cell cycle during which DNA replication occurs.