Cell Structure & Cells in Culture

Vocabulary flashcards covering cell structure, organelles, membranes, endomembrane system, autophagy, and cells in culture.

Cell Theory

The idea that all living things are made of cells; new cells come from preexisting cells; cells are the smallest units of life; energy flow and heredity occur within cells; all cells share basic chemical composition.

Prokaryotic cell

A cell lacking a defined nucleus and most organelles; DNA resides in a nucleoid region; usually unicellular and reproduces asexually.

Eukaryotic cell

A cell with a true nucleus and membrane-bound organelles; generally larger and more complex than prokaryotes.

Plasma membrane

The bilayer surrounding the cell; provides structure and protection and regulates exchange with the environment.

Cytosol

Fluid inside the cell, excluding organelles; contains dissolved nutrients and ions.

Organelle

Ultramicroscopic structures within the cytosol that carry out specific cellular functions.

Nucleus

Membrane-bound organelle that houses DNA and controls cellular activities; contains chromatin and nucleolus.

Nucleolus

Nuclear substructure where ribosomal RNA genes are transcribed and ribosome subunits are assembled.

Chromatin

DNA plus associated proteins in the nucleus when not condensed; becomes chromosomes during cell division.

Chromosome

Condensed DNA-protein structure visible during cell division; humans have 46.

Gene

A DNA sequence that encodes the information for a trait.

Endomembrane system

Interconnected membranes (nuclear envelope, ER, Golgi, vesicles) that modify, package, and transport cellular products.

Endoplasmic reticulum

Network of membranes; rough ER has ribosomes for protein synthesis; smooth ER makes lipids and detoxifies.

Rough ER

ER studded with ribosomes; synthesizes and processes secretory and membrane proteins.

Smooth ER

ER without ribosomes; synthesizes lipids, detoxifies, and metabolizes carbohydrates.

Golgi apparatus

Stacks of flattened membranes that modify, sort, and package proteins and lipids for secretion or delivery.

Lysosome

Acidic vesicles with hydrolytic enzymes that digest macromolecules and recycle materials.

Peroxisome

Vesicles with enzymes that break down hydrogen peroxide and toxins; involved in lipid metabolism.

Vacuole

Vesicle for storage and waste; large central vacuole in plants maintains turgor.

Ribosome

Ribonucleoprotein particle; site of protein synthesis; free or membrane-bound.

Mitochondrion

Powerhouse of the cell; site of ATP production; double membrane with cristae; contains its own DNA.

Autophagy

Lysosomal degradation pathway that recycles cytoplasmic components to support survival and homeostasis.

Autophagosome

Double-membrane vesicle that engulfs cytoplasmic material for lysosomal degradation.

Cytoskeleton

Network of protein filaments (microfilaments, intermediate filaments, microtubules) that provides structure and movement.

Phospholipid bilayer

Two-layer arrangement of phospholipids forming the cell membrane; amphipathic with hydrophilic heads and hydrophobic tails.

Amphiphilic

Molecule with both hydrophilic and hydrophobic regions.

Cholesterol (membrane)

Sterol interspersed in the membrane that stabilizes and modulates fluidity.

Glycolipid

Phospholipid with carbohydrate chains; located on the extracellular surface and part of the glycocalyx.

Glycocalyx

Carbohydrate-rich layer on the cell surface formed by glycoproteins and glycolipids; involved in protection and recognition.

Lipid rafts

Cholesterol- and sphingolipid-enriched membrane microdomains that organize signaling molecules.

Membrane asymmetry

Unequal lipid composition between the inner and outer leaflets of the bilayer.

Flip-flop

Lipid movement from one leaflet of the bilayer to the other; occurs rarely.

Flippase

Enzyme that moves specific phospholipids from outer to inner leaflet (P-type ATPase).

Floppase

Transporter that moves phospholipids from inner to outer leaflet (ABC transporter).

Scramblase

Enzyme that moves lipids in either direction to equilibrate membrane lipids.

Fluid mosaic model

Concept that the lipid bilayer is a dynamic, fluid matrix with proteins dispersed in it.

Integral membrane protein

Proteins that span the membrane and may form channels or transporters.

Peripheral membrane protein

Proteins attached to the membrane surface, not spanning the bilayer.

Channel protein

Integral proteins forming pores that allow selective ion or molecule passage; may be gated.

Carrier protein

Integral proteins that transport solutes by changing conformation; may use ATP.

Receptor protein

Membrane proteins that bind ligands to trigger cellular signaling.

Glycoprotein

Protein with carbohydrate chains; contributes to the glycocalyx and cell identity tagging.

Cell-identity markers

Glycoproteins that help the body distinguish self from foreign cells.

CAMs

Cell adhesion molecules (e.g., integrins) that mediate attachment to cells and extracellular matrix.

Enzymatic proteins

Membrane-associated enzymes that catalyze reactions at the cell surface.

Nucleoplasm

The gel-like liquid inside the nucleus surrounding chromatin.

Endosymbiosis

Theory that mitochondria originated as free-living bacteria absorbed by early cells.

mtDNA

Mitochondrial DNA; encodes some mitochondrial proteins and is maternally inherited.

In vitro

Experiments or processes performed outside a living organism, in a controlled environment.

Primary cell culture

Culture derived directly from tissue; finite lifespan and retains differentiated phenotype.

Secondary culture

Cells from a primary culture that have been subcultured; still finite lifespan.

Immortalized cell line

Cell culture transformed to proliferate indefinitely, often via viral genes or transformation.

SV40 T antigen

Viral oncoprotein used to immortalize cells by inactivating p53/Rb.

EBV

Epstein-Barr virus used to transform B cells and extend culture growth.

hTERT

Telomerase reverse transcriptase; extends telomeres to delay senescence.

Hybridoma

Fusion of two cells to create a monoclonal antibody-producing cell line.

Monoclonal antibody

Antibody produced by a single clone of cells with identical specificity.

Embryonic stem cell

Pluripotent stem cells derived from the inner cell mass of a blastocyst.

Totipotent

Stem cells that can form all cell types and extraembryonic tissues.

Pluripotent

Stem cells that can differentiate into most but not all cell types; cannot form a whole organism.

Multipotent

Stem cells that can differentiate into a limited set of cell types.

Reproductive cloning

Nuclear transfer to create a genetically identical organism; mtDNA from egg cytoplasm.

Therapeutic cloning

Nuclear transfer to generate embryonic cells for therapy, not a whole organism.

Hybridoma production

Creating a cell line that secretes a specific monoclonal antibody.

Trypsin-EDTA

Enzyme solution used to detach adherent cells; EDTA chelates calcium to enhance activity.

PBS

Phosphate-buffered saline; used to wash cells; warmed before use.

3T3

Mouse embryo fibroblast cell line; commonly used in research.

HeLa

Human cervical cancer cell line; widely used in laboratories.

CHO cells

Chinese hamster ovary cells; widely used for protein production and research.

Aseptic technique

Sterile methods to prevent contamination in cell culture.

Laminar flow hood

Sterile workspace that provides a clean, laminar airflow for cell culture work.

Stem cell niche

Microenvironment that maintains stem cell properties and regulates differentiation.

Embryonic stem cell fate

Pluripotent ES cells can differentiate into many lineages; used in research and therapy.

Cloning (reproductive/therapeutic)

Nuclear transfer to create a clone or to derive ES cells for therapy.

Monoclonal antibody applications

Monoclonal antibodies used in diagnosis, therapy, and research.