E3 Flashcards
What are fatty acids?
Molecules with a carboxylic acid group attached to a long hydrocarbon chain. Used for energy and as building blocks for complex lipids.
What are phospholipids?
Major lipid components of cell membranes, consisting of two fatty acids, a glycerol unit, a phosphate group, and a polar head.
What is cholesterol?
A short, rigid lipid molecule in animal cell membranes that reduces membrane fluidity.
What are glycolipids?
Lipids with a carbohydrate attached, found in the extracellular leaflet of the plasma membrane.
What are glycoproteins?
Proteins with oligosaccharide chains attached, important in cell recognition and signaling.
What are transporters?
Membrane proteins that move molecules across membranes, often selectively.
What are anchors?
Membrane proteins that tether the membrane to the cytoskeleton or extracellular matrix.
What are receptors?
Proteins that bind to signaling molecules and initiate a cellular response.
What are enzymes?
Proteins that catalyze specific chemical reactions.
What are transmembrane proteins?
Proteins that span across the lipid bilayer, with domains exposed on both sides.
What are mono-layer associated proteins?
Proteins that are embedded in only one layer of the lipid bilayer.
What are lipid-linked proteins?
Proteins attached to the membrane via covalently bonded lipid groups.
What are peripheral proteins?
Proteins indirectly associated with the membrane by binding to other membrane proteins.
What is a polysome?
A complex of multiple ribosomes translating a single mRNA strand simultaneously.
What is elF4E?
A eukaryotic initiation factor that binds to the 5’ cap of mRNA to begin translation.
What is elF4g?
A scaffolding protein that interacts with elF4E and other components to assemble the translation initiation complex.
What are post-translation modifications?
Chemical changes made to proteins after synthesis, such as phosphorylation or ubiquitination.
What is the 26S proteasome?
A protein complex that degrades poly-ubiquitinated proteins.
What is a protease?
An enzyme that breaks down proteins by hydrolyzing peptide bonds.
What are ubiquitin ligases?
Enzymes that tag proteins with ubiquitin to mark them for degradation.
What is ubiquitin?
A small regulatory protein that is attached to substrates to signal for their degradation.
What is poly-ubiquitinated?
Refers to a protein tagged with multiple ubiquitin molecules.
What are triacylglycerides?
Lipids made of three fatty acids esterified to a glycerol backbone, used for energy storage.
What is flip flop?
The rare transverse movement of lipids between leaflets of a bilayer.
What is apoptosis?
Programmed cell death involving caspases that dismantle the cell in a controlled manner.
What are caspases?
A family of proteases that execute apoptosis by cleaving cellular proteins.
What is a semipermeable membrane?
Describes a membrane that allows some substances to pass through while blocking others.
What is passive transport?
The movement of molecules across a membrane without energy input, down their concentration gradient.
What is active transport?
The movement of molecules against their concentration gradient, requiring energy (usually from ATP).
What is uniport?
A membrane transport protein that moves one type of molecule in one direction.
What is a voltage gradient?
The difference in electrical potential across a membrane due to ion distribution.
What is membrane potential?
The voltage difference across a membrane created by ion gradients.
What is an electrochemical gradient?
The combined effect of a chemical gradient and an electrical gradient on ion movement.
What is the sodium/potassium pump?
An ATP-powered pump that exchanges Na+ out and K+ into the cell.
What are microfilaments?
Thin protein filaments composed of actin, part of the cytoskeleton.
What are microtubules?
Hollow tubes of tubulin that organize cell structure and serve as tracks for motor proteins.
What are intermediate filaments?
Strong, ropelike filaments providing mechanical support to cells.
What is actin?
A globular protein that polymerizes to form microfilaments.
What is alpha-tubulin?
A subunit of microtubules that pairs with beta-tubulin to form dimers.
What is beta-tubulin?
Partners with alpha-tubulin to form microtubule dimers.
What is the (-) end?
The slow-growing end of a microtubule or actin filament.
What is the cortex?
A specialized layer of cytoplasm just beneath the plasma membrane, rich in actin filaments.
What are desmosomes?
Intercellular junctions that anchor intermediate filaments and provide strong adhesion between cells.
What is the nuclear lamina?
A dense fibrillar network inside the nucleus composed of intermediate filaments called lamins.
What are lamins?
Intermediate filament proteins that form the nuclear lamina under the inner nuclear membrane.
What is nucleation?
The initial process in filament formation where small aggregates of subunits come together.
What is elongation?
The phase in which filaments rapidly grow by addition of subunits to the ends.
What is a tubulin heterodimer?
A dimer consisting of alpha-and beta-tubulin that polymerizes to form microtubules.
What is dynamic instability?
The rapid switching between growth and shrinkage at microtubule ends.
What are Microtubule Organizing Centers?
Structures that nucleate and anchor microtubules in cells.
What is a centrosome?
The primary MTOC in animal cells, composed of a pair of centrioles and surrounding matrix.
What are centrioles?
Cylindrical structures made of microtubule triplets, found in centrosomes.
What is y-Tubulin?
A specialized tubulin that helps nucleate microtubule assembly at MTOCs.
What are microtubule associated proteins?
Proteins that bind to microtubules and regulate their stability and function.
What is a kinetochore?
A protein complex on chromosomes where microtubules attach during mitosis.
What is kinesin?
A motor protein that moves cargo along microtubules toward the plus end.
What is dynein?
A motor protein that moves cargo toward the minus end of microtubules.
What is the endomembrane system?
A system of membrane-bound organelles that work together in the synthesis, modification, and transport of proteins and lipids.
What are signal sequences?
Short peptide sequences that direct the transport of a protein to a specific location in the cell.
What are nuclear localization signals?
A sequence of amino acids that directs a protein to the nucleus.
What are nuclear pores?
Large protein complexes that span the nuclear envelope and regulate transport between the nucleus and cytoplasm.
What is a nuclear import receptor?
A protein that binds cargo with an NLS and facilitates its transport into the nucleus.
What is Ran-GTP?
A GTP-bound form of Ran protein found in high concentrations in the nucleus, essential for nuclear transport directionality.
What is Ran-GDP?
The GDP-bound form of Ran found predominantly in the cytoplasm.
What is Ran-GAP?
A GTPase-activating protein that promotes hydrolysis of Ran-GTP to Ran-GDP in the cytoplasm.
What is a guanine nucleotide exchange factor?
A factor that converts Ran-GDP to Ran-GTP in the nucleus.
What is a signal recognition particle?
A ribonucleoprotein that recognizes signal sequences and directs ribosome-mRNA complexes to the ER membrane.
What is a protein translocator?
A membrane-embedded channel through which proteins are threaded during translocation.
What is a stop-transfer sequence?
A hydrophobic region that halts translocation and anchors the protein in the membrane.
What is a start-transfer sequence?
A signal within the protein that starts its insertion into a membrane via the translocator.
What are transport vesicles?
Small, membrane-bound sacs that move proteins and lipids between compartments.
What is endocytosis?
The process by which cells internalize molecules by engulfing them in a vesicle.
What is exocytosis?
The process of vesicles fusing with the plasma membrane to release contents outside the cell.
What is adaptin?
A protein that links clathrin to cargo receptors during vesicle formation.
What is clathrin?
A protein that forms a triskelion shape and assembles into a lattice on vesicles.
What is Rab?
A small GTPase that directs vesicle targeting to specific membranes.
What are v-SNAREs?
Vesicle-associated membrane proteins that mediate vesicle fusion.
What are t-SNAREs?
Target membrane SNAREs that pair with v-SNAREs to mediate vesicle fusion.
What is glycosylation?
The enzymatic process of adding sugar chains (oligosaccharides) to proteins or lipids.
What are chaperones?
Proteins that assist in the proper folding of other proteins and prevent misfolding or aggregation.
What is receptor-mediated endocytosis?
A form of endocytosis in which cells absorb metabolites, hormones, or proteins via the inward budding of the plasma membrane involving receptors.
What is an endosome?
Membrane-bound compartments involved in sorting endocytosed material.
What are endocrine signals?
Molecules that carry signals between cells in the body.
What is neuronal signaling?
Cell signaling over long distances using hormones released into the bloodstream.
What is contact-dependent signaling?
Signaling that requires direct cell-to-cell contact via membrane-bound molecules.
What is the stage of cell signaling where a signal molecule binds to a receptor?
The stage of cell signaling where a signal molecule binds to a receptor.
What is transduction?
The process of converting the signal into a form that can bring about a cellular response.
What is response in cell signaling?
The final stage of cell signaling where the cell performs a specific action.
What are intracellular receptors?
Receptors located inside the cell that bind small, hydrophobic signal molecules.
What are cell-surface receptors?
Receptors embedded in the plasma membrane that bind external ligands.
What is steroid hormone signaling?
Involves small hydrophobic hormones crossing the membrane and binding intracellular receptors.
What are nuclear hormone receptors?
A class of intracellular receptors that act as transcription factors when bound by ligand.
What is nuclear translocation?
The movement of proteins like transcription factors or receptors into the nucleus.
What are ion-channel-coupled receptors?
Receptors that open or close ion channels in response to ligand binding.
What are G-protein coupled receptors (GPCRs)?
A large class of cell-surface receptors that activate intracellular G-proteins upon ligand binding.
What are enzyme-coupled receptors?
Receptors that activate enzymatic activity upon ligand binding, often involving dimerization.
What is guanylyl cyclase?
An enzyme that catalyzes the conversion of GTP to cyclic GMP (cGMP), a second messenger.
What are second messengers?
Small molecules that amplify and distribute signals within the cell.
What is a signaling transduction cascade?
A series of molecular events initiated by a signal that leads to a cellular response.
What is cAMP?
Cyclic adenosine monophosphate, a second messenger derived from ATP.
What is adenylyl cyclase?
An enzyme that converts ATP to cAMP in response to GPCR activation.
What is a phosphorylation cascade?
A series of protein kinases that sequentially phosphorylate one another.
What are receptor tyrosine kinases?
Transmembrane receptors that dimerize and autophosphorylate upon ligand binding.
What is MAP kinase?
A small kinase that acts as a molecular switch in signaling.
What is the Notch signaling pathway?
A contact-dependent signaling pathway that regulates cell fate decisions.
