Structure and Function of Endoplasmic Reticulum

These flashcards cover key vocabulary terms related to the structure and function of the Endoplasmic Reticulum, including its various roles in cellular processes.

Endoplasmic Reticulum (ER)

A structure consisting of flattened vesicles and branched channels extending in the cytoplasm, crucial for lipid and protein biosynthesis.

Rough Endoplasmic Reticulum (RER)

A type of ER with ribosomes on its membranes, involved in protein synthesis, modifications, and transport.

Smooth Endoplasmic Reticulum (SER)

A type of ER without ribosomes, involved in lipid biosynthesis and various metabolic processes.

Co-translational Translocation

The process where proteins are imported into the ER before the complete synthesis of the polypeptide chain.

Post-translational Translocation

The import of proteins into organelles after full synthesis of the polypeptide chain.

Signal Hypothesis

Secretory proteins have a signal sequence that directs them to the ER.

Disulfide Bonds

Covalent bonds formed between cysteine amino acids, important for protein folding and stability.

Glycosylation

The process of adding oligosaccharides to proteins, which aids in proper folding and stability.

Molecular Chaperones

Proteins that assist in the proper folding of other proteins.

N-linked Glycosylation

A type of glycosylation where oligosaccharides are attached to nitrogen atoms in asparagine residues.

Calnexin

A chaperone protein that helps in the folding of glycoproteins in the ER.

ER Stress

A condition arising from the accumulation of improperly folded proteins in the ER, leading to cell dysfunction.

Unfolded Protein Response (UPR)

A cellular response to ER stress that aims to restore normal function by enhancing the folding capacity.

ER-associated degradation (ERAD)

The process of transporting misfolded proteins to the cytosol for degradation.

Proteotoxicity

Cellular toxicity caused by the accumulation of misfolded or unfolded proteins.

Calcium Storage in ER

The ER lumen serves as a storage site for intracellular calcium ions, playing a role in various cellular signaling.

Lipids

Molecules that are hydrophobic and include fats, oils, and cholesterol, synthesized in the ER.

Protein Modifications

Post-synthesis changes to proteins including folding, formation of disulfide bonds, and glycosylation.

Intracellular Signaling

Communication within a cell that uses molecules like calcium to regulate processes including gene expression.

Chaperone Families (hsp60, hsp70)

Groups of heat shock proteins that assist in the folding and stabilization of other proteins.

Protein Synthesis

The process in which cells build proteins based on information from genes.

Biosynthesis of Steroid Hormones

The process occurring in the SER that converts cholesterol into steroid hormones.

Transport Vesicles

Small membrane-bound compartments that transport proteins from the ER to other organelles.

Polypeptide Chain

A chain of amino acids linked by peptide bonds, representing a protein's primary structure.

Cholesterol

A type of lipid important for membrane structure and function, synthesized in the ER.

Acyl-CoA Synthetase

An enzyme that catalyzes the conversion of fatty acids into fatty acyl-CoA, involved in lipid synthesis.

Ubiquitin

A small protein that tags misfolded proteins for degradation in proteasomes.

Cell Proliferation

The process by which cells reproduce and divide, often regulated by cellular signaling mechanisms.

Lipid Biosynthesis

The formation of lipids from acetyl-CoA and other substrates, occurring primarily in the SER.

Protein Trafficking

The process by which proteins are transported to their final locations within the cell.

Oxidation Reaction

A chemical reaction involving the transfer of electrons, significant for forming disulfide bonds in proteins.

Heat Shock Proteins (HSP)

A family of proteins that help prevent misfolding and assist in the renaturation of denatured proteins.

Gene Expression

The process by which information from a gene is used to synthesize proteins.

Cell Death

A process that can be triggered by severe or chronic ER stress, leading to cell injury.

ER to Golgi Transport

The transport of proteins from the ER to the Golgi apparatus for further processing.

Hypoxia

A condition characterized by a deficiency in the amount of oxygen reaching the tissues, can cause ER stress.

Glucosidase

An enzyme that removes glucose residues from glycoproteins in the ER as part of the folding process.

Transmembrane Proteins

Proteins that span the membrane, involved in signaling and transport functions.

Cisternae

Stacked membrane-bound structures in the ER, involved in protein synthesis and modification.

Eukaryotic Cells

Cells that have a nucleus enclosed within membranes, including animal and plant cells.

Cytoplasm

The gel-like substance within a cell, excluding the nucleus, where organelles are suspended.

Protein Folding

The process by which a protein assumes its functional shape or conformation.

Lysosome

An organelle that contains digestive enzymes to break down waste materials in the cell.

Peroxisome

An organelle that contains enzymes for detoxifying harmful substances.

Vesicles

Small membrane-bound sacs within cells that transport materials to different locations.

Plasma Membrane

The outer boundary of a cell that regulates what enters and exits the cell.

Nucleus

The membrane-bound organelle that contains the cell's genetic material.

Golgi Apparatus

An organelle that modifies, sorts, and packages proteins for secretion or delivery to other organelles.

Chaperone Synthesis

The production of chaperone proteins, especially during stress conditions.

Glycoprotein

A protein that has carbohydrate groups attached to the polypeptide chain.

Oligosaccharide

A carbohydrate consisting of a small number of sugar molecules, often attached to proteins.

Signal Sequence

A short peptide present at the beginning of a protein that directs it to the ER.

Chaperone Recognition

The ability of chaperones to identify and bind misfolded proteins.

Misfolded Proteins

Proteins that do not fold into their correct three-dimensional shapes, leading to dysfunction.

Gene Regulation

The process of turning genes on and off to control the production of proteins.

Cell-cell Adhesion

The process by which cells interact and attach to neighboring cells through glycoproteins.

Nuclear Pore

A protein complex that spans the nuclear envelope, allowing transport of molecules in and out of the nucleus.

Extracellular Matrix

A network of proteins and other molecules outside of cells, providing structural and biochemical support.

Stress Factors

Environmental conditions, such as temperature or availability of nutrients, that can induce cellular stress.

Membrane System

The interconnected network of membranes within cells, including ER, Golgi, and plasma membranes.

Cellular Lipids

Lipids that are synthesized and metabolized within cells for energy storage and membrane structure.

Phosphatidylcholine

A major component of cell membranes that is synthesized in the ER.

Acyltransferase

An enzyme that transfers acyl groups to other molecules, playing a role in lipid metabolism.

Lipid Transport

The movement of lipids across cellular membranes, especially important in certain tissues.

Calcium Channels

Proteins that form pores in the ER membrane, allowing calcium ions to flow in and out.

Ca2+ ATPase

An enzyme that pumps calcium ions against their gradient, important for muscle function.

Nuclear Envelope

The double membrane that encloses the nucleus and separates it from the cytoplasm.

Cell Membrane

The semipermeable barrier surrounding the cell, composed of phospholipids and proteins.

Receptor Proteins

Proteins on cell surfaces that bind to specific molecules, triggering cellular responses.

Transport Proteins

Proteins that assist in the movement of substances across cell membranes.

Gene Expression Regulation

The control of the timing and amount of protein production in cells.

Biochemical Pathways

Series of chemical reactions occurring within a cell that lead to the synthesis and breakdown of biomolecules.

Pancreatic Cells

Cells in the pancreas, specialized for producing digestive enzymes.

Lipid-soluble Agents

Substances that can easily pass through lipid membranes, often requiring specific transport mechanisms.