Eukaryotic Membranes

Vocabulary flashcards covering key terms related to cell membranes, transport, and organelles.

Plasma Membrane

Cell boundary; selectively permeable; compartmentalizes; involved in transport, signal transduction, and intercellular junctions.

Amphipathic

Having both hydrophobic and hydrophilic regions (referring to phospholipids in the bilayer).

Diffusion

Movement of substances down their concentration gradient (e.g., gases, nonpolar molecules, small polar molecules).

Facilitated Diffusion

Movement of large and/or polar molecules down their concentration gradient via channel or carrier proteins.

Osmosis

Movement of water across a selectively permeable membrane to a region of higher solute concentration.

Active Transport

Movement of substances against their concentration gradient; requires energy (ATP).

Aquaporins

Channel proteins that facilitate the rapid movement of water across cell membranes.

Channel Proteins

forms hydrophilic channels through phospholipid by layers for solutes

Carrier Proteins

subtle shape changes for translocation across membrane

Co-transport

Active transport of one solute indirectly drives the transport of another substance.

Sodium-Potassium Pump

Example of active transport; uses ATP to move sodium and potassium ions across the cell membrane.

Endoplasmic Reticulum (ER)

½ all cellular membranes

Golgi Apparatus

The cellular warehouse which is responsible for carbohydrate and phospholipid modifications, polysaccharide synthesis, folded proteins forming endoplasmic reticulum.

structured containing flat main membrane sacks, cisternae

SER

smooth, responsible for lipid and steroid synthesis, and carbohydrate metabolism. Muscle CA2+ regulation.

RER

rough, ribosome rich, secreted via insulin and B cells, transport vesicles, protein folding i.e. cisternae, disulphide bridges. ER stress such as redox reactions cause more unfolding

Golgi Transport

consecutive secretary relies on no stimulation, i.e. antibodies

regulated secretary requires stimulation i.e neurotransmitters and insulin

Lysosomes

Digestive organelles containing hydrolytic enzymes; involved in phagocytosis and autophagy.

Mitochondria

organelles containing their own DNA

- responsible for oxidative phosphorylation, Krebs cycle, apoptosis, mutations in mtDNA, and a constant flux state and form reticular for dynamic movement

oxidative phosphorylation

NADH → protein complex complexes = a gradient (+protons to -matrix)

Sarcoplasmic Reticulum

Stores Ca2+ pumps when muscle fibres are stimulated

Endocytosis

Process by which cells take in substances from outside by engulfing them in a vesicle.

mitochondria matrix

containing fluid, DNA, ribosomes and enzymes

mitochondria cristae

responsible for folding; creating a larger surface area, easier for more ATP synthesis i.e. in the liver

Phagocytosis

A type of endocytosis in which a cell engulfs large particles or whole cells.

Receptor-mediated endocytosis

A type of endocytosis in which specific molecules bind to receptors on the cell surface, triggering invagination and vesicle formation. Ligand binds

Exocytosis

Process by which cells release substances to the outside by fusion of vesicles with the plasma membrane from golgi

Nucleus

Control center of the cell, contains DNA organized as chromatin, surrounded by a double-membrane nuclear envelope with pores. Nucleolus for RNA synthesis and Chromatin for DNA coding

Ribosomes

Sites of protein synthesis; can be free in the cytosol or bound to the endoplasmic reticulum.

Translation vs Transcription

Transcription = DNA → RNA

Translation = mRNA → protein.