Structure and Function of the Cell Membrane

Flashcards covering the anatomical timeline, eye disease prevalence, cellular organelle nomenclature, and the biochemical principles of membrane structure and transport based on the lecture transcript.

Age-related Macular Degeneration

An eye disease with a prevalence of 2.1 Million.

Glaucoma

An eye disease with a prevalence of 2.7 Million.

Diabetic Retinopathy

An eye disease with a prevalence of 7.7 Million.

Cataract

An eye disease with a prevalence of 24 Million.

Centrosome

An organelle consisting of the pericentriolar area and centrioles.

Cytoplasm

The cytosol plus organelles, excluding the nucleus.

Fluid mosaic model

A model describing the membrane structure as a "sea of lipids in which proteins float like icebergs," where the membrane is 50% lipid and 50% protein.

Plasma membrane

A thin, $8\,nm$ ($8 \times 10^{-9}$ metre) flexible and sturdy barrier surrounding the cytoplasm of a cell.

Amphipathic

A molecule that has both a polar (hydrophilic) region and a nonpolar (hydrophobic) region, such as a phospholipid.

Phospholipids

Lipids that comprise 75% of the membrane lipids, forming a bilayer with two parallel layers of molecules.

Membrane Fluidity

The ability of lipids to move within the plane of the membrane leaflet, determined by lipid tail length, number of double bonds, and amount of cholesterol.

Integral proteins

Amphipathic transmembrane proteins that extend into or completely across the cell membrane, often featuring hydrophobic regions of non-polar amino acids coiled into helices.

Peripheral proteins

Proteins attached to either the inner or outer surface of the cell membrane that are easily removed from it.

Selective permeability

The property of the membrane that allows some substances to cross while excluding others; it is permeable to nonpolar uncharged molecules like $O_2$ and $CO_2$, but impermeable to ions like $Na^+$ and $K^+$.

Diffusion

The random mixing of particles in a solution as a result of their kinetic energy, moving from an area of high concentration to an area of low concentration.

Concentration gradient

A difference in concentration across the membrane that governs the diffusion of non-charged molecules.

Electrical gradient

Also known as membrane potential, it is an influence on the movement of ions created by the difference in charged ions between the inside and outside of the membrane.

Electrochemical gradient

The combined influence of the concentration gradient and the electrical gradient on the movement of ions.

Capacitor

An analogy for cell membranes because they can separate and store charge.

Cytoplasmic ion concentrations

Specifically characterized by high $K^+$ and low $Na^+$ and $Cl^-$ levels.

Extracellular ion concentrations

Specifically characterized by high $Na^+$ and $Cl^-$ and low $K^+$ levels.

Osmosis

The net movement of water through a selectively permeable membrane from an area of high water concentration to an area of lower water concentration.

Osmotic pressure

The pressure applied to a solution to prevent the inward flow of water across a semi-permeable membrane.