Please enable JavaScript.
Coggle requires JavaScript to display documents.
chapter 7(membrane structure and function) - Coggle Diagram
chapter 7(membrane structure and function)
Passive transport
the, no-energy-required movement of molecules across a cell membrane from areas of higher to lower concentration (down the gradient)
No atp required
Passive transport
Movement of substance from height to low
Active transport
moves molecules against their concentration gradient (from low to high concentration) using cellular energy (ATP) and specific membrane proteins
Requires atp
Movement of substances from low to high against the gradient
Cellular membrane
provides protection for a cell
Filled with fluid mosaics of lipids and proteins
Lipids and proteins are the main components of membranes, but carbohydrates are also important
*Semipermeable
Glycopids
essential lipids containing carbohydrate chains attached to a ceramide or glycerol backbone
Carbohydrontes
Used as identifying materials
essential macronutrients—composed of carbon, hydrogen, and oxygen—that act as the body's primary fuel source, breaking down into glucose for energy
Cholesterol
Used to control fluidity
a waxy, fat-like substance (lipid) produced by the liver and found in all body cells, essential for forming cell membranes, vitamin D, and hormones
Phospholipids
amphipathic molecules, containing hydrophobic (“water-fearing”) and hydrophilic (“water-loving”) regions
phosphatidylcholine (most common, found in lecithin), phosphatidylethanolamine, phosphatidylserine (neuron protection), phosphatidylinositol (cell signaling), and sphingomyelin (myelin sheath component
fluid mosaic model
membrane structure depicts the membrane as a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids
the plasma membrane of animal cells
Cholesterol
a membrane component in animal cells that has variable effects on membrane fluidity at different temperatures
At warm temperatures (such as 37ºC), cholesterol restrains movement of phospholipids
–At cool temperatures, it maintains fluidity by preventing tight packing
membrane
a collage of different proteins, often clustered in groups, embedded in the fluid matrix of the lipid bilayer
structure resembles a tile mosaic
Membrane proteins
functional components of cell membranes (integral or peripheral) that regulate transport, signal transduction, and structural integrity
Integral proteins
penetrate the hydrophobic core
Peripheral proteins
bound to the surface of the membrane
Transmembrane proteins
integral proteins that span the membrane
Cell surface proteins
proteins located on the outer plasma membrane, constituting roughly 30% of human proteins and serving as the interface for cell-environment communication
important in medicine
–For example, HIV enters immune cells by binding to cell-surface protein CD4 and a “co-receptor” CCR5
–Individuals lacking CCR5 are immune to HIV infection
Cell surface membranes
thin, flexible, semipermeable barriers that surround all living cells, separating their contents from the external environment
Transport
moves substances across the cell membrane via passive transport (no energy, high-to-low concentration) or active transport (energy/ATP, low-to-high concentration)
–Enzymatic activity
the rate at which enzymes, as biological catalysts, speed up chemical reactions by lowering activation energy
–Signal transduction
the vital process by which cells convert extracellular signals (hormones, neurotransmitters) into specific, functional intracellular responses, such as growth, division, or metabolism
–Cell-cell recognition
the biological process where cells identify, interact, and communicate with each other or foreign materials using specific molecular markers, primarily glycoproteins and glycolipids on the cell surface
–Intercellular joining
specialized structures that link adjacent cells to maintain tissue structural integrity, enable communication, and regulate transport
–Attachment to the cytoskeleton and extracellular matrix (ECM)
occurs primarily through transmembrane proteins, mainly integrins, which form physical links between extracellular matrix components (like collagen, fibronectin) and intracellular actin filaments
Diffusion
the movement of particles of any substance so that they spread out evenly into the available space
Although each molecule moves randomly, diffusion of a population of molecules may be directional
•At dynamic equilibrium, as many molecules cross the membrane in one direction as in the other
concentration gradient,
the region along which the density of a chemical substance increases or decreases
Each substance moves down its own concentration gradient, unaffected by the concentrations of other substances
Osmosis
the diffusion of free water (water molecules not clustered around another substance) across a selectively permeable membrane
Free water molecules diffuse across a membrane from the region of lower solute concentration to the region of higher solute concentration
Tonicity
the ability of a surrounding solution to cause a cell to gain or lose water
Tonicity depends on the concentration of solutes in the solution that cannot cross the membrane, relative to that inside the cell
isotonic
A solution is isotonic if its solute concentration is the same as that inside the cell
Hyper tonic
A solution is hypertonic if the solute concentration is greater than that inside the cell
Ampipathic Polar
Containing hydrophilic and hydrophobic non polar
a phospholipid
Osmoregulation
Control of solute concentration and water balance
