CAPE Bio (P1) - Membrane Structure and Function

fluid mosaic membrane

a description of the dynamic within the cell membrane in which a phospholipid bilayer is composed of a mixture of different proteins and lipids in which proteins are embedded within a layer of lipids with both substances moving freely within the bilayer

transmembrane protein

those which are embedded into the bilayer and protrude on both sides

channel proteins

transmembrane proteins with a hydrophobic exterior and hydrophilic interior which create a tunnel for polar molecules to travel through

carrier proteins

transmembrane proteins which bind to specific molecules and change their shape as a mechanism of transporting the molecule throughout its structure

glycoproteins

transmembrane proteins that possess a short carbohydrate chain that extends significantly past the outer surface of the cell that recoginizes hormones, wards off pathogens and signals to other cells

glycolipids

lipids that carry out the same role as glycoproteins but possess a singular sugar chain that extends minimally pas the outer surface of the cell

passive transport

instance in which the concentration gradient determines the direction of the net movement of solutes

diffusion

type of passive transport in which molecules and ions move from a region of high concentration to low concentration until evenly distributed

simple diffusion

the instance in which molecules directly move across a membrane

facilitated diffusion

the instance in which ions and polar molecule pass through the membrane with aid from channel or carrier proteins embedded in the lipid bilayer

membrane potential

the difference in the electrical charge inside and outside of a cell

electrochemical gradient

the combination of the concentration gradient of a charged substance and the membrane potential

osmosis

type of passive transport in which water molecules move through a selectively permeable membrane from a region of high concentration to a region of low concentration until evenly distributed

osmotic pressure

the pressure necessary to prevent the movement of water across a selectively permeably membrane through which its solute is not permitted

water potential

potential energy of water

lysis

instance in which animal cells swell and burst due to the intake of water

crenation

instance in which animal cells shrivel due to the loss of water

turgor pressure

the internal hydrostatic pressure in the plant that develops as a result of osmosis in the cell, acting against the cell wall to keep the plant cell turgid

plasmolysis

instance in which the protoplast of a plant cell contracts due to the loss of water

wilting

instance in which non-woody parts of plant lose their rigidity due to loss of water

active transport

instance in which substances are transported across a membrane against a concentration or electrochemical gradient

primary active transport

instance in which cations are transported against their concentration gradients via membrane-bound pumps with the use fof ATP

proton pump

membrane-bound pump composed of protons and an ATPase molecule which usually powers secondary active transport

secondary active transport

the instance in which non-cations are transported against their concentration gradient via the electrochemical gradient created from primary active transport, often proton pumps, without direct use of ATP

bulk transport

the instance in which large quantities of substances are moved across cell membranes against their concentration gradient

exocytosis

the process in which particulate matter or dissolved substances are enclosed in a vesicle and transported to the cell surface as the membrane of the vesicle fuses with the plasma membrane and expels the vesicle’s contents

endocytosis

the process in which particulate matter or substance are taken up by the cell in bulk forming a pocket that encloses the substance and forms a vesicle

phagocytosis

type of endocytosis in which the plasma membrane invaginates and engulfs large particles in a vesicle

pinocytosis

type of endocytosis in which cells rapidly acquire fluids from the blood as tiny vesicle form in the plasma membrane which bring small dissolved substances or fluid into the cell

receptor-mediated endocytosis

the instance in which animal cells capture specific macromolecules from the cell’s environment by aid of receptor proteins which bind to its specific macromolecule, forming a vesicle which migrates into the cytoplasm

coupled transport

type of secondary transport in which the gradients of two different solutes are dependent on each other and linked in a way that the movement of one causes or facilitates the movement of the other in/out of the cell