Cell membrane, cell transport

Cell membrane functions

Cell membrane functions

protects cell from surroundings, internal doesn’t equal external environment, controls what goes in and out

Components of the cell membrane

phospholipids, cholesterol, integral proteins, peripheral proteins, glycoproteins, carrier proteins

Fluid mosaic model

Made of lipids and proteins that move around; the cell membrane is a mosaic of proteins bobbing in a fluid layer of phospholipids

Amphiphilic

the cell is hydrophobic and hydrophilic

What does cholesterol do

stabilizes the cell membrane

Saturated fatty acid

decrease fluidity of cell membrane because they’re solid at room temp

Unsaturated fatty acid

increase fluidity because they’re liquid at room temp

Peripheral protein

located on the outside of the cell membrane, polar

Integral protein

middle is nonpolar, surface is polar; only integral transports; channel and carrier proteins

Carrier proteins

allow certain molecules to pass through; help pump things against their concentration gradient; used for large and charged

Channel protein

allows for large and charged molecules to pass through; no energy required and goes with concentration gradient

cell membrane protein functions (both)

cell structure, enzymes, cell recognition, cell signaling, junctions, anchor cell

What can enter and exit through the bilayer

small and uncharged molecules

What can enter and exit through channel proteins

large and charged/polar molecules

Diffusion

transfer of materials from high to low concentration; no energy

Facilitated diffusion

diffusion of molecules that require a transport protein; passive transport that doesn’t require energy; glucose and amino acids

Simple vs facilitated diffusion

simple is small, nonpolar through bilayer; facilitated requires a transport protein for large, polar; both go from high to low concentration and no energy required

Active transport

movement from low to high conc that requires energy

Sodium potassium pump

3 sodium is pumped out of the cell from low to high with ATP, 2 potassium is pumped into the cell from low to high when phosphate is removed; electrochemical gradient is created which can be used for energy (outside is pos, inside is neg)

Bulk transport

active transport bringing in large, polar molecules; endocytosis (phagocytosis, pinocytosis, receptor mediated endocytosis) and exocytosis

Endocytosis

brings large molecules in (proteins, polysaccharides) and requires energy

Phagocytosis

a portion of the cell membrane engulfs the molecule and brings it in; bringing in a large, solid molecule (protein, polysaccharide, bacteria)

Pinocytosis

takes in a large amount of fluid

Receptor mediated endocytosis

protein on the virus will bind to a receptor on the host cell, cell membrane will fuse w/the virus, bringing it into the cell

Exocytosis

transport vesicle fuses with cell membrane resulting in the release of the substance; requires energy

Glycoproteins

found on the cell membrane and the blood; function as receptors for chemical signaling; help in blood typing; cell to cell recognition

Glycolipids

found on the cell membrane; facilitate cellular recognition; when tagged inappropriately, they cause autoimmune diseases

Hypertonic

higher salt concentration (solute), less solvent

Hypotonic

lower salt concentration (solute), more solvent

Isotonic

equal solute and solvent

Plasmolysis

cell shrinks due to a loss of water from being in a hypertonic solution

Cytolysis

a cell bursts because of excess water entering from being in a hypotonic solution

Uniport transport protein

transports one solute molecule with its concentration gradient; glucose transporter

Symport transport protein

transports 2 different solute molecules in the same direction; sodium-glucose transport

Antiport transport protein

transports 2 different solutes in opposite directions; sodium potassium pump

Primary active transport

uses energy, ATP, and can create an electrochemical gradient

Secondary active transport

using the electrochemical gradient to move the solutes from low to high (sodium glucose transport)

Sodium glucose pump

the electrochemical gradient created from the sodium-potassium pump is used to pump the sodium and glucose back into the cell against their concentration gradient; symporter;

Sucrose/H+ cotransporter

Using energy from ATP, proton pump, pumps protons out of the cell (low to high ), creating an electrochemical gradient. The H+/sucrose transporter moves sucrose into the cell (low to high) using energy from electrochemical gradient powered by the proton pump as protons travel back into the cell from high to low conc.

Cystic Fibrosis Transmembrane Conductance Regulator (CFTR)

channel allowing chloride ions to exit the cell into mucus, maintains balance of salt & water

How does cystic fibrosis change CFTR

the channel has an incorrect shape so chloride ions can’t exit the cell

ENac (epithelial sodium channel) and how it’s affected

allows sodium to enter the cell; mutant CFTR makes ENac more efficient which leads to build up of sodium in the cell, making it hypertonic

What does cystic fibrosis cause

mucus becomes dry because of the hypertonic cell and water is sucked out of the mucus instead of the opposite