Lecture 9: Membrane Structure, Transport and Communication

Flashcards for Lecture 9: Membrane Structure, Transport and Communication

Selective Permeability

The ability of the plasma membrane to allow certain molecules to pass through while restricting others.

Fluid Mosaic Model

A model of the plasma membrane that describes it as a dynamic structure with various components, including lipids, proteins, and carbohydrates.

Phospholipids

Lipids with a polar head and two nonpolar tails, forming the basic structure of the plasma membrane.

Hydrophilic Head

The region of a phospholipid that is attracted to water and faces the aqueous environment.

Hydrophobic Tail

The region of a phospholipid that repels water and faces the interior of the membrane.

Amphipathic Molecule

A molecule with both hydrophilic and hydrophobic regions.

Fluid Mosaic

Lipid membranes with lots of lipids, proteins and also some carbohydrates decorating their surface and that their behavior is also subject to environmental conditions.

Integral Membrane Proteins

Proteins that are embedded in the lipid bilayer.

Peripheral Proteins

Proteins that are not embedded in the lipid bilayer; they are loosely bound to the surface of the membrane.

Glycoprotein

A protein with one or more covalently attached carbohydrates.

Glycolipid

A lipid with one or more covalently attached carbohydrates.

Gases Permeability

Molecules, such as carbon dioxide, nitrogen gas, and oxygen gas, that can easily pass through the membrane due to their nonpolar nature.

Sugar Permeability

A molecule that requires a protein channel or transporter in order to cross the plasma membrane.

Ions Permeability

Ions are very difficult to pass through plasma membrane.

Passive Transport

The movement of molecules across a membrane without the need for energy input.

Active Transport

The movement of molecules across a membrane with the input of energy.

Channels

Transport proteins that do not require energy.

Carriers/Transporters

Transport proteins that may or may not require energy.

Pumps

Transport proteins that require energy.

Diffusion

The movement of a substance down its concentration gradient, from an area of high concentration to an area of low concentration.

Simple Diffusion

Diffusion that does not require the assistance of membrane proteins.

Facilitated Diffusion

Diffusion that requires the assistance of membrane proteins.

Electrochemical Gradient

The combined effect of the concentration gradient.

Aquaporin

A channel protein that allows water molecules to move in and out of a cell.

Active Transport

The movement of molecules against their concentration gradient, from an area of low concentration to an area of high concentration.

Sodium-Potassium Pump

A pump that transports sodium ions out of the cell and potassium ions into the cell.

Electrogenic Pump

A pump that generates voltage across a membrane.

Proton Pump

A pump that actively moves protons into a compartment.

Co-transport

The transport of two substances across a membrane at the same time.

Secondary Active Transport

A form of transport in which one substance moves down its concentration gradient.

Uniport

A transporter that moves a single substance across a membrane.

Antiport & Symport

Secondary transport is when you're moving two things.

Exocytosis

The process by which cells release substances to the extracellular environment through the fusion of vesicles with the plasma membrane.

Endocytosis

The process by which cells take in substances from the extracellular environment through the formation of vesicles.

Junction Proteins

Proteins that help keep cells together in the context of a tissue and also allow them to control movement between the cells.

Tissues

Groups of similar or identical cells that are stuck together.

Tight Junctions

Junction proteins that help sort of zip together the plasma membranes of adjacent cells in animals and they often will form watertight seals.

Desmosomes

Structures that made of multiple different proteins. They help connect layers of tissues.

Gap Junctions

Cell junction that actually allows communication between the plasma membranes of these cells, but it's restricted because it's a very, very small space.

Plasmodesmata

The one that is specifically reserved for plant cells, which kind of resembles a gap junction without the actual gap.

Cadherins

These are transmembrane proteins that reach out and form like molecular Velcro in the extracellular matrix.

Long Distance Signaling

Occurs when signals are secreted and travel throughout the body to reach target cells.

Local Signaling

Signaling that involves direct contact between neighboring cells.

Cell Signaling

The process by which a cell receives and responds to signals from its environment.

Ligand

A relay proteins or chemical that bind to receptors.

Signal Transduction

The process by which a cell converts one kind of signal or stimulus into another.

G Protein-Coupled Receptor (GPCR)

A type of membrane receptor that works with the help of a G protein.

G Protein

A signaling protein that binds to and utilizes GTP.

Activator Complex

GTP gets the signal from the receptor to get a cellular response.

Ligand-Gated Ion Channel

A type of membrane receptor that contains a region that can act as a gate when the receptor changes shape.

Hydrophobic Chemical Messengers

Chemical messengers are friendly with the hydrophobic layer of the the plasma membrane and can go right across.

Lipid Soluble

Hormones that are derived from lipids are soluble in a membrane.

Lipid Insoluble

Hormones, the water loving ones that are hydrophilic, are insoluble in lipid.

Signal Transduction Cascade

Amplification signals like a waterfall as it goes through the cytoplasm.

Phosphorylation Cascade

A cascade of events that involves the addition and removal of phosphate groups from proteins.

Kinase

An enzyme that adds a phosphate group to a protein.

Phosphatase

An enzyme that removes a phosphate group from a protein.

Transcription Factor

A protein that binds to DNA and regulates gene expression.

Cellular Response

A cellular event that is triggered by a signal.

Homeostasis

A state of equilibrium in the internal environment of the body.

Cytosol Face

The part of the plasma membrane that faces the cytoplasm.

Extracellular Matrix Face

The part of the plasma membrane that faces the extracelluar matrix.

Transmembrane Proteins

Proteins that are integrated into the membrane are also often called transmembrane proteins because they span across the membrane.

ATP Utilization

This pump utilizes the energy from ATP to power movement to move sodium ions outside of the cell.

Ions Movement

Transporters are very specifically trying to move ions so that they can maintain an electrical potential across the membrane.

Membrane Permeability

These transport proteins are going to affect membrane permeability, what can come in and out of a cell.

Cytosol Facing Membrane Proteins

Membrane proteins that are inside of the the leaflet that's facing the cytosol because they tend to be able to move around.

Lipid Rafts

Proteins that might impart some kind of function to that region of the plasma membrane.

Cholesterol

Helps keep the fluidity up of the membrane, but also maintain its integrity and can be used sometimes as a signaling molecule.

Glycoproteins Functionality

Helps a cell identify itself to the surrounding tissues and other proteins and chaperones and things on the outside.

Transmembrane Proteins Functionality

These are really important for helping keep the cells in the context of their tissues.

Electrogenic Pump Functionality

Manipulates, it moves electrons or moves moves. It moves electrically charged charged ions.

Cotransport Functionality

A process of transporting two things at once.

Desmosomes Functionality

They help connect those to the actual rest of the tissue.

Integrin Functionality

It helps integrate cells into tissues, but it also contributes the integrity of the tissues.

Cadherins Functionality

These are transmembrane proteins that reach out and form like molecular Velcro in the extracellular matrix.

Channels Functionality

These tend in some, some cases channel, most cases channels don't use any energy at all. This is all passive.

Carrier Proteins Functionality

Cause them to change their confirmation and that change in confirmation causes them to move that thing to the other side of the membrane.

Tight Junctions Functionality

These help sort of zip together the plasma membranes of adjacent cells in animals and they often will form watertight seals.

Sodium Potassium Pump Functionality

You end up charging the membrane by making it everything more positive outside the cell and a little bit more negative on the inside.

Co-Transport Functionality

A way of transporting two things at once. It's called Co transport, and you're going to see in a second it's also called secondary active transport.

Gap Junctions Functionality

They form these sort of 12 subunit little pores where you can actually send things across through the plasma membranes from the cytosol of one to the other.

Plasmodesmata Functionality

These are set up very early as plant cells divide because as the cell walls form between new plants, you have to put sort of hold a finger in the gap to make sure that the cell wall doesn't close all the way.

Adrenaline Functionality

Causes it to buck up and not die or run away and fight another day, whatever it is your adrenaline drives you to do.

Neuron Communication

One neuron releases a neurotransmitter onto the next one and the next cell does something.

Integrin

A transmembrane protein that reaches into the cell and grabbing the cytoskeleton and reaching out of the cell and grabbing the ECM.

Sugars on the Surface Functionality

They may attract signaling molecules and they can act as signaling molecules themselves.

Diffusion Functionality

The movement of molecule from a space to another, generally down the concentration gradient.

Receptor Protein Use

Proteins on the surface of the cell can act as a receptor or receiver of an outside ligand or signal that causes it to convert that message across the membrane into information that the cell needs to change its function or behavior.

Hydro Anthropathic Molecule

The nature of any hydro anthropathic molecule where it's got sort of a polar configuration, one side likes water and one side doesn't.

Six Major Functions of Membrane Proteins

Proteins that are not necessarily involved in transport, but may be involved in communication or helping hold the cells together in the context of a tissue.

Rhodopsin

That protein in the rods of your eye helps you sense changes in light while you were in the dark.

Cellular Response Steps

Something downstream or after this is going to be affected.

Transport proteins

Helps with the movement of things across the membrane that have chemical qualities that the membrane inside doesn't like

Aquaporins

The process by which water molecules move in and out of a cell.

Peripheral Membrane Protein

Protein that has the ability to attach and detach from the cell membrane.

Response Pathways

The result of cells responding to stress in the environment

Down Gradient Trend

Molecules tend to move from an area of high concentration to an area of low concentration to bring the whole group equilibrium.

Shape Changes

Carriers use subtle changes that they undergo in shape about the chemical relationships

Channel and Pump Assistance

Transporters, channels and pumps help set this up