Chapter 5 Cell membrane and transportation

Plasma membrane

The selectively permeable barrier that encloses a cell and regulates the transportation of nutrients, water and waste.

Polar amino acids

Located in interior region of protein or

extend into extracellular fluid & into cytosol, (cytoplasm) They’re also found on the on the surface if the proteins interacting with the aqueous environment.

Non polar amino acids

They’re within the membrane. Specifically located on the proteins surface and interacts with fatty acids in interior membrane. They also anchors protein into membrane

Fluid mosaic structure

The plasma membrane is made up of phospholipid molecules that are embedded with proteins, steroids, glycoproteins and glycolipids that can flow around the surface of the cell.

• FMS and the bilayer arrangement results in the membranes semi-permeability. The hydrophobic interior allow some substances to cross easier than others.

Easy passage

Gasses, small non-polar molecules and small uncharged polar molecules, like water, can pass through the membrane easily.

Difficult passage

Large polar molecules, like glucose, and ions cannot pass through the membrane easily. They require embedded channels and transport proteins.

Integral proteins

Located through the bi-layer, from the outside of the cell to the inside. They function in the transport of molecules and, maintaining the structure.

Peripheral Proteins

They’re loosely bounded to one side of the membrane. Serving as sites for attachment of the cytoskeleton on the inside of the cell and the attachment of the ECM.

Cholesterol

Helps keep the cell membrane flexible, and the cell membrane of plants from freezing. They also reduce fluidity at moderate templates and hinders solidification at low temperatures.

Fluidity

Allows the membrane to change their shape and movement based off the environment and temperature. The tails are unsaturated and not packed tightly.

Viscous

A cell membrane resisted to flow. They’re saturated and tightly packed. High cholesterol levels increases the viscosity of a cell membrane.

Transport protein (Channel proteins)

Function by having hydrophobic channels that haves enzymes that help move food and water.  Some use ATP.

Enzymatic protein

Control metabolic processes by functioning at catalysts. It uses a active site.

Attachment proteins

Attachment points for the cytoskeleton and ECM. Stabilizing internal organelles and the cell.

Cell to cell recognition

Function is communication and recognition using carbohydrates, glycoproteins and glycolipids. Its useful in the immune system.

Intercellular Joining

Stitching cells together to make tissues. Its used in various types of junctions. 

Signal Receptors

Catching hormones or other materials, circulating in the blood. It uses a receptor site.

Diffusion

The movement of particles from areas of high concentrations to low concentrations. The goal is equilibrium.

Passive transport

Movement from high to low concentration without the use of ATP. It plays a primary role in the import and export of materials and waste.

Facilitated Diffusion

Diffusion with the help of transport proteins, without energy.

Osmosis

The transportation of large quantities of water with the use of a Aquaporin.

Aquaporin 

Specific channels that allow large quantities of water to pass through the membrane. 

Carrier proteins

Alternates between 2 shapes, moving a solute across the membrane in both directions. 

Concentration Gradient

Potential energy drives diffusion from low to high concentrations.

Active Transport

Molecular movement from low to high concentrations that require energy and uses a proton pomp. It helps transport charged and large polar molecules. 

Sodium Potassium pump

The pumping of 3 Sodium ions out the cell to insert 2 potassium ions into the cells. It requires energy from ATP by phosphorylation (attaching a phosphate ion to a structure to make it work) activating the protein to grab and move molecules. 

Membrane Potential

The voltage difference across a cell's plasma membrane, created by the unequal distribution of ions inside and outside the cell. Membranes may be polarized by the movement of ions across the membrane. 

• It gives the cell the ability to do work involving the transport of molecules. 

Voltage gradient

• Voltage gradient (difference in charge across the membranes) that works on positive and negative ions. 

The inside of the cell in negative and the outside is positive.

For charged ions a Voltage gradient is created so there’s potential to perform work. Forces in electrochemical gradients drive the diffusion of ions.

Electrogenic Pump

A protein that moves ions across a cell membrane, generating an electrical potential difference (voltage) across it. Its involved in the processes of the electron transportation chain of photosynthesis and cellular respiration. 

Co- transport

Active transport driven by a concentration gradient. Two substances move across a cell membrane together using a single protein carrier

• Protons (H+) act as a party invitation. 

• Very important in helping plant and animal cells be able to take up glucose and sucrose via active transport. 

Endocytosis

Moving materials into a cell

Exocytosis 

Moving materials out of a cell

Phagocytosis

The ingestion of materials. The food vacuole will be digested after fussed with lysosomes.

Receptor Mediated Endocytosis

A cellular process for selectively taking up specific molecules from outside the cell. It involves the binding of a ligand (the molecule) to a specific receptor on the cell's surface, which triggers the binding of the plasma membrane to form a vesicle containing the ligand and its receptor

Hypotonic

Less solute and more water in the cell. It usually bursts and its lysed.

Hypertonic

More solute, less water in a cell. Its typically shriveled.

Isotonic

Equal Solute and water

Water potential

Predicts the direction in which water will floor including factors like solute concentration and physical pressure. 

Toncity

The ability of a surrounding solution to cause a cell to gain or lose water based on the concentration of the solutes outside the cell compared to the inside. 

Pancrine

A type of local signaling, Cell-to cell contact here local messages travel; short distances to the target cell. 

Synaptic

Electric signals travels through a nerve cell to trigger neurotransmitter secretion. 

Long distance

A type of hormonal signaling where hormones travel via the circulatory system to reach the target cell.

Cell communication

1. Reception- Ligand attaches to a receptor protein changing the shape and initiating transduction. 

2. Transduction- The signal travels through cells, and is converted into another signal. 

3. Response- The cell responds to the signal.