Chapter 8: Biological Membranes

Question 1

Cell Plasma membrane.

Answer 1

A semi permeable barrier, it chooses which particles can enter and leave the cell at any point in time. This selectivity is mediated not only by the various channels and carriers that poke holes in their brain, but also by the membrane itself.

Question 2

Glycoprotein coat

Answer 2

Carbohydrates associated with membrane bound proteins create a glycoprotein coat. The cell wall of plants, bacteria and fungi contain higher levels of carbohydrates.

Question 2

Lipid rafts.

Answer 2

Collection of similar lipids, with or without associated proteins that serve as attachment points for other biomolecules. These rafts often serve roles in signaling.

Question 3

Membrane dynamics.

Answer 3

It is a semi solid and in constant state of flux. Fossil lipids move rapidly in the plane of their membrane through simple diffusion.

Question 4

Flippases

Answer 4

Assist in the transition or flip between layers.

Question 5

Fatty acids and triglycerides.

Answer 5

Fatty acids are carboxylic acids that contain a hydrocarbon chain and terminal carboxyl group. Triglycerides also refer to as triglycerides or storage lipids involved in human metabolic process. They contain three fatty acid chains esterified to a glycerol molecule.

Question 6

Phospholipids

Answer 6

They have a phosphate group, a polar head group joins the nonpolar tails, forming a glycerophospholipid, commonly called phospholipid.

Question 7

Sphingolipids

Answer 7

They do not contain glycerol but have a sphingosine backbone. Classes of Sphingolipids and their hydrophilic groups include ceramide, sphingomyelin, cerebrosides, and gangliosides.

Question 8

Cholesterol and steroids.

Answer 8

Cholesterol not only regulates membrane fluidity, but it also is necessary in the synthesis of steroids, which are derived from cholesterol. Membrane stability is derived from interactions with both the hydrophilic and hydrophobic regions that make up the phospholipid bilayer. While cholesterol stabilizes adjacent phospholipids, it also occupies space between them. This prevents the formation of crystal structures in the membrane, increasing fluidity at lower temperatures. It decreases fluidity and it helps hold the membrane intact. Cholesterol composes about 20% of the cell membrane by mole fraction by mass.

Question 9

Waxes

Answer 9

Extremely hydrophobic but are sometimes found in the saline brains of plants. A wax is composed of a long chain fatty acid and a long chain alcohol, which contributes to the high melting point of these substances. Waxes can provide both stability and rigidity within the nonpolar tail region only.

Question 10

Transmembrane proteins.

Answer 10

Passed completely through the lipid bilayer.

Question 11

Embedded proteins.

Answer 11

Are associated with only the interior or exterior surface of the cell membrane.

Question 11

Integral proteins.

Answer 11

Together, transmembrane and embedded proteins are considered integral proteins because of their association with the interior of the plasma membrane.

Question 12

Membrane associated (Peripheral) Proteins.

Answer 12

Maybe bound through electrostatic interactions with the lipid bilayer, especially a lipid raft.

Question 13

Carbohydrates

Answer 13

Are generally attached to protein molecules on the extracellular surface of the cell. Interactions between glycoproteins and water and can form a coat around the cell. It can act as signaling and recognition molecules.

Question 14

Membrane Receptors.

Answer 14

Some of the transporters of facilitated diffusion and active transport can be activated or deactivated by membrane receptors, which tend to be transmembrane proteins.

Question 15

Cell cell junctions.

Answer 15

Cells within tissues can form a cohesive layer via intracellular junctions. They are generally comprised of cell adhesion molecules, which are proteins that allow cell to recognize each other and contribute to proper cell differentiation and development.

Question 16

Gap junctions.

Answer 16

Allow for direct cell cell communication and are often found in small bunches together. Gap junctions are also called connexons and are formed by the aligned meaning direction of poorest composed of six molecules of connexin.

Question 17

Tight junctions.

Answer 17

Tight junctions form a watertight seal, preventing Paracellular transport of water and solutes.

Question 17

Active transport.

Answer 17

Non spontaneous process and requires energy to proceed.

Question 18

Desmosomes

Answer 18

Bind adjacent cells by incurring to their cytoskeletons. They are formed by interactions between transmembrane proteins associated with intermediate filaments inside adjacent cells. Hemi desmosomes have a similar function, but their main function is to attach epithelial cells to underlying structures.

Question 19

Passive transport.

Answer 19

Spontaneous processes that do not require energy to proceed. Utilizes the concentration gradient to supply the energy for particles to move.

Question 20

Osmosis

Answer 20

Specific kind of simple diffusion that concerns water. Lower solute concentration to one of higher solute concentration. It will move from a region of higher water concentration down its gradient to region of lower water concentration.

Question 20

Simple diffusion.

Answer 20

Substrate moved down their concentration gradient directly across the main brain. Particles that are freely permeable to the membrane are able to undergo simple diffusion. There’s potential energy in a chemical gradient. Some of this energy is dissipated as the gradient is used during simple diffusion.

Question 21

Hypotonic

Answer 21

If the concentration of solute inside the cell is higher than the surrounding solution, the solution is said to be hypotonic. Such a solution will cause the cell to swell as water rushing sometimes To the point of bursting (lysing).

Question 22

hypertonic

Answer 22

A solution that is more concentrated in the cell. Water will move out of the cell.

Question 23

Osmotic pressure.

Answer 23

Is the colligative property. A physical property of solution that is dependent on the concentration of the soft particles but not on the chemical identity of those dissolved particles. The membrane allows water, but not solutes to pass through. Because subsistences then to flow or diffuse from higher to lower concentration, water will diffuse from the compartment containing pure water into the compartment containing the water solute mix.

Question 24

Facilitated diffusion.

Answer 24

Molecules that are impermeable to the membrane (large polar charged), it require integral membrane proteins to serve as transported off channels for this substrate. Classic example of facilitated diffusion involves a carrier or a channel protein. Carriers are only open to one side of the selling brain at any given point. This model is similar to a revolving door because the substrate binds to the transport protein (walks in), Remains in the transporter doing a confirmation of change, (spins) and then finally dissociates from the substrate. Writing say, of the transporter (walks out). The carrier is in the occluded state in which the carrier is not open to either side of the phospholipid bilayer. In addition to carriers, channels are also viable transports for facilitated diffusion. Channels may be in an open or closed confirmation. They’re exposed to both sides of the cell membranes and act like a tunnel for the particles to diffuse through.

Question 25

Exocytosis

Answer 25

Occurs when the secretory vessels fused with the main brain, releasing material from inside the cell to the extracellular environment.

Question 25

Mitochondrial membranes.

Answer 25

Mitochondria is the powerhouse of the cell because of the ability to produce ATP by oxidative respiration. Mitochondria contains 2 membranes, the inner and the outer mitochondrial membranes.

Question 25

Primary active transports.

Answer 25

Uses ATP or another energy molecule to direct power the transport of molecules across the membrane. It involves the use of transmembrane ATPase.

Question 26

Secondary active transports.

Answer 26

It is also known as couple transport, also uses energy transport particles across the main brain. However, in contrast to primary, there is no direct coupling to ATP hydrolysis. They harnessed the energy released by 1 particle going down its electrochemical gradient to drive a different particle up its gradient. When both particles flowed the same direction across the main brain, it is termed symport, When the particles flow in opposite direction it is called antiport.

Question 27

Endocytosis

Answer 27

Occurs when the salmon brain invaginates and engulfs material to bring it into the cell. The material is encased in a vesicle, which is important because cells which sometimes ingest toxic substances. Pinocytosis is the endocytosis of fluids and dissolved particles. Phagocytosis is the ingestion of large solids such as bacteria.

Question 28

Outer mitochondrial membrane.

Answer 28

Is highly permeable due to many large pores that allow the passage of ions and small proteins. There’s a space called intermembrane space in between the two layers.

Question 29

Sodium potassium pump.

Answer 29

There is a steady state resting relationship between I and diffusion in the Na+/ K+ ATPase. To maintain a low concentration of sodium ions in high concentration of potassium ions intracellular by pumping 3 sodium ions out every two potassium on the yarn pumped. Mean. This movement of ions remove 1 positive charge from intracellular space of the cell which maintains the negative resting potential of the cell.

Question 29

Inner mitochondrial membrane.

Answer 29

Has much more restricted permeability. It contains numerous infoldings known as Cristae, Which increases the available surface area for the Integra proteins associated with the membrane. It encloses the mitochondrial matrix where the citric acid cycle produces high energy electron carriers used in the electron transport chain.