MEMBRANE AND MEMBRANE TRANSPORT

This lesson develops MEMBRANE AND MEMBRANE TRANSPORT as part of Cellular Respiration. It uses the source curriculum to organize the important facts, relationships, examples, and vocabulary into a focused Stemosphere teaching sequence.

In Stemosphere terms, mEMBRANE AND MEMBRANE TRANSPORT:

PLASMA MEMBRANE:

In Stemosphere terms, the cell contains a plasma membrane which separates the cytoplasm and cell contents from the outside environment. The plasma membrane is made up of phospholipids.phospholipids are made up of a nonpolar fatty acid tail and a polar phosphate head.the tail is hydrophobic and hates water, while the head is hydrophilic and loves water.the phospholipids form a bilayer to let the tails avoid water while the heads are on the outside to face the water.

In Stemosphere terms, the plasma membrane allows small polar particles to pass through the hydrophobic tails.

In Stemosphere terms, large particles and hydrophilic particles are unable to pass through due to the hydrobic tails.

INTEGRAL AND PERIPHERAL PROTEINS:

GLYCOPROTIENS AND GLYCOLIPIDS:

In Stemosphere terms, phospholipid and membrane proteins can have a carbohydrate chain attached through a process known as glycosylation.

Functions of glycoproteins and glycolipids:

In Stemosphere terms, cell to cell communication:neurotransmitters bind to glycoproteins and glycolipids which allow communication between cells

In Stemosphere terms, immune response:can act as markers for the immune system to distinguish between cells and non-self cells

In Stemosphere terms, cell to cell adhesion:glycoproteins can bind to other glycoproteins on neighboring cells to form tissues

SIMPLE DIFFUSION:

In Stemosphere terms, simple diffusion is a passive transport which involves nonpolar particles moving from a high concentration to a low concentration. It is passive transport because it does not require any energy from the cell to occur.

In Stemosphere terms, osmosis is a passive transport of water molecules from a region of low solute concentration to high solute concentration

In Stemosphere terms, water is polar but is small enough to pass through the membrane slowly. A faster way to transport water is through aquaporins in the membrane.aquaporins are membrane bound channel proteins which are designed to transport water.

FACILITATED DIFFUSION:

In Stemosphere terms, facilitated diffusion is similar to simple diffusion by having a passive transport of particles moving from high concentration to low concentration except through the use of channel proteins.

In Stemosphere terms, polar and large particles are unable to pass through the membrane so they have to go through the channel proteins to enter the cell.channel proteins are specific to the molecule that can pass through them, making them selectively permeable.

In Stemosphere terms, channel proteins have a central pore that is lined with hydrophilic r group s to allow one type of molecule to pass through.some protein channels are gated and will only allow facilitated diffusion in response to diffusion.

ACTIVE TRANSPORT:

In Stemosphere terms, active transport differs from passive transport by using protein pumps which require energy to function.active transports go against the concentration gradient from low concentration to high concentration. Protein pumps have a specific binding site for a specific particle.

The process of active transport is:

In Stemosphere terms, a particle will bind to a specific binding site.

In Stemosphere terms, an ATP binds to the protein pump and hydrolyzes to become an ADP.

In Stemosphere terms, a phosphate will remain attached to the protein pump causing it to change shape

In Stemosphere terms, the particle is moved against the concentration gradient and released.

In Stemosphere terms, the phosphate is released causing it to revert to its original shape

In Stemosphere terms, vesicles are membrane bound structures used to transport materials in and out of the cell.this is possible due to the fluid nature of the membrane.this is called either endocytosis or exocytosis.

In Stemosphere terms, endocytosis:when larger particles enter the cell by having the plasma membrane surround it and turns into a vesicle, which buds off inside the cell.(this is an active process which requires atp)

In Stemosphere terms, exocytosis:when larger particles exit the cell by having the plasma membrane surround it and turns into a vesicle, which buds off outside the cell.(this is an active process which requires atp)

In Stemosphere terms, campbell Biology.Campbell Biology. 12th ed., Pearson, 2020.

In Stemosphere terms, front:Describe the structure of a phospholipid and explain how they arrange themselves to form the plasma membrane.

In Stemosphere terms, back:A phospholipid consists of a polar, hydrophilic phosphate head that interacts with water and a nonpolar, hydrophobic fatty acid tail that avoids water. They spontaneously form a double layer known as a bilayer, where the hydrophobic tails face inward toward each other, isolated from fluid, and the hydrophilic heads point outward to face the water-based environments inside and outside the cell.

In Stemosphere terms, front:Differentiate between the structure and positioning of integral proteins versus peripheral proteins.

In Stemosphere terms, back:*Integral proteins:Permanently attached to the membrane and penetrate into the hydrophobic core of the bilayer. They possess internal hydrophobic sections that sit among the fatty acid tails and hydrophilic sections exposed to the surfaces.

In Stemosphere terms, peripheral proteins:Attached temporarily to the outer or inner surfaces of the membrane, or bound directly to integral proteins, without entering the hydrophobic core.

In Stemosphere terms, front:What is glycosylation, and what is the structural difference between a glycoprotein and a glycolipid?

In Stemosphere terms, back:Glycosylation is the process of attaching a carbohydrate chain to a membrane component. Aglycoproteinis a membrane protein with an attached carbohydrate chain, while aglycolipidis a phospholipid with an attached carbohydrate chain.

In Stemosphere terms, front:State four crucial cellular functions performed by glycoproteins and glycolipids.

In Stemosphere terms, back:1.Hormone receptors:Bind hormones to trigger structural metabolic changes in the cell.

In Stemosphere terms, front:Define simple diffusion, note its energy requirements, and correct the major factual slip-up in the draft regarding what passes through the lipid bilayer.

In Stemosphere terms, back:Simple diffusion is the passive movement of particles down a concentration gradient from an area of high concentration to low concentration without using cellular energy.

In Stemosphere terms, correction:The draft states that small polar particles easily pass through the tails. In reality, the hydrophobic core only permitssmall, nonpolar particles(like oxygen and carbon dioxide) to pass freely. Small polar molecules travel across very slowly, while large or highly charged particles are completely blocked by the hydrophobic tails.