Skip to main content

What is the type of membrane transport in which substances move across the membrane along their concentration gradient until equilibrium is reached?

Small neutral and soluble substances are able to travel across the membrane by the process of simple diffusion. During simple diffusion, substances are able to pass unimpeded through the membrane along a concentration gradient. A concentration gradient occurs when there is more of the substance on one side of the membrane than the other.


When substances travel along their concentration gradient, they travel from the side of the membrane where they are present in a higher concentration to the side of the membrane where they are present in a lower concentration. Transport across the membrane continues until the concentration of the substances is the same on both sides of the membrane. Examples: oxygen, carbon dioxide, most lipids.


When water is transported across the membrane by simple diffusion, it is called osmosis.


There are several other processes that are used to transport substances across the membrane. These include:



  • Facilitated Diffusion: Substances travel across the membrane through protein channels.


  • Active Transport: Substances travel across the membrane against their concentration gradient. (i.e. from the side of the membrane with a lower concentration of the substance to the side of the membrane with the higher concentration of the substance). This process requires the input of energy from the breakdown of the molecule ATP.


  • Endocytosis and Exocytosis: Substances travel in and out of the cell by being engulfed by a portion of the cell membrane. Movement into the cell by this process is called endocytosis. Movement out of the cell by this process is called exocytosis.

Comments

Post a Comment

Popular posts from this blog

etymology - Origin of the greeting "Sweet dreams".

Does anybody know the etymology of the phrase "sweet dreams"? I tried googling but did not find anything satisfying. Is this a relatively new phrase of the modern world or has this been in use for some time? I think it's the latter one. Answer The OED has the interjection as "a farewell to someone going to bed" from the 20th century: 1908 Sears Roebuck Catal. 198/1 Tenor Solos..Good Bye, Sweet Dreams, Good Bye. But it goes back until at least the 19th and possibly 18th centuries. John Wolcot, writing under the pseudonym of Peter Pindar, used it in his poem "Orson and Ellen; A Legendary Tale" published in 1801: Also from 1801 in The infernal Quixote (Page 287) by Charles Lucas: In the March 1776 of The Universal Magazine was published "The Serenade. A Pastoral Tale. From the German of Gesner" , where the shepherd Daphnis watches over his beloved as she sleeps and sings: The same tale appears in 1776's as Idyl XI, " Daphnis ...
Post a Comment
Read more

Is there a word/phrase for "unperformant"?

As a software engineer, I need to sometimes describe a piece of code as something that lacks performance or was not written with performance in mind. Example: This kind of coding style leads to unmaintainable and unperformant code. Based on my Google searches, this isn't a real word. What is the correct way to describe this? EDIT My usage of "performance" here is in regard to speed and efficiency. For example, the better the performance of code the faster the application runs. My question and example target the negative definition, which is in reference to preventing inefficient coding practices. Answer This kind of coding style leads to unmaintainable and unperformant code. In my opinion, reads more easily as: This coding style leads to unmaintainable and poorly performing code. The key to well-written documentation and reports lies in ease of understanding. Adding poorly understood words such as performant decreases that ease. In addressing the use of such a poorly ...
Post a Comment
Read more

What are the similarities between the relationships of the characters in The Outsiders and Romeo and Juliet?

At first glance, it might appear as if the characters in  The Outsiders  by S. E. Hinton and  Romeo and Juliet  by William Shakespeare do not have much in common; however, when one isolates the core of the conflicts, it becomes clear that the relationships in both stories are rooted in rivalry and secrecy.  In both  The Outsiders  and  Romeo and Juliet , an overarching theme is rivalry. While   socioeconomic status separates the greasers from the Socs in The Outsiders , last names separates the Montagues from the Capulets, who appear to be relatively equal in terms of socioeconomic status. Due to these rivalries, there are instances of deadly interactions in both stories. In  The Outsiders , Johnny kills Bob (whether his actions were justified or not is debatable). In  Romeo and Juliet , Romeo kills Tybalt and Paris, and Tybalt kills Mercutio. These deaths have profound effects on the main characters. In Ponyboy's case, the Johnny's death and other events in the novel inspire h...
Post a Comment
Read more