Organelle and Plasma Membrane Essay

Published: 2020-04-22 15:06:56
414 words
2 pages
printer Print
essay essay

Category: DNA

Type of paper: Essay

This essay has been submitted by a student. This is not an example of the work written by our professional essay writers.

Hey! We can write a custom essay for you.

All possible types of assignments. Written by academics

1. Prokaryotic and eukaryotic cells are physiologically different in many ways, but both represent functional collections of living matter. It has been theorized that the organelles of eukaryotic cells evolved from prokaryotes living symbiotically within a larger cell. Compare and contrast the structure of the prokaryotic cell with eukaryotic cell organelles, and make an argument for or against this theory.

2. The plasma membrane is the boundary that separates the living cell from its nonliving surroundings. A membrane is a fluid structure with a mosaic, which is a pattern consisting of numerous small pieces or elements fitted together, of various proteins embedded in it when viewed from the top. Phospholipids can move laterally a small amount and can flex their tails. Membrane proteins also move side to side or laterally making the membrane fluid.

Transport proteins allow passage of hydrophilic substances across the membrane.  Passive transport is the diffusion of a substance across a membrane with no energy investment. In passive transport, substances diffuse spontaneously down their concentration gradients, crossing a membrane with no expenditure of energy by the cell. The rate of diffusion can be greatly increased by transport proteins in the membrane. CO2, H2O, and O2 easily diffuse across plasma membranes. Diffusion of water is known as osmosis.

Diffusion is the tendency for molecules of any substance to spread out evenly into the available space. They move from high to low concentration. Facilitated diffusion is a type of Passive Transport aided by proteins. In facilitated diffusion, transport proteins speed the movement of molecules across the plasma membrane. Channel proteins provide corridors that allow a specific molecule or ion to cross the membrane. Carrier proteins undergo a subtle change in shape that translocates the solute-binding site across the membrane.

Active transport uses energy to move solutes against their concentration gradients. It requires energy, which is usually in the form of ATP. In active transport, some transport proteins act as pumps, moving substances across a membrane against their concentration gradients. Cotransport occurs when active transport of a specific solute indirectly drives the active transport of another solute. This involves transport by a membrane protein and is driven by a concentration gradient. Examples of active transport are exocytosis and endocytosis. In exocytosis, transport vesicles migrate to the plasma membrane, fuse with it, and release their contents. In endocytosis, the cell takes in macromolecules by forming new vesicles from the plasma membrane.

That is how the plasma membrane plays a role in active transport and passive transport.

Warning! This essay is not original. Get 100% unique essay within 45 seconds!


We can write your paper just for 11.99$

i want to copy...

This essay has been submitted by a student and contain not unique content

People also read