A) crabby the crab lives in the ocean just off the east coast of the united stat

Question

A) crabby the crab lives in the ocean just off the east coast of the united states. one day, a young child catches Crabby and wants to take him home as pet. The child's family had a freshwater pound in their backyard, and the child plans to allow crabby to live in the pond. Using your knowledge of diffusion, osmosis, and tonicity, explain why the move to the freshwater pond will be deadly of crabby

B) Concisely describe the fluid mosaic model of the plasma membrane. Do not draw a picture. C) Consider the insulin-producing cells in the pancreas and innate immune cells such as macrophages.

Why are endocytosis and exocytosis important in these cells? which process is more important for each cell type? D) Why is a active transport necessary in living organisms?

what kinds of disorders could result from problems with active transport?

E) Explain 3 of the 6 major functions of membrane proteins.

5. A) A certain poison acts by binding to the enzyme ATP synthase, which catalyzed the formation of ATP. Binding of this poison causes the enzyme to become inactive. If excess ADP is added in the presence of this poison, the poison is no longer effective. What purpose does ADP serve in the example? What type of inhibitor is the poison? what evidence led you to this conclusion? What is the difference between an exergonic and endergonic reaction? what is the effect on free energy change and entropy of the system of each of these types of reactions?

6. Propose 3 ways that this pathway could be disrupted in patients with type 2 diabetes and suggest a way that one of these problems could be treated medically.

Explanation / Answer

diffusion

If there is a difference in the concentration of a particular solute between one region of a solution and another, then there is a tendency for the substance to diffuse from where it is more concentrated to where it is less concentrated. This is because of the random collisions among particles which eventually will evenly distribute the solute throughout the volume of the solution. Thus net diffusion occurs “down” a concentration gradient, from an area of high concentration to an area of low concentration, until a state of equilibrium is reached throughout the volume of the solution.

Osmosis

The “concentration” of water in a solution is inversely related to solute concentration – the greater the concentration of total solutes in the solution (regardless of what those specific solutes are), the lower the number of water molecules per unit volume of the solution. Thus water tends to diffuse from more dilute areas (i.e., with lower solute concentration) to more concentrated areas (i.e., with higher solute concentrations).

Cells are surrounded by a semi-permeable membrane which will allow water to pass through but prevent many hydrophilic solutes from passing through. Thus, the diffusion of water into or out of the cell is driven by differences in the total concentration of solutes that cannot pass through the plasma membrane. The diffusion of water across a semi-permeable membrane such as a cell membrane is termed osmosis. Osmosis is thus a special case of diffusion involving only the movement of water (the solvent of the solution) across a barrier permeable to water but impermeable to certain solutes.

Tonicity

Living cells have the potential of gaining or losing water from the surrounding extracellular fluid through osmosis. The net movement of water into or out of the cell is driven by differences in osmotic pressures between the extracellular fluid and the intracellular fluid. Thus, the effect that an extracellular solution has on the osmotic movement of water into or out of the cell is described by the tonicity of the extracellular fluid.

if a cell is placed in a solution with a lower osmotic concentration (for example, distilled water), then the osmotic pressure of the extracellular fluid is less than that of the intracellular fluid. As a result, water flows into the cell, causing it to swell perhaps so much that the cell may undergo lysis (burst). In this situation, the extracellular fluid is said to be hypotonic.

like wise the move to the freshwater pond will be deadly of crabby beacuse water flows into the crabby cells, causing them to swell perhaps so much that the cell may undergo lysis (burst). In this situation, the extracellular fluid/ fresh water is said to be hypotonic.

  The fluid mosaic model of the cell membrane is how scientists describe what the cell membrane looks and functions like, because it is made up of a bunch of different molecules that are distributed across the membrane. If you were to look at a cell membrane using a microscope, you would see a pattern of different types of molecules put together, also known as a mosaic. These molecules are constantly moving in two dimensions, in a fluid fashion, similar to icebergs floating in the ocean. The movement of the mosaic of molecules makes it impossible to form a completely impenetrable barrier.

There are 3 main factors that influence cell membrane fluidity:

The movement of macromolecules such as proteins or polysaccharides into or out of the cell is called bulk transport. There are two types of bulk transport, exocytosis and endocytosis, and both require the expenditure of energy (ATP).

In exocytosis, materials are exported out of the cell via secretory vesicles. In this process, the Golgi complex packages macromolecules into transport vesicles that travel to and fuse with the plasma membrane. This fusion causes the vesicle to spill its contents out of the cell. Exocytosis is important in expulsion of waste materials out of the cell and in the secretion of cellular products such as digestive enzymes or hormones.

Endocytosis, on the other hand, is the process by which materials move into the cell. There are three types of endocytosis: phagocytosis, pinocytosis, and receptor-mediated endocytosis. In phagocytosis or “cellular eating,” the cell’s plasma membrane surrounds a macromolecule or even an entire cell from the extracellular environment and buds off to form a food vacuole or phagosome. The newly-formed phagosome then fuses with a lysosome whose hydrolytic enzymes digest the “food” inside.

Active transport is the process by which dissolved molecules move across a cell membrane from a lower to a higher concentration. In active transport, particles move against the concentration gradient - and therefore require an input of energy from the cell.

Sometimes dissolved molecules are at a higher concentration inside the cell than outside, but, because the organism needs these molecules, they still have to be absorbed. Carrier proteins pick up specific molecules and take them through the cell membrane against the concentration gradient.

In humans, active transport takes place during the digestion of food in the small intestine. Carbohydrates are broken down into simple sugars such as glucose. The glucose is absorbed by active transport into the villi, to be passed into the bloodstream and taken around the body.

active transport is also involved in cellular respiration (the ATPase pump which pumps ATP molecules for energy is driven by active transport).

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.