W11_Cellular process

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Questions and Answers

What term describes the combined influence of the concentration gradient and the electrical gradient on the movement of a specific ion?

Membrane potential

Diffusion force

Passive transport

Electrochemical gradient (correct)

Which of the following is NOT a type of passive transport?

Exocytosis (correct)

Osmosis

Simple diffusion

Facilitated diffusion

What is the primary driving force behind diffusion?

Concentration difference of solutes only

Membrane permeability only

Kinetic energy of particles (correct)

Electrical charge balance

Which type of endocytosis is characterized by the uptake of large particles?

Phagocytosis Signup and view all the answers

Which of the following processes requires energy input?

Active transport Signup and view all the answers

What is the effect of a steeper concentration gradient on the rate of diffusion?

It increases the rate of diffusion. Signup and view all the answers

Which factor does NOT affect the rate of diffusion?

Color of the substance Signup and view all the answers

What distinguishes facilitated diffusion from simple diffusion?

It involves carrier proteins in the membrane. Signup and view all the answers

Ion channels are primarily responsible for the passage of which type of substances?

Small, inorganic ions. Signup and view all the answers

Which of the following statements about diffusion is true?

Diffusion continues until equilibrium is reached. Signup and view all the answers

What characteristic distinguishes gated channels from other types of channels?

They are only open under certain conditions. Signup and view all the answers

Which of the following types of channels are categorized as gated channels?

Ligand gated channels Signup and view all the answers

In carrier-mediated facilitated diffusion, what happens when transport maximum is reached?

The process exhibits saturation. Signup and view all the answers

How does glucose enter body cells?

By binding to specific carrier proteins. Signup and view all the answers

What is the main factor that influences the direction of water movement during osmosis?

Concentration of solute. Signup and view all the answers

Which of the following describes osmosis?

Diffusion of water through a semi-permeable membrane. Signup and view all the answers

What role do aquaporins play in osmosis?

They act as water channels in the membrane. Signup and view all the answers

What occurs during facilitated diffusion through carrier proteins?

Solute binds on the side of higher concentration. Signup and view all the answers

What is osmolarity a measure of?

The total solute concentration of a solution Signup and view all the answers

How many osmol of solute does a 1 M solution of sodium chloride contain per liter?

2 osmol Signup and view all the answers

What effect does increasing osmolarity have on water concentration in a solution?

It decreases water concentration Signup and view all the answers

Which of the following describes tonicity?

The ability of a solution to change cell shape Signup and view all the answers

What characterizes active transport?

Utilization of energy to move molecules against the concentration gradient Signup and view all the answers

Which of the following is NOT a type of primary active transport protein?

C6H12O6-ATPase Signup and view all the answers

What is the primary function of the Na+/K+-ATPase transporter in cells?

To establish and maintain the membrane potential Signup and view all the answers

Which type of transport utilizes an electrochemical gradient across a membrane?

Secondary active transport Signup and view all the answers

What triggers the release of K+ from the pump protein?

Binding of extracellular K+ Signup and view all the answers

Which process involves moving macromolecules into the cell?

Receptor-mediated endocytosis Signup and view all the answers

Which of the following accurately describes secondary active transport?

It uses an electrochemical gradient as its energy source. Signup and view all the answers

What occurs first in the sodium-potassium pump cycle?

Cytoplasmic Na+ binds to the pump protein. Signup and view all the answers

What is a major characteristic of receptor-mediated endocytosis?

It is dependent on the recognition of specific particles. Signup and view all the answers

Which statement about primary active transport is true?

It directly uses ATP to transport ions against their gradient. Signup and view all the answers

What type of co-transporter moves molecules in opposite directions?

Antiporter Signup and view all the answers

Which type of endocytosis involves the uptake of fluids?

Pinocytosis Signup and view all the answers

What is required for the process of exocytosis to occur?

ATP and Ca2+ ions Signup and view all the answers

Which of the following examples illustrates exocytosis?

Release of neurotransmitters from nerve cells Signup and view all the answers

What main role does transcytosis play in cellular function?

It moves substances into, across, and out of a cell. Signup and view all the answers

Where does transcytosis most commonly occur?

Across endothelial cells that line blood vessels Signup and view all the answers

Which neurotransmitter is specifically mentioned as being released via exocytosis?

Acetylcholine Signup and view all the answers

What is the process called when a vesicle merges with the plasma membrane to release its contents?

Exocytosis Signup and view all the answers

Which of the following statements about exocytosis is false?

It is an entirely passive process. Signup and view all the answers

In which cellular function is the synaptic terminal implicated?

Neurotransmission Signup and view all the answers

Study Notes

MPharm Programme: Cell Science - Cellular Process 1 & 2

The lecture covers different transport processes in and out of cells (passive, active, and vesicle transport).
Transport mechanisms across cell membranes are explained.
Examples of transport processes are given, including in the nervous system and neurotransmission.
Body fluid pools (intracellular and extracellular) are also detailed. The intracellular fluid makes up 2/3rds and the extracellular fluid makes up 1/3rd of the total body fluids.
Extracellular fluid includes interstitial fluid, plasma, lymphatic fluid, and cerebrospinal fluid.
Terminology related to solutions, solvents, solutes, and concentration gradients are defined.
The process of molecules moving across cell membranes (specifically the plasma membrane) through concentration and electrical gradients is discussed.
A concentration gradient is a difference in the concentration of a chemical between one place to another (e.g. inside vs outside the cell).
An electrical gradient is a difference in electrical charges between two regions.
The combined influence of concentration and electrical gradients on the movement of a particular ion is called an electrochemical gradient.
Different types of transport processes are covered including passive transport (simple diffusion, facilitated diffusion, osmosis), active transport, endocytosis (receptor-mediated endocytosis, phagocytosis, fluid-endocytosis (pinocytosis)), and exocytosis.
Passive transport does not require energy.
Simple diffusion involves the movement of substances from an area of higher concentration to one of lower concentration.
Facilitated diffusion uses carrier proteins to transport substances across the cell membrane from high to low concentration.
Osmosis is the movement of water across a semi-permeable membrane from an area of higher water concentration to one of lower water concentration.
Factors influencing diffusion include the steepness of the concentration gradient, temperature, mass of the diffusing substance, surface area, and diffusion distance.
Examples of substances that undergo simple diffusion include gases (like CO₂, O₂, N₂), small uncharged polar molecules (like ethanol), and some small uncharged polar molecules (like water and urea). Large uncharged polar molecules (like glucose, fructose) and ions (like K⁺, Na⁺, Cl⁻, Mg²⁺, Ca²⁺, HCO₃⁻, HPO₄²⁻) are impermeable to simple diffusion.
Facilitated diffusion requires a carrier in the membrane, but not ATP.
Ion channels are integral transmembrane proteins that allow the passage of inorganic ions across the cell membrane.
Facilitated diffusion (through carriers) includes protein transporters that move substances down their concentration gradient. These can be saturated, meaning they reach the maximum transport capacity. Glucose uses this mechanism.
Osmolarity is the total solute concentration of a solution.
One osmol of a substance is equal to one mole of solute particles. A 1 molar solution of glucose is 1 osmol. A 1 molar solution of sodium chloride (NaCl) contains 2 osmols due to the dissociation into two ions.
Tonicity refers to the ability of a solution to cause changes in the shape or tone of cells by altering their internal water volume.
Active transport uses energy (ATP) to move molecules/substances against the concentration gradient.
This process includes primary active transport, using ATP directly to move substances, and secondary active transport, using the electrochemical gradient formed from primary active transport to drive the transport of other substances.
Examples of primary active transport include the Na+/K+-ATPase pump, Ca²⁺-ATPase pump, H⁺-ATPase pump, and H⁺/K+-ATPase pump.
Secondary active transport includes co-transporters/symporters (moving two substances in the same direction), and counter-transporters/antiporters (moving two substances in opposite directions).
Vesicular transport types are endocytosis (including pinocytosis, receptor-mediated endocytosis, and phagocytosis) and exocytosis.
In endocytosis, substances are enclosed in vesicles that bud from the plasma membrane, moving into the cell.
Exocytosis releases substances contained in vesicles that fuse with the plasma membrane, moving out of the cell.
There are three main types of endocytosis: receptor-mediated endocytosis, pinocytosis, and phagocytosis.
receptor-mediated endocytosis is selective process that uses receptors on the cell surface to bind to specific molecules.
Pinocytosis is the uptake of liquid by the cell.
Phagocytosis is the uptake of solid particles or cells by the cell.
Exocytosis is a process that moves substances out of the cell. It's used by nerve cells to release neurotransmitters to communicate with other cells.
Transcytosis is a process where substances cross cells by undergoing endocytosis on one side of the cell and exocytosis on the other side.
There are more detailed summary of the processes in the last section of the slides. These are summarized with descriptions.

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Description

Test your knowledge of cell biology concepts related to diffusion and transport mechanisms, including passive transport and endocytosis. This quiz covers key processes and factors that influence the movement of ions and molecules across cell membranes.