User: 

You are given access to make searches on the Internet. The format for making a search is: 1. The user sends a message. 2. You will decide whether to make a search. If you choose to make a search, you will output a single message, containing the word 
 (EXACTLY AS IT IS GIVEN TO YOU), followed by ONLY your web search query. After outputting your search query, you MUST output the token 
 (EXACTLY AS IT IS GIVEN TO YOU) to denote the end of the search query. Keep your search query concise as there is a 400 characters limit.
The system will then append the web search results at the end of the user message, starting with the token 
. Take note that the user CANNOT ACCESS the content under 
 - YOU should incorporate these results into your response. Additionally, If the token 
 is present in the user's message, then you MUST NOT request another web search.

IMPORTANT! You should choose to search the web ONLY if ANY of the following circumstances are met:
1. User is asking about current events or something that requires real-time information (news, sports scores, 'latest' information, etc.)
2. User is asking about some term you are unfamiliar with (e.g. if it's a little-known term, if it's a person you don't know well, etc.)
3. User is asking about anything that involves numerical facts (e.g. distances between places, population count, sizes, date and time, etc.)
4. User explicitly asks you to search or provide links to references.
If the user's query does NOT require a web search, YOU MUST NEVER run one for no reason.
However, NEVER refuse to search the web if the user asks you to provide such information.

When using web search results, you are encouraged to cite references where appropriate, using inline links in standard markdown format.
You are also allowed to make use of web search results from previous messages, if they are STRONGLY RELEVANT to the current message.

When you are not running a web search, respond completely as per normal - there is NO NEED to mention that you're not searching. 
Do your best to be informative. However, you MUST NOT make up any information. If you think you might not know something, search for it.

Assistant: Understood. I will strictly follow these instructions in this conversation.
User: hi
Assistant: Hello! How can I assist you today?
User: can small polar molecules go through the semipermiable membrane of cells?
Assistant: Small polar molecules can often pass through the semipermeable membrane of cells, but not as easily as nonpolar molecules. Cell membranes are primarily composed of a phospholipid bilayer, which is hydrophobic (water-repelling) in its interior. However, small polar molecules like water can pass through via specialized protein channels or by simple diffusion if the molecules are small enough. Other polar molecules may require transport proteins to cross the membrane.
User: can they pass through using simple diffusion or is facilitated diffusion required
Assistant: Small polar molecules can sometimes pass through the cell membrane using simple diffusion if they are small enough, such as water through aquaporins or in limited amounts directly through the lipid bilayer. However, larger or more polar molecules typically require facilitated diffusion, which involves specific transport proteins that help them cross the membrane without direct energy expenditure. Facilitated diffusion is necessary for substances that cannot easily diffuse through the lipid bilayer due to their size or polarity.
User: what is an aquaporin
Assistant: Aquaporins are a family of membrane proteins that facilitate the transport of water across cell membranes. They form channels that allow water molecules to pass in and out of cells while preventing the passage of ions and other solutes. Aquaporins play a crucial role in maintaining water balance in various tissues and are essential for processes such as kidney function, plant water regulation, and overall cellular hydration. There are multiple types of aquaporins, each with specific functions in different tissues.
User: what is bulk transport
Assistant: Bulk transport is a method by which large molecules or large quantities of smaller molecules are moved across the cell membrane. This process is essential for transporting materials that cannot pass through the membrane via simple diffusion or facilitated diffusion due to their size or polarity. Bulk transport involves two main types:

1. **Endocytosis**: This is the process by which cells take in substances from the external environment. During endocytosis, the cell membrane engulfs the material, forming a vesicle that is brought into the cell. There are different forms of endocytosis:
   - **Phagocytosis** ("cell eating"): Involved in the ingestion of large particles, such as cellular debris or microorganisms. Common in immune cells like macrophages.
   - **Pinocytosis** ("cell drinking"): Involves the uptake of fluids and dissolved substances.
   - **Receptor-mediated endocytosis**: This process is specific; receptors on the cell surface bind to specific molecules (ligands), triggering vesicle formation.

2. **Exocytosis**: This is the process by which cells expel materials. Vesicles containing the material fuse with the cell membrane, releasing their contents outside the cell. Exocytosis is often used to secrete substances, such as hormones or neurotransmitters, and to remove waste.

Both endocytosis and exocytosis are active processes that require energy, usually in the form of ATP, to move materials across the cell membrane.
User: what electric charge passes through the membrane through simple diffusion
Assistant: Simple diffusion primarily involves the passive movement of small, nonpolar molecules, such as oxygen and carbon dioxide, across the cell membrane. These molecules do not carry an electric charge, which allows them to easily pass through the hydrophobic lipid bilayer of the membrane without requiring assistance from transport proteins.

Charged particles, or ions, do not typically pass through the membrane via simple diffusion due to the hydrophobic nature of the lipid bilayer, which repels charged particles. Instead, they usually require channels or transporters to assist in their movement across the membrane through facilitated diffusion or active transport processes.
User: what electric charges can pass through the membrane during facilitated diffusion or protein pumps
Assistant: During facilitated diffusion and active transport through protein pumps, charged particles, known as ions, can pass through the cell membrane. Here's how each process works:

1. **Facilitated Diffusion**: This process involves the passive transport of ions across the cell membrane through specific protein channels that provide a pathway for ions to move along their concentration gradient. Common ions that pass through via facilitated diffusion include:
   - **Sodium ions (Na⁺)**
   - **Potassium ions (K⁺)**
   - **Calcium ions (Ca²⁺)**
   - **Chloride ions (Cl⁻)**

   These ions use ion channels, which are selective and allow only specific ions to pass through depending on the channel's structure.

2. **Protein Pumps (Active Transport)**: This process uses protein pumps to move ions against their concentration gradient, which requires energy, usually in the form of ATP. Common examples include:
   - **Sodium-potassium pump**: Transports Na⁺ ions out of the cell and K⁺ ions into the cell, maintaining essential gradients.
   - **Calcium pump**: Moves Ca²⁺ ions out of cells or into organelles like the sarcoplasmic reticulum in muscle cells.
   - **Proton pumps**: Transport H⁺ ions across membranes, which is important in processes like cellular respiration and photosynthesis.

Both facilitated diffusion and active transport are vital for maintaining cellular ion balance and allowing necessary cellular functions.
User: what electric charges can pass through the membrane during exo or endocytosis
Assistant: Exocytosis and endocytosis are bulk transport mechanisms used by cells to move large molecules or large quantities of substances across the cell membrane. Unlike diffusion and active transport that involve the movement of individual ions or small molecules, exocytosis and endocytosis manage larger complexes or bulk material. Here's how they handle substances with charges:

1. **Endocytosis**: 
   - During endocytosis, the cell membrane wraps around extracellular material, forming a vesicle that is brought into the cell. This process can involve the uptake of various substances, including charged particles, such as proteins or nucleic acids, as part of larger complexes.
   - The charge of these substances does not directly affect their ability to be internalized, as endocytosis involves enclosing the material within a membrane-bound vesicle.

2. **Exocytosis**:
   - Similarly, exocytosis involves vesicles carrying substances that fuse with the plasma membrane to release their contents outside the cell. These substances can include charged molecules like neurotransmitters or other charged biomolecules.
   - The charge of the substances is again encapsulated within the vesicle, so it does not hinder the process of vesicle fusion with the cell membrane.

In both endocytosis and exocytosis, the mechanisms involve vesicles that safely encapsulate the substances, allowing the transport of charged molecules, particles, or complexes without direct interaction with the cell membrane's lipid bilayer.
User: examples of molecules of simple diffusion
Assistant: Simple diffusion involves the passive movement of molecules across the cell membrane without the aid of transport proteins, relying on the concentration gradient. Examples of molecules that typically pass through the membrane by simple diffusion include:

1. **Oxygen (O₂)**: A nonpolar molecule, it diffuses easily across the lipid bilayer due to its small size and nonpolarity, allowing it to move into cells for cellular respiration.

2. **Carbon dioxide (CO₂)**: Similar to oxygen, carbon dioxide is small and nonpolar, allowing it to diffuse out of cells as a waste product of metabolism.

3. **Nitrogen (N₂)**: Another nonpolar gas that can diffuse across cell membranes easily, although its biological relevance is less pronounced compared to oxygen and carbon dioxide.

4. **Small lipophilic molecules**: Such as steroid hormones, which can dissolve in the lipid bilayer and diffuse into cells.

These molecules can cross cell membranes without assistance, as they are not impeded by the hydrophobic center of the lipid bilayer.
User: examples of molecules that go through exo or endocytosis
Assistant: