Question

Match each term with its description. (a) Integral membrane protalin _____________ (b) Peripheral membrane protein_________________ (c) Channel__________________ (d) Passive transport___________________ (e) Active transport_______________________ (f) \(\mathrm{Na}^{+}-\mathrm{K}^{+}\) ATPase_______________ (g) Secondary transporter_________________ (h) Antiporter___________________ (i) Symporter______________________ (j) Ion channel______________________ 1\. Facilitated diffusion 2\. Uses the energy of one gradient to create another 3\. Interacts tightly with the membrane interior 4\. Molecules moving in opposite directions 5\. Interacts with the border of a membrane 6\. Allows rapid movement of molecules down a gradient across a membrane 7\. Movement against a concentration gradient 8\. Molecules moving in the same direction 9\. Can be voltage-gated or ligand-gated 10\. Inhibited by digitalis

Short answer

(a)-3, (b)-5, (c)-6, (d)-1, (e)-7, (f)-10, (g)-2, (h)-4, (i)-8, (j)-9.

Step-by-step solution

Understand the Terms

Review each term and description provided in the exercise. This foundational understanding of membrane proteins and transport mechanisms is vital for matching.

Match 'Integral Membrane Proteins'

Integral membrane proteins interact tightly with the membrane interior. Match (a) with description 3.

Match 'Peripheral Membrane Proteins'

Peripheral membrane proteins interact with the border of a membrane. Match (b) with description 5.

Match 'Channel'

Channels allow rapid movement of molecules down a gradient across a membrane. Match (c) with description 6.

Match 'Passive Transport'

Passive transport is facilitated diffusion. Match (d) with description 1.

Match 'Active Transport'

Active transport involves movement against a concentration gradient. Match (e) with description 7.

Match 'Na+-K+ ATPase'

Na+-K+ ATPase is inhibited by digitalis. Match (f) with description 10.

Match 'Secondary Transporter'

Secondary transporters use the energy of one gradient to create another. Match (g) with description 2.

Match 'Antiporter'

Antiporters move molecules in opposite directions. Match (h) with description 4.

Match 'Symporter'

Symporters move molecules in the same direction. Match (i) with description 8.

Match 'Ion Channel'

Ion channels can be voltage-gated or ligand-gated. Match (j) with description 9.

Key concepts

Integral Membrane Proteins

Integral membrane proteins are essential components of biological membranes. These proteins are embedded within the lipid bilayer and often span the entire membrane. Their unique structure allows them to interact intimately with the membrane's interior.

They are crucial for maintaining the structural integrity of the membrane and perform diverse functions:

• Acting as gateways to permit the transport of specific substances across the membrane.
• Facilitating communication between the cell's interior and exterior environments.
• Participating in cellular processes such as signal transduction and cell recognition.

Integral membrane proteins have both hydrophobic and hydrophilic regions. The hydrophobic parts interact with the fatty acid tails of phospholipids, anchoring them firmly in place.

This integration helps them perform their roles efficiently and is crucial for cell functionality.

Active Transport

Active transport is a vital cellular process that requires energy, usually in the form of ATP, to move substances across a cell membrane. Unlike passive transport, which relies on concentration gradients, active transport moves molecules against these gradients.

This process is crucial for various cellular functions, including:

• Maintaining concentration gradients of ions across membranes, essential for nerve impulse transmission.
• Uptake of nutrients into cells and removal of waste products.
• Regulation of pH and cell volume.

There are two primary types of active transport mechanisms:

• Primary Active Transport: Direct use of metabolic energy (like ATP) to drive molecules across the membrane.
• Secondary Active Transport: Use of an electrochemical gradient created by primary active transport to pump other molecules against their gradients.

Active transport is indispensable for maintaining cellular homeostasis and enabling cells to function effectively.

Passive Transport

Passive transport is the movement of substances across a cell membrane without the need for energy input from the cell. This transport mechanism exploits concentration gradients, allowing molecules to move from areas of higher concentration to areas of lower concentration.

Several factors enable passive transport:

• Simple Diffusion: Movement of small or nonpolar molecules directly across the lipid bilayer.
• Facilitated Diffusion: Assistance by proteins such as channels and carriers to help move larger or polar molecules across the membrane.

During facilitated diffusion:

• Channel proteins form pores for specific ions or molecules to pass through.
• Carrier proteins undergo conformational changes to transport substances across the membrane.

With passive transport, cells achieve equilibrium while conserving energy, which is why it is a preferred mode for moving substances like oxygen and carbon dioxide into and out of cells.

Ion Channels

Ion channels are specialized protein pathways found in the membranes of cells, providing routes for ions to pass through the otherwise impermeable lipid bilayer. These channels play critical roles in a variety of cellular processes:

• Facilitating rapid ion movement to help regulate membrane potentials.
• Participating in signal transduction to relay messages across the cell membrane.
• Regulating the flow of ions, which is essential for muscle contractions and nerve impulse transmissions.

Ion channels have unique characteristics such as gates that can be open or closed based on specific stimuli:

• Voltage-gated Ion Channels: Open or close in response to changes in voltage across the membrane.
• Ligand-gated Ion Channels: Operate when a specific chemical ligand binds to the channel.

Overall, ion channels ensure proper cellular function and communication, crucial for the survival and adaptation of organisms.