week 6: membrane and protein traffiking

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Questions and Answers

Which type of lipids primarily constitute the plasma membrane bilayer?

Cholesterol

Sterols

Phosphoglycerides (correct)

Sphingolipids

What is a key function of integral membrane proteins?

Transport of metabolites (correct)

Storage of genetic material

Energy production

Synthesis of lipids

Which integral membrane protein function is not mentioned?

Adhesion

Signalling

Energy metabolism (correct)

Pathogenesis

Approximately what percentage of protein-coding genes do integral membrane proteins represent?

25% Signup and view all the answers

Which of the following is an example of a phosphoglyceride with a glycerol head group?

Phosphatidylglycerol (PG) Signup and view all the answers

What is not a property of the plasma membrane?

Inflexible structure Signup and view all the answers

Which head group is present in phosphatidylcholine?

Choline Signup and view all the answers

What role do integral membrane proteins primarily play in the cell?

Metabolite transport and signaling Signup and view all the answers

What is the primary function of a sodium-potassium pump?

To move 3 Na+ out of the cell and 2 K+ into the cell Signup and view all the answers

How do ATP-binding cassette (ABC) transporters primarily operate?

By transporting substrates in or out of cells using ATP Signup and view all the answers

What defines the role of potassium channels in cellular function?

Facilitating neuronal excitability and muscle repolarization Signup and view all the answers

Which type of membrane transport is characterized by the exchange of two different compounds in opposite directions?

Antiporter Signup and view all the answers

What is the main energy source used by membrane pumps for active transport?

Adenosine triphosphate (ATP) Signup and view all the answers

What does a uniporter transport mechanism primarily involve?

One compound moving across the membrane Signup and view all the answers

What drives the Na-Cl carrier's transport mechanism for calcium ions?

Electrochemical gradient for sodium ions Signup and view all the answers

What is a characteristic feature of pumps compared to channels in membrane transport?

Pumps require ATP or light, while channels do not Signup and view all the answers

Which ion is primarily moved by the proton pump during chemiosmosis?

H+ Signup and view all the answers

What is the role of hydrophobic chains in integral membrane proteins?

To insert into the lipid bilayer of membranes Signup and view all the answers

Study Notes

Plasma Membrane Lipids

Phospholipids are the primary lipids that constitute the plasma membrane bilayer.
Integral membrane proteins are crucial for various cellular functions.

Integral Membrane Protein Functions

Integral membrane proteins facilitate the transport of molecules across the membrane.
They can act as receptors for signals and play a role in cell-cell recognition.
They can also participate in enzymatic reactions and contribute to structural support of the membrane.

Integral Membrane Protein Percentage

Integral membrane proteins represent approximately 20-30% of protein-coding genes.

Phosphoglyceride Example

Phosphatidylcholine is an example of a phosphoglyceride with a glycerol head group.

Plasma Membrane Properties

The plasma membrane is selectively permeable, allowing the passage of certain molecules while restricting others.
It is also fluid, allowing for the movement of lipids and proteins within the bilayer.

Phosphatidylcholine Head Group

The head group present in phosphatidylcholine is a choline molecule.

Integral Membrane Protein Role

Integral membrane proteins play a crucial role in facilitating the transport of molecules, signal transduction, and cell-cell interactions.

Sodium-Potassium Pump Function

The sodium-potassium pump actively transports sodium ions out of the cell and potassium ions into the cell, maintaining the electrochemical gradient across the membrane.

ABC Transporter Operation

ATP-binding cassette (ABC) transporters utilize the energy from ATP hydrolysis to power the movement of molecules across the membrane.

Potassium Channel Role

Potassium channels are specialized proteins that facilitate the selective passage of potassium ions across the membrane, contributing to the establishment and maintenance of the resting membrane potential.

Antiport Transport Mechanism

Antiport is a type of membrane transport characterized by the simultaneous movement of two different compounds in opposite directions across the membrane, often coupled to an electrochemical gradient.

Membrane Pump Energy Source

Active transport mechanisms, like pumps, primarily use ATP as their energy source.

Uniporter Transport Mechanism

A uniporter transport mechanism involves the movement of a single type of molecule across the membrane, driven by the electrochemical gradient of that molecule.

Na-Cl Carrier Transport Mechanism

The Na-Cl carrier utilizes the electrochemical gradient of sodium ions to drive the transport of calcium ions across the membrane.

Pumps vs. Channels

Pumps, unlike channels, actively transport molecules against their concentration gradients, requiring energy expenditure, whereas channels facilitate passive transport along the concentration gradient.

Proton Pump Chemiosmosis

The proton pump primarily moves protons across the membrane during chemiosmosis, generating a proton gradient that drives ATP synthesis.

Hydrophobic Chain Role

Hydrophobic chains in integral membrane proteins interact with the hydrophobic interior of the lipid bilayer, anchoring the protein within the membrane.

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