Question

What functions do membrane proteins serve? synthesize phospholipids for the maintenance and growth of the cell membrane transport nutrients into the cell that cannot otherwise cross the phospholipid bilayer transport wastes out of the cell that cannot otherwise cross the cell membrane prevent small, uncharged substances from crossing the phospholipid bilayer synthesize DNA within the cell using raw materials found outside the cell

Answer 1

Membrane proteins serve various functions including the transport of nutrients into and out of the cell, excretion of wastes, signal transduction, and serving as anchors for structural components. Integral proteins form channels or pumps for transport, while peripheral proteins function as enzymes or recognition sites. Together, they are essential for maintaining cellular homeostasis.

Step-by-step explanation:

Functions of Membrane Proteins

Membrane proteins are crucial for a variety of cellular processes. Firstly, they are involved in the transport of nutrients across the cell membrane. Such nutrients cannot cross the phospholipid bilayer on their own due to their polar nature or size. Similarly, membrane proteins assist in the excretion of waste products like CO₂, which need to be regulated within the cell. Another key role of these proteins is in transmitting signals; acting as signal transducers, they allow the cell to respond to external cues. Additionally, they also serve as anchors for the cell's structural framework, interacting with the cellular cytoskeleton and extracellular matrix.

Specifically, these proteins can be classified into two major classes: integral proteins, which are typically embedded within the lipid bilayer, and peripheral proteins, which are associated with the bilayer's surface. Integral proteins can form channels or pumps that facilitate active and passive transport, while peripheral proteins can function as enzymes or cell recognition sites that aid in immune responses or cell adhesion.

Overall, membrane proteins are indispensable for maintaining the cell's internal environment, allowing for a controlled exchange of substances to sustain cellular life.

Answer 2

• transport nutrients into the cell that cannot otherwise cross the phospholipid bilayer
• transport wastes out of the cell that cannot otherwise cross the cell membrane

Step-by-step explanation:

Cell membrane integral proteins especially trans-membrane proteins facilitate and regulate the movement of particular molecules across the cell membrane. Examples of these molecules are glucose and sodium ions. These molecules are either charged and cannot pass through the hydrophobic lipid layer of the cell membrane and/or are too large to pass through the cell membrane pores (like the aquaporins).Other types of cell membrane proteins are peripheral proteins. Collectively these proteins can have several other functions include cell signaling, enzymatic activity, cell-to-cell recognition , and etcetera.