Question

match the membrane molecule to its function:
column a
1 allow passage of materials that do not normally cross through phospholipids
2 maintain the fluidity of the membrane
3 make up the majority of the molecules of the membrane, in two layers
4 like chemical identification tags for cellular communication
column b
a. membrane proteins
b. membrane carbohydrates
c. cholesterol
d. phospholipids
question 8
what are the jobs of membrane proteins? select all that apply.
a dna replication
b cell division
c membrane fluidity
d enzymatic action
e cellular identification
f transport of substances

Explanation:

• Membrane Proteins:
• Some membrane proteins act as channels or carriers, allowing the passage of substances that don't normally cross the phospholipid bilayer (like polar or large molecules).
• Enzymatic membrane proteins can catalyze reactions either on the inner or outer surface of the cell membrane.
• Proteins involved in cell - cell recognition help cells identify each other, which is crucial for processes like the immune response (where immune cells recognize self and non - self cells) and tissue formation.
• Transport proteins (a type of membrane protein) are responsible for the movement of substances across the membrane, which can be either passive (facilitated diffusion) or active (using energy).
• DNA replication: This process mainly occurs in the nucleus (in eukaryotes) and involves enzymes like DNA polymerase, helicase, etc., which are not membrane proteins.
• Cell division: It is a complex process involving the nucleus (chromosome segregation), cytoskeleton (for cell shape changes and organelle movement), and many intracellular signaling pathways, not membrane proteins as the main actors.
• Membrane fluidity: Cholesterol is the molecule mainly responsible for maintaining membrane fluidity, not membrane proteins.

Answer:

d. Enzymatic action, e. Cellular identification, f. Transport of substances