Question

animation, and answer the following questions below.
a. what kind of molecules diffuse (go through) the cell membrane directly?

b. how can some large molecules and charged ions get through the cell membrane?

1. investigate: select the nuclear membrane closeup. how is the nuclear membrane similar to the cell membrane?

1. investigate: select the mitochondrion closeup. what happens inside the mitochondrion?

1. investigate: select the ribosome closeup. how does the cell make proteins inside the ribosome?

1. investigate: select the vesicle closeup. how do vesicles move through the cell?

Explanation:

Question A

The cell membrane is selectively permeable. Small, non - polar molecules like oxygen ($O_2$), carbon dioxide ($CO_2$), and small lipids can diffuse directly through the lipid bilayer of the cell membrane because they can dissolve in the non - polar interior of the lipid bilayer.

Large molecules and charged ions cannot pass through the lipid bilayer directly. They need the help of transport proteins. There are two main types: channel proteins (which form pores for specific ions to pass through) and carrier proteins (which bind to the molecule/ion and change shape to transport it across the membrane). Also, for very large molecules or particles, processes like endocytosis (cell engulfs the substance) and exocytosis (cell releases the substance) are used.

Both the nuclear membrane and the cell membrane are phospholipid bilayers. They are selectively permeable, meaning they regulate the passage of substances into and out of their respective compartments (nucleus for nuclear membrane, cell for cell membrane). Both have embedded proteins that play roles in transport, signaling, etc.

Answer:

Small, non - polar molecules (such as $O_2$, $CO_2$, small lipids)

Question B