Keystone Review – Cell Membrane
1. C – The polar water molecule is repelled by
the nonpolar, hydrophobic, fatty acid tail.
2. D – Nucleic acids, such as DNA and RNA do
not make up the plasma membrane
3. C – Protein channels provide a way for small
molecules and ions to cross the plasma
membrane.
Keystone Response – Cell Membrane
• Cl –
• O2
• Starch
• No. Chlorine is a polar molecule and
charged molecules cannot pass through the
cell membrane
• Yes. An oxygen molecule is small and
nonpolar. Small, nonpolar, uncharged
molecules can fit through the phospholipid
membrane without assistance.
• No. Starch is a macromolecule. The size of
this molecule prevents it from crossing the
plasma membrane.
Keystone Response – Cell Membrane
A. The cytoskeleton
will be assembled in
the loose ribosomes
in the cytoplasm
because it does not
need to be exported
out of the
cytoplasm.
Keystone Response – Cell Membrane
B. The hormone will be
synthesized in the smooth
ER, which synthesizes lipids
and hormones. It will be
sent to the golgi apparatus
and packaged for export in
vesicles.
Keystone Response – Cell Membrane
C. The cell receptor will be
assembled by ribosomes on
the rough ER. It will be
package into a vesicle that
will be transported to the
golgi apparatus, modified
further, and packaged into a
vesicle that will merge with
the plasma membrane.