Exam 2 Flashcards
(45 cards)
A phospholipid is a
nonpolar lipid molecule that is made amphipathic by the addition of a phosphate
Cooking oil and gasoline are NOT amphipathic molecules because they
Do not have a polar or charged ions
Phospholipids and triglycerides both
have a glycerol backbone
Which of the following is a large organic molecule that is NOT assembled by polymerization of a few kinds of simple subunits ?
a steroid
Lipids that form membranes have what kind of structure ?
polar heads and nonpolar tails; the nonpolar tails interact with water
Which aspect oh phospholipids is most important to the formation of bilayers ?
They are amphipathic
Which of the following crosses lipid bilayers ?
a small , nonpolar molecule like oxygen
Which of the following does not cross the lipid bilayers ?
a sodium ion
Which of the following is TRUE of osmosis ?
in osmosis , water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration
Celery stalks that are immersed in freshwater for several hours become stiff. Similar stalks left in a 0.15 M salt solution becomes limp. From this we can deduce that the freshwater ..
is hypotonic and the salt solution is hypertonic to the cells of the celery stalks
A patient was involved in a serious accident and lost a large quantity of blood. In an attempt to replenish body fluids , distilled — equal to the volume of blood lost– is added to the blood directly via one of his veins. What will be the most probable result of this transfusion ?
The patient’s red blood cells will swell and possibly burst because the blood has become hypotonic compared to the cells
Under what circumstances does membrane transport require energy ?
whenever a solute is moved against its gradient
Where would you most likely find an integral membrane protein ?
spanning the cell membrane , with parts of the protein visible from both the inside and the outside of the cell
Which of the following types of molecules are the major structural components of the cell membrane ?
phospholipids and proteins
For a protein to be an integral membrane protein , it would have to be ?
amphiphathic , with at least one hdrophobic region
All of the following are part of a prokaryotic cell EXCEPT ?
the nucleoid
Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules ?
proteins
Acell with a predominance of free ribosomes is most likely ?
primarily producing proteins in the cytosol
Which type of organelle or structure is primarily involved in the synthesis of oils , phospholipids and steroids ?
smooth endoplasmic reticulum
Which organelle often takes up much of the volume of a plant cell ?
vacuole
Which organelle is the primary site of ATP synthesis in eukaryotic cells ?
mitochondrion
Which plant cell organelle contains its own DNA and ribosomes ?
mitochondrion
Thylakoids , DNA and ribosomes are all components found in ?
chloroplasts
Which structure is common to plant and animal cells ?
mitochondrion
