Quiz 1 Flashcards
Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. Which of the following ions is the most abundant inside a typical mammalian cell?
K+
Na+
Cl-
Ca2+
K+
A disaccharide consists of a sugar covalently linked to another molecule such as an amino acid or a nucleotide.
True
False
False, they are linked by glycosidic bonds
Although covalent bonds are 10–100 times stronger than noncovalent interactions, many biological processes depend on the number and type of noncovalent interactions between molecules. Which of the noncovalent interactions below will contribute most to the strong and specific binding of two molecules, such as a pair of proteins?
van der Waals attractions
electrostatic attractions
hydrogen bonds
hydrophobic interactions
Electrostatic attractions
How does a bilayer arrangement of phospholipids result in higher entropy for the system and thus make membrane formation energetically favorable?
Polar head groups form a hydrogen-bonding network at the interface with water.
Fatty acid tails are highly saturated and flexible.
Hydrogen bonds form between neighboring polar head groups in the bilayer.
Water molecules form cage-like structures around hydrophobic molecules, thus encouraging the latter to cluster together and limit their contact with water.
D.
Consider a transport vesicle containing a membrane glycoprotein. The glycoprotein and the vesicle’s phospholipids are delivered to the plasma membrane, as shown in the figure below. Which of the following is an accurate description of the outcome of this process?
The portion of the glycoprotein that was inside of the vesicle ends up in the cytosol after it is delivered to the plasma membrane.
The fusion event between the vesicle and the plasma membrane randomizes the phospholipids between the cytosolic and noncytosolic faces of the bilayer.
The phospholipids that are delivered to the noncytosolic face of the plasma membrane used to be in the interior (luminal) face of the vesicle.
Some of the individual phospholipid molecules are released into the cytosol to prevent the plasma membrane, and thus the cell, from becoming too large.
C.
What do polysaccharides, proteins, and nucleic acids have in common?
They all contain a phosphate group and are linked by phosphodiester bonds.
They are all made from monomer subunits linked by covalent bonds.
They are all made from monomer subunits linked by ionic bonds.
They are polymers held together by glycosidic and peptide bonds
B.
A bacterium is suddenly expelled from a warm human intestine into the cold world outside. Which of the following adjustments might the bacterium make to maintain the same level of fluidity in its cell (plasma) membrane?
decrease the amount of cholesterol in the membrane
decrease the number of glycolipids in the membrane
add lipids with hydrocarbon tails that are longer and have fewer double bonds
add lipids with hydrocarbon tails that are shorter and have more double bond
D.
Which statement surrounding the discovery of cells is FALSE?
Cells came to be known as the smallest universal building block of living organisms.
New cells arise from the growth and division of previously existing cells.
Scientists concluded that new cells can form spontaneously from the remnants of ruptured cells.
Light microscopy was essential in demonstrating the commonalities between plant and animal tissues.
C.
The terms “prokaryote” and “bacterium” are synonyms.
True
False
False, archaea are also prokaryotes
Carbon atoms can form double bonds with other carbon atoms, nitrogen atoms, and oxygen atoms. Double bonds can have important consequences for biological molecules because they are __________ compared to single covalent bonds.
unstable
long
rigid with respect to rotation
weak
C.
