Biology Ch 5-8 Fifth edition Brooker
BRCC 1033 Questions and Correct
Answers
Describe the chemical composition of biological membranes? ✅Biological membranes
are bilayers of phospholipids with associated proteins and carbohydrates.
What can never be energetically favorable in a biological membrane and therefore will
not occur spontaneously? ✅the flip-flop of phospholipids to the opposite leaflet
Let's suppose an insect, which doesn't maintain a constant body temperature, was
exposed to a shift in temperature from 60°F to 80°F. Which of the following types of
membrane changes would be the most beneficial in helping the insect cope with the
temperature shift? ✅increase the length of the lipid tails of phospholipids
Carbohydrates of the plasma membrane ✅are bonded to a protein or lipid, are located
on the outer surface of the plasma membrane, can function as cell markers for
recognition by other cells.
A transmembrane protein in the plasma membrane is glycosylated at two sites in the
polypeptide sequence. Where in this protein would you expect these two sites to be?
✅in hydrophilic regions that project into the extracellular environment
The tendency for Na+ to move into the cell can be due to ✅The higher numbers of
Na+ outside the cell, resulting in a chemical concentration gradient. And the net
negative charge inside the cell attracting the positively charged Na+
Let's suppose the solute concentration inside the cells of a plant is 0.3 M and the
concentration outside is 0.2 M. If we assume that the solute does not readily cross the
membrane, which of the following statements best describes what will happen? ✅The
plant cells will take up a little water, and the plasma membrane will push against the cell
wall.
What features of a biological membrane are major contributors to its selective
permeability? ✅phospholipid bilayer, transport proteins
What is the name given to the process in which solutes are moved across a membrane
against their concentration gradient? ✅active transport
Large particles or large volumes of fluid can be brought into the cell by ✅endocytosis.
, How are phospholipids transferred to the leaflet of the ER membrane that faces the ER
lumen? ✅Figure 5.6 Phospolipids are transferred to the other leaflet of the ER
membrane via enzymes called flippases.
What structural feature of a polypeptide causes a region of it to form a transmembrane
segment? ✅Figure 5.7 The most common feature causing a transmembrane segment
to form is a stretch (about 20) of amino acids that mostly have hydrophobic (nonpolar)
side chains.
Let's suppose the inside of a cell has a solute concentration of 0.3 M and the outside
has a concentration of 0.2 M. If the membrane is impermeable to solutes, in which
direction will water move? ✅Figure 5.13 Water will move from outside to inside, from
the lower to the higher concentration.
What is the purpose of gating? ✅Figure 5.15 The purpose of gating is to regulate the
function of channels, allowing them to be open or closed.
What is the function of the protein coat? ✅Figure 5.21 The protein coat allows the
budding process at the surface of the Golgi membrane to form a vesicle.
Discuss how transmembrane proteins are important in the binding of cells to each other
and the binding of cells to the extracellular matrix. ✅Figure 5.5 Transmembrane
proteins called cell adhesion molecules bind to each other to promote cell-to-cell
adhesion. In addition, they can bind to filaments in the extracellular matrix, such as
collagen fibers, thereby causing a cell to adhere to the extracellular matrix.
Which amino acid, described in Chapter 3 (see Figure 3.13), would you expect to be
more likely to cross an artificial phospholipid bilayer, leucine or lysine? ✅Figure 5.10
Leucine would be more likely to cross an artificial phospholipid bilayer because it is
more hydrophobic than lysine.
What types of ion gradients are important for the conduction of action potentials across
the plasma membrane of a neuron? ✅Figure 5.11 Gradients of sodium and potassium
ions are important for the conduction of action potentials.
Reactions that release free energy are ✅exergonic and spontaneous.
Enzymes speed up reactions by ✅lowering the activation energy necessary to initiate
a reaction.
For the idealized reaction aA + bB ⇌ cC + dD, suppose that the equilibrium constant,
Keq, is 0.01. If the starting concentrations for A, B, C, and D are 1 M each, what would
you predict based on the value of Keq? ✅The reverse reaction is favored.
BRCC 1033 Questions and Correct
Answers
Describe the chemical composition of biological membranes? ✅Biological membranes
are bilayers of phospholipids with associated proteins and carbohydrates.
What can never be energetically favorable in a biological membrane and therefore will
not occur spontaneously? ✅the flip-flop of phospholipids to the opposite leaflet
Let's suppose an insect, which doesn't maintain a constant body temperature, was
exposed to a shift in temperature from 60°F to 80°F. Which of the following types of
membrane changes would be the most beneficial in helping the insect cope with the
temperature shift? ✅increase the length of the lipid tails of phospholipids
Carbohydrates of the plasma membrane ✅are bonded to a protein or lipid, are located
on the outer surface of the plasma membrane, can function as cell markers for
recognition by other cells.
A transmembrane protein in the plasma membrane is glycosylated at two sites in the
polypeptide sequence. Where in this protein would you expect these two sites to be?
✅in hydrophilic regions that project into the extracellular environment
The tendency for Na+ to move into the cell can be due to ✅The higher numbers of
Na+ outside the cell, resulting in a chemical concentration gradient. And the net
negative charge inside the cell attracting the positively charged Na+
Let's suppose the solute concentration inside the cells of a plant is 0.3 M and the
concentration outside is 0.2 M. If we assume that the solute does not readily cross the
membrane, which of the following statements best describes what will happen? ✅The
plant cells will take up a little water, and the plasma membrane will push against the cell
wall.
What features of a biological membrane are major contributors to its selective
permeability? ✅phospholipid bilayer, transport proteins
What is the name given to the process in which solutes are moved across a membrane
against their concentration gradient? ✅active transport
Large particles or large volumes of fluid can be brought into the cell by ✅endocytosis.
, How are phospholipids transferred to the leaflet of the ER membrane that faces the ER
lumen? ✅Figure 5.6 Phospolipids are transferred to the other leaflet of the ER
membrane via enzymes called flippases.
What structural feature of a polypeptide causes a region of it to form a transmembrane
segment? ✅Figure 5.7 The most common feature causing a transmembrane segment
to form is a stretch (about 20) of amino acids that mostly have hydrophobic (nonpolar)
side chains.
Let's suppose the inside of a cell has a solute concentration of 0.3 M and the outside
has a concentration of 0.2 M. If the membrane is impermeable to solutes, in which
direction will water move? ✅Figure 5.13 Water will move from outside to inside, from
the lower to the higher concentration.
What is the purpose of gating? ✅Figure 5.15 The purpose of gating is to regulate the
function of channels, allowing them to be open or closed.
What is the function of the protein coat? ✅Figure 5.21 The protein coat allows the
budding process at the surface of the Golgi membrane to form a vesicle.
Discuss how transmembrane proteins are important in the binding of cells to each other
and the binding of cells to the extracellular matrix. ✅Figure 5.5 Transmembrane
proteins called cell adhesion molecules bind to each other to promote cell-to-cell
adhesion. In addition, they can bind to filaments in the extracellular matrix, such as
collagen fibers, thereby causing a cell to adhere to the extracellular matrix.
Which amino acid, described in Chapter 3 (see Figure 3.13), would you expect to be
more likely to cross an artificial phospholipid bilayer, leucine or lysine? ✅Figure 5.10
Leucine would be more likely to cross an artificial phospholipid bilayer because it is
more hydrophobic than lysine.
What types of ion gradients are important for the conduction of action potentials across
the plasma membrane of a neuron? ✅Figure 5.11 Gradients of sodium and potassium
ions are important for the conduction of action potentials.
Reactions that release free energy are ✅exergonic and spontaneous.
Enzymes speed up reactions by ✅lowering the activation energy necessary to initiate
a reaction.
For the idealized reaction aA + bB ⇌ cC + dD, suppose that the equilibrium constant,
Keq, is 0.01. If the starting concentrations for A, B, C, and D are 1 M each, what would
you predict based on the value of Keq? ✅The reverse reaction is favored.
