Mastering Biology Chapter 5

The difference between pinocytosis and receptor-mediated endocytosis is that: A) pinocytosis brings only water molecules into the cell, but receptor-mediated endocytosis brings in other molecules as well B) pinocytosis increases the surface area of the plasma membrane, whereas receptor-mediated endocytosis decreases the plasma membrane surface area. C) pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity .D) pinocytosis requires cellular energy, but receptor-mediated endocytosis does not

C) pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity.

A bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in peroxisomes .vacuoles. Golgi vesicles .lysosomes. secretory vesicles.

.lysosomes.

For the following questions, match the labeled component of the cell membrane in the figure with its description. Which component in the accompanying figure is a protein fiber of the extracellular matrix?

A

A phospholipid also has two "tails" made up of two ------- molecules, which consist of a carboxyl group with a long hydrocarbon chain attached.

Fatty Acid

According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids?

They can move laterally along the plane of the membrane

You can recognize the process of pinocytosis when _____. the cell is engulfing a large particle the cell is engulfing extracellular fluid a receptor protein is involved

the cell is engulfing extracellular fluid

What property of dishwashing liquid (detergent) makes it useful to wash grease from pans?

Amphipathic nature. Detergents form micelles around the grease, which are then washed away because the polar head groups facing outward on the micelle are water-soluble.

What is the function of Structure E? A. stabilization of the phospholipids B. detection of environmental change C. structural support of the cell D. cell-cell communication E. transport across the plasma membrane https://mediaplayer.pearsoncmg.com/assets/secs-campbell-membrane-structure

Answer: A. stabilization of the phospholipids Cholesterol helps to stabilize the structure of the plasma membrane.

What role does a transcription factor play in a signal transduction pathway? By binding to a plasma membrane receptor it initiates a cascade. It relays a signal from the cytoplasm to the plasma membrane. It activates relay proteins. By binding to DNA it triggers the transcription of a specific gene. It is a plasma membrane protein that binds signal molecules.

By binding to DNA it triggers the transcription of a specific gene.

A red blood cell placed in a hypertonic solution will shrink in a process called crenation. A red blood cell placed in a hypotonic solution will swell and potentially burst in a process called hemolysis. To prevent crenation or hemolysis, a cell must be placed in an isotonic solution such as 0.9% (m/v) NaCl or 5.0% (m/v) glucose. This does not mean that a cell has a 5.0% (m/v) glucose concentration; it just means that 5.0% (m/v) glucose will exert the same osmotic pressure as the solution inside the cell, which contains several different solutes. A red blood cell is placed into each of the following solutions. Indicate whether crenation, hemolysis, or neither will occur. Solution A: 3.21% (m/v) NaCl Solution B: 1.65% (m/v) glucose Solution C: distilled H2O Solution D: 6.97% (m/v) glucose Solution E: 5.0% (m/v) glucose and 0.9%(m/v) NaCl

CRENATION: A, D, and E HEMOLYSIS: B and C NEITHER: (This activity shows why it is very important to use solutions that are isotonic to body fluids in intravenous solutions (IVs). If an IV solution were hypertonic to the body fluids, cells in the body would shrink. If an IV solution were hypotonic to the body fluids, cells in the body would swell)

Singer and Nicolson's fluid mosaic model of the membrane proposed that membranes

Consist of protein molecules embedded in a fluid bilayer of phospholipids.

For the following questions, match the labeled component of the cell membrane in the figure with its description. Which component in the accompanying figure is cholesterol?

E

Phospholipids form the main fabric of the plasma membrane. One feature of phospholipids is that when they are placed in an aqueous solution, they will self-assemble into a double layer (bilayer) that resembles the bilayer of the plasma membrane. This self-assembly occurs because phospholipids are hydrophilic at one end (the phospholipid head) and hydrophobic at the other end (the phospholipid tails).

EF- A) hydrophilic Cytoplasm- B) hydrophilic PM- C) grey on top, yellow on bottom PM- D) grey on bottom, yellow on top outside MP- E) hydrophilic middle MP- F) hydrophobic outside MP- G)hydrophilic (Phospholipids make up the main fabric of the plasma membrane. In the plasma membrane, the phospholipids are found in a bilayer. The hydrophilic heads are exposed to the aqueous environments of the cytoplasm and extracellular fluid, and the hydrophobic tails are sandwiched within, sheltered from these aqueous environments. Other elements of the plasma membrane conform to the hydrophilic and hydrophobic regions established by the phospholipids. For example, membrane proteins have hydrophilic and hydrophobic regions that are found among the hydrophilic and hydrophobic portions of the plasma membrane, respectively. Cholesterol is a hydrophobic molecule and is found among the hydrophobic tails, which you can see in the figure below)

Because the phosphate group and its attachments are either charged or polar, the phospholipid head is -----------, which means it has an affinity for water.

Hydrophilic

Because the C-H bonds in the fatty acid tails are relatively nonpolar, the phospholipid tails are -------- , which means they are excluded from water.

Hydrophobic

If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell? Hypertonic Hypotonic

Hypotonic

Which of the following membrane activities requires energy from ATP hydrolysis?

Movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid

A critical feature of the plasma membrane is that it is selectively permeable. This allows the plasma membrane to regulate transport across cellular boundaries--a function essential to any cell's existence. How does phospholipid structure prevent certain molecules from crossing the plasma membrane freely?

NONPOLAR: Hydrophobic Can cross easily No transport protein required POLAR: Hydrophilic Have difficulty in crossing the hydrophobic part Transport protein required to cross efficiently IONS: Hydrophilic Have difficulty in crossing the hydrophobic part Transport protein required to cross efficiently (The structure of the plasma membrane makes it selectively permeable, enabling it to regulate the transport of substances into and out of the cell. Small, nonpolar molecules are hydrophobic, so they can easily cross the phospholipid bilayer of the plasma membrane. Polar molecules and ions are hydrophilic, so they cannot very easily cross the hydrophobic portion of the plasma membrane (formed by the phospholipid tails). Water is an unusual molecule because, despite the fact that it is polar, it is small enough to pass directly through the hydrophobic interior of the lipid bilayer, albeit slowly. Polar molecules and ions generally cross the plasma membrane with the help of transport proteins. For example, water crosses the bilayer rapidly via transport proteins called aquaporins)

_____ catalyzes the production of _____, which then opens an ion channel that releases _____ into the cell's cytoplasm.

Phospholipase C ... IP3 .... Ca2+

A red blood cell has been placed into three different solutions. One solution is isotonic to the cell, one solution is hypotonic to the cell, and one solution is hypertonic to the cell. Determine which type of solution is in each beaker based on the cell's reaction.

SOTONIC: normal HYPOTONIC: slightly diluted (almost normal) HYPERTONIC: concentrated (deformed) (For a cell in an isotonic solution, water flows into the cell to the same extent that it flows out of the cell. If a cell is in a hypotonic solution, water flows into the cell, which causes it to swell and potentially burst. For a cell in a hypertonic solution, water flows out of the cell, which causes it to shrink.)

Which of the following particles could diffuse easily through a cell membrane?

Small nonpolar molecules, such as O2 and CO2

A semipermeable membrane is placed between the following solutions. Which solution will decrease in volume? A: 1.4% (m/v) starch B: 7.62% (m/v) starch

Solution A

A semipermeable membrane is placed between the following solutions. Which solution will increase in volume? Solution C: 9% (m/v) NaCl Solution D: 12.4% (m/v) NaC

Solution D

True or false? Osmosis is a type of diffusion.

True (Osmosis is the diffusion of water across a selectively permeable membrane.)

True or false? The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group.

True, the hydrophilic, or water-loving, portion of a phospholipid is the polar head, whereas the hydrophobic portion is the nonpolar tail.

Mammalian blood contains the equivalent of 0.15 M NaCl. Seawater contains the equivalent of 0.45 M NaCl. What will happen if red blood cells are transferred to seawater? The blood cells will expend ATP for active transport of NaCl into the cytoplasm. Water will leave the cells, causing them to shrivel and collapse. NaCl will be exported from the red blood cells by facilitated diffusion.

Water will leave the cells, causing them to shrivel and collapse.

A protein kinase activating many other protein kinases is an example of _____.

amplification

Which of the following would diffuse through the lipid bilayer of a plasma membrane most slowly, if at all?

an amino acid

Which of these acts as a second messenger?

cAMP (cyclic AMP)

2. Phospholipids vary in the small molecules attached to the phosphate group. The phospholipid shown in the figure has a----- attached to phosphate.

choline group

The movement of glucose into a cell against a concentration gradient is most likely to be accomplished by which of the following?

cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis. (Movement of most solutes against their concentration gradient couples the movement of one solute down its concentration gradient to the movement of another (glucose in this case) against its concentration gradient.)

The presence of cholesterol in the plasma membranes of some animals... makes the membrane less flexible, allowing it to sustain greater pressure from within the cell enables the animal to remove hydrogen atoms from saturated phospholipids. enables the animal to add hydrogen atoms to unsaturated phospholipids enables the membrane to stay fluid more easily when cell temperature drops

enables the membrane to stay fluid more easily when cell temperature drops.

Calcium ions that act as second messengers are stored in _____.

endoplasmic reticula

Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm. Using this information, which transport mechanism is most probably functioning in the intestinal cells? active transport pumps facilitated diffusion exocytosis simple diffusion phagocytosis

facilitated diffusion

Identify Structure A. https://mediaplayer.pearsoncmg.com/assets/secs-campbell-membrane-structure

glycoprotein

Which of the following is a substance that acts at a long distance from the site at which it is secreted?

hormone

You know that this cell is in a(n) _____ solution because the cell _____. The figure shows a cell membrane, the extracellular fluid, and the cytoplasm. The concentration of solute is higher inside the cell. The figure shows two states of the cell: when it was just placed in this solute and over the time. Over the time the cell increased in size.

hypotonic ... swelled

Endocytosis moves materials _____ a cell via _____. into ... membranous vesicles into ... facilitated diffusion into ... a transport protein out of ... diffusion out of ... membranous vesicles

into ... membranous vesicles

Some solutes are able to pass directly through the lipid bilayer of a plasma membrane, whereas other solutes require a transport protein or other mechanism to cross between the inside and the outside of a cell. The fact that the plasma membrane is permeable to some solutes but not others is what is referred to as selective permeability. Which of the following molecules can cross the lipid bilayer of a membrane directly, without a transport protein or other mechanism? Select all that apply.

lipids carbon dioxide oxygen water

The majority of solutes that diffuse across the plasma membrane cannot move directly through the lipid bilayer. The passive movement of such solutes (down their concentration gradients without the input of cellular energy) requires the presence of specific transport proteins, either channels or carrier proteins. Diffusion through a transport protein in the plasma membrane is called facilitated diffusion.

only channels allow water molecules and small ions to flow quickly across the membrane provide a continuous path across the membrane only carriers transport primarily small polar organic molecules undergo a change in shape to transport solutes across the membrane both channels and carriers provide a hydrophilic path across the membrane are integral membrane proteins transport solutes down a concentration or electrochemical gradient

What name is given to the process by which water crosses a selectively permeable membrane? diffusion passive transport phagocytosis osmosis pinocytosis

osmosis

Diffusion across a biological membrane is called

passive transport

Facilitated diffusion is a type of _______.

passive transport

A white blood cell engulfing a bacterium is an example of _____. exocytosis phagocytosis pinocytosis facilitated diffusion receptor-mediated endocytosis

phagocytosis

A phospholipid has a "head" made up of a glycerol molecule attached to a single ------ which is attached to another small molecule.

phosphate group

Identify Structure D https://mediaplayer.pearsoncmg.com/assets/secs-campbell-membrane-structure

phospholipid bilayer of membrane

Which of the following types of molecules are the major structural components of the cell membrane?

phospholipids and proteins

A signal transduction pathway is initiated when a _____ binds to a receptor.

signal molecule

What kinds of molecules pass through a cell membrane most easily? large and hydrophobic small and hydrophobic ionic large polar monosaccharides such as glucose

small and hydrophobic

Structure A is a _____. The figure shows a cell membrane with integral molecule, which consists of two similar parts with specific recess. There are many particles in the extracellular fluid. One of these particles is labeled A. https://session.masteringbiology.com/problemAsset/1100513/12/0713q.jpg

solute

When molecules move down their concentration gradient, they move from where they are------to where they are------- .

they are more concentrated to where they are less concentrated.

The primary function of polysaccharides attached to the glycoproteins and glycolipids of animal cell membranes is

to mediate cell-to-cell recognition.

Structure B is a _____. The figure shows a cell membrane with integral molecule marked B, which consists of two similar parts with specific recess. There are many particles in the extracellular fluid. https://session.masteringbiology.com/problemAsset/1100513/12/0713q.jpg

transport protein