Bio 101: Chapter/Lab 5

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

endoplasmic reticula

How does the diffusion rate change when temperature increases?

higher temp=particles move faster=faster diffusion rate -As temperature increases, molecules tend to move more quickly. Therefore, diffusion speeds up at elevated temperatures.

Which of the following would tend to increase membrane fluidity? A lower temperature A greater proportion of phospholipids with unsaturated hydrocarbon tails A greater proportion of phospholipids with saturated hydrocarbon tails A greater proportion large glycolipids relative to lipids having smaller molecular masses A relatively high protein content in the membrane

A greater proportion of phospholipids with unsaturated hydrocarbon tails

Which of the following would be least likely to pass through a plasma membrane without the help of a transport protein? A large polar molecule A large nonpolar molecule A small nonpolar molecule Dissolved gases such as oxygen or carbon dioxide All of the listed substances would pass easily through the membrane.

A large polar molecule

Which of these is a membrane receptor?

B

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.

Which component is a microfilament of the cytoskeleton?

C

Do cells lose water under hypotonic, isotonic or hypertonic conditions? Why? Cells lose water under hypotonic conditions, since the higher solute concentration is found inside the cell. Cells lose water under hypertonic conditions, since the higher solute concentration is found outside the cell. Cells lose water under isotonic conditions, since the higher solute concentration is found inside the cell.

Cells lose water under hypertonic conditions, since the higher solute concentration is found outside the cell.

In what way do the membranes of eukaryotic cells vary? Only certain membranes are constructed from amphipathic molecules. Some membranes have hydrophobic surfaces exposed to the cytoplasm, whereas others have hydrophilic surfaces facing the cytoplasm. Certain proteins are unique to the membrane of each cell type. Only certain membranes of the cell are selectively permeable. Phospholipids are found only in certain membranes.

Certain proteins are unique to the membrane of each cell type.

In what way do the membranes of eukaryotic cells vary? Only certain membranes of the cell are selectively permeable. Certain proteins are unique to the membrane of each cell type. Some membranes have hydrophobic surfaces exposed to the cytoplasm, whereas others have hydrophilic surfaces facing the cytoplasm. Phospholipids are found only in certain membranes. Only certain membranes are constructed from amphipathic molecules.

Certain proteins are unique to the membrane of each cell type.

Which of these acts as a second messenger?

D (cyclic AMP)

Which component is cholesterol?

E

Which of the following statements is correct about diffusion?

It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration. Submit

How does the diffusion rate change when the size (molecular weight) of diffusing molecules increases?

Larger, heavier molecules tend to move more slowly. Therefore, increasing molecular weight slows diffusion.

Which of the following would diffuse through the lipid bilayer of a plasma membrane most rapidly?

O2

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

Oxygen (O2)

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

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

Which of the following enables a cell to concentrate and take in a specific kind of molecule? Passive transport Osmosis Facilitated diffusion Channel proteins Receptor-mediated endocytosis

Receptor-mediated endocytosis

Orange dye moves independently of purple dye

always

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 the following molecules is most likely to passively diffuse across the plasma membrane? Sodium ion Glucose Carbon dioxide Hemoglobin DNA

carbon dioxide

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

choline group

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

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

osmosis

diffusion of water across a selectively permeable membrane -can move freely, still need to look at concentration of water

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?

facilitated diffusion

active transport of cell membrane

from lower to higher concentration; uses ATP; uses a protein

Purple dye moves only from side B to side A.

never

Concentration gradients exist that drive diffusion of both dyes

only before equilibrium is reached

pinocytosis

process by which a cell takes in liquid from the surrounding environment

phagocytosis

process in which extensions of cytoplasm surround and engulf large particles and take them into the cell

function of cell membrane

protection, controlling entry/exit, cell transport (active and passive transport)

The general name for an enzyme that transfers phosphate groups from ATP to a protein is __________. protein kinase protein dehydrogenase peptidase protein cyclase protein phosphatase

protein kinase

The molecule cAMP directly activates __________. receptor tyrosine kinases adenylyl cyclase phosphodiesterase protein kinase A G proteins

protein kinase A

_______ give the cell membrane its mosaic structure

proteins

Second messengers tend to be water-soluble and small. This accounts for their ability to __________. rapidly cross the plasma membrane cross the nuclear membrane and interact with DNA rapidly move throughout the cell by diffusion move from substrate to substrate during a phosphorylation cascade pass quickly from cell to cell

rapidly move throughout the cell by diffusion

You can recognize the process of pinocytosis when _____.

the cell is engulfing extracellular fluid

Early work on signal transduction and glycogen metabolism by Sutherland indicated that __________. A. the signal molecule combined directly with a cytosolic enzyme to form an active quaternary structure B. the signal molecule did not interact directly with the cytosolic enzyme but required an intact plasma membrane before the enzyme could be activated C. the signal molecule worked equally well with intact or disrupted cells D. epinephrine is involved in response to stress E. the cell-signaling pathway involves two separate steps: transduction and response

the signal molecule did not interact directly with the cytosolic enzyme but required an intact plasma membrane before the enzyme could be activated

facilitated diffusion

the transport of substances through a cell membrane along a concentration gradient with the aid of carrier proteins

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because __________. A. the number of molecules used is small and fixed B. they amplify the original signal manyfold C. they always lead to the same cellular response D. they are species specific E. they counter the harmful effects of phosphatases

they amplify the original signal manyfold

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. ions oxygen sucrose carbon dioxide water lipids proteins

water, oxygen, carbon dioxide, lipids

hypertonic

when comparing two solutions, the solution with the greater concentration of solutes

hypotonic

when comparing two solutions, the solution with the lesser concentration of solutes

isotonic

when the concentration of two solutions is the same

Nitric oxide is unusual among animal signal molecules in that it __________. activates proteins by removing phosphate is a gas binds to membrane receptors and cytoplasm receptors acts by directly binding to DNA enters the cell via a protein channel

is a gas

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.

isotonic

both channels and carriers

- provide a hydrophilic path across the membrane - transport solutes down a concentration or electrochemical gradient - are integral membrane proteins

only channels

-provide a continuous path across the membrane -allow water molecules and small ions to flow quickly across the membrane

only carriers

-undergo a change in shape to transport solutes across the membrane -transport primarily small polar organic molecules

Which component is the fiber of the extracellular matrix?

A

Which of these is responsible for initiating a signal transduction pathway?

A

The concentration of solutes in a particular cell is about 2%, but the cell contains almost no sucrose or urea. Sucrose cannot pass through the membrane of this cell, but water and urea can. Osmosis would cause this cell to shrink the most when immersed in which of the following solutions? A hypertonic sucrose solution A hypotonic sucrose solution Pure water A hypertonic urea solution A hypotonic urea solution

A hypertonic sucrose solution

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

Amphipathic nature

How does the diffusion rate change when the concentration of solute molecules decreases?

As the concentration of solute molecules decreases, molecules tend to have fewer molecular collisions. Therefore, diffusion slows at decreased solute concentration.

Which of the following statements is TRUE with regard to this animation? ( https://session.masteringbiology.com/myct/itemView?offset=next&assignmentProblemID=174332800# ) The cell does not expend ATP. The cell is not expending energy. Both sodium and potassium ions are transported against their concentration gradients. Sodium ions are transported down their concentration gradient. Potassium ions are transported down their concentration gradient.

Both sodium and potassium ions are transported against their concentration gradients.

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 H2OSolution D: 6.97% (m/v) glucose Solution E: 5.0% (m/v) glucose and 0.9%(m/v) NaCl Drag each solution to the appropriate bin.

Crenation: A, D, E Hemolysis: B, C

Which of the following processes and organelle(s) account for the replacement of lipids and proteins lost from the plasma membrane? Active transport and the rough endoplasmic reticulum Flip-flop of phospholipids from one side of the plasma membrane to the other and the Golgi Receptor-mediated endocytosis and smooth ER and Golgi Exocytosis and smooth and rough ER Endocytosis and Golgi

Exocytosis and smooth and rough ER

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).

Extracellular fluid: A-hydrophilic B-hydrophilic Plasma membrane: C-gray on top yellow on bottom D-yellow on top gray on bottom Cytoplasm: B-hydrophilic G-hydrophilic

Which of these statements describes some aspect of facilitated diffusion? A. Facilitated diffusion of solutes occurs through phospholipid pores in the membrane. B. There is only one kind of protein pore for facilitated diffusion. C. Facilitated diffusion is another name for osmosis. D. Facilitated diffusion requires energy to drive a concentration gradient. E. Facilitated diffusion of solutes may occur through transport proteins in the membrane.

Facilitated diffusion of solutes may occur through transport proteins in the membrane.

Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the plasma membrane would cholesterol most likely be found? On the inside (cytoplasmic) surface On either surface of the membrane, but not in the interior of the membrane In the interior of the membrane In the interior and on the inside surface, but not on the outside surface On the outside (external) surface of the membrane

In the interior of the membrane

Which of the following statements concerning carbohydrates associated with the plasma membrane is correct? A. Carbohydrates on the plasma membrane are typically short chains of between two and five monosaccharides. B. Membrane carbohydrates have a primary role in cell-cell recognition. C. The carbohydrate composition of most eukaryotic plasma membranes is quite similar. D. Carbohydrates associated with the plasma membrane are located on both surfaces of the membrane. E. Carbohydrates are only found associated with the membranes of prokaryotic cells.

Membrane carbohydrates have a primary role in cell-cell recognition.

diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration; depends on size of molecules, temperature (hotter=faster, colder=slower),

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

Review various transport mechanisms across the cell membrane by matching following Osmosis Diffusion Passive transport Active transport Facilitated diffusion Protein pumps Choices: Transport proteins that help in transport of molecules across the membrane at the expense of ATPs Transport that does not spend energy Diffusion of water across selectively permeable membrane Transport that spends energy and sometimes may occur against the concentration gradient Spontaneous movement of molecules from higher concentration to lower concentration Transport that does not spend energy but still needs assistance from transport proteins

Osmosis: Diffusion of water across selectively permeable membrane Diffusion: Spontaneous movement of molecules from higher concentration to lower concentration Passive Transport: Transport that does not spend energy Active transport: Transport that spends energy and sometimes may occur against the concentration gradient Facilitated diffusion: Transport that does not spend energy but still needs assistance from transport proteins Protein pumps: Transport proteins that help in transport of molecules across the membrane at the expense of ATPs

Which of the following statements about passive transport is correct? A. In passive transport, solute movement stops when the solute concentration is the same on both sides of a membrane. B. Passive transport does not occur in the human body. C. Passive transport operates independently of the concentrations of the moving solute. D. Passive transport operates independently of diffusion. E. Passive transport involves movement of solute in both directions across a membrane, but with a net movement of solute down its concentration gradient.

Passive transport involves movement of solute in both directions across a membrane, but with a net movement of solute down its concentration gradient.

Which of the following pairs correctly matches a membrane transport process to its primary function? A. Osmosis; passive diffusion of water and small solutes across a membrane B. Receptor-mediated endocytosis; engulfing a particle by extending pseudopodia around it and packaging it within a membranous sac called a food vacuole C. Exocytosis; the movement of water and solutes out of the cell by vesicle fusion with the plasma membrane D. Phagocytosis; secretion of large particles from the cell by fusion of vesicles with the plasma membrane E. Pinocytosis; the uptake of water and small solutes into the cell by formation of vesicles at the plasma membrane

Pinocytosis; the uptake of water and small solutes into the cell by formation of vesicles at the plasma membrane

A semipermeable membrane is placed between the following solutions. Which solution will decrease in volume?

Solution A: 1.4% (m/v) starch

A semipermeable membrane is placed between the following solutions. Which solution will increase in volume?

Solution D: 12.4% (m/v) NaCl Submit

fluid mosaic model

Structural model of the plasma membrane where molecules are free to move sideways within a lipid bilayer.

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.

T

If a bowl of fresh strawberries is sprinkled with sugar, a few minutes later the berries will be covered with juice. Why?

The berries are losing water since the internal solute concentration of the strawberry cells is lower (i.e. higher internal water concentration) than on the outside of the cells.

The dialysis tubing that was used in this exercise was described as being selectively permeable. What evidence can support this description?

The fact that not everything is able to cross through the dialysis tubing.

The plasma membrane is referred to as a "fluid mosaic" structure. Which of the following statements about that model is true? A. The fluid aspect of the membrane is due to the lateral and rotational movement of phospholipids, and embedded proteins account for the mosaic aspect. B. Only phospholipids are capable of moving in the membrane. C. The fluid aspect of the membrane describes its structure at normal temperatures, and the mosaic aspect describes the behavior of the membrane as the temperature is lowered. D. The fluid aspect of the membrane is due to the behavior of phospholipids, and the mosaic aspect is due to the presence of carbohydrates. E. The mosaic aspect of the membrane is due to the glycosylation of inner leaflet phospholipids.

The fluid aspect of the membrane is due to the lateral and rotational movement of phospholipids, and embedded proteins account for the mosaic aspect.

Think about your Macromolecules lab. What chemical reagent did you use to test for starch? What colors indicate positive and negative results for these macromolecules? Benedict's reagent tests for starch, becoming brick red when starch is present and remaining blue when starch is absent. A brown paper bag tests for starch and it becomes translucent when starch is present and opaque when starch is absent. The iodine reagent tests for starch, becoming dark indigo (violet) when starch is present and remaining red-brown when starch is absent. Biuret's reagent tests for starch, becoming blue when starch is present and remaining violet when starch is absent.

The iodine reagent tests for starch, becoming dark indigo (violet) when starch is present and remaining red-brown when starch is absent.

If a shipwrecked crew drinks sea water, they will probably die. Why?

The salty sea water is hypertonic to their cells, which would cause them to lose water, becoming dehydrated.

What factor that influences diffusion is responsible for the differential flow of starch and iodine through the bag?

The size of the diffusing molecule relative to the pore size of the dialysis tubing.

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.

Which of the following correctly describes a general property of all electrogenic pumps? A. They can pump a large variety of solutes across a membrane against their concentration gradients. B. They create a high concentration of protons within a cell. C. They create a cell interior that is positively charged relative to the outside of the cell. D. They create a voltage difference across a membrane. E. They pump sodium out of the cell and potassium into the cell.

They create a voltage difference across a membrane.

Why do grocery store owners spray fresh fruits and vegetables with water?

This water is hypotonic to the produce causing it to gain water and look more plump. Turgid fruits and vegetables look more appealing to consumers and therefore they are more marketable.

In osmosis, water travels from an area of low solute concentration to an area of high solute concentration. True False

True

In studying osmosis, what molecule can cross the membrane? Sugar Water Protein Salt Carbon dioxide

Water

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?

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

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

Which of these acts as a second messenger? (no pic)

cyclic AMP

The presence of cholesterol in the plasma membranes of some animals

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

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

Identify Structure A.

glycoprotein

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

hormone

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

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

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.

hypertonic

This cell is in a(n) _____ solution.

hypertonic

You know that this cell is in a(n) _____ solution because it _____.

hypertonic solution ... lost water

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.

hypotonic

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?

hypotonic

You know that this cell is in a(n) _____ solution because the cell _____.

hypotonic ... swelled

Endocytosis moves materials _____ a cell via _____.

into ... membranous vesicles

Testosterone, a lipid-soluble signaling molecule, crosses the membranes of cells throughout the body but affects only target cells because __________. A. only target cells possess the cytosolic enzymes that transduce signals B. only target cells retain the appropriate DNA segments C. intracellular receptors for testosterone are present only in target cells D. most cells lack the Y chromosome E. only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor

intracellular receptors for testosterone are present only in target cells

Determine or estimate the molecular weights of starch, and I2KI (iodine potassium iodide; Lugol's iodine reagent) molecules. Use this information to place these three molecules in order of increasing size (smallest to largest).

iodine potassium iodide, starch

A bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in

lysosomes.

Receptors for signal molecules __________. are never found in the nucleus of a cell are only found associated with the plasma membrane all work via protein kinases may be found embedded in the plasma membrane or found within the cytoplasm or nucleus all work by opening ion channels

may be found embedded in the plasma membrane or found within the cytoplasm or nucleus

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

more concentrated less concentrated

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

passive transport of cell membrane

no ATP needed; diffusion (higher to lower concentration) (spreading; depends on size of molecules); no proteins/help needed; most natural movement

cell signaling

one cell secretes chemicals, one reads them -short distance (ex. growth factors...the free passage of substances in the cytosol from one cell to another is a type of local signaling) or long distance (ex: hormones) communication -reception, transduction, response

There is no net movement of purple dye.

only at equilibrium

There is net movement of orange dye from side A to side B.

only before equilibrium is reached

What name is given to the process by which water crosses a selectively permeable membrane?

osmosis

Diffusion across a biological membrane is called _____.

passive transport

Facilitated diffusion is a type of _______.

passive transport

Which of the following processes includes all the others? Passive transport Transport of an ion down its electrochemical gradient Diffusion of a solute across a membrane Facilitated diffusion Osmosis

passive transport

Is diffusion an active or a passive process? Explain. active, because it uses cellular ATP passive, because it uses cellular ATP active, because it doesn't use cellular ATP passive, because it doesn't use cellular ATP

passive, because it doesn't use cellular ATP

A white blood cell engulfing a bacterium is an example of _____.

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.

phospholipid bilayer of membrane

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

phospholipids and proteins

The difference between pinocytosis and receptor-mediated endocytosis is that

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

What is the function of Structure E?

stabilization of the phospholipids

What event would activate a G protein? phosphorylation of GDP to GTP hydrolysis of GTP to GDP hydrolysis of GDP to GTP phosphorylation of GTP to GDP replacement of GDP with GTP

replacement of GDP with GTP

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?

small and hydrophobic

Structure A is a _____.

solute

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 _____.

transport protein