Ch. 5 - The Wokring Cell

facilitated diffusion

polar or charged substances move across membranes with the help of specific transport proteins - does not require energy and relies on the concentration gradient

enzyme inhibitors have also been developed as

pesticides and deadly poisons for use in warfare

Penicillin is a drug that affects bacterial cells and not human cells. How is this possible?

This is possible because the drug is targeting a structure not found in eukaryotic cells.

The energy needed to initiate a chemical reaction is the ________ a. activation energy b. substrate energy c. active site d. inhibition site

a. ativation energy

Every cell has a(n) ________ that allows it to maintain a cellular envrionemtn that is separate from the environment in which it is found.

plasma membrane

The relationship between an enzyme's active site and its substrate is most like which of the following? a. A comb and hair b. A car and a driver c. A scarf and a hand d. A key and a lock

d. A key and a lock

Nonpolar is to diffusion as ________ is to facilitated diffusion.

polar

feedback inhibition

helps regulate metabolism

ATP

(adenosine triphosphate) main energy source that cells use for most of their work

Entropy

A measure of disorder or randomness.

selective permeability

A property of a plasma membrane that allows some substances to cross more easily than others.

The phosphorylation of ADP creates ______

ATP

Enzymes

Catalysts that decrease the activation energy needed for a reaction to bgein, without being consumed by the reaction

passive transport

Diffusion across a cell membrane does not require energy, so it is called

Complete the table that compares diffusion, osmosis, and facilitated diffusion.

Diffusion: No energy is required; the movement of a substance from an area of high concentration to an area of low concentration. Osmosis: No energy is required; the diffusion of water across a semipermeable membrane. Facilitated diffusion: No energy required; Diffusion of a substance down its concentration gradient through a transmembrane protein channel within the plasma membrane

noncompetitive inhibitor

Does not enter the active site. Instead, it binds to a site elsewhere on the enzyme, and its binding changes the enzyme's shape so that the active site no longer fits the substrate.

chemical energy

Energy stored in chemical bonds

Use the Venn diagram to compare exocytosis with endocytosis.

Exocytosis: The movement of bulk substances outside the cell. Endocytosis: The movement of bulk substances into the cell. BOTH: Neither one of these deals with gradients. They both deal in the specialized transport of large substanes or large amounts of substances.

In pole vaulting, the higher the bar is placed, the more difficult it is to clear it. Explain why this is a good analogy to help students understand enzymes and activation energy.

In this analogy, the bar represents the activation energy necessary for the reaction to occur. The higher the bar, the harder it is to jump. The more activation energy that is required, the harder it will be for there action to occur.

Complete the table that compares terms associated with tonicity.

Isotonic solution: TWO solutions that have the same solute concentration, effect on plant cell - flaccid, effect on animal cell - normal Hypotonic solution: A Solution that has less solute than the solution it is being compared to; effects on plant cell - turgid, effects of animal cell - lyse Hypersonic solution: A Solution that has more solute than the solution it is being compared to; effects on plant cell - shriveled, effect on animal ell - shrivel

Complete the table that compares kinetic with potential energy.

Kinetic energy: The enrgy of motion; EX. Solar energy Potential energy: Energy associated with a substance that can be converted to kinetic energy; EX. Candy bar

In the following reaction, circle the enzyme. (FIGURE)

Lactase Lactose --> Glucose + Galactose CIRCLE LACTASE

Sucrase is the enzyme that breaks down sucrose into glucose and fructose. Will sucrose also catalyze the breakdown of the disaccharide maltose? Briefly explain your answer

No, because maltose will have a different structure than sucrose and so it will not fit into the active site of sucrase.

Complete the Venn diagram comparing inhibitors.

Noncompetitive inhibitors: Bind to a location on the enzyme other than the active site and cause a change in the enzyme's active site. This keeps the enzyme from binding to the proper substrate. Competitive inhibitors: Bind directly to the active site of an enzyme and inhibit the binding the proper substrate. BOTH: They both work to inhibit the activity of enzymes.

True or false: Aquaporins form the specific protein channel through which water diffuses. If false, make it a correct statement.

TRUE

True or false: The fact that all cells have a plasma membrane supports the evolutionary linkage of all life. If false, make it a correct statement.

TRUE

Use Figure 5.15B on page 89 of your textbook to answer this question. Assume that a toxin is introduced to the cell that binds to and removes substance C from the pool of molecules participating in the reaction. Briefly explain what would happen to the amount of substance B. (FIGURE)

The amount of substance B would increase because there would no longer be any feedback inhibition.

Dr. Agre's research into aquaporins hinged on two key observations. List both observations.

The antibody they made did not bind to any part of the Rh antigen and the antibody bound to red blood cells in large quantities.

heat

The energy transferred between objects that are at different temperatures

active site

The part of an enzyme or antibody where the chemical reaction occurs.

Which portion of the Figure 5.10 on page 84 of your textbook illustrates the second law of thermodynamics? (FIGURE)

The portion where heat is being given off by both the cell and the car illustrates the second law of thermodynamics

What feature does diffusion, osmosis, and facilitated diffusion all share?

They are all types of passive transport.

Biologists have described a cell's plasma membrane as being a fluid mosaic. Briefly explain why this is an accurate description. Use the figure on page 78 to help with this.

This is an accurate description because a plasma membrane is made of multiple types of molecules with many different functions (the mosaic) and the molecules are in constant motion around each other (fluid).

A cell pumps certain ions against their concentration gradient to maintain those gradients. What type of cellular work is this considered?

This would be considered transport work.

The graph on page 87 in your textbook illustrates the difference between a chemical reaction with and without an enzyme. Could the reaction represented by the black line still occur without the enzyme? Briefly explain your answer. (FIGURE)

Yes, it would just take more energy to get the reaction started.

A chemical reaction is determined to be endergonic. If you were trying to get that reaction to occur using an additional and separate reaction, what would you do?

You could couple it to an exergonic reaction.

active transport

a cell must expend energy to move a solute against its concentration gradient

Tonicity

a term that describes the ability of a solution to cause a cell to gain or lose water

Match the following terms with their correct description: exergonic reaction, endergonic reaction, metabolism, metabolic pathway a. The sum of all chemical reactions in an organism: _______ b. A series of reactions that either build or break down a molecule: ________ c. A reaction that gives off energy: ________ d. A reaction that requires an input of energy: _________

a. Metabolism b. Metabolic pathway c. Exergonic reaction d. Endergonic reaction

Match the following terms with their description: passive transport, diffusion, concentration gradient, and osmosis a. Diffusion of water across a selectively permeable membrane: ________ b. Movement across a cell membrane that requires no work from the cell: _______ c. Movement of a substance from high to low concentration: ________ d. When there exists a difference in the amount of a substance across a distance: __________

a. Osmosis b. Passive transport c. Simple diffusion d. Concentration gradient

Which of the following statements regarding transport across a plasma membrane is false? a. Passive transport requires an input of energy from the cell. b. Osmosis is the diffusion of water across a selectively permeable membrane. c. Substances always travel down their concentration gradient in passive transport. d. Facilitated diffusion requires a specific transport protein found in the membrane.

a. Passive transport requires an input of energy from the cell.

trasnport proteins

allow passage of hydrophilic substances across the membrane

Isotonic

animal cells are normal, but plant cells are flaccid.

attachment proteins

attach to the extracellular matrix and cytoskeleton, help support the membrane, can coordinate external and internal changes

Which of the following best describes the structure of a plasma membrane? a. Proteins sandwiched between two layers of phospholipids b. Proteins embedded in two layers of phospholipids c. A layer of protein on top of a layer of phospholipids d. Phospholipids sandwiched between two layers of protein

b. Proteins embedded in two layers of phospholipids

Anything that inhibits ATP synthesis in a cell would most likely a. force the cell to use ADP as an energy source. b. result in the death of the cell. c. make the cell start using lipids as energy. d. cause the cell to stop doing mechanical work but not transport work.

b. result in the death of the cell.

Energy is never created or destroyed. What happened to the energy that was stored in your gas tank after your lawnmower comes to a stop as a result of running out of gas? a. The energy was lost. b. Entropy decreased in the universe. c. It was converted to heat. d. The lawnmower gained energy.

c. It was converted to heat.

hypertonic

cell shrinks

Hypotonic

cell swells

Thermodynamics

energy can change form but cannot be created or destroyed AND energy transfers or transformations increase disorder

kinetic energy

energy of motion

potential energy

energy stored in the location or structure of matter

Phagocytosis

engulfing of particle by the cell wrapping cell membrane around it, forming a vacuole

The food we eat contains chemical energy. Is it possible for a candy bar to have potential energy for two different reasons at the same time? Briefly explain your answer

es, it is. The candy bar has potential energy because of the bonds within the molecule, but it could also have potential energy if you placed it near the edge of a table

You are sailing on Lake Superior from Copper Harbor, Michigan, to Isle Royale National Park. A suddens torm causes your sailboat to spring a leak. You immediately grab a bucket and begin bailing water out of the boat. Briefly explain how your predicament could be used as an analogy to help explain both active and passive transport.

f you simply let the water flow into the boat, then water will travel down its concentration gradient (into your boat) until the gradient is abolished (your boat sinks). If you want your boat to stay afloat, then you simply bail water out of the boat. In effect, you are moving water against its concentration gradient to maintain that gradient (keeping your boat afloat)

junction proteins

form intercellular junctions that attach adjacent cells

Substrate

reactant of an enzyme-catalyzed reaction

competitive inhibitor

reduces an enzyme's productivity by blocking substrate molecules from entering the active site

exergonic reaction

releases energy

endergonic reaction

requires energy and yield products rich in potential energy

Glycoproteins

serve as ID tags, may be recognized by membrane proteins of other cells

receptor proteins

signaling molecules bind to receptor proteins, receptor proteins relay the message by activating other molecules inside the cell

Enzymes

some membrane proteins are enzymes, enzymes may be group to carry out sequential reactions

Energy

the capacity to cause change

Omosis

the diffusion of water molecules through a selectively permeable membrane

Diffusion

the tendency for molecules to spread out evenly into the available space

In contrast to passive transport, active transport pumps a substance _____ its gradient.

up

fluid mosaic model

used to describe a membrane's structure—diverse protein molecules suspended in a fluid phospholipid bilayer

Exocytosis

used to export bulky molecules, such as proteins or polysaccharides

Endocytosis

used to take in large molecules

receptor-mediated endocytosis

uses membrane receptors for specific solutes