Biology Chapter 5: Membrane Transport

Questions and Answers

What is active transport?

Molecules move across the plasma membrane against their concentration gradient.

What is facilitated diffusion?

A molecule moves down its concentration gradient using a transport protein in the plasma membrane.

How does water cross the plasma membrane?

Through facilitated diffusion or diffusion.

What is the sodium-potassium pump an example of?

Active transport. Signup and view all the answers

What does endocytosis describe?

The plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. Signup and view all the answers

Energy is conserved. This means that in any system, _____

total energy input equals total energy output. Signup and view all the answers

Potential energy is _____ energy.

stored. Signup and view all the answers

Which of the following is highest in chemical energy?

One molecule of Glucose Signup and view all the answers

In cellular respiration, when is most energy released?

When high-energy electrons 'fall' to lower energy levels. Signup and view all the answers

An enzyme is considered a _________ because it speeds up a chemical reaction without being used up.

catalyst. Signup and view all the answers

In a catalyzed reaction, a reactant is often called a _________.

substrate. Signup and view all the answers

An enzyme is specific because of the shape its __ matches only particular reactants.

active site. Signup and view all the answers

An enzyme speeds up reactions by lowering the ____ .

activation energy. Signup and view all the answers

The _____ _ between an active site and its substrate often strains bonds and helps the reaction proceed.

induced fit. Signup and view all the answers

A ________, which is often a vitamin, binds to an enzyme and plays a role in catalysis.

coenzyme. Signup and view all the answers

High temperatures or changes in pH can ________ an enzyme, causing it to lose its shape and biological activity.

denature. Signup and view all the answers

In oil-based liquids, phospholipids are arranged so that their _ face outward and their _ are orientated inward.

hydrophobic tails...hydrophilic heads. Signup and view all the answers

The movement of molecules from an area of higher concentration to an area of lower concentration is called _____.

diffusion. Signup and view all the answers

When water moves toward the solution with the _ solute concentration, the solution is _.

Greater...hypertonic Signup and view all the answers

Which of these reactions is endergonic?

Protein synthesis Signup and view all the answers

Enzymes are used up when they catalyze a chemical reaction.

False Signup and view all the answers

Passive transport requires no expenditure of cellular energy.

True Signup and view all the answers

What is osmosis?

The diffusion of water across a selectively permeable membrane. Signup and view all the answers

Seawater is dangerous to drink because...

Seawater is hypertonic to your body tissues and drinking it will cause you to lose water by osmosis. Signup and view all the answers

Which of the following statements about the ATP molecule is true?

It releases energy when one phosphate group leaves ATP. Signup and view all the answers

What is feedback inhibition?

A regulatory mechanism in which the production of a substance is inhibited by its own presence. Signup and view all the answers

Study Notes

Membrane Transport and Cellular Processes

Active Transport involves movement of molecules against their concentration gradient, requiring energy.
Facilitated Diffusion uses transport proteins to move molecules down their concentration gradient without energy expenditure.
Water can cross the plasma membrane via facilitated diffusion or directly through the lipid bilayer.
The sodium-potassium pump, an example of active transport, uses ATP to move sodium ions out and potassium ions into the cell.
Endocytosis is when the plasma membrane engulfs external material, forming vesicles.
Exocytosis is the process where vesicles fuse with the plasma membrane to release contents outside the cell.

Energy Concepts

Energy is conserved, meaning the total input equals total output within a system.
Kinetic Energy is energy in motion; Potential Energy refers to stored energy.
One molecule of Glucose is the highest in chemical energy compared to other molecules.
In cellular respiration, energy is mainly released when high-energy electrons transition to lower energy levels.
An enzyme acts as a catalyst, speeding up reactions without being consumed.
A substrate is a reactant in an enzyme-catalyzed reaction.

Enzyme Functionality

Enzymes are specific due to the unique shape of their active sites that match specific substrates.
Enzymes lower the activation energy, facilitating reactions.
The induced fit model describes how enzyme binding can strain substrate bonds, aiding the reaction.
Coenzymes, often vitamins, assist enzymes in catalysis.
High temperatures or pH changes can denature an enzyme, altering its shape and function.

Membrane Structure and Function

Phospholipids in oil-based liquids arrange with hydrophobic tails outward and hydrophilic heads inward, offering protection.
Diffusion refers to the movement of molecules from higher to lower concentration areas.
Solutions with greater solute concentrations are termed hypertonic.
Passive transport, such as diffusion and osmosis, does not require ATP; instead, it relies on concentration gradients.

Osmosis and Water Transport

Osmosis is driven by the water concentration gradient, not directly by solute concentration.
Water flows to areas of lower free water concentration across semipermeable membranes.
Drinking seawater, which is hypertonic to bodily fluids, leads to dehydration through osmosis.

Energy in Biological Systems

Endergonic reactions absorb energy, while exergonic reactions release it.
ATP provides energy for cellular work by releasing a phosphate group.
Inhibition of enzyme reactions can occur through competitive inhibitors, which bind at the active site, or noncompetitive inhibitors, which bind elsewhere.

Thermodynamics in Biology

The first law of thermodynamics states energy cannot be created or destroyed.
The second law of thermodynamics indicates that energy transformations always increase the universe's overall disorder, or entropy.
Cellular energy that is not utilized contributes to increasing disorder, primarily through heat.

Cellular Processes and Transport Types

Phagocytosis describes large particles engulfing by cells, a contrast to standard endocytosis mechanisms.
Aquaporins are specialized proteins that facilitate water transport across membranes.
Feedback inhibition regulates enzyme activity based on product concentration, maintaining homeostasis within cells.

These bullet points encapsulate essential concepts from membrane transport and energy dynamics within biological systems, providing a comprehensive overview for study.

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Description

Explore key concepts in membrane transport with our flashcards for Biology Chapter 5. Learn about active transport, facilitated diffusion, and the movement of water across the plasma membrane. Perfect for reviewing essential terms and definitions in cell biology.