BIOL B11 Chapter 5 The Working Cell

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Questions and Answers

Why does removing a phosphate group from the triphosphate tail in a molecule of ATP release energy?

The three phosphate groups store chemical energy, a form of potential energy. The release of a phosphate group makes some of this potential energy available to cells to perform work.

What is the chemical basis for the term hydrolase?

Hydrolases are enzymes that participate in hydrolysis reactions, breaking down large molecules into the smaller molecules that make them up.

Explain how an inhibitor can disrupt an enzyme's action without binding to the active site.

An inhibitor's binding to another site on the enzyme can cause the enzyme's active site to change shape.

If someone at the other end of a room smokes a cigarette, the movement of smoke is similar to what type of transport?

Diffusion Signup and view all the answers

Explain why it is not enough to say that a solution is 'hypertonic'.

Hypertonic and hypotonic are relative terms that require comparison. Signup and view all the answers

What is the primary difference between passive and active transport in terms of concentration gradients?

Passive transport moves atoms or molecules along their concentration gradient (from higher to lower concentration), while active transport moves them against their concentration gradient. Signup and view all the answers

Which of these types of cellular transport require(s) energy?

Active transport Signup and view all the answers

Explain how ATP powers cellular work.

ATP transfers a phosphate group to another molecule, increasing that molecule's energy content. Signup and view all the answers

What is the source of energy for regenerating ATP from ADP?

Chemical energy harvested from sugars and other organic fuels via cellular respiration. Signup and view all the answers

How does an enzyme affect the activation energy of a chemical reaction?

An enzyme lowers the activation energy. Signup and view all the answers

In what ways does directed evolution mimic natural selection?

Directed evolution involves reproduction and variation. Signup and view all the answers

How does an enzyme recognize its substrate?

The substrate and the enzyme's active site are complementary in shape and chemistry. Signup and view all the answers

What is the primary source of energy for the cell?

Adenosine triphosphate (ATP) Signup and view all the answers

Identify three types of osmotic environments.

Isotonic solution, hypotonic solution, hypertonic solution Signup and view all the answers

What does it mean to say that molecules move 'down the concentration gradient'?

The molecules move from where it is more concentrated to where it is less concentrated. Signup and view all the answers

Why is facilitated diffusion a form of passive transport?

It uses proteins to transport materials down a concentration gradient without expending energy. Signup and view all the answers

What is the term for stored energy?

Potential energy Signup and view all the answers

What is diffusion of molecules across a membrane without the use of energy called?

Passive transport Signup and view all the answers

What are enzymes?

Proteins that speed up chemical reactions Signup and view all the answers

What type of energy is described as 'energy that enables us to move and stay warm'?

Food energy Signup and view all the answers

What type of energy is supplied to automobile engines?

Fuel energy Signup and view all the answers

What is the energy of motion called?

Kinetic energy Signup and view all the answers

What principle states that energy cannot be created or destroyed?

Principle of Conservation of Energy Signup and view all the answers

What is the term for the movement of molecules spreading out evenly into available space?

Diffusion Signup and view all the answers

Identify the type of transport that requires a cell to expend energy.

Active transport Signup and view all the answers

What happens to an animal cell in a hypotonic solution?

It gains water, swells, and possibly bursts. Signup and view all the answers

What is the measure of the amount of disorder in a system called?

Entropy Signup and view all the answers

What energy transformations occur when climbing stairs?

Chemical energy to kinetic energy and stored potential energy Signup and view all the answers

What can excessive water intake lead to?

Hyponatremia or water intoxication Signup and view all the answers

What is the capacity to perform work called?

Energy Signup and view all the answers

The label on a candy bar states it contains how many Calories if it can raise the temperature of water?

150 Calories Signup and view all the answers

Study Notes

Energy and Its Types

Adenosine Triphosphate (ATP): Primary energy source for cells, acting like a battery that stores and releases energy.
Kinetic Energy: Energy of motion; involved when a diver jumps or when muscles move.
Potential Energy: Stored energy based on an object's position or structure; example: a diver at the top of a diving board.
Chemical Energy: Released during cellular respiration, derived from organic molecules, and stored in ATP.

Energy Transformations

Conservation of Energy: Energy can neither be created nor destroyed; it can only be transformed from one form to another.
Entropy: A measure of disorder; increases with every energy transformation, contributing to heat production.
ATP Cycle: Approximately 10 million ATP molecules are consumed and recycled each second in muscle cells.

Enzymes

Definition: Proteins that catalyze and speed up chemical reactions by lowering activation energy.
Activation Energy: The energy needed to start a reaction; reduced by enzymes to facilitate metabolic processes.
Substrates: The specific molecules that enzymes act upon, fitting into the enzyme’s active site through a lock-and-key or induced fit mechanism.
Inhibitors: Molecules that disrupt enzyme function, can bind to active sites or other locations altering the enzyme's shape.

Transport Mechanisms

Passive Transport: Movement of substances across a membrane without energy use, occurring along concentration gradients (e.g., diffusion and osmosis).
Facilitated Diffusion: Passive transport aided by proteins to help substances cross membranes.
Active Transport: Requires energy to move molecules against concentration gradients.

Osmoregulation

Water Balance: Essential for cell survival, involves controlling water concentrations through isotonic, hypotonic, and hypertonic solutions.
Isotonic Solutions: Equal solute concentration; cells remain normal without swelling or shrinking.
Hypotonic Solutions: Lower solute concentration; can cause animal cells to lyse while plant cells become turgid.
Hypertonic Solutions: Higher solute concentration; can result in cells shriveling as they lose water.

Cellular Processes

Exocytosis: Process by which cells export materials via vesicles that fuse with the plasma membrane.
Endocytosis: The process of taking materials into the cell through vesicles.
Phagocytosis: A form of endocytosis where cells engulf large particles.

Energy and Work Relation

Transformation During Activity: Climbing a stairway involves converting chemical energy into kinetic energy and storing potential energy at height.
Caloric Content: Fuel content in food is measured in calories; one calorie can raise 1 gram of water by 1°C.

Conclusion

Interconnected Systems: All living organisms rely on efficient energy transformations and transport processes for survival and functioning, facilitated by enzymes and cellular mechanisms ensuring homeostasis.### Cellular Transport
Passive transport moves atoms/molecules along their concentration gradient (high to low concentration).
Active transport requires energy to move substances against their concentration gradient (low to high concentration).
Facilitated diffusion and active transport are the forms of cellular transport that require energy, with facilitated diffusion being passive.

Energy and Function

Pathways that transform energy and matter: Raising a bucket from a well involves converting food energy into potential energy for the water.
Interactions within biological systems: Walking requires coordination among various enzymes and cellular structures for muscle movement.
Relationship of structure to function: Enzymes stop functioning at high temperatures as their shape (structure) is crucial for their activity (function).

Energy Types and Concepts

Objects at rest can possess potential energy due to their location or structure.
Heat is the most random form of energy, making it difficult to harness for work.

Physical Activity and Energy Expenditure

Riding a bicycle for about one hour burns approximately 300 calories, equivalent to the energy content in one slice of pizza.

ATP and Energy Transfer

ATP powers cellular work by transferring phosphate groups to molecules, enhancing their energy content.
The regeneration of ATP from ADP relies on chemical energy obtained from sugars through cellular respiration.

Enzymatic Action

Enzymes lower the activation energy needed for chemical reactions, facilitating faster reactions.
Enzymes recognize substrates due to complementary shapes and chemistry between the enzyme's active site and the substrate.

Directed Evolution

Directed evolution resembles natural selection by involving reproduction and variation but differs as scientists actively test variations to find the most suitable ones.

Concentration Gradient and Transport Mechanisms

Molecules move "down the concentration gradient" from areas of high concentration to low concentration.
Facilitated diffusion is a passive transport method utilizing proteins to move materials along the concentration gradient without energy expenditure.

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Description

Test your knowledge about the primary energy source for cells with this quiz. Explore the importance of adenosine triphosphate (ATP) in cellular processes and learn why it is considered a superior energy source compared to others. Perfect for students of biology looking to solidify their understanding of cellular energy dynamics.