Chapter 4 – Energy, Enzymes, and Membrane Transport

Fill-in-the-blank flashcards covering energy concepts, thermodynamics, metabolism, ATP, enzymes, and membrane transport from Chapter 4.

energy is stored energy based on position or structure.

Potential

energy is the energy of motion.

Kinetic

A is the amount of energy needed to raise 1 g of water by 1 °C.

calorie

One kilocalorie (kcal) equals calories.

1,000

The study of energy transformations is called .

thermodynamics

The law of thermodynamics states that energy cannot be created or destroyed.

first

The law of thermodynamics states that every energy transfer increases entropy.

second

is a measure of disorder in a system.

Entropy

Biological systems do not defy the 2nd law because they increase the universe’s overall .

entropy

Reactions that require energy input are called reactions.

energy-requiring (endergonic)

Dehydration synthesis and photosynthesis are examples of reactions.

energy-requiring (endergonic)

Reactions that release energy are called reactions.

energy-releasing (exergonic)

Hydrolysis and cellular respiration are examples of reactions.

energy-releasing (exergonic)

In a redox reaction, is the loss of electrons.

oxidation

In a redox reaction, is the gain of electrons.

reduction

ATP is classified as a .

nucleotide

ATP consists of adenine, ribose, and phosphate groups.

three

The hydrolysis reaction ATP + H₂O → ADP + Pᵢ + energy energy.

releases

Energy from ATP hydrolysis is coupled to reactions.

energy-requiring (endergonic)

ATP synthesis is coupled to reactions.

energy-releasing (exergonic)

Biological catalysts are called .

enzymes

The molecule upon which an enzyme acts is its .

substrate

The specific region of an enzyme that binds the substrate is the .

active site

The transient association of enzyme and substrate is the complex.

enzyme-substrate

After catalysis, molecules produced are called .

products

Enzymes lower the energy of reactions.

activation

An inhibitor that competes with substrate for the active site is a inhibitor.

competitive

An inhibitor that binds away from the active site and changes enzyme shape is .

non-competitive

End-product inhibition that shuts down a pathway is called feedback inhibition.

negative

Most enzymes are made of , though some are RNA.

proteins

Extreme temperature, pH, or salt concentration can alter enzyme and function.

shape

A cell membrane is permeable because of its phospholipid bilayer.

selectively

Movement of molecules down their concentration gradient without energy is called transport.

passive

Non-polar molecules cross the membrane down their gradient by diffusion.

simple

Water moves down its gradient through .

osmosis

During osmosis, water moves from a solution to a hypertonic solution.

hypotonic

Polar molecules and ions move down their gradient via diffusion, using transport proteins.

facilitated

Transport against a gradient that requires energy and proteins is transport.

active

The Na⁺/K⁺ pump is a classic example of transport.

active

Bulk import of large particles into the cell is called .

endocytosis

When solid material is engulfed, the specific form of endocytosis is .

phagocytosis

When fluid is engulfed, the specific form of endocytosis is .

pinocytosis

Bulk export of materials out of the cell is called .

exocytosis

Both endocytosis and exocytosis require energy and .

vesicles