Cell Biology, Membrane Transport, Energy, and Metabolism

Comprehensive practice flashcards reviewing plant cell organelles, plasma membrane structure and transport, thermodynamics, enzyme kinetics and regulation, and cellular energetics.

Chloroplast

A double membrane organelle found in eukaryotic plant cells that serves as the location of photosynthesis.

Central Vacuole

A plant cell organelle that takes up $50\text{--}90$ percent of the cell's internal space and stores water, toxins, and minerals.

Phospholipid Bilayer

The plasma membrane structure composed of hydrophilic phosphate heads on the exterior surfaces and hydrophobic methyl tails hidden between them.

Integral Proteins

Membrane proteins that penetrate or stick through the phospholipid bilayer.

Peripheral Proteins

Membrane proteins that do not protrude into the phospholipid bilayer but stick to one surface of the membrane.

Receptor Surface Proteins

Membrane proteins that bind specific chemical signals known as ligands.

Ligands

Specific chemical signals that bind to receptor surface proteins.

Channel Proteins

Membrane pores with passages that allow water and hydrophilic solutes to pass through the plasma membrane.

Gated Channels

Protein channels across the membrane that open and close under specific circumstances.

Carriers ("Pumps")

Highly selective membrane proteins that bind solutes such as glucose and electrolytes that fit inside the protein to transport them.

Cell-Adhesion Proteins

Membrane proteins that allow cells to adhere to one another and to extracellular material.

Cell Identity Markers

Glycoproteins with attached carbohydrates that act as name tags for the cell.

Concentration Gradient

A difference in concentration between two regions, down which molecules move from an area of high concentration to an area of low concentration.

Passive Transport

The movement of material from an area of high concentration to an area of low concentration without the use of cellular energy ($\text{ATP}$).

Simple Diffusion

The passive movement of material directly across the phospholipid bilayer, such as gases and nonpolar molecules.

Facilitated Diffusion

The passive movement of material in or out of a cell using transport proteins.

Osmosis

The movement of water from an area of high concentration to low concentration without the use of $\text{ATP}$.

Hypertonic Solution

An environment containing a high amount of solute and low amount of solvent compared to inside the cell, causing water to exit and the cell to shrink.

Hypotonic Solution

An environment containing a low amount of solute and high amount of solvent outside the cell compared to inside, causing water to enter and the cell to bloat.

Isotonic Solution

A solution with an equal amount of solute and solvent outside compared to inside, resulting in no net water movement and allowing the cell to maintain homeostasis.

Active Transport

The movement of material from an area of low concentration to high concentration requiring energy in the form of $\text{ATP}$.

Sodium-Potassium Pump

A carrier protein mechanism that actively moves sodium and potassium across the plasma membrane using $\text{ATP}$, moving $3$ sodium ions out and $2$ potassium ions in.

Endocytosis

A form of bulk transport characterized by the net movement of material from the outside to the inside of the cell.

Phagocytosis

A form of endocytosis that involves the bulk movement of large material to the inside of the cell.

Receptor-Mediated Endocytosis

A bulk transport mechanism involving the selective uptake of specific material into the cell.

Pinocytosis

A type of endocytosis that involves the movement of liquid material to the inside of the cell.

Exocytosis

A bulk transport process involving the net movement of material from the inside to the outside of the cell.

Energy

The ability to do work or cause a change.

Potential Energy

Stored energy.

Kinetic Energy

Energy of motion or movement.

First Law of Thermodynamics

The thermodynamic principle stating that energy cannot be created or destroyed.

Second Law of Thermodynamics

The thermodynamic principle stating that as energy changes forms, the amount of useable energy decreases and heat increases.

Endergonic Reaction

An anabolic reaction system where the products have more energy than the reactants, requiring an input of energy.

Exergonic Reaction

A catabolic reaction system where the reactants have more energy than the products, releasing energy.

Coupled Reaction

A reaction system in bioenergetics that uses an exergonic reaction to drive or start an endergonic reaction.

Biochemical Pathway

A series of connected chemical reactions in metabolism.

Redox Reactions

Coupled oxidation-reduction reactions that transfer high-energy electrons from one molecule to another.

Oxidation

A chemical process in which high-energy electrons are lost.

Reduction

A chemical process in which high-energy electrons are gained.

Adenosine Triphosphate (ATP)

An energy transfer compound and nucleotide composed of an adenine base, a ribose sugar, and three high-energy phosphate groups.

Phosphorylation

The addition of a phosphate group to a molecule.

Enzymes

Biological catalysts made of proteins in their tertiary or 3-D structure that speed up naturally occurring chemical reactions without being consumed.

Activation Energy

The energy needed to get a chemical reaction started, which is lowered by enzymes.

Active Site

The pocket or cleft on an enzyme where substrates bind to accelerate a chemical reaction.

Feedback Inhibition

A cellular control mechanism in which cells inhibit the function of an enzyme when adequate amounts of products are present.

Allosteric Regulation

A form of enzyme regulation in which the activity of an enzyme is enhanced or suppressed by the presence of a specific molecule.

Competitive Inhibition

A regulatory mechanism where two or more molecules that are similar in structure compete for the same active site on an enzyme.

Cofactors

Inorganic ions that enhance the functions of enzymes.

Coenzymes

Organic molecules that enhance the function of enzymes.

Endosymbiotic Theory

The theory proposing that eukaryotic organelles like mitochondria and chloroplasts originated via endosymbiosis between prokaryotic cells and a host cell.