Cell Biology: Transport, Energy, and Organelles

Vocabulary practice flashcards covering cellular energy (ATP/ADP), passive and active transport mechanisms, membrane structure and tonicity, cell theory milestones, and organelle structures and functions.

Energy

The ability to do work; required by all organisms to grow, reproduce, transport, move, and perform chemical reactions.

ATP (Adenosine Triphosphate)

A renewable cellular energy molecule with 3 phosphate groups that stores energy in chemical bonds; releases energy when a phosphate is broken off.

ADP (Adenosine Diphosphate)

The low-battery form of ATP containing 2 phosphate groups, produced when a phosphate bond is broken to release energy; recharges back into ATP when a phosphate is reattached.

Active Transport

The movement of substances across a cell membrane against their concentration gradient (from low to high concentration), requiring cellular energy ($\text{ATP}$).

Protein Pumps

Carrier proteins that use energy ($\text{ATP}$) to move charged molecules across the cell membrane from low concentration to high concentration.

Endocytosis

An active transport process in which the cell membrane folds inward around a molecule, pinches off to form a vesicle, and brings materials into the cell.

Phagocytosis

A form of endocytosis that brings solid particles into the cell, often referred to as 'cell eating'.

Pinocytosis

A form of endocytosis that brings liquids into the cell, often referred to as 'cell drinking'.

Exocytosis

An active transport process where an intracellular vesicle fuses to the cell membrane and releases its contents (such as waste or proteins) out of the cell.

Passive Transport

The movement of molecules down their concentration gradient (from high concentration to low concentration) without requiring cellular energy.

Diffusion (Simple Diffusion)

A passive transport process where small, uncharged molecules move directly through the phospholipid bilayer from an area of high concentration to low concentration.

Facilitated Diffusion

A passive transport process where large or charged molecules travel across the cell membrane through protein channels from high to low concentration.

Osmosis

The passive diffusion of water molecules across a selectively permeable membrane without requiring energy.

Solute

The substance that is being dissolved in a solution (e.g., salt or sugar).

Solution

A liquid mixture containing dissolved molecules (solute) evenly distributed in water.

Isotonic Solution

A solution where the solute concentration is equal inside and outside the cell; water moves in and out at the same rate, and cell size stays the same.

Hypotonic Solution

A solution with a lower solute concentration outside the cell than inside; water enters the cell, causing it to swell or grow.

Hypertonic Solution

A solution with a higher solute concentration outside the cell than inside; water leaves the cell, causing it to shrink.

Cytolysis

The bursting of an animal cell caused by excessive swelling when placed in a hypotonic solution (such as pure water).

Turgor Pressure

The osmotic water pressure inside a plant cell created when water flows into the central vacuole, giving plants the rigidity to stand upright.

Plasma (Cell) Membrane

A selectively permeable boundary between the cell and its environment that regulates what enters and leaves to maintain homeostasis.

Phospholipid Bilayer

A two-layered sheet of phospholipids that forms the structural basis of the cell membrane.

Hydrophilic Head

The polar, water-loving phosphate portion of a phospholipid that faces outward toward the aqueous environment.

Hydrophobic Tail

The nonpolar, water-fearing fatty acid portion of a phospholipid that turns inward away from water.

Integral Proteins

Proteins that penetrate completely through the phospholipid bilayer to transport molecules across the membrane.

Peripheral Proteins

Proteins attached loosely to the surface of the cell membrane, functioning as enzymes or receptors for cell signaling.

Glycolipids

Carbohydrates covalently bonded to membrane lipids that participate in cell-to-cell recognition.

Glycoproteins

Carbohydrates covalently bonded to membrane proteins that enable cell-to-cell recognition (e.g., helping white blood cells distinguish self from non-self).

Cholesterol

A lipid embedded within the bilayer that maintains membrane permeability and flexibility by preventing fatty acid tails from packing too tightly together.

Fluid Mosaic Model

A concept describing the cell membrane as a flexible layer where molecules can shift and move ('fluid') and which is composed of many different components ('mosaic').

Cell Theory

A fundamental biological theory stating that: 1) all living things are made of one or more cells, 2) the cell is the basic unit of life, and 3) all cells come from pre-existing cells.

Hooke

The scientist who observed cork tissue and first coined the term 'cells'.

Ivan Leeuwenhoek

The scientist who was the first to observe living unicellular pond creatures, which he termed 'animalcules'.

Schleiden

The scientist who concluded that all plants are composed of cells.

Schwann

The scientist who concluded that all animals are composed of cells.

Virchow

The scientist who showed that cells reproduce through cell division and proposed that all cells come from pre-existing cells.

Folded Membranes

Membranous structures that provide an advantage to cells by increasing surface area in a compact space so they can perform more chemical reactions.

Structures Common to All Cells

The four cellular structures shared by all cells: cytoplasm, DNA, ribosomes, and the cell membrane.

Prokaryotes

Simple unicellular organisms that lack a nucleus and membrane-bound organelles; bacteria are the only example.

Eukaryotes

Organisms composed of complex cells that contain a true nucleus and membrane-bound organelles.

Nucleus

The control center of the eukaryotic cell that encloses and protects DNA (chromatin).

Nucleolus

A structure located inside the nucleus that is responsible for producing ribosomes.

Nuclear Envelope

The protective membrane that surrounds and covers the nucleus.

Ribosome

The cellular structure that serves as the site of protein synthesis.

Rough ER

An endomembrane system connected to the nucleus that has ribosomes attached and is involved in transporting proteins.

Smooth ER

An endomembrane system without ribosomes that makes and transports lipids.

Golgi Apparatus

An organelle that processes, packages, and ships organic molecules like proteins and lipids to their final destination.

Vacuole

A storage organelle for water and waste; in plant cells, it functions to maintain cellular shape and turgor pressure.

Mitochondria

The powerhouse of the cell; the organelle that serves as the site of cellular respiration to generate usable cellular energy.

Chloroplasts

Green organelles in plant cells that serve as the site of photosynthesis, converting sunlight energy into sugars.

Cell Wall

A rigid outer layer in plant cells made of the carbohydrate cellulose that provides structural support, protection, and prevents bursting in hypotonic environments.

Lysosome

An organelle containing enzymes that digests waste and food particles within the cell.

Centrioles

Paired organelles that assist in organizing cell division.

Cytoplasm

The intracellular fluid surrounding organelles that serves as the primary site of cellular chemical reactions.

Cytoskeleton

A framework of protein rods that helps the cell maintain its shape and enables intracellular movement.

Cilia

Short, hair-like surface projections that facilitate cell movement.

Flagella

Long, tail-like cellular appendages that provide locomotion for the cell.

Energy

The ability to do work; required by all organisms to grow, reproduce, transport materials, move, and perform chemical reactions.

ATP (Adenosine Triphosphate)

A renewable energy molecule containing $3$ phosphate groups that stores usable energy within chemical bonds; releases energy when a phosphate group is cleaved off.

ADP (Adenosine Diphosphate)

The low-energy form of ATP containing $2$ phosphate groups; recharges back into ATP when a phosphate group is reattached.

Active Transport

The movement of substances across a cell membrane against their concentration gradient (from low concentration to high concentration), requiring cellular energy in the form of $\text{ATP}$.

Protein Pumps

Carrier proteins embedded in the cell membrane that require cellular energy to transport charged molecules from low to high concentration.

Endocytosis

An active transport process where the plasma membrane folds inward around a molecule, pinches off to form a vesicle, and brings materials into the cell.

Phagocytosis

A type of endocytosis commonly referred to as "cell eating," in which the cell engulfs solid particles.

Pinocytosis

A type of endocytosis commonly referred to as "cell drinking," in which the cell takes in liquid droplets.

Exocytosis

An active transport process in which an internal vesicle fuses with the cell membrane to release contents such as wastes or proteins out of the cell.

Passive Transport

The movement of substances across a cell membrane down their concentration gradient (from high to low concentration) without requiring cellular energy.

Diffusion

The passive transport of small, neutral/uncharged molecules directly through the phospholipid bilayer from an area of high concentration to low concentration.

Facilitated Diffusion

A type of passive transport in which large or charged molecules pass through specific protein channels from high to low concentration without energy.

Osmosis

The diffusion of water molecules freely across a selectively permeable membrane from an area of higher water concentration to lower water concentration.

Solute

The substance that is dissolved within a solution (such as salt or sugar).

Solution

A homogeneous mixture formed by dissolving solute molecules into a solvent such as water.

Selective Permeability

A property of the cell membrane that allows it to control which substances enter and leave the cell in order to maintain homeostasis.

Phospholipid Bilayer

A double-layered sheet of lipids that forms the core structure of the plasma membrane, consisting of polar heads and nonpolar tails.

Phosphate Head

The polar, hydrophilic ("water loving") portion of a phospholipid that faces outward toward aqueous cellular environments and attracts water.

Fatty Acid Tails

The nonpolar, hydrophobic ("water fearing") portion of a phospholipid that faces inward away from aqueous solutions and repels water.

Integral Proteins

Proteins that penetrate completely through the lipid bilayer, serving as transport channels, enzymes, or receptor sites.

Peripheral Proteins

Proteins that attach to the exterior or interior surface of the phospholipid bilayer.

Glycolipids

Carbohydrates bonded to lipids on the outer membrane surface that function in cell-to-cell recognition.

Glycoproteins

Carbohydrates bonded to membrane proteins that aid in cell-to-cell recognition, allowing immune cells to identify self from non-self.

Cholesterol (Membrane)

A lipid embedded within the phospholipid bilayer that maintains membrane flexibility and permeability by preventing fatty acid tails from packing too closely together.

Fluid Mosaic Model

A model describing the plasma membrane as "fluid" because molecules can shift and move within the bilayer, and a "mosaic" because it is made of many distinct parts.

Isotonic Solution

A solution where the solute concentration is equal inside and outside the cell, resulting in water moving in and out at equal rates and no change in cell size.

Hypotonic Solution

A solution that has a lower solute concentration outside the cell than inside; causes net water movement into the cell, making it swell or grow.

Hypertonic Solution

A solution that has a higher solute concentration outside the cell than inside; causes net water movement out of the cell, making it shrink.

Cytolysis

The swelling and bursting of an animal cell caused by excessive intake of water when placed in a hypotonic solution.

Turgor Pressure

The internal osmotic water pressure in plant cells generated as water enters the central vacuole, giving plants the rigidity to stand upright.

Cell Theory

A fundamental biological theory stating that all living things are made of one or more cells, the cell is the basic unit of life, and all cells come from pre-existing cells.

Robert Hooke

The scientist who observed cork tissue and first coined the term "cells."

Anton van Leeuwenhoek

The scientist who was the first to observe living unicellular pond organisms, referring to them as "animalcules."

Matthias Schleiden

The scientist who determined and stated that all plants are composed of cells.

Theodor Schwann

The scientist who determined and stated that all animals are composed of cells.

Rudolf Virchow

The scientist who proposed that all new cells arise from pre-existing cells through cell division.

Folded Membranes

Internal membrane structures that increase available surface area within a compact space, allowing the cell to perform more chemical reactions.

Universal Cellular Structures

The four structural components shared by all cells: cytoplasm, DNA, ribosomes, and the cell membrane.

Nucleus

The control center of the eukaryotic cell that encloses and protects DNA (chromatin).

Nucleolus

A dense region located inside the nucleus responsible for the synthesis of ribosomes.

Nuclear Envelope

The membrane that encloses and covers the nucleus, separating its contents from the cytoplasm.

Ribosome

A cellular structure that serves as the site of protein synthesis.

Rough ER (Endoplasmic Reticulum)

A membrane network connected to the nucleus that is studded with ribosomes; involved in transporting proteins.