Biology 12 – Unit 2: Cell Structure, Function & Membranes

Vocabulary flashcards covering key terms from Unit 2 notes: cell theory, organelles, membrane structure, transport processes, and size relationships.

Microscope

Instrument whose invention allowed the first study and discovery of cells.

Matthias Schleiden

19th-century German botanist who concluded that all plants are made of cells.

Theodor Schwann

19th-century German zoologist who concluded that all animals are made of cells.

Rudolf Virchow

Scientist who added the principle that cells arise only from pre-existing cells.

Cell Theory

States that all organisms are composed of cells and that cells come from pre-existing cells.

Prokaryotic Cell

Cell type lacking a nucleus and most organelles; found only in the Bacteria (Monera) kingdom.

Eukaryotic Cell

Cell type with a true nucleus and membrane-bound organelles (e.g., plant, animal, fungi, protist cells).

Kingdom Monera

The only kingdom composed entirely of prokaryotic organisms.

Chloroplast

Large double-membraned plant organelle containing chlorophyll; site of photosynthesis.

Cell Wall

Rigid cellulose layer outside plant plasma membrane that provides support and protection.

Central Vacuole

Large, single-membraned storage sac in plants that can occupy up to 90 % of cell volume.

Mitochondrion

Double-membraned organelle that burns glucose to make ATP via cellular respiration.

Nucleus

Largest organelle; surrounded by a double nuclear envelope with pores; stores DNA.

Nuclear Envelope

Double membrane around the nucleus perforated by pores for molecule passage.

Nucleolus

Dark region inside the nucleus that produces and stores ribosomal RNA.

Chromatin

Uncondensed DNA-protein complex found in the nucleus; coils into chromosomes during division.

Chromosome

Rod-shaped, condensed chromatin structure containing hereditary DNA.

Cytoplasm

Gel-like colloid inside the cell in which organelles are suspended.

Plasma Membrane

Phospholipid bilayer that regulates entry and exit of substances; selectively permeable.

Phospholipid

Fat molecule with a phosphate head and lipid tails; forms bilayer of cell membranes.

Fluid Mosaic Model

Current membrane model: proteins float in a semi-fluid phospholipid bilayer.

Glycoprotein

Membrane protein with an attached carbohydrate chain that acts as a cell marker.

Glycolipid

Membrane phospholipid with an attached carbohydrate chain acting in cell recognition.

Smooth Endoplasmic Reticulum

Tubular membrane network without ribosomes; synthesizes lipids and detoxifies drugs.

Rough Endoplasmic Reticulum

ER studded with ribosomes; synthesizes proteins destined for export or membranes.

Ribosome

Two-subunit RNA-protein complex; site of protein synthesis; free or ER-bound.

Polysome (Polyribosome)

String of ribosomes simultaneously translating the same mRNA.

Golgi Apparatus

Stack of flattened sacs that modifies, packages, and sorts proteins into vesicles.

Vesicle

Small membrane-bound sac for transport or storage of molecules within the cell.

Lysosome

Golgi-derived vesicle containing hydrolytic enzymes for digestion and autodigestion.

Cytoskeleton

Network of microtubules and microfilaments providing shape, support, and organelle movement.

Cilia

Short, numerous membrane-bound microtubule projections used for cell movement.

Flagella

Long, whip-like microtubule structures that propel cells such as sperm.

Cellular Respiration

Process in mitochondria that uses oxygen to break down glucose and generate ATP, releasing CO₂.

Diffusion

Passive movement of solute particles from high to low concentration until equilibrium.

Osmosis

Diffusion of water across a selectively permeable membrane from high to low water concentration.

Facilitated Transport

Passive, carrier-mediated movement of solutes down their concentration gradient.

Active Transport

Carrier-mediated movement of solutes against the concentration gradient using ATP.

Isotonic Solution

Solution with equal solute concentration to the cell; no net water movement.

Hypertonic Solution

Solution with higher solute (lower water) concentration than the cell; causes cell to shrink.

Hypotonic Solution

Solution with lower solute (higher water) concentration than the cell; causes cell to swell.

Selectively Permeable

Describes membranes that allow some substances to pass while restricting others.

Surface-Area-to-Volume Ratio

Relationship limiting cell size; small cells have more membrane relative to volume for exchange.

Endocytosis

Active process of engulfing material into the cell by membrane in-folding.

Phagocytosis

Form of endocytosis involving engulfment of very large particles (“cell eating”).

Pinocytosis

Form of endocytosis involving uptake of small droplets of fluid (“cell drinking”).

Exocytosis

Active process of vesicles fusing with the plasma membrane to release contents outside the cell.

Blebbing

Pinching off of membrane sections from ER or Golgi to form transport vesicles.

Microscope

Instrument whose invention allowed the first study and discovery of cells.

Matthias Schleiden

19th-century German botanist who concluded that all plants are made of cells.

Theodor Schwann

19th-century German zoologist who concluded that all animals are made of cells.

Rudolf Virchow

Scientist who added the principle that cells arise only from pre-existing cells.

Cell Theory

States that all organisms are composed of cells and that cells come from pre-existing cells.

Prokaryotic Cell

Cell type lacking a nucleus and most organelles; found only in the Bacteria (Monera) kingdom.

Eukaryotic Cell

Cell type with a true nucleus and membrane-bound organelles (e.g., plant, animal, fungi, protist cells).

Kingdom Monera

The only kingdom composed entirely of prokaryotic organisms.

Chloroplast

Large double-membraned plant organelle containing chlorophyll; site of photosynthesis.

Cell Wall

Rigid cellulose layer outside plant plasma membrane that provides support and protection.

Central Vacuole

Large, single-membraned storage sac in plants that can occupy up to 90 % of cell volume.

Mitochondrion

Double-membraned organelle that burns glucose to make ATP via cellular respiration.

Nucleus

Largest organelle; surrounded by a double nuclear envelope with pores; stores DNA.

Nuclear Envelope

Double membrane around the nucleus perforated by pores for molecule passage.

Nucleolus

Dark region inside the nucleus that produces and stores ribosomal RNA.

Chromatin

Uncondensed DNA-protein complex found in the nucleus; coils into chromosomes during division.

Chromosome

Rod-shaped, condensed chromatin structure containing hereditary DNA.

Cytoplasm

Gel-like colloid inside the cell in which organelles are suspended.

Plasma Membrane

Phospholipid bilayer that regulates entry and exit of substances; selectively permeable.

Phospholipid

Fat molecule with a phosphate head and lipid tails; forms bilayer of cell membranes.

Fluid Mosaic Model

Current membrane model: proteins float in a semi-fluid phospholipid bilayer.

Glycoprotein

Membrane protein with an attached carbohydrate chain that acts as a cell marker.

Glycolipid

Membrane phospholipid with an attached carbohydrate chain acting in cell recognition.

Smooth Endoplasmic Reticulum

Tubular membrane network without ribosomes; synthesizes lipids and detoxifies drugs.

Rough Endoplasmic Reticulum

ER studded with ribosomes; synthesizes proteins destined for export or membranes.

Ribosome

Two-subunit RNA-protein complex; site of protein synthesis; free or ER-bound.

Polysome (Polyribosome)

String of ribosomes simultaneously translating the same mRNA.

Golgi Apparatus

Stack of flattened sacs that modifies, packages, and sorts proteins into vesicles.

Vesicle

Small membrane-bound sac for transport or storage of molecules within the cell.

Lysosome

Golgi-derived vesicle containing hydrolytic enzymes for digestion and autodigestion.

Cytoskeleton

Network of microtubules and microfilaments providing shape, support, and organelle movement.

Cilia

Short, numerous membrane-bound microtubule projections used for cell movement.

Flagella

Long, whip-like microtubule structures that propel cells such as sperm.

Cellular Respiration

Process in mitochondria that uses oxygen to break down glucose and generate ATP, releasing CO₂.

Diffusion

Passive movement of solute particles from high to low concentration until equilibrium.

Osmosis

Diffusion of water across a selectively permeable membrane from high to low water concentration.

Facilitated Transport

Passive, carrier-mediated movement of solutes down their concentration gradient.

Active Transport

Carrier-mediated movement of solutes against the concentration gradient using ATP.

Isotonic Solution

Solution with equal solute concentration to the cell; no net water movement.

Hypertonic Solution

Solution with higher solute (lower water) concentration than the cell; causes cell to shrink.

Hypotonic Solution

Solution with lower solute (higher water) concentration than the cell; causes cell to swell.

Selectively Permeable

Describes membranes that allow some substances to pass while restricting others.

Surface-Area-to-Volume Ratio

Relationship limiting cell size; small cells have more membrane relative to volume for exchange.

Endocytosis

Active process of engulfing material into the cell by membrane in-folding.

Phagocytosis

Form of endocytosis involving engulfment of very large particles (“cell eating”).

Pinocytosis

Form of endocytosis involving uptake of small droplets of fluid (“cell drinking”).

Exocytosis

Active process of vesicles fusing with the plasma membrane to release contents outside the cell.

Blebbing

Pinching off of membrane sections from ER or Golgi to form transport vesicles.