IB Biology HL - Unit B2.2: Organelles + Compartmentalization

Organelle

Discrete cell structure performing specific functions.

Solid organelles

Includes ribosomes and cytoskeleton components.

Single membrane-bound organelles

Includes lysosomes and endoplasmic reticulum.

Double membrane-bound organelles

Includes nucleus and mitochondria.

Cell wall

Non-organelle structure providing support to cells.

Cytoskeleton

Non-organelle structure maintaining cell shape.

Cytoplasm

Non-organelle fluid filling the cell.

Compartmentalization

Separation of cellular processes into distinct areas.

Ultracentrifugation

Technique for separating cell components by density.

Cell fractionation

Process of isolating organelles from cells.

Differential centrifugation

Method separating particles based on size and density.

Transcription

Process of synthesizing RNA from DNA.

Translation

Process of synthesizing proteins from mRNA.

Eukaryotic cells

Cells with compartmentalized organelles and nucleus.

Prokaryotic cells

Cells without a defined nucleus or organelles.

Gene expression regulation

Control of how genes are expressed in cells.

Post-transcriptional modification

Editing mRNA before translation occurs.

Ribosomes

Sites of protein synthesis in cells.

Lysosomes

Organelles containing digestive enzymes.

Mitochondrial function

Involves energy production through cellular respiration.

Chloroplasts

Organelles responsible for photosynthesis in plants.

Nobel Prize for Cell Organelle Research

Awarded in 1974 for significant discoveries in cell biology.

Post-transcriptional modification

mRNA alterations before leaving the nucleus.

Gene expression regulation

Controls cellular response and specialization.

Compartmentalization

Formation of membrane-bound organelles in cells.

Lysosomes

Organelles containing enzymes for macromolecule breakdown.

Acid hydrolases

Enzymes in lysosomes active at pH 5.

pH difference

Cytoplasm pH is 7; lysosomes pH is 5.

H+ ion pumping

Maintains acidic environment in lysosomes.

Phagocytic vacuoles

Isolate engulfed particles for digestion.

Mitochondrion

Organelle for ATP production via aerobic respiration.

Outer membrane (mitochondrion)

Separates mitochondrion from cytoplasm.

Inner membrane (mitochondrion)

Contains enzymes for oxidative phosphorylation.

Intermembrane space

Holds protons for chemiosmosis in mitochondria.

Cristae

Folds in mitochondria increasing surface area.

Matrix (mitochondrion)

Contains enzymes for the Krebs cycle.

70S Ribosomes

Enable mitochondria to synthesize some proteins.

Chloroplast

Organelle for photosynthesis in plant cells.

Thylakoid membrane

Contains chlorophyll for light-dependent reactions.

Photosystems

Capture light energy during photosynthesis.

Stroma

Fluid containing enzymes for the Calvin cycle.

Double membrane (nucleus)

Nuclear envelope with nuclear pores for transport.

Nuclear pore complexes

Selective passageway for molecules in nucleus.

Nuclear membrane dynamics

Breaks down and reforms during cell division.

Ribosomes

Cellular structures that synthesize polypeptides.

Free Ribosomes

Ribosomes that float in cytoplasm, synthesize internal proteins.

Bound Ribosomes

Ribosomes attached to rough ER, synthesize export proteins.

Polypeptide Chains

A sequence of amino acids forming proteins.

Endoplasmic Reticulum (ER)

Membrane system involved in protein and lipid synthesis.

Rough ER

ER with ribosomes, synthesizes proteins for export.

Golgi Apparatus

Stacked sacs modifying and packaging proteins and lipids.

Cisternae

Flattened membrane-bound sacs in the Golgi apparatus.

Glycoproteins

Proteins with carbohydrate groups added for cell functions.

Transport Vesicles

Vesicles that carry molecules to the Golgi apparatus.

Exocytosis

Process of exporting materials from the cell.

Endocytosis

Process of importing materials into the cell.

Vesicles

Membrane-bound sacs transporting substances within cells.

Clathrin

Protein that coats vesicles during their formation.

Lysosomes

Vesicles containing enzymes for macromolecule digestion.

Secretory Vesicles

Vesicles that transport materials to the plasma membrane.

Endomembrane System

Network of membranes producing and transporting molecules.

Phospholipid Bilayer

Double layer of phospholipids forming cell membranes.

Quaternary Structure

Complex protein structure formed by polypeptide chains.

Integral Membrane Proteins

Proteins embedded in the plasma membrane.

Vesicle Formation

Process of vesicles budding from organelles.

Fluidity of Membranes

Ability of phospholipid bilayers to change shape.

Cell Membrane

Barrier controlling entry and exit of substances.