IB Biology A2.2 Definitions

This page contains our IB Biology definitions for A2.2. By learning each one of these definitions, you will fully cover the content for IB Biology 'Cell structure'.

All Topic 2 Sub-topics (HL)A2.1: Origins of cells A2.2: Cell Structure (HL)A2.2: Further cell structure (HL)A2.3: Viruses B2.1: Membranes And Transport (HL)B2.1: Further membranes and transport B2.2: Organelles & Compartmentalisation (HL)B2.2: Further organelles B2.3: Cell Specialisation (HL)B2.3: Further cell specialisation (HL)C2.1: Chemical signalling C2.2: Neural Signalling (HL)C2.2: Further neural signalling D2.1: Cell Division (HL)D2.1: Cell cycle (HL)D2.2: Gene expression D2.3: Water Potential (HL)D2.3: Further water potential

autosomal chromosomes

The homologous pairs of chromosomes that do not determine sex

binary fission

A reproductive method where all internal structures are copied and split equally into two identical daughter cells

Chloroplast

Organelles in plant cells where light-dependent reactions of photosynthesis occur

Cristae

Folds of the inner membrane in mitochondria, increasing the surface area for oxidative phosphorylation

diploid

A cell that contains both chromosomes in a homologous pair

eukaryote

A multicellular organism with complex cell structure and compartmentalization

Grana

Stacks of thylakoids that optimize light absorption and are distributed throughout the stroma

haploid

A cell that contains one chromosome of the homologous pair

homologous chromosomes

Paired chromosomes with the same gene sequence but potentially different alleles

integral protein

A protein embedded in the plasma membrane

light microscopy

Microscopy that uses light to view objects and has a low resolution

Matrix

The cytoplasm of the mitochondria, containing enzymes for the link reaction and Krebs cycle

Mitochondria

Organelles in cells where the link reaction, Krebs cycle, and oxidative phosphorylation occur, producing ATP

Nucleus

The organelle in eukaryotic cells that contains genetic material, controls the cell, and is bounded by a double nuclear membrane

plasmid

A single chromosome of naked circular DNA found in prokaryotes

prokaryote

A unicellular organism with simple cell structure and no compartmentalization

resolution

The ability of a microscope to distinguish two objects

Ribosomes

Organelles responsible for protein synthesis, found free within the cytoplasm and associated with the endoplasmic reticulum

scanning electron microscopy

Microscopy that uses an electron beam to view the surface of an object

sex chromosomes

The homologous pair of chromosomes that determines sex

Stroma

The chloroplast cytoplasm containing starch grains, lipid droplets, and enzymes for the light-independent reactions

Thylakoids

Internal membrane systems in chloroplasts that increase surface area for light-dependent reactions

transmission electron microscopy

Microscopy that uses an electron to beam to view very small and thin slices and has a high resolution

Vesicles

Small membrane-bound sacs formed during exocytosis or endocytosis, transporting substances within and out of the cell

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