IB Bio HL Unit 1 - Subcellular Structure and Function

Cell Wall

Found in Plants, Bacteria and Fungi (or animals). Made of cellulose (plants), peptidoglycan (bacteria), and chitin (fungi). Provides support and mechanical strength, also prevents excess water uptake.

Centrosome

Found in animals only, it is made of a microtubule organizing center. The microtubules form spindle fibers and contribute to cell division (Mitosis)

Chloroplast

Found in plants. Double membrane structure with internal stacks of membranous discs, the site of photosynthesis. Manufactures organic molecules and stores them in various plastids.

Cytoskeleton

Found in all (Bacteria, Plants, Animals, Fungi). A filamentous scaffolding within the cytoplasm. Provides internal structure and controls intracellular transportation.

Cytosol/Cytoplasm

Found in all. Mostly water but full of enzymes and other molecules. Holds organelles in place and catalyzes reactions.

Rough Endoplasmic Reticulum/Rough ER

Found in Animals, Plants, Fungi. Folded membrane studded with ribosomes. Synthesizes proteins for export.

Smooth Endoplasmic Reticulum/Smooth ER

Found in Animals, Plants, and Fungi. Folded membrane continuous with the nuclear envelope. Produces lipids and metabolises toxins.

Golgi Apparatus

Found in Animals, Plants, and Fungi. Many vesicles and folded membranes that are located near the cell membrane. Sorts, stores, modifies, and exports of secretory products.

Lysosomes

Found in animals. Membranous sacs filled with hydrolytic enzymes. Breakdown/hydrolysis of macromolecules.

Mitochondrion

Found in animals, plants, and Fungi. Double Membrane structure, the inner membrane is highly folded into internal cristae.

Nuclear envelope

Found in plants, animals, and fungi. A Double Membrane surrounds the nucleus. Controls movement in and out of the nucleus.

Nucleoid region

Found in bacteria. Area in prokaryotes where the bacterial DNA in concentrated. Place for DNA to be held.

Nucleolous

Found in plants, animals, and fungi. Dense darker region in nucleus. Site of ribosome synthesis.

Nucleus

Found in plants, animals, fungi. Double membrane structure with pores. Stores genetic material (DNA) as chromatin.

Peroxisome

Found in animals, plants, and fungi. Membranous sac containing a variety of catabolic enzymes. Catalyses the breakdown of toxic substances (H2O2) and other metabolites.

Cell membrane (plasma membrane)

Found in bacteria, plants, animal, fungi. Phospholipid bilayer embedded with proteins. Barrier around the cell, semi-permeable and selective.

Ribosome

Found in bacteria (70s), plants (80s), animals (80s), and fungi (80s). Two subunits made of rRNA and protein; larger in eukaryotes (80S) than prokaryotes (70S). Polypeptide synthesis (translation). Cytoplasmic ribosomes synthesize proteins for use within the cell, and bound ribosomes synthesize proteins for secretion (export).

Vacuole

Found in plants (large and central), animals (small, temporary), and fungi (variety of sizes). Fluid-filled internal cavity surrounded by a membrane (tonoplast). Maintains hydrostatic pressure.

Vesticle

Found in plants, animals, and fungi. Membranous sac. Moves proteins and other products around the cell.