Diatoms

Dinoflagellates

Microscopic algae that can live in oceans and freshwater, some of which perform photosynthesis and others that consume organisms.

Alveolata

A group of single-celled organisms, including dinoflagellates, ciliates, and parasites, characterized by small sacs called alveoli under their membrane.

Plastids

Structures within cells that carry out photosynthesis, similar to chloroplasts in plants.

Endosymbiosis

The process by which one organism lives inside another; dinoflagellates acquired their plastids from ancient red algae this way.

Flagella

Whip-like tails that aid in the movement of dinoflagellates.

Transverse flagellum

A flagellum located in a groove (cingulum) that enables the dinoflagellate to spin.

Longitudinal flagellum

A flagellum that protrudes from the sulcus, propelling the dinoflagellate forward.

Cingulum

A groove that wraps around the cell and houses the transverse flagellum.

Sulcus

A groove that runs along the bottom portion of the dinoflagellate cell.

Chromosomes

DNA structures within the nucleus; in dinoflagellates, they remain tightly packed at all times.

Nucleoproteins (DVNPs)

Proteins that package DNA in dinoflagellates, differing from the histones used by most eukaryotes.

Diatoms

A type of algae known for its silica (SiO₂) glass-like shells, vital to the oxygen supply on Earth.

Frustule

The hard outer shell of a diatom composed of silica.

Epitheca

The larger upper half of a diatom's shell.

Hypotheca

The smaller lower half of a diatom's shell.

Mitosis

A form of asexual reproduction where a single cell divides into two identical cells.

Sexual Reproduction

A process by which diatoms create gametes to restore size after becoming too small from mitosis.

Carbon Fixation

The process by which diatoms convert CO₂ into organic compounds through photosynthesis.

Sediment

Layers formed at the ocean's bottom when diatoms die and their silica shells sink.

Primary Producers

Organisms like diatoms that produce energy-rich compounds using sunlight, serving as the base of the food chain.