1. Cellwall: Cells of Ulothrix are covered by a two-layer wall. The outer layer is composed of pectose and the inner layer is composed of cellulose. It gives specific shape to cells and protects them from external injury.
2. Plasma membrane: The thin membrane inside the cell wall is called plasma membrane. It is composed of lipids and proteins. It has tiny pores. A variety of chemicals pass through these pores in and out of the cell.
3. Protoplasm: All the living parts of the cell inside the cell wall are collectively called protoplasm. It consists of two parts. Cytoplasm and nucleus.
(i) Cytoplasm: The parts of cytoplasm are-
Chloroplast: Each cell contains one chloroplast. It is ribbon or girdle or cup or ring shaped. It produces food in the process of photosynthesis.
Pyrinoid: Each chloroplast contains one or more pyrinoids. It is made up of proteins. It stores carbohydrates.
Cell vacuole: Each cell has a small cell cavity. It is filled with tissue. Covering the central cavity is the primordium utricle.
Stored food: Starch is stored as stored food in their cells.
(ii) Nucleus : Ulothrix is a unicellular alga. Each of its cells has a well-formed nucleus. It controls all biological functions of cells.