Non-membranous Organelles: Ribosomes, Centrioles, Cilia & Flagella

Vocabulary flashcards focusing on ribosomes, centrioles, cilia, basal bodies, rootlets, flagella, and related concepts from the lecture notes.

Ribosome

Rounded cytoplasmic organelle formed of ribonucleoprotein (RNA); site of protein synthesis; consists of two subunits formed in the nucleolus.

Nucleolus

Nuclear region where ribosome assembly begins; ribosomes are formed here before passing through nuclear pores to the cytoplasm.

Ribosomal RNA (rRNA)

RNA component of ribosomes; associates with proteins to form functional ribosomes.

Attached ribosomes

Ribosomes attached to the outer surfaces of rough endoplasmic reticulum; synthesize secretory proteins (hormones or enzymes).

Free ribosomes

Ribosomes freely dispersed in the cytoplasm; synthesize intracellular proteins; numbers rise in growing, secretory, cancer, and dividing cells.

Nissl’s granules

Isolated bodies formed by clumps of ribosomes and rough endoplasmic reticulum in nerve cells.

Polysomes

Clusters of ribosomes attached to each other forming spiral or rosette-shaped structures during active translation.

Microsomes

Small ribosome-rich particles; rich in glucose-6-phosphatase enzyme.

Centrioles

Non-membranous organelles near the nucleus; paired; essential for cell division and cilia formation; wall composed of microtubules arranged in triplets.

Centrosome

Area near the nucleus where centrioles are located.

Cilia

Motile hair-like projections on certain epithelial cells; beat to move fluids or particles; formed by centrioles dividing into pro-centrioles near the cell surface.

Basal body

Centriole that forms the base of a cilium; contains 27 microtubules arranged in nine triplet bundles.

Rootlet

Structure of nine microtubules arranged singly; extends downward from the basal body to fix it to the cytoplasm.

Flagellum

Long, singular motile projection; structurally like the cilium shaft with nine doublets; in humans, only spermatozoon has a single flagellum.

Kartagener syndrome

Immotile cilia syndrome; presents with recurrent chest infections and infertility due to defective ciliary movement.