Internal Organization of the Cell

Inside the nucleus:

- Nuclear membrane: separates contents from the cytoplasm
- Chromatin: in two forms, heterochromatin that is DNA not being transcribed and euchromatin where DNA is transcribed
- Nucleolus of DNA where ribosomal genes make rRNA that is combined with proteins to produce the ribosomes.

Cytosol: a sol-gel liquid in which metabolic reactions and protein synthesis occur

Rough Endoplasmic Reticulum: a membrane compartment for protein synthesis

Smooth Endoplasmic Reticulum: a membrane compartment for steroid hormone synthesis and for detoxification of drugs

Mitochondrion: organelle that makes ATP which serves as energy source for chemical/mechanical work

Golgi apparatus: organelle that functions to process and package proteins and lipids

Lysozymes: formed by Golgi and contain enzymes to break down unwanted or foreign ingested material

Peroxisomes: exudate toxic materials, and can kill bacteria

Inclusion bodies are inert, stored materials

- Fat or lipid droplets: stored triglycerides/cholesterol for energy source and biosynthetic reactions

- Glycogen granules: major form of stored carbohydrate

- Pigment/lipofuscin: undigested waste materials

Cytoskeleton: internal scaffolding of the cell, contains:

- Microtubules: rigid protein cylinders for cell shape and to guide organelles/molecules to destinations

- Microfilaments: assist contraction, stabilize shape

- Intermediate filaments: resist tension and connect cells through special junctions

Surface specializations are linked to cytoskeleton

- Microvilli: slender extensions of plasma membrane

- Cillia: hairlike and motile at the surface

- Flagella: a much longer cilium for propulsion