Ultra structure of an animal cell

Structure of a typical animal cell and its organellesUltra structure of an animal cellElectron micrograph of an animal cell

Nucleus and nucleolusThe largest organelle in the cell.Surrounded by a double membrane which is nuclear membrane. Nuclear membrane contains many pores called nuclear pore.Contains chromosomes and nucleolus.Normal stage, chromosomes appear as diffused net work, called chromatin.DNA in the chromosome bonded to the protein histone to form chromatin

In some parts chromatin appears to be densely packed- heterochromatin.In some parts chromatin appears loosely packed-Euchromatin.Nuclear pore allow the entry of molecules and the exit of mRNA.A small spherical body composed mainly of protein which is located in the nucleus nucleolus.It is the site of rRNA synthesis.

Electron micrograph of nucleus

MitochondriaTiny rod like structures in the cytoplasm.They are the power house of the cell.Here energy is released through various biochemical reactions..It is the site of aerobic stage of respiration.Have two membranes.Inner membrane has folds called cristae.This is the site of oxidative phosphorylation.The interior of the mitochondria is called matrix which contain enzymes.Electron micrograph of mitochondria

Ribosome Very minute structures having nearly 25nm in diameter.Do not have membrane.They are composed of protein and RNA.Some are found free in the cytoplasm.Some are attached to the surface of endoplasmic reticulum.They have two sub units.Smaller subunit is made up of one rRNA and proteins.Larger subunits are made up of two rRNA and proteins.

Function : site of protein synthesis (translation)

Electron micrograph of ribosome

Structure of ribosome

Questions Explain how the inner membrane of mitochondria adapted to its function

Describe two structural difference between the double membrane surrounding a mitochondrion and the double membrane surrounding a nucleus.