Cell Organelles

Nucleus/nuclear envelope/nucleolus

• Nucleus is surrounded by a double membrane (nuclear envelope), which contains many pores

• Nucleus contains chromatin (consists of DNA wound around histone proteins) and these make up nearly all the organism’s genome

• The nuclear envelope separates the contents of the nucleus from the rest of the cell

• The pores allow large substances (e.g. mRNA) to leave the nucleus and substances (e.g. steroid hormones) to enter the nucleus

• Ribosomes are made in the nucleolus 

Rough Endoplasmic Reticulum

• RER is the system of membranes enclosing fluid-filled spaces (cisternae)…