Nucleus Flashcards
What is a nucleus?
A membrane-bounded organelle which is present in most eukaryotic cells. It is the storehouse for most of the genetic information (DNA= Deoxyribonucleic acid) in our cells.
What does the DNA do?
It contains genes, that are instructions for making proteins.
What are the tasks of the nucleus?
There are two important tasks:
1) Protect the DNA carefully.
2) Let the DNA be available for use at the proper times.
Molecules that damage the DNA must be kept out of the nucleus.
What is the composition of the nucleus?
The nucleus is composed of the cell`s DNA, that is enclosed in a double membrane called the nuclear envelope.
What is special about the nuclear envelope?
Each membrane in it is similar to the membrane surrounding the entire cell. The nuclear envelope is pierced with holes called pores.
What do pores do?
They allow large molecules to pass between the nucleus and cytoplasm.
What is else in the nucleus?
The nucleus also contains the nucleolus. The nucleolus is a dense region, where tiny organelles are assembled for making proteins. These organelles are called ribosomes.
What is special about the ribosomes?
The ribosomes are a combination of proteins and RNA molecules.
REMEMBER!
The nucleus stores and protects DNA!
