Nucleus

What is the main function of the nucleus in a cell?

• Stores genetic material (DNA)

• Controls cell activities.

What type of cells contain a nucleus?

Eukaryotic cells (e.g., plant and animal cells)
Not found in prokaryotic cells.

Which structure inside the nucleus is responsible for making ribosomes?

Nucleolus.

What is the nuclear envelope, and what is its function?

Double membrane around the nucleus
Protects DNA
Regulates what enters/exits the nucleus.

What is stored in the nucleus?

DNA (deoxyribonucleic acid)
Contains genetic instructions.

How does the nucleus control the activities of the cell?

DNA is transcribed into mRNA
mRNA leaves nucleus to make proteins
Proteins control cell functions.

What is chromatin, and how is it related to chromosomes?

Chromatin = loose DNA + proteins
During cell division, chromatin condenses into chromosomes.

What role do nuclear pores play in the nucleus?

Act as gateways
Allow RNA and proteins to move in/out of the nucleus.

What happens to the nucleus during cell division (mitosis)?

Nuclear envelope breaks down
Chromosomes become visible
DNA is divided into two new nuclei.

How does the nucleolus differ from the rest of the nucleus?

Dense region inside nucleus
Site of rRNA synthesis
Starts ribosome assembly.

Why is the nucleus often called the “control center” of the cell?

Contains DNA instructions
Regulates all cell processes and functions.

How would a cell function differently if its nuclear envelope were damaged?

Uncontrolled transport of materials
Harmful substances may enter
Vital molecules may escape
Can cause disruption or cell death.

Compare the nucleus in eukaryotic cells to the nucleoid region in prokaryotic cells.

Eukaryotic cells: have a membrane-bound nucleus
Prokaryotic cells: have a nucleoid (DNA region without membrane).

How do mutations in DNA within the nucleus affect cell function?

Can change protein instructions
May lead to disease or malfunction.

How do proteins and RNAs move in and out of the nucleus?

Move through nuclear pores
Transport is regulated and selective.