No nucleus, but a nucleoid

The idea

Bacteria lack a well-defined nucleus and nuclear membrane and instead have a nucleoid, which distinguishes them from cells of yeast, protozoa, algae, fungi, plants and animals.

Look for the nucleus

Yeast, protozoa, algae, fungi, plants and animals all have a well-defined nucleus with a nuclear membrane. Let us look at a bacterium.

What do you expect to find in a bacterial cell?

• A well-defined nucleus, just like the others
• Something different from a well-defined nucleus
• Nothing inside

Nucleus or nucleoid?

Read each clue and tap the part.

A nucleoid

Bacteria do not have a well-defined nucleus and nuclear membrane. Instead they have a nucleoid. This distinguishes them from cells of yeast, protozoa, algae, fungi, plants and animals.

• Cell | Has
• Yeast, protozoa, algae, fungi, plants, animals | A well-defined nucleus with a nuclear membrane
• Bacteria | A nucleoid: no well-defined nucleus, no nuclear membrane

Notes

Bacteria lack a well-defined nucleus and nuclear membrane. They have a nucleoid instead. Yeast, protozoa, algae, fungi, plants and animals have a well-defined nucleus.

Check yourself

What do bacteria have instead of a well-defined nucleus?

Which cell has a well-defined nucleus with a nuclear membrane?

Which group of microorganisms has a nucleoid?

• A nucleoid — correct. Yes. The nucleoid distinguishes bacteria from other cells.
• A chloroplast. A chloroplast is found in plant cells. Bacteria have a nucleoid.
• A vacuole. A vacuole stores substances. Bacteria have a nucleoid instead of a well-defined nucleus.
• A yeast cell — correct. Yes. Yeast, protozoa, algae, fungi, plants and animals all have one.
• A bacterial cell. Bacteria have a nucleoid, not a well-defined nucleus.
• Bacteria — correct. Yes. This is what distinguishes them from the other kinds of cell.
• Protozoa. Protozoa have a well-defined nucleus.
• Algae. Algae have a well-defined nucleus.