Structure and Function of the Nucleus in Animal Cells

Lia Kim, Amanda Robb
  • Author
    Lia Kim

    Lia Kim has a B.S. in Earth Systems from Stanford University. She also has certifications in Phytobiotechnology and Ethnopharmacognosy from University of Hawai'i of Manoa.

  • Instructor
    Amanda Robb

    Amanda has taught high school science for over 10 years. She has a Master's Degree in Cellular and Molecular Physiology from Tufts Medical School and a Master's of Teaching from Simmons College. She is also certified in secondary special education, biology, and physics in Massachusetts.

Do animal cells have a nucleus? Yes! Learn the structure of the nucleus and understand its functions within the cell. Updated: 12/01/2021

Table of Contents


The Nucleus

A nucleus is an organelle within a cell that encloses DNA. DNA stands for deoxyribonucleic acid, a molecule that contains genetic information. The nucleus not only stores DNA but directs the synthesis of ribosomes, acting like the boss of a cell.

Do animal cells have a nucleus? Yes! All animals are eukaryotes, meaning they are made up of many cells with a true nucleus. The animal nucleus is membrane-bound, which is one of the many structural components that differentiates them from prokaryotic organisms like bacteria.

The dark brown circle is the nucleus of a living onion skin cell. All eukaryotic cells have a membrane-bound nucleus.

The dark brown circle is the nucleus of a living onion skin cell. All eukaryotic cells have a membrane-bound nucleus.

Animal Cells vs. Plant Cells

Both animals and plants are eukaryotes, meaning they both have a nucleus, plasma membrane, ribosomes, mitochondria, peroxisomes, and cytoplasm. However, animal cells and plant cells have important structural differences.

  • Animal cells have centrosomes and lysosomes, while plant cells do not.

The centrosome is a cellular structure, or an organelle, involved in animal cell division that is found near the nucleus. It is also where all microtubules originate. Microtubules are major components involved in cell division and maintenance of cell shape. The microtubules help separate the chromosomes into the daughter cells. It is important to note that while plant cells do not have centrosomes, they are still capable of cell division.

The lysosome is an organelle that contains digestive enzymes. Plant cells do not have lysosomes, but instead, have vacuoles. Both lysosomes and vacuoles break down waste products, excess or worn-out cell parts, or destroy viruses and bacteria.

Animal cells have both lysosomes and vacuoles, while plant cells only have vacuoles. Plant cells also have a large central vacuole, which stores water to maintain pressure in the cell.

  • Plant cells have a rigid cell wall, plasmodesmata, chloroplasts, and plastids, which are all lacking in animal cells.

The cell wall in plant cells helps maintain the shape of the cell and protects it. The main component within the plant cell wall is cellulose, a polysaccharide. The crunchiness in raw vegetables is due to cell walls breaking! Plant cells also contain plasmodesmata, which are membrane-lined channels that connect different plant cells together and enable cell-to-cell communication. Animal cells have gap junctions, which have a similar function to plasmodesmata but are structurally different.

Another unique organelle within a plant cell is a chloroplast. Chloroplasts allow plant cells to conduct photosynthesis, an important series of reactions that convert carbon dioxide, water, and energy from light into sugar and oxygen. The greenness of plants is due to the pigment called chlorophyll that is found in chloroplasts. Plant cells also have plastids, which stores pigments, unlike animal cells.

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  • 0:00 The Nucleus
  • 1:17 Structure
  • 2:27 Storing DNA
  • 3:39 Making Ribosomes
  • 3:58 Copying DNA
  • 5:20 Lesson Summary
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The Animal Nucleus Structure

In a eukaryotic cell, the nucleus is one of the largest organelles. It is not just a rigid, solid ball-like structure; it has pores, a nuclear membrane, nucleoli, and is filled with nucleoplasm.

  • The double-layered membrane that encloses the nucleus (which differs eukaryotic cells from prokaryotic cells) is called the nuclear membrane, or nuclear envelope. The inner membrane is called the nuclear lamina.
  • The nuclear membrane has pores to allow certain molecules to pass in and out of the nucleus with the help of certain proteins.
  • The nucleolus (plural: nucleoli) is a small, dense structure within the nucleus that contains ribosomal DNA, RNA, and ribosomal proteins to form ribosomes. The ribosomes, after they are transported out of the nucleus to the endoplasmic reticulum, become sites of protein synthesis. The nucleus can contain up to four nucleoli.
  • The nucleoplasm is a semifluid, gel-like matrix where the nuclear components like chromatin (a complex of DNA and protein) are suspended.

Nucleus Function in an Animal Cell

What does the nucleus do in an animal cell? It does many important things that allow for animals to live. The function of the nucleus in an animal cell include organizing, protecting, storing, and copying DNA, as well as making ribosomes. The following sections will elucidate each of the functions of the nucleus.

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Frequently Asked Questions

What are the main functions of nucleus?

The function of the nucleus in an animal cell include organizing, protecting, storing, and copying DNA. The nucleus also contains nucleoli, a site that makes ribosomes, an important organelle for protein synthesis.

Do all animal cells have a nucleus?

All animals are eukaryotes. They belong to the Domain Eukarya. All eukaryotes have a membrane-bound nucleus. Thus, animal cells have a nucleus!

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