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Do animal cells have vacuoles?


I overheard a rather heated argument about whether or not animal cells have vacuoles.

One person said that they do, but they're much smaller than vacuoles in plant cells.

The other person said they don't. While there is something there that acts similar to a vacuole, it's slightly different. The person also noted that the only websites that say that something as a vacuole aren't credible sites (ie. not University sites, etc… )

I'm really curious as to which it is: Do animal cells have vacuoles or not?


They are both right.

Animal cells do have vacuoles, but they are smaller, larger in number (plant cells usually have just one or a few large vacuoles) AND serve a somewhat different purpose than those of plants.

A vacuole is basically a membrane-covered compartment (vesicle) filled with molecules, that shouldn't, right now, be in the cytoplasm. For plants, this means long-term storage of water and waste products, which cannot be removed from the cell due to the cell wall. For animals it means mostly taking part in exocytosis and endocytosis - they are much more dynamic structures.

And about some half-professional sources, here is a bit from Molecular Biology of the cell which in fact calls plant vacuoles "a kind of specialized lysosome".


Yes! As a matter of fact Animal Cells do have vacuoles. Even though they are much smaller than the Large Central Vacuole of Plant Cells they still do exist in Animal Cells. Unlike the Large Central Vacuole of the Plant Cells they do not take up 90% of the cells and there are multiple vacuoles, but small ones might I add. Also in a Plant Cell there is only one vacuole the Large Central Vacuole.


Yes, animal cells do have vacuoles. They just have a larger number of them and some sites call them with different names. In a plant cell there is just one vacuole. Pictures of cells in textbooks,online,etc should show you that they have vacuoles, despite contrary beliefs elsewhere.


Vacuole

Vacuoles are one-membrane cellular organelles and important components of a eukaryotic cell (the eukaryotic cell has a nucleus and a membrane – outer shell). However, not all eukaryotic cells have vacuoles among their organelles. Vacuoles are mainly found in plant and fungal cells. Do animal cells have vacuoles? Yes, animal cells do have vacuoles, but they are smaller, larger in number (plant cells usually have just one or a few large vacuoles) and serve a somewhat different purpose than those of plants.


What are Plant Vacuoles

Plant vacuoles refer to a cavity within the cytoplasm, which is covered by a single membrane and contains the cell sap in plant cells. The membrane that surrounds the plant vacuoles is called the tonoplast. These vacuoles mainly contain water and occupy up to 90% of the total volume of the cytoplasm in mature plant cells. These vacuoles also contain mineral salts, sucrose, amino acids, proteins, and waste materials. Plant vacuoles contain water-soluble pigments. The vacuole of a plant cell is shown in figure 1.

Figure 1: Plant Vacuole

The main function of the plant vacuoles is to maintain the turgor pressure of the cell. The plasma membrane of the cell is pushed against the cell wall by the turgor pressure. Plant cells obtain water into their vacuoles through osmosis. Vacuole helps to maintain the shape of the cell during dehydration. They are important for the maintenance of osmotic concentration of the cell. Plant vacuoles that contain digestive enzymes may serve as lysosomes. Dissolved anthocyanin in the epidermal cells of the Rhoeo is shown in figure 2. Anthocyanin is a water-soluble pigment in plant cells.

Figure 2: Anthocyanin in the Rhoeo Vacuoles

One of the most significant roles of the plant vacuoles is the detoxification of heavy metals inside the cell.


Structure and Function of Vacuoles in Animal Cells

Vacuoles in animal cells mostly store substances they aren’t needed as much for breaking down substances because lysosomes, another organelle in animal cells, do that. Animal cell vacuoles are typically small, and each cell can contain multiple vacuoles. Vacuoles can store different substances depending on the type of cell they are in. For example, in fat cells, vacuoles will often store large amounts of lipids.

Vacuoles in animal cells also help with the processes of endocytosis and exocytosis. Endocytosis is when substances that can’t passively move through the cell membrane are actively transported into the cell. These substances can include anything from nutrients to toxins to cell debris. Exocytosis is the opposite it’s the process of actively moving molecules out of a cell.

During these processes, the vacuole is where the substances are stored or broken down before/after they are moved into/out of the cell.


Differences between plant, fungal and animal cells

Animal cells have slight differences to the eukaryotic cells of plants and fungi. The clear differences are the lack of cell walls, chloroplasts and vacuoles and the presence of flagella, lysosomes and centrosomes in animal cells.

Plant and fungal cells have cell walls. A cell wall is an external structure that surrounds the plasma membrane and provides protection and structural support. Plant cells also have chloroplasts and vacuoles. Chloroplasts are the site of photosynthesis and vacuoles are large sac-like organelles used to store substances.

Plant cells lack flagella, lysosomes and centrosomes. Fungal cells typically have lysosomes and centrosomes but very few species have flagella. The main difference between fungal and animal cells is the presence of a cell wall in fungal cells.

Summary

  • Animal cells are typically large, specialized eukaryotic cells – they contain a nucleus and numerous organelles
  • The plasma membrane surrounds an animal cell
  • Almost all of a cell’s DNA is kept inside its nucleus
  • Endoplasmic reticulum (ER) is a network of membranes connected to the nucleus – it includes the smooth ER and the rough ER
  • Cellular respiration occurs in the mitochondria
  • Ribosomes produce proteins – they can be found in the endoplasmic reticulum or freely floating
  • Animal cells have lysosomes for digestion, centrosomes to help with cell division and sometimes flagella to help with movement – none of these three organelles are found in plant cells
  • The cells of animals lack cell walls, chloroplasts and vacuoles which are all found in plant cells
  • Different types of specialized cells are found in different tissues and have features relative to their function e.g. nerve cells have axons and dendrites to send and receive messages.

Last edited: 30 August 2020

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This is world’s #1 textbook for beginning biologists and has been hugely valuable to me over the years. This is the resource that I recommend above anything else for aspiring biologists.


Contractile Vacuoles in Microorganisms

A contractile vacuole (CV) is an organelle, or sub-cellular structure, that is involved in osmoregulation and waste removal. Previously, a CV was known as a pulsatile or pulsating vacuole. CVs should not be confused with vacuoles which store food or water. A CV is found predominantly in protists and in unicellular algae. In freshwater environments, the concentration of solutes inside the cell is higher than outside the cell. Under these conditions, water flows from the environment into the cell by osmosis. Thus, the CV acts as a protective mechanism against cellular expansion (and possibly explosion) from too much water it expels excess water from the cell by contracting. However, not all species that possess a CV are freshwater organisms some marine and soil microorganisms also have a CV. The CV is predominant in species that do not have a cell wall, but there are exceptions. Through the process of evolution, the CV was mostly eliminated in multicellular organisms however it still exists in the unicellular stage of several multicellular fungi and in several types of cells in sponges, including amoebocytes, pinacocytes, and choanocytes.

Figure (PageIndex<1>): Contractile vacuole of Euglena: Structure of Euglena: 1 &ndash Flagellum 2 &ndash Eye spot / Pigment spot / Stigma 3 &ndash Photoreceptor 4 &ndash Short second flagellum 5 &ndash Reservoir 6 &ndash Basal body 7 &ndash Contractile vacuole 8 &ndash Paramylon granule 9 &ndash Chloroplasts 10 &ndash Nucleus 11 &ndash Nucleolus 12 &ndash Pellicle

The CV&rsquos phases of collecting water (expansion) and expelling water (contraction) are periodical. One cycle takes several seconds, depending on the species and the environment&rsquos osmolarity. The stage in which water flows into the CV is called diastole. The contraction of the CV and the expulsion of water from the cell is called systole. Water always flows from outside the cell into the cytoplasm and only then from the cytoplasm into the CV. Species that possess a CV always use it, even in very hypertonic (high concentration of solutes) environments, since the cell tends to adjust its cytoplasm to become even more hyperosmotic (hypertonic) than the environment. The amount of water expelled from the cell and the rate of contraction are related to the osmolarity of the environment. In hyperosmotic environments, less water will be expelled and the contraction cycle will be longer.


Why Do Plant Cells Have Bigger Vacuoles Than Animal Cells?

Plant cell vacuoles serve the same vital storage functions for nutrients, water and wastes as those in animal cells but are much larger because they also provide structural stiffness in combination with the plant's cell walls. This is why water-starved plants droop their cells have essentially deflated. If a living but wilted plant once again receives sufficient water, it regains its former stiffness as the vacuoles refill.

Because of the size of the vacuoles in plant cells, often occupying most of the space in each cell, they are used for many of the functions for which animal cells use other organelles. For instance, plant vacuoles tend to be acidic and contain enzymes that act like those in lysosomes in animal cells. They also contain many compounds important in cell defense. Sometimes, they are even used to trap pathogens and toxic substances. Their importance in plant cells is much greater than in animal cells.

Plant vacuoles have variety beyond the large, water-filled central vacuoles, however. Many fruits and seeds have protein-storing vacuoles, for instance. Some plants even use vacuoles for rapid defensive movements. While plant cell vacuoles differ greatly from animal cell vacuoles, they have several similarities to those in algae and even in yeasts.


Looking at animal and plant cells under a microscope

You can easily find samples of animal and plant cells to look at under a microscope. See below to explore more:

Cheek cells (more specifically, epithelial cells) form a protective barrier lining your mouth. All you need to do is to gently scrape the inside of the mouth using a clean, sterile cotton swab and then smear the swab on a microscopic slide to get the cells on to the slide.

You can see our step-by-step guide, “Look at your cheek cells.“

[In this figure] Cheek cells stained with Methylene Blue.
The left image is a low magnification. You can see the nuclei stained with a dark blue (because Methylene Blue stains DNA strongly). The cell membrane acts like a balloon and holds all the cell parts inside, such as a nucleus, cytosol, and organelles.
The right image is a high magnification. This check cell is about 80 micrometers in diameter. You can also see some small rod-shaped bacteria on the right image. Don’t worry they are normal oral microbes.

[In this figure] Microscopic view of onion skin.
The onion skin is a layer of protective epidermal cells against viruses and fungi that may harm the sensitive plant tissues. This layer of skin is transparent and easy to peel, making it an ideal subject to study plant cell structure. Without stains, you can only see the cell walls of onion cells. By staining of Eosin Y, now you can see a nucleus inside an onion cell.

You can follow our step-by-step guide, “Look at the Plant Cells” to prepare your own onion skin slide.


What Are the Differences Between Plant and Animal Cells?

Plant cells have to perform two functions that are not required of animal cells:

  1. Produce their own food (which they do in a process called photosynthesis).
  2. Support their own weight (which animals usually do by means of a skeleton).

The structures possessed by plant cells for performing these two functions create the primary differences between plant and animals cells. These structures are:

Structures Unique to Plant Cells

  • Cell Wall: A wall on the outside of the membrane, which, in combination with the vacuole (as described below), helps the plant cell maintain its shape and rigidity.
  • Plastids: Used in photosynthesis to convert sunlight, carbon dioxide, and water into food. The most well-known plastids are chloroplasts, which contain the chlorophyll that gives many plants their green hue.
  • Large Vacuole: While animal cells may have many tiny vacuoles, a plant cell usually has a single large vacuole, which serves as a storage tank for food, water, waste products, and other materials. The vacuole has an important structural function, as well. When filled with water, the vacuole exerts internal pressure against the cell wall, which helps keep the cell rigid. A plant that is wilting has vacuoles that are no longer filled with water.

While animal cells do not have a cell wall, chloroplasts, or a large vacuole, they do have one component plant cells do not. This is:


Do animal cells have vacuoles? - Biology

Plant cells have a cell wall, chloroplasts and other specialized plastids, and a large central vacuole, whereas animal cells do not.

Figure 1. These figures show the major organelles and other cell components of (a) a typical animal cell and (b) a typical eukaryotic plant cell. The plant cell has a cell wall, chloroplasts, plastids, and a central vacuole—structures not found in animal cells. Plant cells do not have lysosomes or centrosomes.

If you examine Figure 1b, the diagram of a plant cell, you will see a structure external to the plasma membrane called the cell wall. The cell wall is a rigid covering that protects the cell, provides structural support, and gives shape to the cell. Fungal and protistan cells also have cell walls, as do some prokaryotic cells. While the chief component of prokaryotic cell walls is peptidoglycan, the major organic molecule in the plant cell wall is cellulose (Figure 2), a polysaccharide made up of glucose units. Have you ever noticed that when you bite into a raw vegetable, like celery, it crunches? That’s because you are tearing the rigid cell walls of the celery cells with your teeth.

Figure 2. Cellulose is a long chain of β-glucose molecules connected by a 1-4 linkage. The dashed lines at each end of the figure indicate a series of many more glucose units. The size of the page makes it impossible to portray an entire cellulose molecule.