<h2 class="section-header"><strong class="title">Vesicles and Lysosomes</strong></h2>
<p class="para"><em class="emphasis">Vesicles</em> are small, membrane-bound spherical sacs which facilitate the metabolism, transport and storage of molecules. Many vesicles are made in the Golgi body and the endoplasmic reticulum, or are made from <a data-lesson="parts-of-the-cell" data-subject="biology" data-tutorial="cell-biology" href="https://app.ulearngo.com/biology/cell-biology/parts-of-the-cell">parts of the cell</a> membrane. Vesicles can be classified according to their contents and function. Transport vesicles transport molecules within the cell.</p>
<p class="para"><em class="emphasis">Lysosomes</em> are formed by the Golgi body and contain powerful digestive <a data-lesson="enzymes-2" data-subject="biology" data-tutorial="biology-foundations" href="https://app.ulearngo.com/biology/biology-foundations/enzymes-2">enzymes</a> that can potentially digest the cell. Lysosomes are formed by the Golgi body or the endoplasmic reticulum. These powerful enzymes can digest cell structures and food molecules such as <a data-lesson="carbohydrates" data-subject="biology" data-tutorial="biology-foundations" href="https://app.ulearngo.com/biology/biology-foundations/carbohydrates">carbohydrates</a> and proteins. Lysosomes are abundant in animal cells that ingest food through food vacuoles. When a cell dies, the lysosome releases its enzymes and digests the cell.</p>
<h2 class="section-header"><strong class="title">Vacuoles</strong></h2>
<p>Vacuoles are membrane-bound, fluid-filled organelles that occur in the <a data-lesson="cytoplasm" data-subject="biology" data-tutorial="introducing-the-cell" href="https://app.ulearngo.com/biology/introducing-the-cell/cytoplasm">cytoplasm</a> of most plant cells, but are very small or completely absent from animal cells. Plant cells generally have one large vacuole that takes up most of the cell's volume. A selectively permeable membrane called the <em class="emphasis">tonoplast</em>, surround the vacuole. The vacuole contains <em class="emphasis">cell sap</em> which is a liquid consisting of water, mineral salts, sugars and amino acids.</p>
<p><a href="https://data.ulearngo.com/assets/75551c91-e399-4859-945f-408a79c06305"><img alt="vacuole" class="size-full wp-image-100168 alignnone" height="127" src="https://data.ulearngo.com/assets/75551c91-e399-4859-945f-408a79c06305" width="382"/></a></p>
<h3 class="para">Functions of the Vacuole</h3>
<ul class="bullet">
<li class="item">The vacuole plays an important role in <a data-lesson="digestive-system-organs" data-subject="biology" data-tutorial="human-biology" href="https://app.ulearngo.com/biology/human-biology/digestive-system-organs">digestion</a> and excretion of cellular waste and storage of water and organic and inorganic substances.</li>
<li class="item">The vacuole takes in and releases water by <a data-lesson="osmosis-2" data-subject="biology" data-tutorial="cell-biology" href="https://app.ulearngo.com/biology/cell-biology/osmosis-2">osmosis</a> in response to changes in the cytoplasm, as well as in the environment around the cell.</li>
<li class="item">The vacuole is also responsible for maintaining the shape of plant cells. When the cell is full of water, the vacuole exerts pressure outwards, pushing the <a data-lesson="cell-membrane" data-subject="biology" data-tutorial="introducing-the-cell" href="https://app.ulearngo.com/biology/introducing-the-cell/cell-membrane">cell membrane</a> against the cell wall. This pressure is called turgor pressure.</li>
<li class="item">If there is not sufficient water, pressure exerted by the vacuole is reduced and the cells become flaccid causing the plant to wilt.</li>
</ul>

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Vesicles, Lysosomes and Vacuoles

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Vesicles, Lysosomes and Vacuoles

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