Lysosomes and Vacuoles

My AP Biology Thoughts Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is Shriya and I am your host for episode #53 called Unit 2 Cell Structure and Function: Lysosomes and Vacuoles. Today we will be discussing the importance of each in regards to the cells and our bodies, and how they fit into the overarching topic of Cell Structure and Function.

Segment 1: Introduction to Lysosomes and Vacuoles

• We will begin by discussing what exactly lysosomes and vacuoles are and why they are so important for our cells to contain
• Both of these are essential organelles, and organelles are subcellular structures with specific jobs to perform in the cell, much like an organ does in the body
• Lysosomes are membrane-bound sacs of enzymes which digest cellular macromolecules
• They are made by proteins from the ER and enclosed in vesicles by the Golgi apparatus and are formed by budding from the Golgi apparatus
• They break down excess cell parts, and can be used to destroy invading viruses and bacteria so if the cell is damaged beyond repair, lysosomes can help it self-destruct through a process called apoptosis
• Lysosomes also play a role in phagocytosis which is when a cell engulfs a molecule to break it down which is known as “cell eating”
• White blood cells have more lysosomes than other cells because they destroy bacteria, dead cells, cancerous cells, and foreign matter through disgestion
• Vacuoles are fluid-filled enclosed structures separated from the cytoplasm by a single membrane which are found mostly in plant cells and fungi
• They have a less prominent role in some protists, animal cells, and bacteria and in animal cells they function to sequester waste products; in plant cells, they help maintain water balance
• Overall, they function to provide nutrient storage, detoxification, and as waste exportation
• Vacuoles are also known as “specialized lysosomes” because both function to get rid of waste products, but when that product is water, the vacuole activates its function to balance water inside and outside a cell

Segment 2: More About Structure/Function of Lysosomes and Vacuoles

• Above is a picture of the structure of lysosomes which are generally known to be very acidic meaning it has to be protected from the rest of the inside of the cell
• The membrane around it stores the digestive enzymes that require the acidic, low-pH environment, also known as hydrolytic enzymes
• Hydrolytic enzymes break down large molecules into smaller ones such as large amino acids into smaller proteins and by doing so they provide necessary nutrients to the rest of the cell
• Storing the large molecules is detrimental to your health and can cause disease
• Another type of lysosome storage disease is where the small molecules that are produced from those large molecules can't get out of the lysosome
• They're stored there because the transporters for moving these small molecules out are missing genetically
• Above, is a picture of the vacuole which is similar to vesicles, another organelle, because both are membrane-bound sacs, but vacuoles are significantly larger than vesicles and are formed when multiple vesicles fuse together
• Filled tight with water, the vacuole pushes the cytoplasm into a thin strip...