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Cells

Organelles

5 min read•june 18, 2024

Riya Patel

Biology 🧍

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Components of Eukaryotic Cells and their Functions.

What is a Cell?

Did you know that your body is composed of approximately 37.2 trillion cells? That's a whole lot! After reading that fact, you're probably wondering why we consist of so many cells, and that's because each cell has a specific function. While some cells work to send signals to your brain, others help digest food, filter urine, pump blood, and much more!

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What is a Cell Composed of?

A cell is composed of multiple membrane-bound structures called organelles, which each have specific structures and functions to allow the cell to carry out its daily processes. For a brief overview of organelles and what they do, check out this guide!

So, you might be wondering, what are the different types of organelles in our cells? How do they look? More importantly, how do they help our cells? In the table below, we'll summarize each cell part, along with its structure and function. In order to make the memorization process easier for you, the table also relates each organelle to different parts of a restaurant that help it function!

Brief Overview of Cellular Components

Cell Part	What Type of Cell is it Found in?	Structure	Function	Analogy to a Restaurant
Nucleus	Animal and plant cells	Double membrane; contains small pores to allow mRNA to pass-through	Control center of the cell- stores DNA 🧬	Manager 😎
Mitochondria	Animal and plant cells	Double membrane; the inner membrane is folded into cristae	Powerhouse of the cell- produces ATP ⚡	Stove 🍳
Endoplasmic Reticulum	Animal and plant cells	Membrane studded with ribosomes (rough) or without ribosomes (smooth)	Produces proteins (rough) or lipids (smooth) 🔨	Kitchen 🍴
Golgi Apparatus	Animal and plant cells	Combination of vesicles and membranes; found near the cell membrane	Sorts, stores, and prepares products 📦	Waiters 💁
Vacuole	Plant cells	Fluid-filled sac surrounded by a membrane	Stores water and other excess fluids 🚰	Fridge 🧊
Chloroplast	Plant cells	Double membrane; contains stacked discs called thylakoids	Photosynthesis occurs here 🌱	Solar Panels on Roof 🌤
Cell Wall	Plant cells	Outer membrane; made of cellulose	Provides additional structure and support ➕	Walls of the Restaurant 🚧
Cell Membrane	Prokaryotes and eukaryotes	Phospholipid bilayer with amphipathic proteins	Regulates what goes in 👈 and out 👉of the cell	Front Door 🚪
Lysosome	Animal cells	Membrane sac full of enzymes; break down molecules using water	Facilitates the breaking of bigger molecules 💔	Janitor 🧼
Ribosomes	Prokaryotes and eukaryotes	Subunit made of RNA and protein	Site of protein synthesis and translation 🏗️	Chefs 👨‍🍳
Cytoplasm	Prokaryotes and eukaryotes	Gel-like fluid; fills entire cell	Stores all of the organelles in a cell 🏪	Dining Room 😋
Cytoskeleton	Prokaryotes and eukaryotes	Composed of microtubules and various filaments	Provides structure and helps in transport 🚕	Building 🏨

Be sure to check out this video if you need a more in-depth refresher on the structures and functions of cellular components.

Now that we've briefly discussed cellular components and what they do, let's get into more detail. While all organelles play essential roles in the cell, you must remember more information about some specific ones covered below.

Nucleus

The nucleus contains a cell's deoxyribonucleic acid, or DNA, in a double helix structure. DNA contains the blueprints for all the proteins that allow our body to function; however, the processes of transcription and translation must occur for our bodies to use this DNA later. Transcription occurs within the nucleus, while translation occurs outside of it. The nucleus involves itself in these processes by providing a barrier between DNA and the rest of the cell. When this DNA moves outside of the nucleus, it must translate into mRNA and then leave through the nuclear membrane's pores.

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Endoplasmic Reticulum

The endoplasmic reticulum (ER) is a membrane found inside the cell, which has multiple folds called lumen. There are two different types of endoplasmic reticulum: the smooth ER and the rough ER.

Image Courtesy of Unsplash

Smooth ER

Smooth ER is referred to as “smooth” because nothing covers its surface. The smooth endoplasmic reticulum makes lipids and steroids, and these molecules are vital in storing energy and upholding the membrane of a cell. The smooth ER also aids the cell and body in getting rid of toxins.

Rough ER

Unlike smooth ER, rough ER is described as “rough” because ribosomes stud its surface. Because of this particular feature, the rough endoplasmic reticulum is in charge of creating proteins. These proteins have different signals attached to them, telling them whether they will stay part of the cell membrane or be expelled.

Golgi Apparatus

The Golgi apparatus helps pack and prepare membranes for transport.

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There are four different paths that a protein can take when it reaches the Golgi apparatus:

The protein can go back to the cytosol. Typically, this path is for proteins sent to the Golgi apparatus by the endoplasmic reticulum accidentally.
The protein can go to the cell membrane. This path causes the vesicle to form and fuse with the cell membrane.
The protein can be secreted. There has to be a specific amount of vesicles for this secretion to occur, and a signal must be sent.
The protein can go to the lysosome. When this path occurs, the vesicle will use its enzymes to break down the lysosome using water.

Lysosome

The lysosome is spherical in shape, and it is full of enzymes that break down molecules that cross the membrane using water. Lysosomes only function at a pH of 5, meaning that the area they occupy outside the cell is more acidic than its optimal pH of 7.

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Mitochondria

Mitochondria produce adenosine triphosphate or ATP, which is the cell's primary energy source. The cell goes through cellular respiration, which first begins in the cytoplasm and then takes place in the mitochondria, to create ATP. Therefore, mitochondria are vital in creating and providing energy to all of the cells within our body.

Image Courtesy of Pixabay

Closing

In this article, we discussed cells and the specific functions of their organelles. To review this material, check out this fantastic study guide! Good luck studying! 😊

🤝Connect with other students studying cell organelles with Hours.

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