Organelles are structures in cells, each performing a distinctive function, similar to little organs in a cell.
Here, we have a basic guide to fundamental organelles in an Eukaryotic, or animal, cell. This information can be helpful to middle school science courses to AP biology courses:
Inside a eukaryotic cell:
Organelle #1: Nucleus and Nucleolus
The nucleus, located as a central body to the cell, directs cellular activity and also contains heredity information (DNA) in the form of chromatin (thin, fiber-like structure).
In the middle of the nucleus, we have the nucleolus, which makes small organelles called ribosomes (this will be discussed later in the blog)
The nuclear envelope encloses the nucleus, its nuclear pores allowing certain RNA strands and proteins to pass through.
(note: during mitosis, or cell division, chromatin coil up into a different structure called chromosomes)
The Nucleus:
Organelle #2: Endoplasmic Reticulum and the Ribosome
The endoplasmic reticulum (ER) is connected to the nucleus. It is separated into two sections: the rough ER (colored in red-orange below), and the smooth ER (colored in pink).
The rough ER holds an abundance of ribosomes, an organelle that makes protein from reading mRNA. The rough ER serves as a transport station for newly-formed protein to be transported by a vesicle to the Golgi apparatus (3).
Ribosomes in the rough ER are called bound ribosomes, in which they make proteins for extracellular use. Ribosome not in the ER are called free ribosomes, which proteins are for intracellular uses.
The smooth ER does NOT have any ribosomes, and is used for lipid storage and detoxification.
Organelle #3: Golgi Apparatus
The Golgi apparatus, or Golgi body, is an organelle that checks and modifies proteins and lipids received from places such as the ER before delivering them to their respective places via transport vesicles.
Organelle #4: Mitochondria
The mitochondria is an energy transducer, and the site for cellular respiration, a process that takes sugar and oxygen to produce energy in the form of adenosine triphosphate (ATP).
Fun Fact: mitochondria also has its own DNA, in which is passed down only by the mother.
Organelle #5: Centrioles, microtubules, and intermediate filaments
[numbers indicated in the illustration above]
(1) Centrioles are organelle that create spindle fibers during cell division to split hereditary material (remember, in mitosis, DNA is replicated so the mother cell can make two daughter cells identical to the mother)
(2) Microtubules act as transport railways for nutrients and other organelles. They also compose the spindle fibers.
(3) Intermediate Filaments hold the cell up/ support the structure.
Organelle #6: Lysosome
Lysosomes are organelles containing digestive enzymes that are able to break apart and/or recycle cell parts or pathogens.
All of these organelles float in an aqueous substance called cytosol, or cytoplasm.
Everything is enclosed as a cell by the cell membrane, made up of a phospholipid bilayer:
This bilayer is selectively permeable, meaning that it only allows certain particles to enter into the cell. This is because some molecules are repelled by the non-polar insides.
I hope this guide has helped. As I was under a time constraint for this blog, I am fully aware that I have not added a couple organelles (such as peroxisomes and other structures such as microvilli). I will add them soon. Thank you for tuning in!
References:
Urry, Lisa A., et al. Campbell Biology in Focus. Pearson, 2020.
helpful :D