When studying organelles it can get a little confusing. It’s like getting lost in a corn maze. Zoom out to the view the big picture. Review the basics. Then zoom in step by step.
We’ve got the hierarchy of life – Biosphere, ecosystem, community, population, organism, organ system, organ, tissue, cell, organelle (inside the cell), and molecule. To give an example, let’s use our hearts. The biosphere is Earth. The ecosystem is Ohio. The community is our town. The population is animals (including humans) within our town. The organism is the individual animal. The organ system is the cardiovascular system. The organ is the heart. The tissue is we’ll pick the endocardium which is the innermost layer of tissue inside the heart. The cell is one of the many cells that make up the heart. The organelles are the little mini-organs inside the cell with lots of jobs to do. The molecules are little chemical units. Molecules are made up of atoms.
We have domains. There are 3 types of domains.
Eukarya – A human is pushing a Eureka vacuum and the dog started barking at the vacuum and accidentally knocked over the plant.
In the Eukarya domain we have kingdoms.
We have species. We’re going to be looking at animal cells and plant cells. Our bodies are entirely made up of cells. Every cell has a job. This is where we get into looking at what is inside the cell. So let’s zoom in magic school bus style to take an animated tour of your cells.
Prokaryotic cells do not have a nucleus. Instead they have a nucleoid. They are simpler.
Eurkaryotic cells do a lot. There are similarities and differences between animal and plant cells. Let’s look at animal cells. Humans count as animals. We are mammals.
We can categorize the organelles (miniature organs) inside the cell into 4 different groups by their main function.
Nucleus – contains your DNA. That gives the genetic instructions. The nucleus is like the manager’s office in a factory.
Nuclear envelope – encloses the nucleus
Nucleolus (pronounced new-clay-less) – inside the nucleus, site of ribosome synthesis (creation). Memory tip: the new-cLAY-less lays in the nucleus
Chromatin – is coiled up DNA and protein inside the nucleus
Endoplasmic reticulum – is a network of sacs and tubules
Rough ER – holds the ribosomes. Memory tip: If you are rough housing and crack a rib, you have to go sit in the rough ER.
Smooth ER – is for detox. Alcoholics and drug addicts actually have more smooth ER. Memory tip: If you sip too much of that smooth drink, you’ll end up laying in the ER detoxing getting transferred to rehab.
Ribosomes – make protein.
Cytoskeleton – is there for structural support. Memory tip: our skeleton gives our body structure. For a cell, the cytoskeleton gives it structure. The cytoskeleton has 3 main types of fibers: microtubule, intermediate filament, and microfilament. Memory tips: We didn’t really get into the function of those components in biology 1. I just remembered they were there by thinking about PVC piping for the microtubules, the springs in a bed giving support to a mattress for intermediate filament, and for microfilaments being solid rods in a twisted chain I think of a front porch that has support beams that look twisted like a fishtail braid.
Golgi – is the organizer. The Golgi organelle is the sorting dock. They receive contents, sort them, and ship them. Memory tip: A goldfish named Golgi works at a warehouse. He loves to organize all the boxes and put them in the semis they need to be in to get to their destination. He’s a little OCD goldfish. Golgi loves his job.
Lysosome – is a digestive enzyme that recycles and cleans up. Memory tip: Visualize a pacman eating litter. Or remember that Lysol is for cleaning.
Mitochondria – is for cellular respiration and ATP synthesis. My memory tip: Take a mighty breath and it will give you energy.
Organelles in plants are a little bit different. Animal cells have a plasma membrane around them. Plant cells don’t. Instead they have a cell wall. Memory tip: She has plants hanging on her wall. Plant cells also have chloroplasts, central vacuoles, and contractile vacuoles.
Chloroplasts – converts solar energy (sunlight) to chemical energy using the process of photosynthesis. This is what makes plants green.
Central vacuoles – holds water and contains pigment
Contractile vacuoles – pump water
My memory tip to remember what is different about plant cells: Chloe is a sunflower. She’s been a bad girl. She’s in jail. Chloe is sitting in the center of her jail cell staring at the wall. She’s also 9 months pregnant and having contractions. She’s ready to push this baby out. (Chloe cues chloroplasts, center of the jail cell cues central vacuoles to hold water, staring at the cell wall reminds me that plants have a cell wall, and she’s having contractions to cue contractile vacuoles that pump or push out).
I hope this is helpful. I know it’s just an intro to touring the eukaryotic cell, but these are the memory tips I used to ace biology. Feel free to share.
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