Well… This is my VERY FIRST blog post! Woohoo!!
So, the idea of this blog is basically biology, with a few glimpses of chemistry and even fewer glimpses of physics. That’s it- maybe at the end of each blog, you’ll get some cool stuff about space, ’cause hey! It’s space! Buuuut… So much biology.
Anyways, my first few blogs will be all about the brain, nerves, our five senses, etc. Everything to do with one of our most important organ systems- the nervous system.
However, before we begin with literally ANYTHING, we do need to establish what I like to call The Extreme Basics- cells.
This first blog post will be about cells- their organelles, how they produce ATP, the different kinds of cells and stem cells… Today, we are only going to be doing cells.
#1- The Organelles
This is the cross-section of an animal cell, showing us its organelles- we are going to be studying these organelles today!
- THE NUCLEUS- The nucleus is made of two subparts- nucleolus and nuclear envelope, with nuclear pores dotting the surface of the nuclear envelope, and nucleoplasm being the equivalent of cytoplasm. The nucleolus makes ribosomal subunits from from proteins as well as ribosomal RNA- these subunits are known as rRNA, and the rRNA subunits are sent out through the nuclear pores to the rest of the cell, after which the rRNA become ribosomes. The nucleolus disappears during cell mitosis and meiosis. Chromatin floats around in nucleoplasm in the nucler envelope. When neccessary, chromatin wraps itself around a protein called a histone and shortens to form chromosomes- which are made of DNA[ Full form of DNA- deoxyribonucleic acid. Prokaryotes contain only RNA- ribonucleic acid. Prokaryotes do not contain DNA, and nor do they have a nucleus.]. In non-dividing cells, chromatin remains chromatin, but, in dividing cells, chromatin forms chromosomes. Whoa. That was looooong.
- THE CYTOPLASM- The cytoplasm is a jelly-like clear substance enclosed in the cell membrane. It is a medium for chemical reactions to take place, and all the organelles float around in the cytoplasm. Chill- not much info on the cytoplasm 🙂
- RIBOSOMES- Ribosomes are the sight of protein synthesis. Proteins are integral part of each cell, whether eukaryote or prokaryote- be it directing chemical reactions or repairing damage. Strangely enough, the location of a ribosome determines which kind of protein it makes. If the ribosome is free-floating, then it makes protein that will be used only inside the borders of the cell. If it is, however, attached to the endoplasmic reticulum, then it manufactures proteins that are utilized either outside or inside the cell. Picky ribosomes, I tell you.
- GOLGI COMPLEX– The Golgi complex is basically a system of flattened sacs and tubes– looking alot like a stack of pancakes. It is also known as the Golgi body. The Golgi complex has a shipping face, or side- called the cis face. Vesicles filled with substances pinch of the end of the cis face to be transported or stored around or out of the cell. The receiving end, or face is called the trans face. The function of the Golgi complex is to modify, sort and package molecules received from the Endoplasmic Reticulum.
- MITOCHONDRION– The mitochondrion is often refered to as the ‘Powerhouse of the cell’, since it is the site of cellular respiration. It’s responsible for making ATP[ full form- adenosine triphosphate]. It makes ATP by combining oxygen and glucose. This, however, is only the ATP made through aerobic respiration-respiration with oxygen. There is another kind of respiration- anaerobic respiration, which is respiration without oxygen. Anaerobic respiration produces very little energy, and is mainly done with fermentation. The amount of mitochondria in a cell differs upon the cell’s function- for example, a muscle cell will have lots of mitochondria since it will need extra energy to move around and stuff. Mitochondria also have their own DNA- called mtDNA, and direct their own division. They also have a complex inner structure, as you can see. UGH, I can’t paste the damn picture. Sorry, I suck at this technology stuff- but here’s a link to the photo of a mitochondrion’s inner structure- https://i.pinimg.com/originals/96/32/ad/9632ad1d9df143872f4fdc2469f2d5f7.jpg Yeah. There ya go. The outer membrane is what encloses the contents of the mitochodrion. The inner membrane is folded to increase surface area for chemical reactions. The cristae is basically a fancy name for the fold in the inner membrane, and the matrix is a thick, viscous fluid filling the cristae. My, my- who woulda thought that there was this much info on the mitochondrion? Guess it proves that food is important, no matter what…
- ENDOPLASMIC RETICULI– The reticuli basically serve as a highway for transporting goods. They are a network of hollow membrane tubules. There are two kinds of Endoplasmic reticuli- Smooth Endoplasmic reticulum and Rough Endoplasmic reticulum. The Smooth ER has no ribosomes attached to it, and the Rough ER does. The Rough ER makes membrane proteins on its surface, and then those proteins are brought to the Rough ER’s interiors to be modified, packaged and transported. The Smooth ER makes membrane lipids[steroids], regulates calcium and destroys toxic substances. The Endoplasmic reticuli also export thing to the Golgi complex in transportation vesicles.
- PEROXISOME– Peroxisomes have two main functions. The first is to break down fatty acids so that they can be used as energy during cellular respiration and to be used for forming membranes. Their second main function is to transfer hydrogen from compounds to oxygen so that hydrogen peroxide is created, and then convert that hydrogen peroxide into water. Yes, yes- take a second to absorb that. Took me about half an hour to write that last sentence. Also, just realized- peroxisome, hydrogen peroxide. Crazy, right?
- LYSOSOMES– Lysosomes. Right. Take some time to learn how to pronounce that without stammering or stuttering. Good. Now you may read on. Lysosomes are like the stomach of the cell. Their strucuture isn’t half as complicated as a mitochondrion’s, so you’re spared. Yay. Okay, I was saying. Their structure is basically a phospholipid[ learn to pronounce that, too] membrane that separates the inside of the organelle from the membrane’s surroundings. Lysosomes are basically floating garbage bags, and the membrane allows molecules to get inside the organelle while not letting the digestive enzymes contained within the lysosome to escape. Our complexly-pronounced floating garbage bags are responsible for moving damaged or obsolete parts of the cell toward the outermost part of the cell which is closest to the cell membrane. The damaged cell part enters the lysosome through the membrane,then is digested by the lysosome, and is then removed from the lysosome in transport vesicles to be dumped at the border. Guess what, guys! Our floating garbage bag friends are also called cell suicide bags! My goodness, first garbage bags, then suicide bags! My poor lysosomes must have self-esteem issues. All right, back to business. When a cell is no longer needed, it commits suicide by activating an intracellular death program. This is called apoptosis or necrosis. Apoptosis[or necrosis], in more detail, is basically lysosomes exploding, their digestive enzymes seeping out, and then our rogue digestive enzymes digest the entire cell to death.
- VACUOLES- Vacuoles[pronounced with a hard ‘c’] are multi-purpose membrane-bound sacs- alot like Ziploc bags. They have loads of important functions and uses. In animal cells, they’re smaller and in plant ce- uh oh, no spoilers. Right. In animal cells, they are partially responsible for storage, waste disposal, growth and protection of the cell.
- MICROTUBULES- Microtubules are exactly like a cell’s conveyor belts. They move vesicles, granules, organelles and chromosomes all with the help of special attachment proteins. In a structural manner, microtubules are linear polymers of alpha and beta tubulin[tubulin is a globular protein]. Microtubules also play an important role in the cytoskeleton.
- CENTROSOME- Two centrioles make up one centrosome. Centrosomes are only found in animal cells. That’s it. Nowhere else. Centrioles play a key role is cell mitosis[cell division- the process where a parent cell gives way to two new daughter cells]. Centrosomes pull apart chromatids and spindle fibres develop from this organelle during cell mitosis. Centrosomes are also responsible for carefully arranging microtubules in the cytoplasm. WE’RE DOOOOOONEEEEE!!!!!![P.S, I know I missed a key part in the cell’s organelles- cell membrane. But that comes waaaaaaay later. I’m not that stupid.]
OK, folks. Now we have covered only the animal cell’s organelles in detail. The list below is a small collection of a few important specialized cell parts. No list[that an egghead like me can make] will ever be able to compile all the different special cell parts. Let’s do this! Also, I [think] I figured out how to add pictures in every part of the list. Sorry if the above list was kinda boring, I’ll try to include as many pics and stuff in this list.
#2- Specialized organelles
- This is a chloroplast, a plastid that’s full of chlorophyll. The chloroplast is only present in plant cells, and plays a key role in photosynthesis. A thylakoid is a membrane-bound flattened sac which is bound by a pigmented membrane. A granum[plural- grana] is a stack of thylakoids. The stroma is a colorless fluid surrounding surrounding the grana. The inner membrane is a membrane enclosing the grana and stroma. The outer membrane is, well, a membrane surrounding the inner membrane that surrounds the grana and stroma. See? Easy! Aghhhhhhh- STILL CAN’T POST THE IMAGE! DAMMIT! You know what, take the URL- see it if you want to, ignore it if you want to. Here. http://www.nature.com/scitable/content/ne0000/ne0000/ne0000/ne0000/14705175/U3CP5-1_ChloroplastStructu_ksm.jpg
- Right, the next one is a leucoplast. It’s a colorless plastid that has only one function- to store strach, lipids and proteins. It’s only found in a plant cell. Aaaaaand the URL[this image, by the way, is the close-up of the contents of a leucoplast]-https://live.staticflickr.com/2434/3912814209_0883606c46_b.jpg
- Our last plastid! Chromoplast! These are, once again, only found in plant cells. They store pigments and impart colour to fruits and flowers. This is my fave plastid. In the URL below, the image is quite intersting. The little reddish dots are the chromoplast, the orangey parts being the rest of the cell, and do you see the the dark orange-brown borders? Those are the cell walls. Here’s the link-http://www.daviddarling.info/images/chromoplasts.jpg
- So, now we talk about the Central Vacuole! Only found in plant cells, and this is a large one. And there’s only one vacuole in a mature plant cell. The CV has a membrane called the tonoplast, and the CV also plays a key role in keeping the cell rigid by maintaining turgor pressure. In a plant cell, the CV stores cell sap. In the image, the greenish butter slab with the arrow pointing at it is the CV. https://s3.amazonaws.com/user-media.venngage.com/711997-6cdf26b3d7fddc2812c950781e151925.png
- Relax, only two more to go. Right, so this one’s a cell wall. Plant cells and some fungi cells have this. A plant cell wall is made of cellulite, a fungi cell wall is made of chitin[pronounced kay-teen]. It’s not like these cells don’t have a cell membrane- they do have a cell membrane, it’s simply that the cell wall is added protection and helps the cell retain its shape. Here ya go. You’re welcome, by the way. https://factslegend.org/wp-content/uploads/2018/04/cell-wall.jpg
- Okaaay, one more to go! Yay! Right. You know what a flagellum[plural: flagella] is? No? OK, so now you’ll know. Flagella are tiny hairlike structures present on the cell capsule of a prokaryote that, when flapped, propel it forward and help it to move. In the image link, the long white threadlike lines are the flagella. Not the short ones, the loooooong ones. Here’s the link, by the way-https://image.shutterstock.com/image-illustration/bacterium-pseudomonas-aeruginosa-isolated-on-260nw-386499232.jpg
- Our last one. Cilia[pronounced with a soft ‘c’]! Similar to flagella, these are found on any cell, especially found on the cells lining our lung airways. The cilia[singular- cilium] are tiny hairlike structures that help sweep foreign objects away using gentle waving motions. https://www.thoughtco.com/thmb/i6nXOzXL9i-_xVPhTUGM-72v9Gw=/768×0/filters:no_upscale():max_bytes(150000):strip_icc()/ciliated_epithelial_cells-5a7cb8926edd650036eb92da.jpg
MUH PEEPS! Thank you soooo much for sticking through all this stuff. It might seem monotonous or boring, but I promise, it’s SUPER important. OK, let’s not waste more time and move on to…[drumroll] THE FLUID MOSAIC!
This, my friends, is also called more commonly the cell membrane. But, the cell membrane is also extremely complex and essential to life. The cell membrane is also selectively permeable, meaning only a few kinds of molecules are allowed in and out the cell, and the rest get kicked out.The structure is also what we’re currently going to be studying- in great detail.
- PHOSPHOLIPID- You see those little blue things with two black tails? Those are phospholipids. Phospholipids have a head made of glycerol and phosphates, and tails made of fatty acids. The heads are hydrophilic, which means they attract water. The tails are hydrophobic, which means they repel water. Since there is a bilayer of phospholipids, this means that water doesn’t get inside the cell membrane and like… mess it up since the tails are hydrophobic.
- CHOLESTEROL- Cholesterol is a type of lipid. It’s crucial to the cell membrane because it is more rigid than other lipids, and helps the membrane to sort of… keep it together.
- GLYCOPROTEIN- A glycoprotein is a protein with a carbohydrate attached to it. They are responsible for cell to cell recognition and binding of other molecules. Glycoproteins are also important for cross-linking cells to add strength to a tissue. Glycoproteins in plant cells are what allows plants to stand upright and straight despite gravity.
- PERIPHERAL PROTEIN– Peripheral proteins are made of amino acids, and do not enter the hydrophobic space, but instead only penetrate the hydrophilic areas. They are responsible for communication via use of chained reactions. These proteins also have simple enzyme functions, and form a vast network for gathering information.
- INTEGRAL PROTEIN– These proteins, unlike peripheral proteins, penetrate the whole cell membrane. Carrier proteins carry molecules from one side of the membrane to the other, and is also known as a membrane transport protein. A channel protein is a basically a special arrangement of amino acids, and can be gated[opens and closes upon commands or signals], or non-gated[free to go or come, and always open]. These channel proteins serve as a pathway for ions and water.
We’re done with the fluid mosaic, guys! Also,in case you want to know more about the cell membrane, here’s a coolish video by Dr. Bruce Lipton- https://www.youtube.com/watch?v=84S36MQU_uk. Now, guess what we do! The three basic cell processes- mitosis, necrosis[apoptosis], and cellular respiration.
#4-Cell Processes[Mitosis, Necrosis and Cellular Respiration]
- The GIF you’re seeing above is a representation of cell mitosis. First comes interphase, where the cell begins to duplicate DNA. Then comes prophase, where the cell tightly condenses its DNA and begins to form mitotic spindles. During the early prophase, the nucleolus disappears. This is followed by the prometaphase, where the nuclear envelope dissolves into membrane vesicles, and microtubules begin to invade the nuclear space. Then occurs metaphase, where the centrosomes pull the chromosomes to opposite ends of the cell, which causes them to align along the equatorial plane. The equatorial plane is an imaginary line along the midline of the cell. Anaphase follows metaphase, and in late anaphase, the reformation of a second nucleus occurs. Then comes telophase, in which the new membrane forms around the daughter cells’ chromosomes, which means the nucleolus reappears. This membrane is formed from the parent cell’s membrane vesicles, and now, mitosis is complete but cytokinesis isn’t. Cytokinesis shifts all cellular components into two equal halves, and now the cell divides. By the way, this whole thing only occurs in eukaryotes. Prokaryotes multiply using binary fission, which I am not going to write about. WE’RE DONE!
- Yes, that is exactly how a cell dies. That is currently happening in your body. Let’s have a minute of silence, please. Thank you. Moving on. There isn’t too much to say here, so you’re spared. When a cell is damaged, or begins to use up too much of the body’s resources, it programs itself to die. The lysosomes-which contain enzymes- break open, and then those enzymes digest the cell to death. Or, another way of cell death is the cell membrane folds up, the nucleus shrinks and fragments, and whatever’s left of the cell goes ka-BOOM!
- Hmmmm. That GIF looks confusing, so let me explain it to you. Before I start explaining it to you, let me clarify that we are only doing aerobic respiration. No anaerobic. OK? Right. So, cellular respiration is the combining of glucose and oxygen to form ATP[ adenosine triphosphate], and waste products being oxygen and water. The chemical formula is- C6H12O6 + O2 –> CO2 + H2O + ATP. Easy-peasy. ATP is the energy for the cell to go about its functions and stuff. I’m not going into the details of the process of cellular respiration, because (A) That would take up far too much space and (B) It is a very long, complicated process full of words that are hard to pronounce and I do not wish to bore you. So, that’s it. We’re done with the three basic processes of cells!
I promise, only stem cells and types of cells it forms left to go. That’s it. Just one more thing left. And now that I finally figured out how to add pics, vids and GIFs, it’ll be way less boring. Also, I’m super sorry again for compacting this much info into one blog- but only because it’s just like sort of establishing the base, or for some geniuses, this is like a revision. So, my next posts won’t be as long. And they’ll be more engaging. OK, one last thing to go, then if you want, you can watch the awesome Space Bonus video, and then you won’t be seeing me until after two weeks! LET’S DO THIS!
#5- Stem Cells and Specialized Cells
So, what are stem cells? They’re basically cells that can diffrentiate into lots of different types of other specialized cells, as you can see above.Some types of stem cells can also multiply into even more stem cells before maturing into a specialized cell. These types are called pluripotent stem cells. Stem cells are found in both- animals and plants. These amazing cells are very important to life. Stem cells reside in a specific part of each tissue called the stem cell niche. Cool, right? Now, my prime focus wasn’t only stem cells- it was also the types of cells that they can form, only animal cells. [You’re safe- just three types. And not too many details. Relax.]
- RED BLOOD CELLS- Stem cells can form red blood cells. These cells have no nucleus, and ferry oxygen around. They’re biconcave, which means they curve inward on both sides.
- MUSCLE CELLS– Muscle cells make up muscles. They are long and thin. These cells also have lots of mitochondria since they require more energy.
- NERVE CELLS- Nerve cells are long, thin cells. The longest nerve cell is about a metre long! They carry electrical impulses back and forth.
And, we are done. I know, seems unbelievable. YAY! How did you like this first blog? Please leave comments down below. Also, I [will try]to post twice a month. And here’s your Space Bonus- https://www.youtube.com/watch?v=i93Z7zljQ7I