1.1 Introduction to Cells

19/08/17 1.1: Introduction to cells 1 Ila According to the cell theory, living organisms are composed of cells. Cells ivere first discovered by Robert Hooke (who isn't related to the captain) when he was observing cork under a microscope He noticed that there were compartments which looked like the cells that monks lived in monastries Thus, cells came to be known as cells. He was also the guy who put forth the cell theory cells are the smallest unit of life- the building. blocks, if you will all diving organisms are composed of cells cells (new ones) arise from preexisting cells. I found some more points on Wikipedia but I think for now, this is all you need to know. Some common features of cell are: cells contain genetic material which contain instinctions for the cells activities. there is a membrane which separates. the inside of the cell from the outside (duh) chemical reackons, catalysed by awesome enzymes, take place inside the cell cells produce their own energy Another important thing to meet is MR. SHE-Ng. Actually, now his name will be MR RHENG It's a mnemonic for the seven functions of life. Metabolism Basically breaking down food and producing energy. Reproductsong: having offspring! Response: Okay, this one is actually interesting. You know how we're always told that the nucleus is the brain of the cell? Well, it in't exactly. The cell inembrane is sort of the brain. Why? Because it's the thing that that actually can feel its environment and surroundings! This is not Robert Hooke Asendbrane nadeus Lonteins DNAY mater (not the case for all cell motochondria haduces ATP mole wea le ener →l intend to never do this Tommy The nucleus has all the wded instructions on how to respond to something but it's the cell membrane that fells it, "Hey! There's a bloody amoeba coming. our way!" Or "Look, food!" That's pretty much what this function is about-feeling things. Homeostasis: This is basically just maintaining the internal environment of the cells. Skin cells are examples because they have to regulate the temperature of the body. Excretion Getting rid of waste products. A fancy. word for pooping. Nutrition to grow, you need food! Growth: All cells grow; every livingthing grows. However, there are some exceptions to the cell theory Actually, there are quite a few. Striated muscle cells are one example. They form during fetal development when thousands of vells merged together when their cell membranes kind of dissolved. However, rather than their nucleus dissolving too, they just stayed intact. Thus, the muscle all is a long, chain-slab with multiple nucki. It defres the cell theory. because it is very large and contains A LOT of goddamn brain imposters aka nuclei.. Then there's the case of fungi They're made of hyphae which are long tubular structures. They also branch out a lot. Some fungi are made of aseptate hyphae which don't have any dividers. The dividers are called septa.. tryway, since they don't have septa, there are, again, multiple mucker which defies the cell theory. Giant algae are also another exception. One specific specics & the Acetabularia. Good luck memonising that! So, the interesting thing about this giant algae is that it cangrew to a ginormous size! Well, relatively speaking. Although it has only ONE nucleus, it can grow as long as 100 mm which is big for a cell. The reasoning behind it being an exception is that if Nutrition abo tachedes things like minerals and vitamins Except for me and leter Pan My opinion on these exceptions are that they're not. The follow all three parts of the theory. I think peeps just concider them a exceptions because they don't bok like the conventional cell think it's really mean made of protein. borne misde Aseptale hyphae I know it looks ugly. Tommy Acetabularia you saw this algae, you would think that it comprised of a myriad cells. However, it isn't. It's only made up of one. 1.1.6 Organisms consisting of only one cell carry out al functions of life in that cell One example is taramecium. It is a protozoan (belongs to Protista kingdom) and lives in marine environments (WHOO! Go Poverdon!). It's a heterotroph which means it relies on other organisms for food. Kind of sad. The Paramecium has alia around it which are basically microtubules (the structure inside the cell made of protein coiled together) poking out of the cell membrane. It's used to escape scary predators and beat food towards it. Food goes into the base of the oral groove where foud vacuoles form. The anal pore is responsible for excretion. Paramecium generally feeds on bacteria and yeasts. Another example is Scenedesmus. It is a freshwater green alga which forms colonies of 4, 8, 16 to be safe - no one attacks large numbers right? As to why those specific numbers, I think it's because they lock together nicely. It grows these Viking horns, called protective spines, on the four corner of the colony. It's used to scare predators. It's an autotroph which means it produces its own food. In this case, Scenede-simus wes photosynthesis. It takes C*O_{2} from air, K_{2}*D ned sunlight to make glucove and O_{2} That's why peeps want to plant trees. More oxygen! 11 & Surface area to volume ratio is important. in the limitation of cell size. Thells don't grow indefinitely or forever They have a limit. The smaller the cell, the easier it is for nutrients and waste products to go in andout. As the cell gets bigger, V increases faster than SA. The point of this undentend is to understand that you don't have to be multcellular to escrit. Or live cilla hair-like structures. vacuole contrachle water oral Grouve food food nukis 2 types to camy out different functions Pore -wall plast Kude protective spines anat sure that units are header columps Make Cube SA W SA/V Ratio L 2 3 3 6n ^ 2 14c * m ^ 2 54c * m ^ 2 23 2 16 64 Tammy A bigger ratio (between SA and v) is better because it means that stuff can go in and out of a cell at a much faster rate. A bigger ratko, by the way, means that the volume is smaller. If the cell were too big, the exchange of materials and energy would be less efficient, and exchanging resources is, like, super important for cells. Volume is proportional with how much heat! waste is produced and how fast resources are consumed. S.A. is proportional to how quickly things move in and out of the cell because the barnier counts as S.A. This may be a bit countess countering at first but it makes sense There is more room in the well which leads to more rens and all However, if there's more surface, there are more means for stuff to 5o in and out if that mabaser Md. Multicellular organisms have properties that emerge from the interaction of their cellular components. This is actually pretty straightforward. Emergent properties are essentially functions that are performed when cells work together A neuron, for instance, on its own can't achieve much but thousands of neurons working toge ther is much more effective. The whole is inore than the sum of its parts. Emergent properties are utilite evenjwhere around us. For instance, in if everyone does their individual work maybe our productivity scan. att added up would be so/to However, if we work much more. This collabora TOGETHER, we can accomplish Is the reason Honio Sapiens sapiens are so evolved itHunt 1.1.e. Specialied tissues can develop by cell differentiation in multi-cellular organisms 11f. Differentiation involves the expression of some genes and not others in a cell's genome... These key understandings ave linked together which is why they've been grouped together. (duh). All cells contain DNA, the coded instructions. for all the body's funcions-heart beat, harr colour, eye cobur etc. However, only certain genes. are expressed in cells because the cell won't have to waste its resources on carrying out functions it doesn't NEED to carry out. So genes are turned off in cells and only the required ones are Agere is a series of bouses ATCS, which can span 100 or even a thousand bases. WHOO! skin cell so those genes aren't This skin cell doesn't need to be able to see because the eyes do that exprened Tommy turned on, or EXPRESSED. Specialised tissue is basically a group of cells (specialised cells) which carry out the same function. In multicellular organisms, different specialised tissue is neponible e for different things. I guess it makes the body more productive. What does the turnine off of cells look like? When we say that genes are expr to essed, it means that only those proteins are made. Where and how do they know if they need create certain proteins? well, the cellmembrane is the thre brain and sort of verses it. Ilig. The capacity of stem cells to divide and differentiate along different pathways is necessary in embryonic development and also makes stem cells suitable for therapeutic uses. Stem cells are special for two reasons: You should remember them like 1. They are undifferentiated meaning they this haven't specialised yet. Self-renewal can keep prodvung Stem cells 2. They are self-sustaining meaning that they can either dinde into more stem cells or choose to specialise. Potency can differentiate into various types of cells. There are different types of stem cells. Before we get into that, take a look at the. diagram. when we are babies, we desire to be... EVERYTHING. As we grow older, we start a specific career path and stick similar case with stem cells. to choose to it. It's a When an egg and sperm cell comes together, it forms a zygote. This zygote divides and becomes a blastocyst. The blastocyst contains a few cells called "inner cell mass! These are pluripotent embryonic cells. Pluri-potent cells (stem) can become any cell type in the body except for placental cells which make up the lining of the uterus. So, those ICM cells specialise into OTHER cell types. Thus, every cell in the body can. trace its ancestry to embryonic stem cells. This brings me to my next point. There are two types of stem cells in DUCABR zygote mitosis ↓ hollow space blastocyst gooox inner cell mass (ICM) stem cells Cpluripoten Kinda nonic, right? mammals: embryonic and somatic (adult stem cells). Somatic cells are kind of like. the repair system of the body. They replenish tissues that need to be replaced. The other categories of stem cells, besides pluripotent, is multipotent meaning those stem cells can give rise to various types of cells. but only ones within a specific family. For instance, hematopoietic (hem-ah-toe-po-ee-tick) stem cells give rise to different blood cells such as WBC and RBC. There are totipotent stem cells which are like the ultimate stem cells ever theey're only found in the zygote and can make literally ANY type of cell. Another category is unipotent meaning it can create only ONE type of cell. An example? Epithelial stem cells which are skin cells. Now, there's a treatment called Embryonic Stem Cell Cloning (ESC cloning) aka therapeutic doning. Basically what happens is that an egg cell is taken and its nucleus is extracted The scientist then takes the nudeus of a somatic cell (from the patient's body) and inserts it into the egg cell. The egg contains the genetic material of the patient it is stimulated to dinde and form a cluster of cells called the blastocyst (sound familiar?) These cells are pluripotent which is an advantage. The cells also don't get rejected by the patient's body. Some cons are that many attempts are required for this to be successful. Also, the embryo dies which is sad and has a lot of ethical concerns. HEIRARCHY OF STEM CELLS TOTIPOTENT : ultimate ↓ PLURI POTENT. great too ↓ MULTIPOTENT not bad ↓ UNIPOTENT: meh Eggcell → anudeate (w/o nude nucleos somatic cell It's basically substituting the nucleus. egg all with nucleus of Somatic au Tommy Investigation of furictions of life in Parameaum and one named photosynthetic unicellular organism... Function Paramecium Scenedesmus Metabolism food vacuoeles ingest food which contain enzymes for digestion. glucose molecules are produced from chlorophyll pigments. Response Cilia allow it to move around They form colonies for prot-ection and mayabo grow protective spines Reproduction Divide asexually Dinde asexually Homeostasis Diffusion of gases occur Cell wall controls diffusion of water to prevent it from destroying the cell. Excrekon Waste is removed through the anal pore. exchanges gases through diffu-sion. Nutrition Is a heterotroph, thus feeds on bacteria. Food goes in through the oral grove. is an autotroph, uses sunlight for photosynthesis. Growth All cells grow. The cells will get larger until they finally dinde. Use of stem cells to treact Stargardtis disease and one other named condikon. Stargardt's Macular Dystrophy is caused by a recessive mutation gene. It's basically a malfunction of membrane protein in retkina cells and so, the vision worsens. Embryonic stem cells are used to treat it ① LESC Chuman embryonic stem cells) are cultured to develop into retinal pigment epithelium (RPE) cells. These RPE cells are injected below the retina of the eye The cells then develop and replace the damaged RE cells. myented stem cells being cultured hematopoeitic Stem cells Another cancer which can be treated. may stem cells is leukemia. Leukemia is a Londition where a patient has too many. white blood cells that is, it's protucing like Nay too many. Adult stem cells are used which can only become lalood cells. topoets The diseased cells are removed from. the bone marrow with a needle. The stem cells are extracted and stored. stored & cultured transplant into patent The patient undergoes chemother aphy to kill all the cancer cells. In doing so, all the blood cells are killed so the bone marrovo cannot produce anymore blood cells The stem cells are restored to the bore marrow where they produe RBC and WBC. Ethics of the therapeutic use of stem cells from specially created embryas, from the umbilical cord bood of a new born baby and from an adults own issues. PROS Help improve life No ethical issues with adult stem cells Embryos haven't differentiated and so, don't have the ability to think or feel pain So, it's not exactly killing a human.. If embryos are produced for the purpose of research, then they wouldn't have had at least a chance for living. CONS Depends on the source of stem cells Embryonic stem cells raise concerns because this means killing the embryo and ridding it of its chance of life. Although the embryo isn't exactly alive, some people believe that it is still a human being. Use of light microscope, calculate magnification and actual sizes of drawings. The formula for magnification is size of image ma Can be shown The formula as a triangley Imm 1000 µm (micrometer) actual size Remember to use the same units of measurement. 1µm 1000 nm (nanometer)