GENERIC MAGAZINE

Topic 2:

CELLSAre they inside you?

BONUS:

Division

Scandal

ALL INSIDE OF

YOUR BODY

Cell TheorySI Measurements

Cell TypesMembranes

Volume 4 Issue 2

TABLE OF CONTENTSCell Theory - How real is it?An introduction to the three rules of cell theory and the evidence there to back it as well a the contradictions to this commonly taught fact.

SI Units: The Global StandardWe take you through the measurements and an exclusive tutorial on how to use them to determine magnification and actual size.

Is SA:V Ratio the New Black?Our look at the hottest trend among cells worldwide: the surface area to volume ratio. What is it for?`

How Stem Cells Can Affect YouThe origins, the types, the uses, and the controversy surrounding this up and coming science.

Cells Fall Victim to Social DarwinismProkaryotic cells are rapidly begin held as lesser cells be people, and Will Parsons investigates.

Liver Cells, the Popular KidThe best example of a eukaryote? A Liver Cell! Check out this piece on the cells that make you up.

MembranesCells Caught DividingThe new craze called mitosis is sweeping the nation. Learn where to look. Is it right under your nose?

Cornell Stem Cell ProjectBuchon Lab

Cornell Stem Cell ProjectBrain Stem Cells

Brain Cells

Human Red Blood Cells

Skin Cells

TOUR THE CELL!

CELL THEORY - Your Questions AnsweredBy: Mary Grace Bedwell

Many of you readers have been asking recently: What exactly is the Cell Theory. Well, today we have your questions on the matter answered. The following headings are actual questions from our readers, answered just for you.

“I heard that there are three rules for the Cell Theory. Can you please explain them to me?”- IBO in New York, NYHey there, IBO! I most certainly can. Basically, the rules of Cell Theory are as follows:1. All living things are made of cells.

Multicellular organisms have specialized cells to carry out various metabolic functions in the cells.

2. Cells are the smallest units of life. Organelles are able to carry out carious metabolic functions, but are unable to survive alone.

3. Cells come only from other cells. Originally p e o p l e b e l i e v e d i n “ s p o n t a n e o u s generation,” but a man named Louis Pasteur disproved that. Cells were found to multiply only by division and to have come from simpler and common ancestors, suggesting that they have always just divided.

I hope this helped!

“What can you tell me about the evidence for this cell theory?”- Stu in Fairhope, ALHiya! There are four main scientists whose work is used to back cell theory. The first important guy is Robert Hooke. He was an optics enthusiast, and upon looking at a piece of cork through his microscope, discovered that the wood was divided into what he called cells. The second important figure, known as the father of microbiology, is Anton van Leeuwenhoek, seen

to the left. Leeuwenhoek used lenses to look over the cloth

he made in his factory and determine its quality. Using his lenses, he discovered what he called animalcules in water. Because of this, he is credited with the actual discovery of cells. Another important figure

in proving cell theory is Louis Pasteur. In 1884,

people believed that things came randomly from other things (like maggots from meat) by way of spontaneous generation. His experiment involving crook-necked bottle and come boiled broth disproved this idea. You can read all about his experiment over on

Amoeba Mike’s page: SPONTANEOUS GENERATION. The fourth and final gentleman on the list is Robert Remak. This unhappy man was a sc i ent i s t tha t discovered cell division u p o n o b s e r v i n g chicken embryos. His results, while fasc inat ing and ground-breaking, were not credited to him, a Jewish s c i e n t i s t . H i s f i n d i n g w e r e ignored until they were plagiarized and published in 1858 by a fellow called Rudolf Virchow.

“Can you tell me what the limitations of the cell theory are? I may be wrong, but wouldn’t it be more than just a theory if it was 100% unopposed?” - Mark in Summerdale, ALRight you are, Mark! There are four main oppositions to the cell theory.1. Muscle cells. They’re multi-nucleated and

very long, with m i n i m a l division.

2. A m o e b a s . T h e y ’ r e unicellular, but can perform all of the seven funct ions of life: nutrition, reproduction, m o v e m e n t , growth, response to stimulus, excretion, homeostasis.

3. Fungal Hyphae. They’re very large and multi-nucleated as well, only they have no

division into cells.4.Viruses. They present the biggest issue, as they are only able to reproduce when

they are in control of a host cell. So, in a sense, they may

not even be considered cells at all. What do you think?

Send in your questions to:Mary Grace Bedwellc/o General Magazine1 General RoadNew York, New York 12345

The International System of Units and MagnificationBy: Mary Grace Bedwell

Basically, every country in the world besides the United States uses a means of measurement know as the International System of Units. This system of units is based off the meter, and can be used to measure a variety of things, just like the system of measurement we use in America, Imperial measurements. However,

the SI units are much easier to use because you can easily go from a meter to a kilometer, a nanometer to a kilometer, or anywhere in between simply. Try going from inch to mile that easily! The SI system of measurement is excellent for comparing the sizes of different things we see in science, such as molecules and bacteria. See the chart below for the relative sizes of six things you commonly observe over a microscope, or for more examples of size, check out this website and slide the bar to go through the scale.

molecule 1nm thickness of a membrane 10 nm viruses 100 nm

bacteria 1μm organelles up to 10μm eukaryotic cell up to 100 1μm

When looking at these under a microscope, knowing the actual size of an object is still very important to get a mental picture of what you are looking at. To determine the actual size of an object, divide the measured length of an object by the magnification on your microscope. When looking at a specimen, sometimes the magnification is unknown. If this happens, you can easily find the magnification by dividing the measured length by the length that represents it on the scale bar. That sounds a lot more confusing in words than it actually is, so here’s a look at some examples to help the idea stick.

See how awesome SI Units are? Someone convince America to switch, and our lives will be about 15,000x (see what I did there) easier! Here’s some more looks under the microscope!

Day after day, we are haunted by the phrase “Size doesn’t matter” and “I’m big son.” Well guess what everybody. I’m here today to tell you that it does, and that being big is overrated. Especially when it comes to your cells. Though society supplies certain ideals, your body’s cells are going a different way this season. They refuse to go along with the way of the modern age, and for that they are commended. Cheers to you, cells. Cheers to you. Their need for a small surface area to volume ratio is incredibly important to your body, and today you are going to learn why. The importance of the surface to volume ratio has got to do completely with the fact that it serves as a limiting factor for the cell and cell size.Many reactions occur within the cell. Substances need to be taken into the cell to fuel these reactions and the wast products of the reactions need to be removed. When the cell increases in size so does its chemical activity. This means that more substances need to be taken in and more need to be removed. The surface area of the cell is vital for this. Surface area affects the rate at which particles can enter and exit the cell, whereas the volume affects the rate at which material are made or used within the cell, hence the chemical activity per unit of time. As the volume of the cell increases so does the surface area however not to the same extent. When the cell gets bigger its surface area to volume ratio gets smaller, as you can see in the four cubes on the right. This surface area to volume ratio is incredibly useful and vital to organisms, so they have to adapt to the changes the ratio causes. Diffusion pathways are shorter, so more efficient - molecules do not have to travel so far to get in or out of the cell, so it takes less time and (if it is active transport) energy. In addition, concentration gradients are easier to generate, which makes diffusion more efficient. Small, warm-blooded mammals lose heat very quickly due to their large surface area to volume ratio. They need to east almost constantly because of this, but that gives them the energy they need. Desert plants would lose their water quickly with flat leaves, so they minimize their ratio in older to conserve water. Some plants even change their metabolism to save water. Cool, right?Still need help? Visit this site to learn more about the surface area to volume ratio.

To learn more about c e l l s a n d t h e i r structure, check out this link and click on “Cell Structure.”

How to Make Your Small Surface Area to Volume Ratio Work for YouBy: Mary Grace Bedwell

Stem Cells ExplainedBy: Mary Grace Bedwell

In the world of stem cells, there are a lot of questions regarding what they are, what they do , and how they can affect you. So, let’s dive into this exciting topics with our first question: 1. What are emergent properties? Emergent properties are seen at every level of increasing complexity from the atom to the molecule, to the cell, to the organism to the biosphere.

2. How do stem cells carry out specialized functions? Cells differentiate to carry our specialized functions by expressing some of their genes but other. All of the cells in the body carry the same genes in their nuclei, but cells are different in what they express. The ones not in use are “turned off.”Determining what gene will be expressed is determined by environmental factors around the cells.

3. What do the “-potents”mean? The “potents” referred to here is talking about the terms totipotent, pluripotent, nullipotent, etc. Each one of these words indicated a different division potential of a cell. Once a stem cell has differentiated, it can only make more stem cells of the differentiated cell. The five types of cell differentiation potentials are as follows:- Totipotent cells - Can become any type of cell- Pluripotent cells - Can become any type of cell,

excluding embryonic membrane cells- Multipotent cells - Can become a number of

different cell types- Unipotent - Can only become one type of cell- Nullipotent - Cannot divide (red blood cells)

4. Where do stem cells come from? Pluripotent cells are found in human embryos that are only a few days old. They have also been developed from fetal tissue (older than 8 weeks of development. There are also cells called induced pluripotent stem cells. “IPSCs are adult cells that have been genetically reprogrammed to an embryonic stem cell–like state by being forced to express genes and factors important for maintaining the defining properties of embryonic stem cells,” says the National Institute of Health. This discovery was released in 2007, but in 2006 mouse IPSCs were tested. You can watch a video about Cryopreservation of these mouse cells here. The NIH went on to say that non-embryonic (including adult and umbilical cord blood) stem

cells have been identified in many organs and tissues. Typically there is a very small number of multipotent stem cells in each tissue, and these cells have a limited capacity for proliferation, thus making it difficult to generate large quantities of these cells in the laboratory. Stem cells are thought to reside in a specific area of each tissue where they may remain quiescent (non-dividing) for many years until they are activated by a normal need for more cells, or by disease or tissue injury.

5. What is a therapeutic use of stem cells? In the treatment of lymphoma, bone marrow is destroyed in chemo- or radio-therapy. Before this aggressive treatment takes place, stem cells are harvested from the bone marrow and stored. These harvested cells can be used to replace the damaged bone marrow, producing healthy blood cells in the recovering patient. Stem cells are also useful in instances other than cancer. Here is an article on how a neurological disease, Multiple Sclerosis, is potentially being treated and/or cured by regrowing myelin sheaths around nerves from bone marrow.

6. What is the debate over stem cells? That is a very loaded question, and if you are really interested, refer to this TIME article.

7. What do stem cells look like?

If you have more questions, check out the NIH’s FAQ page about stem cells here.

Even though being called a “single-celled organism” is a common insult, I must ask the question: “Are single-celled organisms really as simple as people claim they are?” My study of the E. coli Bacteria has begun to make me think otherwise. Though single-celled organisms are seen as lesser beings, they still hold many of the same characteristics as multicellular organisms. For instance, the cell wall that protects the cell from the outside environment and maintains the shape of the cell, as well as preventing the cell from bursting if internal pressure rises is found in all plant cells. Other similarities are the semi-permeable plasma membrane that all cells have as well cytoplasm and ribosomes. The semi-permeable is important to all cells and determines what flows in and out of the cell through the use of integral and peripheral proteins, diffusion, and active transport. Cytoplasm is found in every type of cell and contains many enzymes used to catalyze chemical reactions of the metabolism, and ribosomes are found in the cytoplasm. These are all of major components of the eukaryotic cells found in multicellular elements. The main difference between the two are their “Brains.” Prokaryotes contain a nucleoid region instead of a true nucleus. This seems to be main cause for the social injustice that is committed everyday without even a thought of the origin of their jab. However, the nucleoid is intelligent when you consider that the function is to contain DNA which stores the hereditary material that controls the cell and will be passed on to daughter cells. Though the membrane has no nuclear membrane or nucleoli it completes all of its functions as the brain of the cell. Eukaryotic cells might be more complex or have more organelles, but they can not compete to prokaryotic cells in the field of multiplication. Binary Fission allows prokaryotic cells to reproduce at a rate much faster than a multicellular organism could ever reproduce.

So, single-celled organisms are not that much different from multicellular organisms. Multicellular organisms may have a “true nucleus,” but they are not more efficient or effective in every category. Single-celled organisms are animals, too.

Next time you see one of these little guys, be sure to think twice before you call them simple. They are no simpler than this guy.

If I only had a

brain!!

Are Prokaryotic Cells Victims of Social Darwinism?By: Will Parsons

More on Prokaryotes and Eukaryotes

Hey ignoramus! After learning about prokaryotes, I bet you’re wondering what eukaryotes are like... but maybe not. If you are, this is the article for you! Liver cells are composed of the six primary organelles that make up eukaryotes, making them supreme. Therefore, we will use them as examples. These six organelles include the ribosomes, the endoplasmic reticulum, lysosomes, the Golgi apparatus, mitochondrion, and a nucleus. Sort of like (or exactly like) your internal gizzards and whatnot. The ribosomes are sites of protein synthesis, which is the production of proteins. Messenger RNA is translated in ribosomes. The rough endoplasmic reticulum modifies proteins to alter their function or destination. Lysosomes contain digestive enzymes to hydrolyze macromolecules into their monomers (or for the simple minded: it breaks them down). The Golgi apparatus receives proteins from the rough ER and modifies them further. It also packages the proteins for transport. Mitochondrion converts chemical energy into ATP to power the cell. The nucleus contains hereditary information and controls the cell.

“Oh that’s great Alan, but what do they look like?”BAM.

So, how do they stack up with prokaryotes? Well ignoramus, prokaryotic cells have naked DNA as opposed to eukaryotic cells with DNA associated with proteins. Prokaryotic cells have DNA free-floating in the cytoplasm. Eukaryotic cells do not have this. Theirs is inside the nuclear envelope. As opposed to prokaryotic cells, eukaryotic cells have mitochondrion. Prokaryotic cells are smaller than the 80S eukaryotic cells, reaching about 70S. There are no internal membranes in a prokaryotic cell. So, in conclusion, eukaryotes are better.Now you aren’t an ignoramus anymore!

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Liver Cells - The Perfect CellBy: Alan Burns

Send in your votes toCell Battlec/o General Magazine1 General RoadNew York, New York 12345

PROKARYOTES EUKARYOTES

Plants Versus AnimalsBy: Alan Burns

So, everyone knows that plants and animals differ, but who actually knows how? I do. But you don’t ignoramus. Look below for more information!

Plant Cells to the left.Animal Cells are to the right.They have different extracellular structures.

Q: What are the extracellular components of cells?

Extracellular components in plant cells maintains cell shape, prevents excessive water uptake, and holds the whole plant up against gravity. Components in the animal cell secrete glycoproteins to form the extracellular matrix, which functions in support, adhesion, and movement. I don’t know what any of that means...

WANT MORE INFORMATION?CLICK HERE.

Membranes and OsmosisBy: Alan Burns

Here at General Magazine, we know that you have a lot of questions about membranes and what they do. Today, I, Alan Burns, am going to answer these questions.

Q: What is the structure of the membrane? The membrane is similar to a water bed. Not really but sort of. The cell membrane is composed of phospholipid molecules. The molecules are further divided into two other molecules: hydrophobic hydrocarbon tails and hydrophilic phosphate heads. The tails are repelled by water and the heads are attracted, causing them to arrange in a consistent structure. This structure is composed of hydrophilic heads on the edges of the membrane (exposed to the inside and outside of the cell) and the hydrophobic tails are positioned in between them, making up the middle of the membrane. The membrane is in a fluid state, causing movements and flexibility.

Q: What is the role of proteins in the cell membrane? Membrane proteins can act as as hormone binding sites, electron carriers, pumps for active transport, channels for

passive transport. They can also be used for cell to cell communication and cell adhesion.

Q: Why are membranes important? Why, they help with diffusion and osmosis, of course!Q: What is the difference between diffusion and osmosis? Diffusion is the passive movement of particles from a region of high concentration to a region of low concentration. Osmosis is the passive movement of water molecules, across a partially permeable membrane, from a region of lower solute concentration to a region of higher solute concentration.

Q: What is passive transport, anyway? Passive transport is the form of transport that requires no energy or ATP. It’s rolling out of bed instead of standing out of bed. Because the cell membrane is semi-permeable (that is, it allows some things through and out), passive transport allows things to easily go in and out of the cell. Transport can either be by facilitated or simple diffusion. Facilitated diffusion is uses channel proteins to do the job. Simple diffusion only requires a concentration gradient ad free-flowing molecules.

Q: But I’ve also heard of this “Active” transport... The only difference between passive and active transport is that active transport requires ATP. Walking to school instead of riding the bus. It does the exact same thing as passive transport but some things require energy. The advantage is that even if there is a gradient things can be transported against it. Protein pumps accomplish this.

Q: What are vesicles for? Vesicles carry proteins to the rough endoplasmic reticulum. Afterwards they carry them to the Golgi apparatus for further modification. Then *breathes* they carry this protein to the membrane and release them out of the cell. This is called

exocytosis. Endocytosis is the opposite in that things go into the cell.

Q: How does the fluidity of the cell membrane help in flexibility and cell shape during exocytosis and endocytosis? The phospholipids are not strongly connected, therefore causing the weak bonds to slide around and move, allowing for endocytosis and exocytosis to be carried out. It also flexes inwards and outwards because of these weak bonds. The attractions, however, of the weak bonds allow for the membrane to reconnect after one of these processes.

I hope this has helped! Here are some fun biology puns to make this boring topic better!

Biology Puns

• We just hired a molecular biologist. Man is he small!• Q: What do you call the leader of a biology gang?

A: The Nucleus• Biology is the only science where multiplication means

the same thing as division.• Q: What is it called when someone is in favor of

young people? A: Protien!

• Biology grows on you!• Adenine proposing to guanine: "You know dear,

mismatches are made in heaven."• Q: What's a pirate's favorite amino acid?

A: Arrrrrrginine• A mushroom walks into a bar and the bartender says,

"sorry we don't serve mushrooms here." And the mushroom replies, "Why? I'm a Fun-gi?"

• A red blood cell walked into a busy restaurant. The hostess asked, "Would you like to sit at the bar?" The red cell answered, "No thanks, I'll just circulate."

• Q: What does a biologist call a disease? A: A culture shock.

Mitosis, the process that opens the door to your new life. After cytokinesis you’ll have to get used to sharing that vein with your children(and those white blood cells that think they rule the circulatory system because they create some antibodies). However, for now I’ll take it slow and tell you all about interphase. During Interphase, the you’ll grow larger. Interphase is an active process of life during which protein synthesis, DNA replication, and the number of mitochondria and/or chloroplast. Don’t be bothered by this. It is natural; this is called G1 phase of interphase or gap phase 1. This is followed by phase S (synthesis) during which your genome is replicated. Finally, G2 (gap phase 2) is the second growth phase which separates the newly replicated genome and marks the end of interphase. If you’ve reached this step, then you are doing well; you have already cleared the majority of mitosis. Interphase is the longest stage. Now let’s move on to the fourth stage of mitosis. Prophase is the first step in this process. During Prophase, you’ll find that your chromosomes will supercoil and therefore become bulkier and shorter. Your nuclear envelope will disintegrate, and your spindle microtubules will grow and extend from each pole to the equator. At metaphase your chromatids will move to the equator. As you might already know, your sister chromatids are two DNA molecules formed by DNA replication and are therefore identical. Your sister chromatids are then separated in anaphase as the spindle microtubules attaches to centromere and pulls the sister chromatids to opposite poles. As the sister chromatids separate they are

called chromosomes. This means that each pole has the same chromosomes (same genetic material). During Microtubules, your microtubules break down, your chromosomes uncoil and the nuclear membrane reforms. This is the stage in which you will begin to cleave. Do not be afraid of this stage; this guide gives you all that you need to know. Cytokinesis is the stage in which you will split into two. You will then have broken into two separate entities: These two daughter cells that carry your characteristics. Your daughter cells will be completely genetically identical in their nuclei. By the end of mitosis, which is a process that involves growth, embryonic development, tissue repair and asexual reproduction, you will die. Don’t worry though, your sacrifice is for the greater good.

P.S. - I hope you read this while you were undergoing mitosis, because otherwise you will be terrified of this process.

What to Expect When You’re CleavingBy: Will Parsons

CELLS CAUGHT DIVIDINGBy: Alan Burns

If you leave a cell by itself, its only going do what its made to. That’s why you have to keep an eye on them until they are an older cell. Cells, as the youngsters say nowadays, “divide” or “multiply” when left alone. All cells have the natural urge to divide, since it is in their nature. They HAVE to to reproduce. But cells must wait until they are mature, that is, gone through interphase. Then it is good to start a cell family. If they divide when they are young, it will not result well since they have not had time to grow to the appropriate size.

Be careful when you watch this video.

TOPIC 2: CellsHas been brought to you by:

“LOOK SMART,” Inc.Will,

Mary Grace,andAlan