Biological Principles, Simplified

 Transport There are two types of transport that occur between cells: passive and active transport.  Passive Transport -  Molecules naturally move from an area of high concentration to low concentration. This does not use energy. There are 3 types of passive transport: simple diffusion , facilitated diffusion , and osmosis .      - Simple Diffusion: Small and nonpolar molecules more from an area of high to low concentration. If there is more than one solute, then those solutes will be equally distributed across a membrane. These molecules will be able to easily pass through the membrane, which is why it's called simple diffusion: nothing is needed to help it pass through.       - Facilitated Diffusion: Polar molecules and ions impeded by the bilayer of the membrane are diffused passively with the help of transport proteins spanning the membrane. Diffusion will occur through protein channels. Again, it moves from high concentration to low concentration. If a large amount of glucose

 Surface Area to Volume Ratio This is a very short lesson on a bit of math you'll encounter in biology, but it's fairly important.  Remember how the mitochondrion has a double membrane? Here's a simplified drawing of the mitochondrion.  In the Electron Transfer Chain (ETC), ATP energy is created. It is found in the inner membrane of the mitochondrion.  Compare these two pictures: which one has more ETCs? The wrinkled mitochondrion has more ETCs, which means it can produce more energy. More energy means the cell will be more successful. Notice that the wrinkled mitochondrion has more membrane than the rounded mitochondrion - if we were to stretch the inner membrane until it was flat and without wrinkles, there would be much more membrane.  This idea, that more membrane equals more ETCs, can be exhibited by the Surface Area to Volume Ratio. More membrane per volume means a higher surface area to volume ratio (6 units^2 SA: 1 unit^3 V) (so, more wrinkled). A lower surface area

 Junctions and Communication Cells are packed very tightly next to each other inside living organisms. If you've ever seen an onion cell under a microscope, you'd see the plant cells all right next to each other. There are practically no gaps between cells. In the images below, each rectangular shape is a cell. The purple color is due to staining (adding color) so it's more visible.  In order to pass information between cells, as well as things like ions and molecules, cells need a way of communication. This comes in the form of junctions . Junctions can be 'seams' or 'gaps' between cells that either increase or decrease communication and allow for the passage of molecules.  Plasmodesmata - found only in plant cells. Has a small channel that directly connects the cytoplasm of neighboring plant cells via traversing the cell wall. Its goal is to move water, nutrients, and other molecules between cells. It increases communication  because molecules, solutes, an

 Cell Organelles The cell is the most basic functional and structural unit of life. It is incredibly tiny - 7 to 8 cells could fit in the width of a single strand of hair! Cells make up everything in us, from our fingernails to tissues and organs.  Some organisms are made up of just one cell and called unicellular (one-cell) organisms. Other organisms, like us humans, have trillions of cells in our bodies. The largest creature on earth, the blue whale, has approximately 100 quadrillion cells.  A cell is like a water ballon in that it holds water (and many other molecules and structures) inside of it.  There are three domains of organisms generally agreed upon: prokaryotes, eukaryotes, and bacteria. I shall mainly focus on prokaryotes and eukaryotes.  Prokaryotes are microscopic organisms belonging to the domains Bacteria and Archaea. They look like the character Plankton from SpongeBob - like a capsule with antennae.  Eukaryotes are organisms belonging to the domain Eukarya and include