CELL BIOLOGY NOTES:Biological cell There are many single cells and many multi cellular organisms like us. Single cells have organelles that help them function Organelles:· Mitochondrion: cell organelle involved in respiration· Cytoplasm: fluid that surrounds a cell that forms the vacuole· Golgi Apparatus: processing area for the glycoprotein· Endoplasmic reticulum: organelle involved in the synthesis of protein· Vesicles: Packages of substances that are secreted or used by the cell· Nucleus: it is the brain of the cell, it has the genetic information of the cell that determines ...view middle of the document...
· Some white blood cells contain powerful digestive enzymes to eliminate pathogens by breaking them down to the molecular level.· Cells at the back of the eye are sensitive to light stimuli, and thus can interpret differences in light intensity which can in turn be interpreted by our nervous system and brain.Many of these cells contain organelles, though after some cells are specialised, they do not possess particular characteristics as they do not require them to be there. i.e. efficiency is the key, no resources are wasted and the resources available are put to their idyllic optimum.Cell Membrane A cell membrane or the plasma membrane is a semi permeable layer that consists of phospholipid (fat) molecules and proteins. It covers the circumference of the cell Purpose is to ensure that the cytoplasm remains inside, the membrane ensures what is to enter and exit through the cell, thus it is selective.There are a number of ways in which the process of allowing entities to flow in and out of the cell membrane is possible. These include:1. Cell TransportThe way in which ions can be moved through the cell membrane are:· Active transport: it is when a molecule is actively assisted with a carrier through the process allowing it pass a natural concentration gradient.· Passive transport (Diffusion): it is the movement of a molecule through high concentrations (outside a cell) to low concentrations (inside a cell) via a carrier. This process doesn't require energy.· Simple diffusion: movement of molecules from areas of high concentration to areas of low concentrations in a free state. Osmosis of water involves this kind of diffusion through a selectively permeable membrane (plasma membrane)The Breakdown of materials in a cell.Cells can sometimes breakdown complex molecules into simple molecules which can then be rebuilt into what is required by the body with these new raw materials.Such as:Pinocytosis is where the contents of a structure such as bacteria are drank, essentially breaking down molecules into a drinkable form.Phagocytosis is where the contents are eaten.Absorption and secretionAbsorption is the uptake of materials from a cell' external environment. Secretion is the ejection of material.The Breakdown of Materials in a CellIn cells, sometimes it is required to breakdown more complex molecules into more simple molecules, which can then be 're-built' into what is needed by the body with these new raw materials.'Pinocytosis' where to contents of a structure (such as bacteria) are drank, essentially by break...
