Cell Biology

• Active site = the area on an enzyme that the substrate fits or binds to (specific for each enzyme).
• Cell membrane= controls the entry and exit of substances.
• Cell wall = contains cellulose and is the structural support for plant cells.
• Chloroplasts = site of photosynthesis.
• Cytoplasm = site of most cell reactions.
• Denatured = When enzymes / their active sites are destroyed, often due to excessive temperatures.
• Diffusion = the random movement of substances from high concentration to low concentration.
• Enzymes = proteins made by living cells, which speed up the rate of chemical reactions.
• Lock and key model = the model used to describe enzyme action.
• Mitochondria = site of aerobic respiration producing energy.
• Nucleus = contains chromosomes which carry genetic information and controls the activity of the cell.
• Organs = several tissues performing specific functions.
• Organ systems = group of organs that work together to perform a specific function.
• Osmosis = The diffusion of water through a selectively permeable membrane, from a region of high water concentration to a region of low water concentration.
• Specialised cells = cells that are adapted to perform specific functions.
• Substrate = substances on which enzymes act.
• Tissue = a group of similar cells with a similar function.
• Vacuole = contains a watery sugar solution (sap).
• Every organism, except viruses, contains one or more cells.
• The size of the organism depends on the number of cells and not the size of the cells.
• Plant cells have cell walls, chloroplasts and a large permanent vacuole present.
• Animal cells have no cell wall, no chloroplasts and no permanent vacuole present.
• The cell membrane controls substances entering and leaving the cell.
• Cytoplasm is where most chemical reactions take place.
• The nucleus contains chromosomes which carry genetic information and controls the activities of the cell.
• The cell wall contains cellulose; it supports the plant's structure.
• Chloroplast absorbs the light for photosynthesis.
• The vacuole is space filled with cell sap.
• Cell sap is a dilute solution of sugars and mineral salts.
• The mitochondria is the site of aerobic respiration.
• magnification = power of eyepiece lens × power of objective lens
• Light microscopes need light to pass through an image to be able to see it.
• The properties of light means that it is impossible to magnify on light microscopes larger than ×1000.
• The image on an electron microscope is displayed on a monitor because we cannot see electrons.
• Electron microscopes have larger magnifications than light microscopes (up to ×50,000,000)
• Electron microscopes use electron beams instead of light to show images.
• Electron microscopes can only be used to see and study dead cells.
• Biological staining of cells is used to see cells in greater detail through a microscope.
• The most common biological stains in school laboratories are iodine and methylene blue.
• Iodine makes the nucleus more obvious and stains any starch pigment.