Key Concepts In Biology

• Eukaryotic cells have a nucleus, mitochondria, chloroplasts, and a cell membrane.
• Prokaryotic cells don't have a nucleus, instead they have a small circular structure called a plasmids
• Nucleus - contains genetic material and controls the activities of the cell.
• Mitochondria - Site of aerobic respiration, where most of the energy for cellular respiration is produced
• Ribosomes - Site of protein synthesis in the cell.
• Cell Membrane - controls what goes in and out of the cell, controls the movement of substances in and out of the cell
• Cytoplasm - where most of the chemical reactions take place.
• Rigid Cell Wall - Made of cellulose and supports the cell.
• Chloroplast - contains chlorophyll, which absorbs light energy for photosynthesis
• Large Vacuole - Contains cell sap, which is a solution of sugars and salts.
• Chromosomal DNA - Controls the cells activities and replication.
• Plasmid DNA - A small circular DNA molecule that is found in bacteria.
• Flagellum - A long, thin tail that is used for movement in bacteria.
• Egg Cell is adapted to its function by: Containing nutrients in the cytoplasm to feed the embryo, has a haploid nucleus and its membrane changes structure to make sure the offspring ends up with the right amount of DNA.
• Sperm Cell is adapted to is function by: having a long tail to swim to the egg, lots of mitochondria in the middle to provide energy, acrosome at the head where enzymes needed to digest through the membrane of the egg and it has a haploid nucleus.
• Ciliated Epithelial Cells - line the surface of organs and the cilia beat to move substances in one direction.
• Light Microscopes work by passing light through the specimen. They let us see the specimen's structure. And can be used to study living cells.
• Electron Microscopes have higher magnification and higher resolution than light microscopes. They let us see smaller things in more detail like internal structures of cells.
• Total Magnification = Eyepiece Lens Magnification X Objective Lens Magnification.
• Magnification = image size / actual size
• Catalyst - A substance that increases the rate of a chemical reaction without being used up in the reaction
• Substrate - A substance that is used by an enzyme to carry out a reaction.
• Enzymes are biological catalysts, they speed up reactions but do not get used up during the process.
• The active site on an enzyme is where substrates bind to it.
• Lock & key model - The shape of the active site matches the shape of the substrate so only one type of molecule can fit into it.
• If the temperature is too high or low then the enzyme will denature.
• pH affects the activity of enzymes because if the pH changes from the optimum value then the bonds holding the amino acids together may break down causing the enzyme to denature.
• Substrate Concentration - the higher the concentration of the substrate, the faster the reaction rate.
• Carbohydrase convert carbohydrates into simple sugars. E.g. Amylase breaks down starch into glucose.
• Proteases convert proteins into amino acids and peptides.
• Lipases convert lipids into glycerol and fatty acids.
• Benedict's Regent is used to test for sugars. Sample turns brick-red if sugar is present.
• Iodine solution is used to test for starch. Sample turns blue-black if starch is present.
• The Biuret test is used to test for proteins. The solution will turn from blue to purple if there is protein.
• The Emulsion test is used to test for lipids. If lipids are present they will precipitate out of the liquid and show up as a milky emulsion.