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UIUC BIO 141 - Midterm Notes - Bio 141

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Midterm Notes:Amino Acids- These are the building blocks of protein, they consist of an amino group, a central carbon, a carboxyl group, one of twenty different side chains. Amino acids formed by dehydration synthesis form peptide bonds. Nonessential amino acids are made by the body, and essential amino acids cannot be made by the body, so you must get them from your diet. Peptide Bonds- an amide type of covalent chemical bond linking two alpha-amino acids from the carboxyl group and the C1 and one amino acid from N2 of another amino acid. This releases a molecule of water meaning it was formed by dehydrationsynthesis. They are rigid and planar. The N terminal is the amide group, and the C terminal is the carboxyl group. Enzymes- Major players in the function of cells in the body, these are catalyst for reaction, and they make many chemical reaction possible. When an enzyme is formed, it is made by stringing together between 100 and 1,000 amino acids in a very specific order. The chain is then forded into a unique shape, and this shape allows it to carry out its function. Maltase and Lactase change the chemical make up of Maltose and Lactose so that the body can digest them. Enzyme Classes- 1. Oxidoreductase- An enzyme that catalyzes the transfer of electrons from one molecule to another (OIL RIG) Examples are dehydrogenases, reductases 2H2O2-> 2H2O and O2 (Peroxidase)2. Transferase- Enact the transfer of a specific functional group from one molecule toanother. Transaminases catalyze the transfer of amino group, and Kinases catalyze the transfer of a phosphate group.3. Hydrolase- An enzyme that catalyzes the hydrolysis of a particular substrate. Esterases, proteases and lipases are examples. 4. Lyase 5. Isomerase6. Ligase Anabolism and Catabolism- Anabolism uses up energy and is ENDERGONIC, this is when small molecule join to make up larger ones. Catabolism gives off energy and is EXERGONIC larger molecule are broken down into smaller ones, eg. Peroxidase Hydrolysis and Dehydration Synthesis- Hydrolysis adds water to the molecule to dissolve the bond. Dehydration synthesis bonds molecule together by removing water. Structure of Proteins- The Primary Structure is a sequence of amino acids. The secondary structure is the interaction of the group with an alpha helix and the beta pleated sheets. The Tertiary structure is the final folded shape and is the final level of structure for proteins with only a single polypeptide shape. The Quaternary structure is two or more tertiary structures.pH, Acids, and Bases- is a measure off hydrogen ion concentration, the measurementof the activity of free hydrogen (H+, Acid) and the hydroxyl (OH-, Base). An acid is a chemical species that donates protons or hydrogen ion and/or accepts electrons. IN pH the higher the concentration of hydrogen ion the higher the acidity and lower thepH. PH scale ranges from 0-14, pH of <7 is acidic, and a pH of >7 is basic. The pH scale is logarithmic, therefore a pH of 6 is ten times more acidic than a pH of 7 and a pH of 9 is a hundred times for basic than a pH of 7. PH is temperature dependent. If the pH is lower than the isoelectric point the amino acid acts as a base and accepts a proton at the amide group and yields a positive charge. If the pH is higher than the isoelectric point the amino acids acts like and acid and donates a proton yielding a positive charge. Depending on the charge in electrophoresis is will be attracted to the opposite pole of its charge. Polar and Non-Polar- Polar bond are covalent bonds where the pair of electrons are unequally shared between 2 atoms. The unequal sharing of the electron pairs causesa molecular dipole. Nonpolar bonds are covalent bonds where 2 atoms share a pair of electron equally, and the electronegativity is equal. Water- is a polar covalent bond that forms hydrogen bonds with other water molecules, and is amphoteric (acts a acid or a base). Is solid form is less dense than its liquid form because of the hydrogen bond holds water molecules further apart in a solid state than in its liquid state. Important points, high heat of vaporization, strong surface tension, displays capillary action, high specific heat, and hydrophobic effect, nearly universal solvent. Hydrophilic and Hydrophobic- Hydrophilic molecules are polar and ionic meaning they have charge and hydrophobic molecules are nonpolar. Hydrophilic particles may need protein carriers for facilitated diffusion, and when particles are hydrophobic a simple passive diffusion occurs. Carbohydrates- Molecules with a 1:2:1 ratio of carbon, hydrogen, and oxygen. These are good for storage of energy. Monomers are called monosaccharide’s and the most common monomer is glucose C6H12O6. The simplest carbohydrate is monosaccharide’s and in them 6 carbon sugars plays an important role. Lipids- Insoluble in water, the high proportions of nonpolar c-h bonds causes the molecule to be hydrophobic. Lipid monomers contain glycerol which is a three carbon chain with a hydroxyl group attached, dehydration synthesis joins the fatty acids to the glycerol at the functional groups. Fatty acids are a chain of 16.18 carbon with a carboxyl group attached to the end. Good for long term energy storage. Saturated fats have no double bonds between the carbons of the fatty acid chains and the are solids at room temperature. Unsaturated fats have double bonds between come of the carbons of the fatty acid chains these are liquid at room temperature. Phospholipids are composed of glycerol, 2 fatty acid nonpolar tails, anda polar phosphate group headMembrane Structure and Function- Membranes are composed of a phospholipid bilayer with a hydrophilic head and a hydrophobic tail. These are catergorezied as the fluid mosaic model because it describes the structure of the plasma membrane. Membrane proteins are held in the membrane and do not fall out due to the surface tension of the water. Channel proteins facilitate the transport of substances across a cell membrane, they act as facilitated diffusion or active transport depending on the concentration gradient inside and outside the cell membrane. There are two forms of this open channel and gated channel. Carrier proteins carry substances from one side of a biological membrane to the other. Often found in a cells membrane but also found in the membranes internal organelles such as mitochondria and chloroplast this is facilitated diffusion example is the sodium potassium pump. Symporter proteins

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