Lab 3 Flashcards
Enzymes
- are catalysts that speed up chemical reactions but are not themselves consumed or changed by the reactions.
- speed up chemical reactions by lowering the activation energy required to make reactions proceed within the narrow range of temperatures in which living organisms function.
- Without enzymes, most biochemical reactions would take place at a rate far too slow to keep pace with the metabolic needs and other life functions of organisms.
- Most enzymes are proteins. = is a sequence of amino acids (primar y structure) that is folded in a three-dimensional shape.
–> complex ones
Hydrogen bonds in proteins
Hydrogen bonds along the polypeptide backbone (secondar y structure) create coils and folds in the protein that contribute to its overall shape.
active site
The complex 3-D structure of enzymes, consisting of one or more folded polypeptide chains, includes the formation of an active site - a special area into which the substrate (material to be acted on by the enzyme) will fit
Enzyme specificity
is due to the structure of the enzyme’s active site which must match the shape of the substrate molecule it acts upon. The interaction of the active site with the substrate lowers activation energy.
Factors that can change the shape of enzymes
Enzymes are complex proteins , therefore,
- changes in temperature
- alterations in pH
- the addition of certain ions or molecules
- the presence of inhibitors all may affect the structure of an enzyme’s active site
and thus the activity of the enzyme and the rate of the reaction in which it participates.
- rate of an enzymatic reaction can also be affected by the relative concentrations of enzyme and substrate in the reaction mixture.
The effect of temperature on the rate of an enzyme
- catalyzed reaction increases as temperature increases, up to a point at which the rate is maximum.
- This temperature is usually close to the optimal temperature for an organism. The rate then declines with a further increase in temperature
- Increased temperature increases molecular movement/ vibration.
- Once the temperature climbs above 50°C, most proteins in living tissue become denatured - their secondary or tertiary protein structure breaks down due to the increased kinetic energy.
The Effect of pH on Enzyme Action
- The presence of ions can interfere with the pattern of positive and negative charges within a protein molecule, thus changing the way the protein folds.
- Enzyme: shape of the active site may be changed.
–> expect, then, that changes in pH (reflecting the concentrations of hydrogen and hydroxide ions) would affect the action of enzymes. - most favorable pH value (when the enzyme is most active) is the optimum pH.
- Extremely high or low pH values usually result in a complete loss of enzyme activity due to denaturation , the breakdown of the secondar y and tertiary structure of a protein.
Lactase
- an enzyme that catalyzes the hydrolysis of lactose.
- Lactose is a disaccharide, made of glucose and galactose, that is found in dairy products.
- When a person consumes dairy products, the lactose is converted into galactose and glucose by the lactase enzyme
lactose intolerant
- which means unable to digest lactose.
- People with lactose intolerance do not have enough lactase enzymes to digest lactose.
–> all depends on how much lactase enzyme each person makes, which is determined by genetics. - This results in lactose accumulating in the large intestine, where it is fermented by bacteria.
- Fermentation of lactose by bacteria creates a lot of gas, which is the cause of abdominal discomfort for people who are lactose intolerant.
over the counter lactase
- over the counter products that contain the enzyme lactase
- The enzyme supplement must first pass through the stomach, where the pH can range from pH 1 (empty stomach) to pH 5 (full stomach), to get to the small intestine (pH 8) where the lactase will hydrolyze lactose into galactose and glucose.
Enzyme assay
- Therefore, we will use a substrate that is similar to lactose, ONPG, which can be used in place of lactose.
- ONPG consists of galactose and o-Nitrophenol that are joined by a bond that is cleaved by lactase
- The products are galactose and o-nitrophenolate; o-nitrophenolate is yellow in color and can be measured by spectrophotometry.
Renewable energy
- refers to energy created from processes that make energy at the same rate, or faster, than the energy consumed.
Exs: Solar, wind, hydro, and geothermal.
- The development of less harmful and renewable energy sources is critical to the health of our planet. b/c form. Fossil fuels (nonrenewable) are major contributors to greenhouse gas emissions
Ethanol fermentation process
- is a combustible fuel that burns cleaner than gasoline and is obtained by the fermentation of sugar by microorganisms.
- source of sugar used for fermentation to produce ethanol comes from plant material.
- ethanol produced via fermentation is distilled and then blended with gasoline to create a cleaner source of fuel.
- Not only does ethanol combustion release less carbon monoxide and dioxide, the CO 2 that is produced will then be absorbed by growing plants used to make the ethanol.
- Overall, this leads to a balance in the amount of CO 2 produced with the amount of CO 2 absorbed, and a renewable source for ethanol production.
Ethanol production
- made by the process of fermentation in microorganisms.
- Organisms rely on generating energy from sugar and the first step in this process is glycolysis.
- Glycolysis is accomplished by converting glucose into two molecules of pyruvate and does not require oxygen as a reactant.
- Metabolic pathways for further catabolism can continue to occur anaerobically (in the absence of oxygen) by fermentation or more commonly and efficiently through the use of oxygen (aerobically) by cellular respiration
Glycolysis
(glucose catabolism) means “splitting of sugar” and represents an almost universal initial method of liberating the potential chemical energy stored within glucose for cellular work ( ATP)
