Lab 6, 8 Flashcards
All living things are composed of
o Four basic classes of molecules: carbohydrates, proteins, lipids, and nucleic acid
Carbohydrates
– starch and sugar
Sugars
o Monosaccharide
o Simple molecules
o Made up of carbon hydrogen and oxygen
o glucose
Starches
o Long chains or polymers of simple sugars
o Polysaccharides
o amylose
How to detect the presence of different classes of molecules in solutions?
o By using specific agents
What to look for as an indication that a particular type of molecule is present?
o Change in color
What does it mean when the color changes?
o Test is positive for the presence of that particular molecule
How can we be sure that the physical changes we see are only due to the presence of the molecule?
o A control reaction is always performed for comparison
Distilled water in an experiment is an example of
o Control substance that provides a negative result
Testing for the presence of Starch in solution
o Add IKI solution 5 drops to 1% amylose
Adding IKI solution to starch will change the color from to?
o Brown to blue/black
o Positive
What solution to use when testing for sugar?
o 10 drops Benedict’s solution to 1% glucose
o Boil for 10 minutes
Adding Benedict’s solution to sugar/glucose will change the to color from to?
o Light blue to Orange means positive
Proteins
o Complex arrangements of amino acids
o Amino acids linked to each other in long chains
o gelatin
What solution to use when testing for protein?
o Biuret’s solution
o 1% gelatin
Adding Biuret’s solution to protein (gelatin) will change color from to?
o Light blue to pinkish purple
o Orange
Lipids
o Fats and oils
o Hydrophobic – does not mix with water
Fats
– solid at room temperature
Oil
– liquid at room temperature
Hydrophobic of lipids can be overcome by using what chemical and why?
o Bile salts
o Because they share both the properties of lipids and water (polarity)
How to test for lipids
o brown paper – one side of each drop distilled water and vegetable oil on other side and let dry for 5 minutes
what happens during the test for lipids? Why?
o Distilled water remains intact while the oil was absorbed by the paper
o water is cohesive with polar bond and wants to remain together while oil does not have same property
How to make lipid more soluble?
o 20 drops of water and 20 drops of oil with 20 drops of bile salts and mix
o because fat is hydrophobic and bile salt is hydrophilic the fat does not want to bind with salt
Procedures for making a 4% salt solution
o 8 gram of table salt NaCL and 192 ml of distilled water
Enzymes
o Facilitate and make possible most of the chemical reactions occurring in living organism
Which is the substrate, which is the enzyme: starch, amylase
o starch is substrate
o amylase enzyme
Digestion of starch happens in the human digestive system at 37 C, appropriate condition vs less than optimum condition
o appropriate condition: starch (polysaccharide is digested a disaacharide sugar (maltose) by the amylase enzyme (in saliva)
o les than: enzyme becomes denatured and lose its ability to function
denatured
o lose its conformational structure
Present of sugar is indicated byu appearance of a?
o Red, orange, or yellow
Describe the action of an enzyme in a chemical reaction
o It lowers the activation energy in a reaction
What does it meanb when an enzyme has been denatured? What are consequences?
o Looses it conformational structure
o The substrate cannot bind with the enzyme
Each enzyme has a temperature and pH optimum. What does this mean?
o That the enzyme function at best at it’s optimum level during a certain temperature and pH
Can an enzyme be reused if it is destroyed during a chemical reaction?
o Yes, an enzyme remains unchanged to be used again and again
How does temperature affect enzyme function?
o Temperature speeds up the reaction, but the hotter it gets the possibility that the enzyme breaks down
Reagent
– Indicator chemicals
How Does pH affect enzyme function
o The more basic it is the less effective the enzyme function is, the optimum level is at 7 pH, Acidic is slighty less than effective than pH7
How does concentration of the enzyme (amylase) affect starch digestion?
o It slightly make enzyme more effective
Can starches be broken down without enzymes?
o Yes by reaching the2 activation energy of the reaction without the help of Amylase
o it’s not done because the reaction takes a long time to activate
Passage of molecules into and out of cells is regulated by
o Plasma (cell) membrane
Selectively permeable membrane
o membrane allows only certain molecules to cross freely
Small molecules may simply diffuse across the plasma membrane, but large substances must?
o May need to be transported by carrier proteins that span the membrane
Diffusion
o Net movement of molecules from a region of higher concentration to a region of lower concentration
osmosis
o diffusion of water across deferentially permeable membrane from an area of higher water concentration to an area of lower water concentration
solution
o contains both a solute (particles) and a solvent (liquid) that dissolves the solute
tonicity
o relative concentration of solute and solvent outside of a cell compared to inside the cell
lysis
o disintegration of a cell by rupture of the cell wall or membrane
crenation
o eukaryotic cell – shrink after exposed to hypertonic solution
plasmolysis
o cell walls – cells lose water in hypertonic solution
o cell walls intact – inner membrane shrinks
emulsification
o breakdown of fat globules into smaller, uniformly distributed particles
bile
o mixture of substances that is produced by the liver and stored ibn the gallbladder
o emulsifies fats and aids in their digestion
monomer
o subunit that serves as a building block of a polymer
polymer
o a large molecule consisting of many identical or similar monomers linked together by covalent bonds
