Bio lab exam 2 Flashcards
what is an enzyme?
an organic molecule (usually a protein) that speeds up a chemical reaction
What does an enzyme act as?
a catalyst
what would happen if a chemical reaction didn’t have an ezyme?
it would happen very slowly
what is a catalyst?
a molecule that speeds up a chemical reaction but is not permanently altered by the reaction
how does an enzyme catalyze a reaction?
the enzyme binds to one or more of the reactant molecules
what are the substrates of an enzyme?
the reactant molecules that the enzyme binds to
what is the active site of an enzyme?
the part of an enzymes shape that comes in contact with the substrate
what can effect an enzymes activity?
temperature, pH, substrate concentration
how does temperature effect an enzymes activity?
enzymes denature at a high temperature, but at warm temperatures an enzymes activity is higher
when a substrates concentration is higher what happens to its activity?
it gets higher
what happens when an enzyme reaches saturation?
any additional increase in substrate concentration will not increase enzyme activity
what does it mean when an enzyme is saturated?
all available enzyme active sites are occupied and working at maximum efficency
what is Vmax?
when an enzyme is at maximum activity
what usually ends in “ase”?
enzyme
Would an enzymes activity be higher at 0°C or 25°C?
25°C, because the random movement would be higher, but the temperature wouldn’t be high enough to denature the protein
What enzyme did you measure the activity for in lab six?
Glucose oxidase
In lab six, you measured the absorbency of the pink dye, what does the rate of increase in the absorbency mean?
Glucose oxidase enzyme activity
What is the formula for a serial dilution?
DF = V1+ V2 / V1
How do you find the dilution factor?
Divide all of the concentrations by the next concentration they should all equal the same number
How do you find V2?
The final volume
When making a serial dilution what are the steps?
- Transfer V2 of water to each of the cuvettes
- Transfer V1 of the stock solution to the first Cuvette
- Transfer V1 from the first Cuvette to the second Cuvette
- Repeat
- Discard V1 from the last Cuvette
What is chromatography?
A technique used to separate molecules that are in a mixture
What type of chromatography did we use in lab seven?
Thin layer chromatography ((TLC))
What did we use thin layer chromatography for in lab seven?
To separate photosynthetic pigment molecules from an extract of spinach leaves
When using thin layer chromatography, the pigments separate from each other according to what?
Charges or lack of charges
What are the two phases in a TLC set up?
The stationary phase and the mobile phase
What is the stationary phase?
The coating of silica on the TLC plate, which is a rectangular strip of plastic
What charge does silica have?
Polar
What is the location on the plate where the line of extract is applied called? (TLC)
The origin
What is the mobile phase?
A mixture of two nonpolar organic solvents: petroleum ether and acetone
What is the developing chamber? (TLC)
A sealed glass jar that contains the solvent mixture
What does the developing chamber prevent? (TLC)
Evaporation
What molecules are attracted to the silica coating? (TLC)
Charged pigment molecules
Why are charged pigment molecules attracted to the silica coating?
Because the silica coating is polar
What molecules are attracted to the mobile phase?
Uncharged molecules
Why are uncharged molecules attracted to the mobile phase?
Because the mobile phase is nonpolar
What molecules will migrate slowly? (TLC)
Charged pigments
What molecules will migrate faster? (TLC)
Uncharged pigments
What is the solvent front? (TLC)
The leading edge of the solvent
When is the TLC plate removed from the developing chamber?
When the solvent front is near the opposite end of the TLC plate
What are some common problems that can occur in TLC?
At the start of TLC spinach extract dissolves into solvent, at the end of TLC pigment bands on the TLC plate appear wavy or curved instead of straight, at the end of TLC, all pigment bands are faint, at the end of TLC pigment bands are very broad and overlap each other
What could cause the spinach extract dissolving into the solvent at the start of TLC?
There could be either too much solvent in the developing chamber or the spinach extract was applied to low on the TLC plate
How can you prevent spinach extract dissolving into the solvent at the start of TLC?
Apply the extract at a location that will be above the level of the solvent in the chamber
How can you prevent pigment bands on the TLC plate, appearing wavy or curved instead of straight?
Wear gloves when handling the TLC plate, apply the extract in as straight of a horizontal line as possible, use a light touch when applying the extract, after inserting the TLC plate into the developing chamber close the lid of the chamber so that it is tightly sealed
What could be the cause of all pigment bands, being faint at the end of TLC?
Two little spinach extract was originally applied to the TLC plate
How can you prevent all pigment bands, being faint at the end of TLC?
Make sure the line of extract at the origin is densely colored (apply several layers of extract)
How can you prevent pigment bands, being very broad and overlapping each other at the end of TLC?
When applying the spinach extract allow each layer to air for a few seconds before applying the next layer