Lab Exam 2 Flashcards
What is chemical potential?
Measure of free energy available to do the work of moving a mole of molecules from one location to another
What is the law of diffusion?
Molecules move from areas of higher chemical potential to areas of lower chemical potential
Give an example of a time chemical potential is used
To move a molecule through a cell membrane
The relationship between concentration of dissolved substance and chemical potential is what?
Proportional
Molecules move from areas of _____ concentration to areas of _____ concentration
High concentration to Low concentration
What is osmosis?
Movement of water molecules from regions if higher water potential to regions of lower water potential across a selectively permeable membrane
What is water potential?
Measure of the chemical potential of water molecules
What is water potential affected by?
Amount of other substances dissolved in water
The ______ the concentration of a dissolved solute in water, the _____ the water potential
Greater, lower
What is the water potential of pure water?
0
When solute is added to pure water, does the water potential become negative or positive
Negative
Water moves across membranes toward areas with ______ concentration of solutes, where the water potential is ______
Higher, lower
Give two examples of passive transport
Diffusion
Osmosis
What does passive transport mean?
Molecules are moving down concentration or free energy gradients
What is active transport?
Moving a molecule against a gradient and requiring energy
What movement is exhibited in Brownian movement?
Jiggling
Can you see water molecules in a microscope ?
No
Would an increase in temperature increAse or decrease the rate of Brownian movement?
Increase
Why are molecules in liquids in constant movement?
Due to their kenetic energy
What is the rate of diffusion controlled by? (4 things)
The size of the diffusing particle
The temperature
The viscosity of the medium
The concentration gradient
Does the net movement of molecules slow down as equilibrium is reached? Why?
Yes, because the concentration gradient is smaller
What can you say about the chemical potential of pigment molecules at different distances from the center of a spreading pigment spot
At the center the chemical potential is higher, away from the center is lower
How is chemical potential of pigment molecules related to their rate of movement?
As the chemical potential decreases, the rate of movement slows down.
Does net diffusion eventually come to an end? Why?
Yes, because equilibrium was reached
What type of membrane does a cell membrane have?
Semi permeable
What molecules can move freely through the cell membrane?
Hydrophobic solute molecules, water, small polar uncharged molecules
Solutes diffusing through a selectively permeable membrane diffuse from an area of ______ chemical potential to an area of _____ chemical potential
High,
Lower
What happens it two solutions diffusing contain equal concentrations of solute?
Their chemical potentials are equal and no net movement of particles occurs
In a laboratory how can molecules of different sizes be separated?
Molecules of different sizes can be separated by dialysis using artificial semipermeable membranes
How do living membranes select molecules of differing sizes to go through them?
They change their pore size by altering lipid and protein content
What can you say about the effects of molecular size on the diffusion of molecules across a semi permeable membrane?
If the molecule is very big then it won’t go through the membrane
What is an isosmotic/isotonic medium?
Medium that has the same concentration of osmotically active particles as are present inside the cell
What is a hyperosmotic/hypertonic medium?
Medium that has higher concentration of osmotically active particles that forces a cell to lose water by osmosis to the medium
What is plasmolysis and what does it occur in?
Plasmolysis is when a cell becomes dehydrated and shrinks and it occurs in plants
What is crenation and what does it occur in?
Crenation is when a cell becomes dehydrated and shrinks. It occurs in red blood cells
What is a hypoosmotic/hypotonic medium?
Medium that has a lower concentration of osmotically active particles.
What is turgidity and in what does it occur?
Turgidity is when a cell gains water by osmosis and swells
What is hemolysis? And in what does it occur?
Hemolysis is when a cell gains water and swells and can continue to gain water until it bursts. It occurs in red blood cells
What does lysed mean?
The cell burst
What is the relationship between the increase in mass and the molarity of sucrose in the dialysis bag?
There’s a proportional relationship
If two solutions are isotonic to each other, how do their solute concentrations compare?
They are the same
What are enzymes?
Proteins that control reactions in cells
What are biological catalysts?
Accelerate metabolic reactions to a biologically useful rate by lowering activation energy.
Enzymes are ______ proteins
Globular
Enzymes folds create the _____ site
Active
Each amino acid has one specific _______
Substrate
What is the alteration of the active site called?
An induced fit
Any structural change in an enzyme will __________ it by altering its ________ and _______ the reaction rate
Denature
Active site
Slowing down/stopping
What is an inhibitor?
A molecule that binds to the active site preventing a substrate from bonding and prevents chemical reactions
Enzymes function best at optimal _______ and ______
Temperature
pH
What enzyme is found in living tissues?
Catalase
What does the enzyme catalase do?
Breaks down hydrogen peroxide in cells
What is hydrogen peroxide broken down into?
Oxygen and water
The presence/absence of what gas will determine if a reaction is taking place
O2
What is the enzyme responsible for the browning process of fruits?
Catecholase
What is the substrate of catecholase?
Catechol
When does the browning reaction begin?
When the enzyme and substrate are brought together by cell damage in the presence of oxygen.
Why does oxygen start the browning process in fruit? What molecule does it form?
Oxygen promotes the exchange of electrons and pulls electrons from catechole which forms benzoquinone.
What does heat do to an enzymatic reaction?
Denatures the protein and decreases/stops reaction
Explain what happens when a protein is denatured
It loses shape, substrate can no longer go in it, no more active area = no rx
What is solid milk called?
Curd
What is liquid part of milk called?
Whey
What enzyme is required to produce cheese curd?
Rennin
What is the major protein in milk?
Casein
What does rennin do to casein?
Converts it to paracasein
What does para casein do?
Clots or curds the milk.
What is velocity?
Rate of rx
Why is there no increase in reaction rate once the saturation level of the substrate is reached?
All enzymes activation sites are occupied so no further substrate can be used
Does an increase in enzyme concentration influence the mass of curd produced?
Yes the more concentrated the more curd produced
