Ch, 5 + 6 Quiz Flashcards
Membranes are _______ permeable, some molecules _____ pass and some ______
selectively;can;cannot
______ molecules, ____, and ______ molecules cannot pass through a lipid bilayer
Charged;ions;large
_____ non-polar or ______ molecules can pass through a lipid bilayer
small;uncharged
which of these can and which cannot pass through a lipid bilayer?
O2, Na+, Co2, Cl-, H2o, Glucose
CAN: O2, Co2, H2O CANNOT: Na+, Cl-, Glucose
What is diffusion?
The movement of molecules of a substance across a semi-permeable membrane, often from higher concentration to lower concentration
One gram of table salt is placed at the bottom of 200mL of water. If left alone for several hours, what will happen to the sodium and chlorine ions as they dissolve in water?
The sodium and chlorine ions will dissipate/diffuse and evenly disperse themselves within the water.
200mL of water is placed on one side of a two chambered beaker – labeled “start” in the diagram below. A lipid bilayer seperates the two chambers. What will eventually happen to the water? Use the box labeled “finish” to diagram your answer and include the volume of water you expect to see on each side of the membrane.
By way of osmosis, the water will evenly diffuse across the bilayer, going from high concentration to low concentration until it is 100mL and 100mL.
This time the two chambers are seperated by a piece of impermeable plastic. We start with a 1% NaCl solution on one side and a 2% NaCl solution on the other side (diagram labeled ‘start’). If we remove the plastic what will eventually happen to the solutions? Use the box labeled ‘finish’ to diagram your answer.
ASK CAHOON THIS Q
This time the two chambers are seperated by a semi-permeable membrane that is left in place. We start with 1% NaCl solution on one side and a 2% NaCl solution on the other side (diagram labeled ‘start’). What will eventually happen to the solutions? Use the box labeled ‘finish’ to diagram your answer. Include water volumes and salt percentages on each side.
Diffusion would occur from left to right, being that the salts cannot pass through the semi-permeable membrane, the water would diffuse from the left (higher concentration) to the right (lower concentration)
What is osmosis, and how is it related to the problem above?
Osmosis is the process by which molecules of a solvent (typically water) pass through a semipermeable membrane from high concentration to low concentration. ASK CAHOON IF THIS IS ALWAYS LIKE THIS.
The two chambers are still separated by a semi-permeable membrane that is left in place. We start with a 1% NaCl solution on one side and a 2% NaCl solution on the other side. What could you add to either side to prevent osmosis from occurring?
Make both sides even
What is a hypertonic solution?
High solute concentration, low water concentration, in a hypertonic solution, the net movement of water will be out of the body and into the solution.
What is a hypotonic solution?
Low solute concentration with high water concentration. Net movement of water from solution into the body
What is an isotonic solution?
Solution that has the same solute concentration and water concentration, no net movement.
A vesicle containing a 3% solution of sucrose is placed into a solution of 1% sucrose. Are the solutions inside the vesicle and in the surrounding solution hypertonic, hypotonic, or isotonic? What do you predict will happen to the vesicle?
Solution inside vesicle is hypertonic compared to the surrounding solution, surrounding solution is hypotonic compared to vesicle. Vesicle will likely shrink due to movement of solution to the outside of the vesicle.
A vesicle containing a 5% solution of sucrose is placed into a solution of 5% sucrose. Are the solutions inside the vesicle and in the surrounding solution hypertonic, hypotonic, or isotonic? What do you predict will happen to the vesicle?
The vesicle is isotonic compared to the surrounding solution, surrounding solution is isotonic. Altogether the solution is isotonic, no movement will take place.
What category of amino acids would you expect to find on the parts of a membrane protein that are in contact with the interior of the lipid bilayer?
Hydrophobic
What category of amino acids would you expect to find on the parts of a membrane protein that are in contact with the exterior of the lipid bilayer?
Hydrophilic
How does a cell transport molecules across its plasma membrane?
Diffusion, primarily passive diffusion/transport
What is the difference between passive transport and active transport across a cell’s plasma membrane?
Passive Transport - no energy high to low concentration with the gradient, Active - requires ATP, low to high against the gradient
Define passive transport
The passage of a molecule across a membrane that DOES NOT require energy expenditure by the cell
3 methods of passive transport
Diffusion;Ion protein channels; Glucose carrier protein, Aquoporins
Define diffusion
Movement of molecules across a semipermeable membrane, typically high to low concentration
Define Ion protein channels
Ion protein channels span across the membrane and allow for the passage of ions from one side to the other. ex. Calcium channel
Define glucose carrier protein/glucose transporter
Transporter proteins that facilitate the diffusion of glucose
Define Active Transport
The passage of a molecule across a membrane that DOES require energy expenditure by the cell
2 methods of Active Transport
Pump Carrier Protein; Coupled Transport
Define Bulk Transport
Movement of large materials/amounts across the membrane.
2 Methods of Bulk Transport
Endocytosis;Exocytosis
Define endocytosis
movement rom exterior to interior
Define exocytosis
movement from interior to exterior
3 methods of endocytosis
Phagocytosis;Pinocytosis;Receptor Mediated
2 methods of exocytosis
Constitutive; - constant Regulated, - on/off switch, signaled
Define Phagocytosis
Movement of large particles (food) into the cell
Define Pinocytosis
Similar process as phagocytosis, movement of liquids
Define Receptor Mediated Endocytosis
A molecule fits into a membrane embedded protein which then begins the process of endocytosis - anticipated signals - how viruses “trick” cells
Define Constitutive Exocytosis
Secretion of molecules, involvs the formation of a newly synthesized membrane and proteins. ASK CAHOON.
Define Regulated Exocytosis
Secretion of molecules, involves a signal and receptor to form a vesicle. On/off switch
Glucose is an essential source of energy for most cells, yet it cannot efficiently diffuse through the outer plasma membrane surrounding the cell. How do glucose molecules get into a cell?
Facilitated Transport by way of glucose transport protein
It is essential that a cell control the concentration of sodium ions (Na+ ) in its interior. Ions cannot diffuse through the outer plasma membrane surrounding the cell. How do cells move sodium across its outer membrane?
Ions move across the membrane by way of ion channel proteins via facilitated diffusion
What are the differences and similarities of protein channels and protein carriers?
Both form protein pathways across the membrane, carriers can transport either active or passive, channels can only transport via passive.
What are the differences and similarities of pumps and coupled transport mechanisms? Both are active transport but make sure you consider how they utilize energy differently.
Protein pumps expand cellular energy to move molecules against the concentration gradient.
Coupled Transport is the process by which the transmembrane protein moves one molecules with the concentration gradient, essentially sacrificing it. The energy of this diffusion is then used to transport an unwanted molecule against the gradient.
How does bulk transport differ from channel protein style transport?
Channel proteins are specialized and specific where as bulk transport is the process of transporting large substances or bulk amounts, not as specialized. ASK CAHOON bulk active transport passive
What is a membrane embedded glycoprotein?
A molecule made of a sugar (carbohydrate) attached to a protein molecule
A phospholipid bilayer may also be called a…
Membrane
Which cannot pass through a phospholipid bilayer?
Glucose
Molecules that can pass through a membrane _____ follow the principles of diffusion
will
What happens if a compound cannot pass through a membrane?
Osmosis related, don’t worry
What is osmosis?
The response of a membrane bound vesicle or cell to compounds that cannot pass through a membrane
Osmosis is a phenomenon created by
the semi-permeable nature of membranes
Interior is hypertonic compared to the surrounding solution. What happens?
Diffusion/movement outside of the vesicle, vesicle shrinks
Interior is hypotonic compared to surrounding solution. What happens?
Movement inside the vesicle, vesicle grows
Interior and surrounding solution are isotonic. What happens?
No movement
Membranes block the passage of molecules needed for cell survival, like carbohydrates. How do cells acquire these molecules?
Diffusion
How can a protein be both hydrophilic and hydrophobic so it can reside in a membrane?
A transmembrane protein will be made of a combination of hydrophobic and hydrophilic amino acids so it can reside in both environments simultaneously
What is passive transport?
The passage of a molecule across a membrane that DOES NOT require energy
Enzymes are highly specialized _______ that catalyze chemical reactions.
proteins
_____ reduce the energy of activation for a chemical reaction that in turn increases the speed at which it will proceed
Catalysts
What is the first law of thermodynamics?
Energy cannot be created/destroyed, can be stored, transferred, converted
Where is energy stored in the molecule?
Covalent chemical bonds
How is enzyme catalysts related to activation energy of a chemical reaction?
Chemical reactions require energy for activation, cells use energy in chemical reactions to maintain homeostasis. Enzyme catalysts lower this energy required for activation.
Refer to graph 1A: - In the example graph above, label the reactants, the transition state, and the products.
Far left reactant, middle transition, far right product
In the example graph above, what represents the activation energy?
Activation energy is the gap between reactant and transition state
In the example graph above, is any energy released during the transfer of the phosphate ATP to ‘protein X’?
ASK CAHOON, yes
Refer to graph 1B: How has the enzyme changed the activation energy of this reaction?
The change in activation energy is represented by the solid line. The enzyme has catalyzed this reaction and lowered the activation energy required.
Has the enzyme changed the amount of energy released by the transfer of the phosphate?
ASK CAHOON, no
How are enzymes usually represented in biochemical nomenclature?
As an arrow
Enzyme names usually end in ________
-Ase
How many different reactions can an enzyme catalyze?
ASK CAHOON, answer is either, they are specific or they can catalyze millions
If you saw “Peptidyl Transferase” and “Protease” in a reaction with no description or explanation associated with it, how would you know they are enzymes?
End in -ase
There are two enzymes shown in example 2. What is/are the substrate(s) and product(s) for peptidyl transferase (the left to right reaction)?
Alanine, serine (LEFT OF REACTION)
What is/are the substrate(s) and product(s) for protease (the right to left reaction)?
di-peptide (RIGHT OF REACTION)
What is the name of the special pocket where the substrate(s) fit?
Active site
Sometimes enzymes need to be controlled, what “controls” them?
inhibitors
What is competitive inhibition of an enzyme?
A competitive inhibitor is an inhibitor that blocks the active site so substrate cannot enter ; binds to the active site ex. penicillin
What is allosteric inhibition of an enzyme?
Binds to the enzyme outside of the active site - changes the shape of the enzyme and it no longer functions- ex. antidepressants
How many different enzymes are necessary for this conversion? Conversion from xanthosine to caffiene image.
4
What do we call a multi-step process like the one in this diagram?
Metabolic/biosynthetic pathway - Enzymatic control of biosynthesis
What would happen in a plant cell that normally makes caffeine if the enzyme Theobromine Synthase was inhibited or missing?
ASK CAHOON, caffeine wouldnt form?
Passive transport does not include…
Protein pumps
What is facilitated diffusion?
The passage of molecules with their concentration gradient through special protein channels.
A protein channel….
Relies on the power of diffusion to move molecules across a membrane;Is specific to one type of ion or molecule; can be ‘opened’ or ‘closed’ by the cell
What protein channel allows water to move across a membrane?
Aquaporin
A carrier protein….
Relies on the power of diffusion to move molecules across the membrane;is specific to one type of ion or molecule;can be ‘opened’ or ‘closed’ by the cell. Can be against concentration
What is active transport?
The passage of a molecule across a membrane that DOES require energy expenditure by the cell
How does a protein pump move solutes across a membrane from place of low concentration to a place of higher concentration?
ATP
How does coupled transport move solutes across a membrane from a place of low concentration to a place of higher concentration?
Sacrifice of molecule, utilizes energy from diffusion to transport unwanted molecule
What is considered bulk transport?
Exocytosis;Phagocytosis;Endocytosis
Examples of carrier proteins/protein pumps
Glucose carrier / na+/k+ pump
What would happen to the vesicle if there was a 2% sucrose solution inside the vesicle (V) and a 5% sucrose solution surrounding it (C)?
Movement/Transportation inside vesicle, vesicle would grow
What would happen to the vesicle if the solution inside is hypotonic compared to solution “C” surrounding it?
The cell expands
What would happen to the vesicle if there was a 2% CO2 solution inside the vesicle (V) and a 1% CO2 in the solution surrounding solution (C)?
The cell shrinks, movement outside of the vesicle to the surrounding solution
How can a protein have a domain that exists in the hydrophilic exterior of a cell, another domain that passes through the hydrophobic interior of a plasma-membrane, and then a third domain extending the hydrophilic interior of the cell?
Proteins can be amphipatic, philic and phobic. This amphipatihic property allows proteins to integrate into lipid bilayers. ASK CAHOON.
Protein Channel
Relies on the power of diffusion to move a specific ion across a membrane with its concentration gradient
Protein Pump
Uses cellular energy to move an ion across a membrane against its concentration gradient (ATP)
Phagocytosis
The movement of a large solid particle into a cell from the environment
Pinocytosis
The movement of a large amount of liquid into a cell from the environment
Glycoprotein
A protein with carbohydrate attached
Diffusion
The passive movement of small non-polar molecules directly across a membrane, no protein channels necessary
Coupled Transport
A transport protein that moves one type of molecule with its concentration gradient and the energy generated by that transport allows the movement of a second or unwanted molecule across the concentration gradient
Aquaporin
Protein channel that facilitates the movement of water across a biological membrane
State whether each atom or molecule can or cannot pass through a biological membrane
A small non-polar molecule like water
A large uncharged molecule like sucrose
Ions like Na+, Cl-, Ca+
CAN: a small non polar molecule like water
CANT: large uncharged molecules like sucrose, ions like na+, cl-, ca+
Why are enzymes essential for the success and maintenance of life as we know it?
Enzymes are the workers, they help facilitated biological reactions in all living systems. They aid in nearly every biological reaction, without them life would be extremely hard to maintain
If you had never seen the word hexokinase before, how could you identify an enzyme?
-Ase
What is the substrate of hexokinase? Refer to image
LEFT OF THE ARROW
What is the product of hexokinase? Refer to image
RIGHT OF THE ARROW
Name and define the two categories of enzyme inhibitors
competitive inhibitor: binds to the active site blocks it so the substrate is unable to enter
allosteric inhibitor: binds to the outside of the active site, changing the shape of the enzyme so it no longer functions
What is the starting material for glycolysis?
Glucose (STARTING MATERIAL = REACTANT)
Where would a competitive inhibitor bind to the hexokinase enzyme?
Active site
Where would an allosteric inhibitor bind to the hexokinase enzyme?
Outside active site
If a hexokinase inhibitor were added, what products would not be made?
LIST PRODUCTS AFTER HEXOKINASE
How does an enzyme catalyze a chemical reaction?
Enzymes catalyze reactions by reducing the amount of activation energy required, thus increasing the rate of the reaction
According to the biosynthetic pathway below, how many enzymes are needed to convert the amino acid tryptophan to the hormone melatonin?
COUNT THE ARROWS
A vesicle containing a 3% solution of sucrose is placed into a solution of 5% sucrose. Are the solutions inside the vesicle and in the surrounding solution hypertonic, hypotonic, or isotonic? What do you predict will happen to the vesicle?
Vesicle is hypotonic compared to surrounding solution, surrounding solution is hypertonic compared to vesicle. Vesicle will likely grow in size due to the movement of solution inside the vesicle.
What is a chemical catalyst?
Something that promotes a chemical reaction but does not participate in the reaction
