Cell Bio Exam 2

Irreversible inhibitors

Inhibitors covalently bonded to an enzyme or otherwise permanent interaction

Reversible inhibitors

Inhibitors non-covalently (temporarily) bonded to an enzyme

Competitive inhibition

Type of inhibition in which the inhibitor is partially similar to the substrate, and takes the place of the substrate

Does not change; increases

In competitive inhibition, the V_max _________, while the K_m _______.

Non-competitive inhibition

Type of inhibition in which the inhibitor binds to the allosteric site

Decreases; does not change

In non-competitive inhibition, the V_max _________, while the K_m ________.

Allosteric regulation

Type of enzyme regulation in which the binding of the inhibitor changes the shape of the shape of the active site

Allosteric effectors

Small organic molecules that regulate enzymes

Allosteric inhibition

Type of allosteric regulation in which the binding of the effector causes the enzyme to change to its low-affinity form

Allosteric activation

Type of allosteric regulation in which the binding of the effector causes the enzyme to change to its high-affinity form

Plasma membrane

Thin lipid bilayer separating 2 aqueous environments

Receiving information, import and export of small molecules, capacity for movement and expansion

What are 3 functions of the plasma membrane?

Amphipathic

Having both hydrophobic and hydrophilic components

Inner leaflet

Which leaflet is phosphatidylethanolamine found?

Breaks down the contractile ring

What is the function of phosphatidylethanolamine?

Break down contractile ring

Cell signaling

Signal transport

Apoptosis

Outer leaflet

Which leaflet is phosphatidylcholine found?

Cell signaling

What is the function of phosphatidylcholine?

Break down contractile ring

Cell signaling

Signal transport

Apoptosis

Inner leaflet

Which leaflet is phosphatidylinositol found?

Signal transport

What is the function of phospatidylinositol?

Break down the contractile ring

Cell signaling

Signal transport

Apoptosis

Inner leaflet

Which leaflet is phosphatidylserine found?

Apoptosis

What is the function of phosphatidylserine?

Break down the contractile ring

Cell signaling

Signal transport

Apoptosis

Outer leaflet

Which leaflet is sphingomyelin found?

Scramblase

Enzyme found in ER that randomly flips phospholipids from the cytosolic face to the environmental face

Flippase

Enzyme found in the Golgi that moves specific lipids to the correct surface in an asymmetric manner

Cholesterol

What is the main sterol found in animals?

ER

From what organelle do membranes originate?

Cholesterol

What lipid is found in equal amounts in both leaflets of the lipid bilayer?

Simple diffusion

What function of the plasma membrane is possible without membrane proteins?

Cytosolic; ER

New membrane phospholipids are synthesized by enzymes bound to the _______ side of the __________ membrane

Fatty acid tails point toward each other

In biological membranes, the lipid bilayer contains phospholipids, each with at head and two fatty acid tails. They are arranged so that __________

Transition temperature

The specific temperature at which a lipid changes from a solid to a liquid phase

Longer

The _______ the carbon chain, the less fluid and more stable the membrane

Greater

The ______ the number of double bonds, the less fluid the membrane

Less fluid

At high temperatures, cholesterol makes the membrane _______

More fluid

At low temperatures, cholesterol makes the membrane _______

Covalent modification

Changes in enzymatic activity when functional groups are added or removed

Zymogen

Enzyme that is inactivated until it has reached its destination

True

(T/F) Depending on the stress applied, enzymes that are not at their optimum temperature may function less or not at all

True

(T/F) While methionine is the first amino acid translated, it is not always the first amino acid in the primary structure of a mature protein

Hydrolases

The equation AB + H2O = A + B would be catalyzed by what enzyme class?

Enzymes do not function as well at temperatures other than the optimal temperature

A sick person often runs a fever, and this fever can inhibit the growth of bacteria because…

Substrate

Reactant on which an enzyme works

Alternate substrate

Naturally occurring substances the enzyme may work with

Artificial substrate

Non-naturally occurring substance used by the enzyme

K_cat = V_m/[E]

What is the equation for the turnover number

The initial reaction velocity changes depending on the substrate concentration

What is the principle of MM kinetics?

Higher

The smaller the K_m, the _______ the affinity of the enzyme for its substrate

Saturation

The inability to increase reaction velocity beyond a finite upper limit

Lineweaver-Burk

What method uses the double reciprocal of the MM plot?

Ribozyme

Catalytic RNA

Peptidyl transferase

Ribozyme that catalyzes the formation of peptide bonds during translation

Can be determined using the Lineweaver-Burk plot and is equal to the substrate concentration at V_max/2

The MM constant:

Can be determined using the Lineweaver-Burk plot

Is equal to twice the V_max

Is equal to the substrate concentration at V_max/2

Zymogen

All are examples of ribozymes or ribozyme activity except:

Peptidyl transferase

Autocatalytic RNAs

Ribonuclease P

Intron removal from pre-rRNA

Zymogen

Ribozymes catalyze the formation of peptide linkages

Which of the following statements about the RNA world model is true?

Self-catalytic DNA was the first nucleic acid

DNA was translated directly into protein

Ribozymes catalyze the formation of peptide linkages

RNA was reverse transcribed into DNA before being transcribed and translated into proteins

All RNA sequences act as ribozymes

Characteristics of the transported substance and the gradient

What are the two things to worry about when performing passive transport

Down the concentration gradient

Which direction does simple diffusion move?

Small, nonpolar molecules

What moves via simple diffusion?

Down the concentration gradient

What direction does facilitated diffusion move?

Channels and transporters

What proteins are used during facilitated diffusion?

Water, glucose, and ions

What moves via facilitated diffusion?

Na+, K+, Ca 2+, Cl-

What ions are most often transported via channels?

Continuously

When an ion channel is open, the ions flow _______ until closed

Na+ is smaller than K+ so only Na+ is allowed to fit through the channel

How does the Na+ ion channel work?

The carbonyl-oxygen atoms displace the water that K+ is bound to and allows the K+ to pass through

How does the K+ ion channel work?

False

(T/F) The major difference between simple and facilitated diffusion is that facilitated diffusion requires energy

True

(T/F) Different glucose transporters are needed in different parts of the body

Glut-4

Glucose transporter that is insulin sensitive and found in cells that have the ability to increase glucose transport

Glut-1

Glucose transporter that is not insulin sensitive and is found on RBCs

Glut-2

Bidirectional glucose transporter that is found in the liver and intestinal cells

Stimulates glucose uptake on insulin-sensitive cells that causes vesicles to take glucose out of the plasma

How does insulin lower the body’s blood sugar?

Uniport

Channel that moves one molecule in one direction

Symport

Channel that moves two molecules in the same direction

Antiport

Channel that moves two molecules in opposite directions

Antiport

What type of channel (uniport, symport, antiport) is the chloride-bicarbonate exchanger?

The energy for transport is generated by the molecular bonds of the substance being transported

Which is not a characteristic of facilitated diffusion using a transport protein?

It requires binding of the molecule being transported

It is specific for the molecule being transported

The energy for transport is generated by the gradient of the substance being transported

The energy of the transport is generated by the molecular bonds of the substance being transported

Transport of the substance is the result of a conformational change

Glucose

Of the following molecules, which would not be expected to be moved across a membrane by simple diffusion?

Oxygen

Fatty acids

Water

Glucose

Ethanol

Absorb water and eventually burst

If a hospital patient is mistakenly given an IV of pure water instead of a saline solution that is isotonic to blood, the patient’s red blood cells will…

Allow water to move through protein channels in the cell membrane in both directions

Absorb water and eventually burst

Shrink and collapse

Lose their function, and the water level in the plasma will be maintained by white blood cells instead

Release water to the plasma along its concentration gradient

Against the gradient

What direction does active transport move?

Pumps

What protein(s) is/are used during active transport

Anything that can’t be moved via simple transport

What moves via active transport?

Concentrates solutes, removes wastes, maintain non-equilibrium concentrations of inorganic ions

What are 3 functions of active transport pumps?

Na+/K+ pump

Active transport pump that uses energy from ATP hydrolysis to transport Na+ and K+ against their electrochemical gradients

Negatively

The Na+/K+ pump maintains the cell so that the intracellular space is ________ charged

3; 2

For every _____ Na+ transported out of the cell, ____ K+ are transported in

False

(T/F) The sodium potassium pump uses 1 ATP per ion transported

True, but not bidirectional

(T/F) The sodium potassium pump is a type of antiporter

Na+ driven symport

Type of secondary transport in which Na+ travels down gradient, forcing another molecule up gradient

The Na+ - glucose symporter

What is an example of secondary active transport

Conformational changes

One similarity between facilitated transporters and pumps is their activity depends on…

Down; up

Glucose transport into red blood cells requires facilitated diffusion while glucose transport into intestinal cells requires active transport. This difference in transporters is due to the transport being _____ the concentration gradient into red blood cells and _____ the concentration gradient into intestinal cells

Negative; 3; 2

The sodium-potassium pump makes the cell interior more ____ by pumping ____ sodium ions out of the cell for every _____ potassium ions pumped in

Relationship between the membrane potential and ion concentration

What does the Nernst equation represent?

Negative

The membrane potential of a nerve or muscle cell at rest is _____

Na+ floods into the cell and causes a spike in membrane potential

What happens when the action potential threshold is reached?

Na+ channel inactivation

What causes the absolute refractory period?

The Na+ channel is closed

What happens during the relative refractory period?

Axon

Where are the voltage gated sodium ion channels on a neuron?

Metatropic

Neurotransmitter receptor that sends signals to the majority of the body

Ionotrophic

Neurotransmitter receptor that sends signals to the muscles

Depolarize and hyperpolarize

Bound transmitters can…