First Exam Flashcards
Binding of the _______ _______ causes enzymatic activity on the intracellular side of enzyme linked receptors
Signaling molecule
What is a transmembrane protein with a binding site for the signaling molecule outside the cell called?
An enzyme-linked receptor
What is the active site of an enzymatic reaction?
A combination of binding and lowering activation energy
Endocrine cell signaling is typically carried through ________
The bloodstream
Are cofactors organic or inorganic?
Inorganic
_____ change the receptor’s shape (and function) which sends a message throughout the membrane
Ligands
What causes enzymatic activity on the intracellular side of enzyme linked receptors?
Binding of the signaling molecule
Ion channels are __________
A type of surface receptor
What’s the difference between cofactors and coenzymes?
Cofactors are inorganic, coenzymes are organic biomolecules
Neural and synaptic signals are an example of ______ signaling
Paracrine
What are examples of paracrine signaling?
Neural and synaptic signals
What type of signaling targets far away cells?
Endocrine
Where are ion channels found?
In the plasma membrane
Describe the second domain of surface receptors
It extends through the plasma membrane
What type of signaling often doesn’t have to go through the cell membrane?
Gap junctions
_____ is a chemical substance that binds to a receptor
Ligands
What are enzymes?
Protein catalysts that speed up reactions by lowering the required activation energy
When is ATP considered free energy?
When the bond is broken
What do noncompetitive inhibitors do?
They bind to the enzyme at a different location, causing a slower reaction rate
What are gap junctions?
A connection between two cells where direct cytoplasm exchange can occur; a special type of paracrine signaling
What does autocrine cell signaling affect?
Itself, and in some cases other nearby cells
What is GDP diphosphate?
Used up energy
What is a docking site for signaling molecules?
The external domain of surface receptors
____ signaling can remind a cell to __________________
Autocrine signaling can remind a cell as to what to develop into
What’s an example of a positive metabolic feedback loop?
Breastfeeding
What typically provides the energy for endergonic reactions?
ATP
What happens when substrates bind the active sites of an enzyme?
There is a small change in shape to maximize
Describe the external domain of surface receptors
It’s a docking site for signaling molecules
Define surface receptors
Hydrophilic ligands bind on the surface of the cell
When are enzymes most effective?
When the temperature and pH are optimal
What is receptor up-regulation?
A regulation that increases the number of receptors synthesized and amplifies the signal molecule’s effect
_____ receptors bind to hydrophilic ligands, _____ receptors bind to hydrophobic ligands
Surface receptors bind to hydrophilic ligands, intracellular receptors bind to hydrophobic ligands
What do enzyme-linked receptors have inside the cell?
An enzyme component
What is the type of cellular respiration that requires oxygen where nutrients are catabolized to CO2 from H2O called?
Aerobic respiration
What type of cell signaling targets itself?
Autocrine
What is aerobic respiration?
A type of cellular respiration that requires oxygen where nutrients are catabolized to CO2 from H2O
Gap junctions are also called ______ _____ _____
Direct connection signaling
What are the 4 steps of the cell signaling process?
Transmission, reception, transduction, response
What is the first step of the cell signaling process?
Transmission
Each component in a transduction pathway acts as a _______ _____
Molecular switch
What is an acronym for the 4 steps of the cell signaling process?
TRTR
What is an example of a direct connection?
Desmosomes
Cells extract energy from food to generate ATP in a processes called glucose catabolism, also known as _____ _______
Cellular respiration
What is a combination of binding and lowering activation energy called?
The active site
What domain of surface receptors extends through the cytoplasm and transmits the signal inside the cell?
The third domain/ the tail
Which is more common; positive or negative feedback loops?
Negative feedback loops
What are coenzymes?
Organic biomolecules
What is the second step of the cell signaling process?
Reception
What’s an example of a receptor being activated and triggering the synthesis of a secondary messenger?
G-protein and cyclic AMP (cAMP)
What is necessary to maintain homeostasis?
Communication
What type of reaction is spontaneous, exergonic or endergonic?
Exergonic
What is disorder and chaos called?
Entropy (S)
Energy transfers aren’t ______ ______
Completely efficient
Living systems are ______ systems
Open systems
What are the three classes of surface receptors?
Ion channels, enzyme linked receptors, and g-proteins
What converts chemical signals into electrical signals?
Ion channels
What is enthalpy?
The total energy in a system
What is the first law of thermodynamics?
The law of conservation of energy; that energy cannot be created nor destroyed
What does the end product of a metabolic pathway do?
It influences the rate or progression of the pathway itself
What is the third domain of surface receptors?
The tail
What binds to an enzyme at a different location, causing a slower reaction rate?
Noncompetitive inhibitors
Is endocrine signaling fast or slow?
Slow
What do molecular switches do?
They relay signals, and can also amplify them
What must happen in order to transmit a new signal?
Every activated molecule in a transduction/ signaling pathway must be inactivated in order to transmit a new signal
What do ligands change?
The receptor’s shape/function
Are spontaneous reactions fast or slow?
Slow
What is glucose catabolism?
Cellular respiration
What is a characteristic of reception?
It’s a highly specific process
What does an endergonic reaction look like regarding free energy?
🔺G < 0
What type of signaling is organism-wide systemic signaling?
Endocrine signaling
What type of cell signaling is important after differentiation?
Autocrine signaling
What are enzyme linked receptors?
A transmembrane protein with a binding site for the signaling molecule outside the cell
What does the third domain/tail of surface receptors do?
It extends through the cytoplasm and transmits the signal inside the cell
What two things do ion channels do?
They open or close in response to the binding of a ligand, and they convert chemical signals into electrical signals
What are examples of coenzymes?
Vitamins and electron carriers
Define cells
The smallest living unit of life
Free energy is gained in what type of reaction?
Endergonic
Some enzymes require one or more _____ or ______ to function
Cofactors or coenzymes
What is the total energy in a system?
Enthalpy (H)
What are redox reactions?
Coupled oxidation reduction reactions
What positions two substrates so they align perfectly for a reaction?
Enzymes
What is entropy?
Disorder and chaos (S)
Enzyme linked receptors are ___________
A type of surface receptor
What reminds a cell what to develop into?
Autocrine cell signaling
What are the three categories of responses?
Ion channels open or close, enzyme activity is altered, or specific gene activity is turned on or off
Where is the enzyme component of enzyme-linked receptors found?
Inside the cell
What type of cell signaling can work as a reminder?
Autocrine
What does an exergonic reaction look like regarding free energy?
🔺G > 0
What can change or be present at different times in the development of cells?
Receptor types
What contorts or stresses a substrate so it’s less static and more likely to react?
Enzymes
Desmosomes are ______ _________
Direct connections
Activation of _______ can trigger the synthesis of small molecules called secondary messengers
receptors
Molecular switches are found in what?
Transduction
Name a type of specialized ligand
Hormones
What are competitive inhibitors?
Molecules that are a similar shape to the substrate, competing with the substrate for the active site
Gap junctions are a special type of _____ ______
Paracrine signaling
Why is reception a highly specific process?
Because only target cells have specific receptors to pick up those particular signals
What is free energy?
The amount of energy available to do work (G)
What do enzymes do?
They work as catalysts by lowering the activation energy of a reaction to speed it up
What is GTP triphosphate?
A molecule that has a lot of energy
What’s a characteristic of receptor types?
They can change or be present at different times in the development of cells
________ is a connection between two cells where direct cytoplasm exchange can occur
Gap junctions
What is transduction?
When a signal is relayed through a sequence of molecules
What are secondary messengers?
Small molecules synthesized by the activation of receptors
What type of receptor has 3 domains?
Surface receptors
What is also known as ligand-gated channels?
Ion channels
What happens through the release of chemical signals?
Communication
What are the two types of metabolic feedback loops?
Positive and negative feedback
What type of cell signaling is slower and longer lasting?
Endocrine
What does cellular respiration do? (Basic explanation)
Convert food to ATP
How do cells drive endergonic reactions?
By coupling them with exergonic reactions
How does communication between cells happen?
Through the release of chemical signals
What is phosphorylation?
Adding phosphorus with changes protein shape and function
What is the smallest living unit of life?
Cells
What is important to remember when considering intracellular reception?
Phospholipid bilayer composition
Define intracellular receptors
Hydrophobic ligands can enter the cell and bind to intracellular receptors
What is the fourth step of the cell signaling process?
Reception
What are molecules that are a similar shape to the substrate and compete with the substrate for the active site called?
Competitive inhibitors
What is a special type of paracrine signaling?
Gap junctions
What are ligands?
A chemical substance that binds to a receptor
Free energy is released in what type of reaction?
In an exergonic reaction
What are chemical reactions where electrons are transferred from one molecule to another called?
Redox reactions
What uses gap junction signaling?
Cardiac muscle
What is the third step of the cell signaling process?
Transduction
What domain of surface receptors extends through the plasma membrane?
The second domain
What are the three domains of surface receptors?
External, second, and tail
What is required for enzymes?
Cofactors
How can the amount of activation energy be lowered?
By catalysts
What type of cell signaling is typically carried far across the body through the bloodstream?
Endocrine cell signaling
How do cells regulate enzymes/ what affects enzymatic activity?
By modifying temperature/pH, producing molecules that inhibit or promote enzyme function, or availability of coenzymes or cofactors
What type of signaling targets nearby cells?
Paracrine
What are the two main types of receptors?
Surface and intracellular
What do allosteric enzymes do?
They change their confirmation upon binding to an effector, which results in an apparent change in binding affinity at a different ligand binding site?
What is Gibbs free energy equation?
🔺G = (🔺H)-T🔺S
How can cells help control their environment and meet needs?
By regulating enzymatic activity, they can adjust temperature or pH
Energy is needed for what type of reaction?
Endergonic
What are coupled oxidation reduction reactions?
Redox reactions
G-proteins are __________
A type of surface receptor
Define activation energy
The energy required for a reaction to proceed
What do cofactors and coenzymes do?
They help enzymes do the job
What type of signaling is used by tumors? What does it cause?
Paracrine signaling is used by rumors to cause neighboring cells to have the same growth problem
What type of cell signaling is typically hormones?
Endocrine
How are molecular switches usually regulated?
By the addition or removal of phosphate groups
What is another name for cellular respiration?
Glucose catabolism
What are hormones?
Specialized ligands
What is something nearly all cells have?
Receptors
What is receptor down-regulation?
A regulation that involves transporting receptors to lysosomes that destroy them
Enzymes work as ______
Catalysts
What are ion channels also called?
Ligand-gated channels
How do enzymes lower activation energy?
By either: positioning the two substrates so they align perfectly, providing optimal pH, contorting or stressing the substrate so it’s more likely to react, or temporarily reacting with the substrate
Any chemical diffusion is considered _____ signaling
Paracrine
