Bio I - 8 Flashcards
Where does the cell extract energy from?
Sugars and other fuels
What do cells use energy for?
To perform work
Some organisms even convert energy to light, as in bioluminescence. 
What is metabolism?
Metabolism is the totality of an organisms chemical reactions
What is a metabolic pathway?
A metabolic pathway begins with the specific molecule and ends with a product. Each step is catalyzed by a specific enzyme. 
How do catabolic pathways release energy?
By breaking down complex molecules into simpler compounds
What is an example of a pathway of catabolism?
Cellular respiration
What is an anabolic pathway?
Anabolic pathways consume energy to build complex molecules from simpler ones. 
What is an example of amabolism?
The synthesis of proteins from amino acids
What is bio energetics?
It is the study of how energy flows through living organisms. 
What is energy?
Energy is the capacity to cause change.
What is kinetic energy?
It is energy associated with motion
What is heat/thermal energy?
It is kinetic energy associated with random movement of atoms or molecules
What is potential energy?
It is energy that matter possesses because of its location or structure.
What is chemical energy?
It is potential energy available for release in a chemical reaction. 
True or false: energy can be converted from one form to another
True
What is thermodynamics?
Thermodynamics is the study of energy transformations
True or false: In an open system such as that approximated by liquid in a thermos, is unable to exchange energy or matter with it surroundings 
False
(An isolated system)
What happens in an open system? What is an example of an open system?
Energy and matter can be transferred between the system and its surroundings. 
Organisms
What is the first law of thermodynamics?
The energy of the universe is constant. Energy can be transferred and transformed but it cannot be created or destroyed. 
What is the first law of thermodynamics also called?
The principle of conservation of energy
What is the second law of thermodynamics?
Every energy transfer or transformation increases the entropy/disorder of the universe. 
True or false: living cells unavoidably convert organized forms of energy to heat
True
What is spontaneous processes?
Spontaneous processes occur without energy input they can happen quickly or slowly
What happens when a process occurs without energy input?
It must increase the entropy of the universe
What do organisms replace ordered forms of matter and energy with?
Less ordered forms
What do cells create ordered structures from?
Less ordered materials
How does energy flow into an ecosystem and how does it flow out?
Energy flows into an ecosystem in the form of light and exits in the form of heat
True or false: the evolution of more complex organisms does violate the second law of thermodynamics
False
What is free energy?
A living systems free energy is energy that can do work when temperature and pressure are uniform, as in a living cell.
Review pic in photos
Did it
What processes are spontaneous?
Only processes with a negative free energy
What can spontaneous processes be harnessed to do?
Perform work
What is free energy a measure of?
A systems instability, its tendency to change to a more stable state. 
What happens during a spontaneous change?
Free energy decreases and the stability of a system increases
When can a process be spontaneous and perform work?
Only when it is moving toward equilibrium
What is an exergonic reaction?
An exergonic reaction proceeds with a net release of free energy and is spontaneous
What is an enderGonic reaction?
It absorbs free energy from it surroundings and is non spontaneous 
What happens when reactions in a close system reach equilibrium?
They do no work
What is a defining feature of life about metabolism?
Metabolism is never at equilibrium
Why are cells not in equilibrium?
They are open system experiencing a constant flow of materials
What does a catabolic pathway in a cell release?
Free energy in a series of reactions
What are the three main kinds of work that a cell does?
Chemical
Transport
Mechanical
What is energy coupling?
To do work cells manage energy resources by energy coupling, the use of an exergonic process to drive an enderGonic one
What is most energy coupling in cells mediated by?
ATP
What is ATP?
Adenosine triphosphate it is a cells energy shuttle
What is ATP composed of?
Ribose/a sugar
Adenine/ a nitrogenous base
3 phosphate groups 
How can the bonds between the phosphate groups of ATP’s tale be broken?
By hydrolysis
When is energy released from ATP?
When the terminal phosphate bond is broken
What are the three types of cellular work of a cell powered by?
The hydrolysis of ATP
What can the energy from the exer Gonic reaction of ATP hydrolysis be used for?
To drive an enderGonic reaction 
Overall the coupled reactions are ________ 
Exergonic
How does ATP drive enderGonic reactions?
By phosphorylation, transferring a phosphate group to some other molecules such as a reactant. The recipient molecule is now called a
Phosphorylated intermediate.
What is also powered by ATP hydrolysis?
Transport and mechanical work in the cell
What does ATP hydrolysis lead to?
A change in proteins shape and binding ability
How is ATP a renewable resource?
 It is generated by addition of a phosphate group to an adenosine diphosphate 
Where does the energy come from to phosphorylate ADP?
Catabolic reactions in the cell
How was the ATP cycle a revolving door?
Energy passes during its transfer from catabolic to anabolic pathways
What is a catalyst?
A catalyst is a chemical agent that speeds up a reaction without being consumed by the reaction
What is an enzyme?
An enzyme is a catalytic protein
What is an example of an enzyme catalyzed reaction?
Hydrolysis of sucrose by the enzyme sucrase
What does every chemical reaction between molecules involve?
Bond breaking and Bond forming
What is the activation energy? (Or free energy of activation)
The initial energy needed to start a chemical reaction
What is activation energy often supplied in the form of?
Thermal energy that the reactant molecules absorb from their surroundings
How do enzymes catalyze reactions?
By lowering the activation energy barrier
Do enzymes affect the change in free energy?
No instead they hasten reactions that would occur eventually
What is the reactant that an enzyme acts on called?
The enzymes substrate
What happens when an enzyme binds to its substrate?
It forms an enzyme substrate complex
True or false: the reaction catalyzed by each enzyme is very specific
True
What is the active site?
It is the region on the enzyme where the substrate binds
What does the induced fit of a substrate bring?
Chemical groups of the active site into positions that enhance their ability to catalyze a reaction
How can the active site lower an Activation energy barrier?
Orienting substrates correctly
Straining substrate bonds
Providing a favorable microenvironment
Covalently bonding to the substrate
How can an enzymes activity be affected?
By the general environmental factor such as temperature and pH
And chemicals that specifically Influence the enzyme. 
Each enzyme has an optimal ______ and_______ in which it can function. 
Temperature and pH.
Optimal conditions favor the most active shape for the enzyme molecule
What are cofactors?
Cofactors are non-protein enzyme helpers
Are cofactors inorganic or organic?
They can be both
What is an organic cofactor called?
Coenzyme
What do coenzymes include?
Vitamins
What is a competitive inhibitor?
They bind to the active site of an enzyme competing with the substrate
What is a noncompetitive inhibitor?
They bind to another part of an enzyme causing the enzyme to change shape and making the active site less effective
What are examples of inhibitors?
Toxins poisons pesticides and antibiotics
What are enzymes?
Proteins encoded by genes
What does changes in genes lead to?
Changes in amino acid composition of an enzyme
What does altered amino acids in enzymes result in?
Novel enzyme activity or altered substrate specificity 
What is an example of under new environmental conditions a novel form of an enzyme might be favored?
Six amino acid changes improve substrate binding and break down and E. coli
How does a cell tightly regulate its metabolic pathways?
By switching on or off the genes that encode specific enzymes or by regulating the activity of the enzymes
What does allosteric regulation?
May either inhibit or stimulate an enzymes activity. It occurs when a regulatory molecule binds to protein at one site and affects the proteins function at another site. 
What are most allosterically regulated enzymes made from?
Polypeptide subunits
What does the binding of an activator stabilize?
The active form of the enzyme
What does the binding of an inhibitor stabilize?
The inactive form of the enzyme
What is cooperativity?
Is a form of allosteric regulation that can amplify enzyme activity
What does one substrate molecule prime an enzyme to do?
To act on additional substrate molecules more readily
Why is cooperativity allosteric?
Because binding by a substrate to one active site affects catalysis in a different active site
What is feedback inhibition?
The end product of a metabolic pathway shuts down the pathway
What does feedback inhibition prevent?
A cell from wasting m chemical resources by synthesizing more product than it is needed
What helps bring order to metabolic pathways?
Structures within the cell
What do some enzymes act as?
Structural components of membranes
What is an example of an enzyme residing in specific organelles in eukaryotic cells?
Enzymes for cellular respiration are located in mitochondria
