Week 5 Recall Questions Flashcards
A: What is energy?
What are some examples of different types of energy?
• light energy
• heat energy
• mechanical energy
• gravitational energy
• electrical energy
• sound energy
• chemical energy
• nuclear or atomic energy
A: What is energy?
What are some examples of different types of kinetic energy?
Kinetic energy is the energy possessed by an object because it is in motion.
• waves in the ocean
• a falling rock
• a kicked football.
• Photons of light
• radiant
• thermal
• sound
• electricity
• mechanical
A: What is energy?
What are some examples of objects or molecules that contain potential energy?
Potential energy is stored energy, the energy an object has because of its position or chemical structure.
A boulder at the top of a cliff because of its position in the gravitational field of Earth.
Molecule of glucose. It has potential energy because of the energy stored in its bonds.
Water at the top of the falls has high potential energy because of its location in Earth’s gravitational field.
* reactants contain a lot of PE.
(Products have low PE)
A: What is energy?
How does movement of electrons change the amount of potential energy stored in a molecule?
Electrons can only exist in discrete energy states.
As an electron is attracted to and moves closer to one atomic nucleus, it loses potential energy.
- This potential energy is converted to other types of energy such as light or heat.
Conversely, to move an electron further away from a nucleus requires an input of energy, as the further away from the nucleus the more potential energy an electron possesses
A: What is energy?
What is the first law of thermodynamics?
• Energy is neither created nor destroyed, only transferred and transformed
A: What is energy?
How does the first law of thermodynamics apply to energy conversions?
potential energy can be converted into kinetic energy.
the more PE, the more KE something will posses.
- KE can be transformed into other types of energy: heat, sound, and mechanical energy
the total energy of a system remains constant, even if it is converted from one form to another
A: What is energy?
What is the second law of thermodynamics?
- Every energy transfer or transformation increases the entropy of the surroundings
-“more random/disorganized E is, more entropy there is”
Entropy: the tendency of energy to become dispersed or spread out.
Con:
Although energy can be transformed from one form into another, a portion of the energy will always be lost to the surroundings by the tendency of energy to spread out.
A: What is energy?
Based on the second law of thermodynamics, why is heat released by a cell carrying out chemical reactions?
• In cells, some energy in any transformation becomes heat
- Heat = most disorganized form of energy, therefore release of heat = increase in entropy
— random b/c increased random molecular motion. - Not available to do work, and is lost from system.
- heat is waste b/c not able to use it, therefore released into environment.
—> causes increase in entropy.
A: What is energy?
In thermodynamics, what does the term spontaneous tell us about the speed of a reaction?
• rxn occurs without having to add additional energy that’s taken from the surroundings.
—> can typically be slow processes.
• Chemical reactions will proceed spontaneously (without adding energy) if they result in an increase in entropy.
A: What is energy?
What are examples of spontaneous processes or reactions in the cell?
Polymer:
- Complex Organized (low entropy)
———Energy released———
- Some does work
- Some lost as heat (increase in entropy)
- Hydrolysis rxn
———>
Monomer:
- Less complex, Less organized (higher entropy)
• cellular respiration
—> release in E and overall increase in entropy.
- 7 molecules
— O2 (gas)
— Glucose (solid)
—————> - 12 molecules
— CO2. (Gas)
— H2O (liquid)
• diffusion (passive process)
- high concentration of molecules on 1 side of membrane
- low concentration of molecules on other side of membrane
— called concentration gradient = form of stored potential energy
- overtime molecules spontaneously move to low side until roughly equal on both sides.
- spon b/c areas of more organized to areas that are disorganized/random.
- releases E
A: What is energy?
Can a non-spontaneous process happen in the cell? Can you give an example?
• yes.
• must add energy to drive process forward.
— E comes from surrounding environment
• Creates localized area of lowered entropy within cell.
—> b/c as increase structure in cell, is a decrease in entropy.
• heat is still released to surrounding, causing increase in entropy of surrounding.
• overtime results in production of metabolic waste.
—> have high entropy.
- hence why cells able to do this, b/c eventually revert back to high entropy.
• from disorganized/random and not complex —> organized and complex
Ex:
• photosynthesis
- 12 molecules
— CO2. (Gas)
— H2O (liquid)
———Light energy———> - 7 molecules
— O2 (gas)
— Glucose (solid)
A: What is energy?
What kind of energy is available to perform work (= energy transferred by mechanical means, or force x displacement) in the cell?
Gibbs free energy ( G ): the amount of energy that is actually available in a system to do work.
A: What is energy?
Write out the formula for calculating Gibb’s free energy. What does each of the terms (H, S, and T) stand for?
∆ G = ∆ H - T ∆ S
∆ H- the change in the enthalpy,
H - Enthalpy. In a molecule, enthalpy reflects the number and kinds of chemical bonds that exist between atoms.
T- is the temperature in Kelvin (K).
∆S- the change in the entropy of the system over the course of the reaction
S- Entropy
A: What is energy?
What are some examples of endergonic reactions from the previous topic?
- Endergonic Reaction:
- Absorbs free energy from the surroundings to power the reaction (🔺G > 0) (is +)
-( E used to make the products) - Not spontaneous
- Entropy locally decreased
- low E reactants —E—> high E products
- E can be from inside or outside of cell
- Ex:
— making a polymer from monomers.
— Photosynthesis
A: What is energy?
What are some examples for exergonic reactions from the previous topic?
- Exergonic Reaction:
- Releases free energy (🔺G < 0) (Is -)
- Occurs spontaneously
- Entropy increases
- 🔺G represents the change in available energy as a process is occurring.
- High E reactants —Energy—> low E products
- Exs:
— breaking polymers into monomers.
— the break-down of glucose
— the melting of ice
A: What is energy?
What are some examples for catabolic pathways?
• Breakdown of starch into glucose
- starch — + H2O. Hydrolysis Rxn, catalyzed by amylase —> Glucose + Energy
• cellular respiration
- glucose —> CO2 + H2O + energy
A: What is energy?
What are some examples for anabolic pathways?
• Synthesis of polypeptide from amino acid monomers
- Dehydration reaction
- amino acids —attached by peptide bonds—> larger, more complex, higher energy polymer (polypeptide)
Or - amino acids —+ energy—> polypeptide
• photosynthesis
- CO2 + H2O + light energy—> sugar
A: What is energy?
How does diffusion across a membrane release free energy (see Figure 3.8 in the textbook).
- molecules spontaneously move from a compartment where it is at a higher concentration to a compartment where its concentration is lower.
- Increase in entropy as the molecules and their associated energy spread out.
–> Release of free energy during diffusion can be harnessed by the cell to do work.
In Depth:
- Phosphorylation can cause a protein to change shape. (is powered by ATP)
- active transport process(requires E)
a. Transport work: ATP phosphorylates transport proteins.
- Move material from 1 side of membrane to other.
- for every molecule protein transport across, 1 ATP broken down & P group temporarily attached to protein.
- P attach = shape change = allow protein to release molecule on other side of membrane.
- Pi released afterwards & protein goes back to original shape
A: What is energy?
What is energy coupling?
• Energy released from one reaction is used to power another reaction that requires energy.
- Energy released from catabolic (exergonic) reactions used to power anabolic (endergonic) reactions
A: What is energy?
What are examples of energy coupling in the cell?
• Cellular respiration:
- Glucose —> CO2 + H2O + Energy (cell transfers E to use in ⬇️)
• Polypeptide synthesis:
Amino acids + energy —> polypeptide
(E used to make new bonds)
A: What is energy?
What molecule does the cell use to transfer energy?
• ATP = Adenosine triphosphate
- Powers cellular work by coupling exergonic/catabolic processes to endergonic/anabolic processes
- 3 phosphate groups (full neg charges)
- ribose sugar
- adenine nitrogenous base (purine)
-IS A NUCLEOTIDE
A: What is energy?
What are some examples of cellular work(= energy transferred by mechanical means, or force x displacement) that rely on ATP?
1. Movement:
* Movement of transport vesicles around cell
* Flagella and cilia
Ex:
* Binding and hydrolyzing ATP can cause a protein to change shape.
(b) Mechanical work: ATP binds noncovalently to motor proteins and then is hydrolyzed
- For every ATP protein breaks down, causes small shape change that causes protein to move
2. Transport:
* Moves substances across membrane against concentration gradient
3. Chemical:
* Driving endergonic chemical reactions
Ex:
- Phosphorylation makes molecules more reactive, causing endergonic chemical reactions to occur.
a. Individual reactions
- Glutamic acid + Ammonia—>Glutamine
🔺G = + 3.4 kcal/mol
- ATP —> ADP + Pi 🔺G = -7.3 kcal/mol
3.4 - (-7.3) = -3.9 kcal/mol. —> Energy lost as heat/waste energy
b. Coupled reaction mechanism
Glutamic acid—(reacts w)ATP—ADP(releases)—>Glutamyl phosphate (high E intermediate)—(reacts w)Ammonia—Pi(releases)—> Glutamine
A: What is energy?
How is energy stored in ATP? How is it released?
Energy is stored between the second and third phosphate groups of ATP. When the cell requires energy, the third phosphate group becomes detached from ATP, releasing energy in that bond for the cell to use.
- Energy released when the terminal (end) phosphate removed.
- Why ATP hydrolysis exergonic?
—> Repulsive forces between negatively-charged phosphate groups make ATP less stable than ADP. - Leaves behind molecule that only has 2 P groups attached to C ring and nitrogenous base = ADP = Adenosine diphosphate.
+ releases free energy.
