top hat questions topic 1-4
Lipid Bilayer Diffusion
Overview of Diffusability Across Lipid Bilayer
Factors affecting diffusion: Size, Polarity
Substances Tested for Diffusion
A. H+ (Hydrogen Ion)
Result: No
B. Glucose (C6H12O6)
Characteristics: Large, polar
Result: Diffuses slowly
C. Water (H2O)
Characteristics: Small, polar
Result: Diffuses slowly
D. Methane (CH4)
Characteristics: Nonpolar
Result: Fast diffusion
Free Energy Change Calculation
Given Information
Temperature: 310K
Enthalpy Change (ΔH): -11.0 kJ/mol
Entropy Change (ΔS): -20.6 J/mol·K
Free Energy Change Calculation (ΔG)
Formula used:
Convert units where necessary (ΔS needs to be in kJ for consistency):
Substitute values in:
Calculate:
Result:
Answer Choices
A. ΔG = -6.4 kJ/mol
B. ΔG = +6.4 kJ/mol
C. ΔG = 4.6 kJ/mol
D. ΔG = +4.6 kJ/mol
Conditions for Spontaneity of a Reaction
Reaction Enthalpy (ΔH)
Given: ΔH = +12 kJ/mol
Spontaneity Condition
Equation:
To be spontaneous, ΔG < 0
Choices
A. TΔS > +12 kJ/mol
B. TΔS > 0
C. TΔS < 0
D. Endothermic reactions cannot be spontaneous
Implication of Conditions: For spontaneity, there must be enough increase in entropy (TΔS) to outweigh the enthalpy contribution.
Hexokinase and Reaction Mechanism
Role of Hexokinase
Binds: ATP and Glucose
Action: Transfers phosphate from ATP to glucose
True Statements Regarding Hexokinase
A. Hexokinase catalyzes a connected reaction
B. Hexokinase catalyzes a coupled reaction
C. Hexokinase speeds up an exergonic reaction
D. Hexokinase makes an endergonic reaction exergonic
Membrane Viscosity Modulation
Question: How to prevent membranes from becoming too viscous?
Options
A. Increase saturated phospholipids
B. Increase unsaturated phospholipids
C. Increase cholesterol
D. Both A and C
E. Both B and C
Discussion Point: The role of cholesterol and unsaturated fatty acids in maintaining membrane fluidity.
Three-Domain System Classification
Understanding Prokaryotic Organisms
A. Archaea are prokaryotic
B. All prokaryotic organisms are single-celled
C. All bacteria are prokaryotic organisms
D. All prokaryotic organisms are bacteria
Identifying the FALSE Statement: D is false, as Archaea are also prokaryotic but not bacteria.
Liposome Concentration Experiment
Scenario: Liposome with internal Cl- concentration 10M placed in a beaker with Cl- concentration 5M
Outcome Choices
A. Cl- diffuses into the liposome
B. Water diffuses out of the liposome
C. No net movement of Cl- or water
D. Water diffuses into the liposome
E. Cl- diffuses out of the liposome
Potential Energy in Molecules
Importance of Covalent Bonds
A. Many non-polar covalent bonds
B. Many polar covalent bonds
C. Many hydrogen bonds
D. Many ionic bonds
Explanation: Non-polar covalent bonds are associated with higher potential energy.
Molecular Identification: CH₂-CH₂ Structure
Entity: Molecule depicted in structure
Answer Choices
A. Triacylglycerol
B. Saturated fatty acid
C. Unsaturated fatty acid
D. Polypeptide
E. Phospholipid
Details: Evaluation based on structural features presented in the image.
Hydrophilic or Hydrophobic Compounds
Depicted Molecule
Structure: H₂N-CH-COOH (with methyl group)
Answer Choices
A. Hydrophilic amino acid
B. Hydrophobic amino acid
C. Hydrophilic oligopeptide
D. Hydrophilic sugar
E. Hydrophobic nucleotide
Taxonomic Classification Order
Kingdom Taxonomic Groups
Order from Most Inclusive to Most Specific
A. Phylum
B. Class
C. Order
D. Family
E. Genus
Organism Classification by Nutritional Sources
Organism Utilizing CO2 and Energy from Iron
Classification: Chemolithoautotroph
A. Chemolithoautotroph
B. Photoheterotroph
C. Chemoorganoautotroph
D. Photoautotroph
Liposome Environment Status
Experiment Evaluation: Liposome with 10M Cl- inside and 5M outside
Environmental Types
A. Isotonic environment
B. Hypertonic environment
C. Hypotonic environment
D. Hypnotic environment
Biological Reaction Characteristics
Criteria for Biological Reactions
A. Exothermic
B. Endothermic
C. Spontaneous
D. Instantaneous
Surface Area to Volume Ratio in Cells
Effect of Cell Size
Choices
A. Both surface area and volume increase, ratio decreases
B. Both increase, ratio stays the same
C. Both increase, ratio increases
D. Surface area increases, volume decreases, ratio increases
Endothermic Reactions Characteristics
Characteristics
A. Do not happen in cells
B. Products have more enthalpy than reactants
C. Release heat to surroundings
D. Have a negative ΔH
E. Release heat and have negative ΔH
Application of 1st Law of Thermodynamics
Application to Open Systems (e.g., Living Cell)
A. Does not apply as energy can come into the system
B. Does not apply as energy can leave the system
C. Energy can both come into and leave the system
D. Both A and B
Re-evaluation of Free Energy Change Calculation
Performing ΔG Calculation Again: Clear step by step breakdown of formulas and constants.
Choices Upon Re-evaluation: Initial figures vs deduced outcomes.
Free Energy Concept
Definition of Free Energy
A. Kinetic and potential energy in a system
B. Dispersion of energy in a system
C. Amount of energy available to do work
D. Energy destroyed in a reaction
Energy Conservation in Endothermic Reactions
Mechanisms
A. Heat leaves the system and replaced by heat from surroundings
B. Heat from surroundings transformed into kinetic and potential energy in the products
C. Heat released to surroundings
D. Potential energy turned to kinetic in products
Enzyme Catalyst Modification
Effects of Adding Enzyme Catalyst
A. Rate of a chemical reaction
B. ΔG of a chemical reaction
C. ΔG‡ of a chemical reaction
Possible Answers
D. All the above
E. Only A and B
F. Only B and C
G. Only A and C
Endosymbiotic Theory and Chloroplast Origin
Event Descriptions
A. Archaea-like host engulfs bacteria efficient at aerobic respiration
B. Early eukaryotic cell engulfs photosynthetic bacteria
C. Bacteria-like host engulfs archaea-like cell efficient at photosynthesis
D. Early eukaryotic host engulfs archaea-like cell efficient at aerobic respiration
Phospholipid vs. Triacylglycerol Similarities
Similarities Discussion
A. Fatty acid tails
B. Glycerol anchor
C. Phosphate group
D. Both A and B
E. Both A and C
Comments on Structure: Differences in hydrophilic and hydrophobic components.
Endosymbiotic Theory Recap
Summarizing Key Concepts
A. Ancient Eukaryote evolves into modern bacteria/archaea
B. Eukaryotic organelles are bacteria infections
C. Eukaryotic cells as hybrids
D. Mitochondria from photosynthetic bacteria
Homopentamer Structure Characteristics
Defining a Homopentamer
A. Five amino acids in primary structure
B. Each subunit same primary structure
C. Presence of quaternary structure
D. Evaluating statements for truth
2nd Law of Thermodynamics Application
Application during Energy Transformations
A. Energy of the system + surroundings spreads out
B. System energy spreads out
C. Surroundings energy spreads out
D. Universe energy becomes concentrated
Cellular Reaction Requirements
Requirements for Cellular Reactions
A. Must be spontaneous
B. Must be exothermic
C. Must be exergonic
D. Products have less free energy than reactants
E. Total entropy must decrease
Chemolithoheterotroph Carbon Source
Carbon Acquisition in Chemolithoheterotroph
A. Inorganic molecules
B. Organic molecules
C. Either source
D. Neither source
Large Polar Molecule Transport
Transport Mechanism Discussion
A. Passive diffusion
B. Facilitated diffusion
C. Primary active transport
D. Secondary active transport – symport
E. Secondary active transport - antiport
Secondary Active Symporter Requirements
Evaluating What is Required
A. Solute moving against its concentration gradient
B. Solute moving with its concentration gradient
C. Integral membrane protein
D. ATP
E. All are required
Prokaryotic vs Eukaryotic Cells
Distinctions
A. Presence of a cell wall
B. Unicellularity
C. Presence or absence of ribosomes
D. Presence or absence of a nucleus
Secondary Structure of Proteins
Definition of Secondary Structure
A. Number and orientation of subunits
B. Three-dimensional shape of the protein
C. Folding of polypeptide into helices and sheets
D. Sequence of amino acids in a protein
Feature of Bacteria Differentiating from Other Life Forms
Differentiating Characteristics
A. Size
B. Unicellularity
C. Being prokaryotic
D. Most having cell walls made from peptidoglycan
Facilitated Transport Requirements
Necessary Elements for Facilitated Transport
A. Concentration gradient
B. Integral membrane protein
C. ATP
D. All required
E. None required
Final Reaction of Glycolysis
Reactants and Products
Reaction:
Classifications of Reaction Types
A. Coupled reaction
B. Connected reaction
C. Non-spontaneous reaction
D. Isomerization
Classification of New Species Discovered
Characteristics of New Organism
Uses organic molecules for energy
Uses inorganic molecules for carbon
Possible Classifications
A. Chemoorganoheterotroph
B. Chemoorganoautotroph
C. Chemolithoheterotroph
D. Chemolithoautotroph
E. Photochemoautoheterolithotroph
Induced Fit Model in Enzyme Catalysis
Truth Statements Regarding the Model
A. Enzymes increase activation energy of a reaction
B. Enzymes change shape when substrate enters the active site
C. Active site perfect match for substrate (Lock & Key model)
D. Active site can bind more than one substrate
E. All statements considered