Biomolecules and Water Structure

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Questions and Answers

What is the relationship between Delta G and spontaneity of a reaction?

Delta G = 0 means the reaction is at equilibrium (correct)

Delta G tells nothing about reaction spontaneity

Delta G < 0 indicates a non-spontaneous reaction

Delta G > 0 signifies an exergonic process

Which of the following characteristics is true for fibrous proteins?

They are long, rod-shaped and insoluble in water (correct)

Fibrous proteins are soluble in water

They are typically catalytic in function

Fibrous proteins have a compact spherical structure

In the context of protein digestion, which statement about peptide bonds is correct?

Peptide bonds can freely rotate around the C-N bond

Peptide bonds occur through simple diffusion in membranes

Peptide bonds are characterized by partial double bond character (correct)

Peptide bonds form between hydroxyl and carboxyl groups

Which statement best describes the role of membrane proteins?

Membrane proteins can act as channels or receptors Signup and view all the answers

How does secondary active transport differ from primary active transport?

It relies on electrochemical gradients but not ATP directly Signup and view all the answers

Which of the following statements about entropy is correct?

For spontaneous reactions, total entropy change is positive Signup and view all the answers

One key function of myoglobin is to?

Store oxygen in muscle tissues Signup and view all the answers

What does the isoelectric point (pI) of an amino acid represent?

The pH at which the amino acid has zero net charge Signup and view all the answers

What determines the rate of a chemical reaction according to enzyme kinetics?

The concentrations of reactants and the rate constant Signup and view all the answers

Which structure is responsible for the unique left-handed helix formation in collagen?

Unique amino acid sequence with Gly-Pro-Pro repeats Signup and view all the answers

What defines an anabolic pathway in metabolism?

Pathway that synthesizes molecules and utilizes energy Signup and view all the answers

Which statement accurately describes the role of ATP in biological processes?

ATP is a universal energy currency for driving cellular processes. Signup and view all the answers

Which of the following describes the Henderson-Hasselbalch equation?

pH = pKa + log(A-)/(HA) calculates the relationship between acid and its conjugate base. Signup and view all the answers

What is the primary outcome of oxidation/reduction reactions in cells?

To convert energy contained in electrons into a usable form. Signup and view all the answers

What type of bonding primarily describes the interactions between water molecules?

Hydrogen bonds formed by attractions between dipoles. Signup and view all the answers

How does a hypotonic environment affect a cell?

The cell will gain water, potentially leading to swelling or bursting. Signup and view all the answers

Which of the following groups is primarily responsible for hydrogen bonding?

Hydroxyl (-OH) and carboxylic acid (-COOH) functional groups. Signup and view all the answers

What defines the state function in the context of thermodynamics?

A property that is independent of the pathway between states. Signup and view all the answers

Which type of biochemical reaction involves a nucleophile displacing a leaving group?

Nucleophilic substitution reaction. Signup and view all the answers

The rate of enzyme-catalyzed reactions is primarily influenced by which of the following factors?

Temperature and the concentration of the substrate. Signup and view all the answers

Which of the following statements correctly describes the nature of hemoglobin's oxygen binding curve compared to that of myoglobin?

Hemoglobin exhibits a cooperative binding behavior leading to a sigmoidal curve. Signup and view all the answers

Which type of bond primarily stabilizes the secondary structure of proteins?

Hydrogen bonds Signup and view all the answers

What is indicated by the Michaelis-Menten constant (Km) in enzyme kinetics?

The substrate concentration at which the reaction velocity is half of Vmax. Signup and view all the answers

Which of the following statements is true regarding the effect of competitive inhibitors on enzyme kinetics?

Competitive inhibitors decrease Vmax without affecting Km. Signup and view all the answers

What role does molecular chaperones play in protein folding?

They prevent misfolding and assist in achieving the correct native state. Signup and view all the answers

In Anfinsen's experiment, which condition was found to restore the activity of ribonuclease A (RNase A) most effectively?

Removal of urea followed by oxidation in the presence of beta-mercaptoethanol. Signup and view all the answers

Which of the following best describes the quaternary structure of proteins?

It consists of multiple polypeptide chains held together by non-covalent interactions. Signup and view all the answers

Which statement accurately reflects the role of coenzymes in enzymatic reactions?

Coenzymes assist in catalyzing reactions by transferring chemical groups between enzymes. Signup and view all the answers

What determines whether a reaction is spontaneous in terms of Gibbs free energy?

The Gibbs free energy change, with negative values indicating spontaneity. Signup and view all the answers

Which of the following describes uncompetitive inhibition in enzyme kinetics?

Inhibitors bind to the enzyme-substrate complex, reducing Vmax without affecting Km. Signup and view all the answers

Study Notes

Lecture 1: Biomolecules

Biomolecules are distinguished by family name, group structure, group name, and significance.
Four major classes of small biomolecules are listed, along with the polymers/macromolecules they form, identified by their chemical structure.
Amino acids are molecules with an amino group and an acidic group.
Sugars contain an aldehyde or ketone group and alcohol groups.
Sugars can be drawn as linear or circular structures.
Fatty acids have an acidic group and an alkyl group (long hydrocarbon).
Nucleotides are the most complex small biomolecules, containing a sugar, a nitrogenous base, and one or more phosphate groups.

Lecture 2: Water Structure and Properties

Water molecules are polar with positive and negative dipole moments.
Hydrogen bonds form between water molecules.
Water exhibits electrostatic and partially covalent properties.
Water forms hydrogen bonds with four other water molecules as ice.
Water is a good solvent for charged and polar substances.
Water has a high dielectric constant.
Functional groups that hydrogen bond include hydroxyl (-OH), amine (-NH2), amide (-CONH2), carboxylic acid (-COOH), nitrile (-CN).

Lecture 3: Water Ionization, pH, Buffers

pH = -log[H+].
Acids donate protons; bases accept protons.
Ka is the acid dissociation constant (Ka= (H+)(A-)/(HA)). pKa = -log(Ka).
Buffers maintain a relatively constant pH, commonly via a mixture of weak acids and conjugate bases.
Acidosis is blood pH < 7.35; alkalosis is blood pH > 7.45.
Bicarbonate and phosphate are important biological buffers.
The Henderson-Hasselbalch equation calculates pH, pKa, and relative amounts of acid/conjugate base.

Lecture 4: Biochemical Reactions

5 major types of biochemical reactions are described.
Organisms generate energy via various pathways.
Energy transfer, anabolic, catabolic, and signal transduction pathways are discussed.
Nucleophilic substitutions, addition, and oxidation/reduction reactions are explained.

Lecture 5: Energy, Reactions, ATP

Energy in chemicals is used to drive biological processes.
Matter and energy are interconvertible.
Laws of thermodynamics dictate energy processes in the universe. (1st, 2nd, 3rd Law).
Open and closed systems describe energy exchange.
State and non-state functions are defined.
Enthalpy (H) is a state function, measuring internal energy/heat content.

Lecture 6: Prokaryotes, Eukaryotes, and Biological Membranes

Major components of cells and their functions are described.
Comparisons between prokaryotes and eukaryotes are made (e.g., size, nucleus, membrane-bound organelles).
Biological membranes are described as thin, flexible structures with hydrophilic/hydrophobic components.
Membranes act as selective barriers.
Simple diffusion, facilitated diffusion, active transport, primary/secondary active transport are described.

Lecture 7: Amino Acids

Amino acids are organic compounds with amino (R-NH2) and carboxyl (R-COOH) groups.
L- and D-isomers of amino acids are discussed
There are 20 standard amino acids described with examples and characteristics (polar, nonpolar, acidic, basic).
Titration curves and isoelectric points (pI) for free amino acids are discussed.

Lecture 8: Proteins and Peptides

Proteins are linear polymers of amino acids linked by amide linkages (peptide bonds).
Properties of peptide bonds are discussed.
Fibrous and globular proteins are types with different structures and functions. Examples like keratin and collagen are given and their functions.
Polypeptide chains use the primary amino acid sequence and create complex 3D structures - primary, secondary, tertiary, and quaternary structures in proteins.

Lecture 9: Protein Structure

Protein primary structure is the amino acid sequence.
Protein folding involves the transition of linear polypeptide chains into native, functional 3D structures.
Anfinsen's experiment demonstrated the importance of primary structure for proper protein folding.
Types of secondary structure (alpha-helix, beta-sheet) and the roles of tertiary and quaternary structures are discussed.
The role of prosthetic groups and coenzymes are described.
Protein folding and the role of chaperones.

Lecture 10: Properties of Enzymes

Enzymes, as protein catalysts, accelerate biochemical reactions.
The rate of chemical reactions can be expressed in terms of rate constants.
Enzyme kinetics are characterized by constants (e.g., V_max, K_m, K_cat).

Lecture 11: Enzyme Kinetics

Methods to measure enzyme kinetics are described.
The Michaelis-Menten model explains how enzyme activity (V₀) changes with substrate concentration [S].
Terms like V_max and K_m are discussed
Graphical plots and analysis.

Lecture 12: Enzyme Inhibition

Enzyme inhibitors reduce enzyme activity.
Reversible and irreversible inhibitors are described.
Competitive and non-competitive inhibitors, as well as pure, mixed, uncompetitive inhibitors are discussed
Effects on Km and Vmax are described, and graphical representations.

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Description

Explore the fascinating world of biomolecules and water properties in this quiz. Learn about the four major classes of biomolecules such as amino acids, sugars, fatty acids, and nucleotides, and understand the unique characteristics of water. Test your knowledge on their structures, functions, and significance.