42 Questions
What is the result of differing electronegativities in a molecule?
The formation of an electric dipole
What is the approximate percentage of oxygen in a human being?
96%
What is the primary reason for the formation of hydrogen bonds between water molecules?
The differences in electronegativities between oxygen and hydrogen atoms
What is the approximate energy required to break a hydrogen bond?
20 kJ/mol
What is the common trait shared by all living organisms on Earth?
They all have a common origin
How many major types of biomolecules are found in living organisms?
4
Which of the following functional groups does not form hydrogen bonds?
C-H bonds
What is the number of different amino acids found in biological molecules?
20
Why do polar compounds dissolve in water?
Because of their ability to form hydrogen bonds with water
What is the variable part of an amino acid?
The R group
What is the term for the electrostatic connections between water molecules?
Hydrogen bonding
What is the result of amino acids polymerizing to form proteins?
A polypeptide chain
What type of interactions are important in biochemistry?
Weak hydrogen bonds
What is the significance of the shape of a protein?
It determines the protein's function
What is the term for the bonding between water and other functional groups?
Hydrogen bonding
What is the name of the force that brings hydrophobic residues together?
Hydrophobic effect
What is the term for the shorter sequence of amino acids that make up a protein?
Peptide
What is the pH of a solution in which the concentration of H+ is equal to the concentration of OH-?
7
What type of biomolecule is Met-Enkephalin?
A peptide
What is the name of the equation that describes the extent of ionization of water?
Keq
What is the term for the hydrophobic groups in a protein structure?
R groups
What type of bonds are responsible for the stability of protein 3D structure?
All of the above
What is the name of the protein that illustrates the principles of tertiary structure?
Myoglobin
What is the role of proline residues in protein structure?
Initiating bends
What is the term used to describe the clustering of hydrophobic residues in protein structure?
Hydrophobic interactions
What is the term used to describe the process of protein folding into a compact structure?
Tertiary structure
What is a characteristic of proteins that are highly stable?
They are unable to change shape
What is the result of hydrophobic collapse and formation of secondary structures?
A faster formation of 3D structure
What limits the amount of motion a protein can undergo and the number of conformations it can achieve?
The native state of the protein
What is the process of protein folding?
A non-random process
What is the result of the series of smaller changes involving fewer residues?
The acquisition of 3D structure
What is the role of hydrophobic collapse in protein folding?
To speed up the formation of 3D structure
What is true about the free-energy funnel of protein folding?
It is a non-random process
What is the relationship between the number of amino acids and the formation of 3D structure?
There is no relationship between the two
What is the primary function of chaperone proteins in protein folding?
To prevent protein aggregation
What happens to the shape of a chaperone protein when it binds ATP?
It changes shape to bind to misfolded proteins
What is the result of protein misfolding?
Protein aggregation
What is the native structure of a protein?
The final conformation of a protein after synthesis
What is the role of heat shock proteins in protein folding?
To mediate protein folding
What is the result of chaperone proteins releasing misfolded proteins?
The protein folds correctly
What is the characteristic of a protein surface recognized by chaperone proteins?
Hydrophobic surfaces
What are diseases resulting from the formation of protein aggregates called?
Amyloidoses
Study Notes
Hierarchical Organization of a Multicellular Organism
- The human body is composed of 96% H, C, N, and O.
- Elements in biological molecules vary in their abundance.
Biomolecules
- There are 4 major types of biomolecules: amino acids, carbohydrates, lipids, and nucleic acids.
- Amino acids are the building blocks of proteins and have a central carbon atom bonded to an amino group, a carboxyl group, and a variable R group.
Amino Acids
- There are 20 different amino acids, each with a unique R group.
- Amino acids polymerize to form proteins.
- Proteins have a primary structure, which is the sequence of amino acids.
Proteins
- Proteins have a secondary structure, which is the folding of the polypeptide chain.
- Hydrophobic R groups are yellow.
- When the polypeptide chain gets long, folding occurs, resulting in a protein.
- The shape of a protein is critical to its function.
Hydrogen Bonding
- Hydrogen bonds occur between a hydrogen atom in a polar bond and any strongly electronegative atom (usually O or N).
- Hydrogen bonds form between alcohols, aldehydes, ketones, and NH groups.
- It takes about 20 kJ/mol to break hydrogen bonds.
pH and Biochemistry
- pH is an important biochemical parameter.
- The extent of ionization is described by Keq.
- At 25°C, Keq = 1.8 x 10-16 M.
Protein Structure
- Tertiary structure refers to the compact, water-soluble folding of proteins.
- Interactions that dictate protein 3D structure include covalent bonds, ionic bonds, hydrogen bonds, Van der Waals forces, and hydrophobic interactions.
- Many strong and weak interactions stabilize protein 3D structure.
Myoglobin
- Myoglobin illustrates the principles of tertiary structure.
- Hydrophobic residues are clustered inside the protein (stabilized by Van der Waals forces).
- Hydrophilic residues are on the outside of the protein.
Protein Folding
- Protein folding is not a random process.
- Hydrophobic collapse and the formation of secondary structure occur rapidly.
- A series of smaller changes involving fewer residues leads to the acquisition of 3D structure.
Chaperones
- Protein folding is mediated by chaperones.
- Chaperones bind to misfolded proteins, preventing them from sticking together.
- Chaperones release the protein, allowing it to fold and reach its native state.
Amyloidoses
- Amyloidoses are diseases resulting from the formation of protein aggregates, called amyloid fibrils or plaques.
This quiz covers the basics of biochemistry, focusing on the hierarchical organization of a multicellular organism, particularly the human being. It explores the elements found in biological molecules and their common origin.
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