week 4 Flashcards
What is the significance of electron shells in atoms?
Electron shells determine how atoms will interact with each other; the first shell holds 2 electrons, the second and outer shells can hold up to 8 electrons each.
How does the electron configuration of an atom influence its reactivity?
Atoms with outer shells that are not filled are more reactive, tending to form chemical bonds to achieve a full outer shell.
How do atoms form molecules?
Atoms can form molecules by sharing electrons, or by losing or gaining electrons, resulting in bonded atoms.
What is the octet rule and its relevance to chemical bonding?
The octet rule is the tendency of atoms to form stable molecules by having eight electrons in their outermost shells.
What are chemical bonds?
A chemical bond is an attractive force that links atoms together to form molecules. There are several kinds of chemical bonds.
what is a covalent bond?
atoms share one or more pairs of electrons, so that the outer shells are filled
what is a polar covalent bond?
A polar covalent bond results when electrons are drawn to one nucleus more than to the other, because one atom has more electronegativity
what is an ionic bond?
When one atom is so electronegative that it removes an electron from another atom to form an ionic bond.
what are isomers?
molecules with the same chemicalformula, but atoms are arranged differently
what are structural isomers?
differ in how their atoms are joined together
what is an optical isomer?
Optical isomers occur when a carbon atom has four different atoms or groups of atoms attached to it.
- Some biochemical molecules that can interact with one optical isomer are unable to “fit” the other
Optical isomers result from asymmetrical carbons.
Describe hydrophobic and van der Waals interactions in terms of their interaction basis and bond energy.
Hydrophobic interactions occur between nonpolar substances in the presence of polar substances, especially water, with bond energies of 1-2 kcal/mol. Van der Waals interactions are due to the interaction of electrons of nonpolar substances with a typical bond energy of about 1 kcal/mol. Both types of interactions contribute to the stability and folding of proteins, albeit weaker than covalent or ionic bonds.
What characterizes a covalent bond and what is its bond energy range?
A covalent bond is characterized by the sharing of electron pairs between atoms. The bond energy for covalent bonds typically ranges from 50 to 110 kcal/mol, making them quite strong and stable under physiological conditions.
How do ionic bonds and hydrogen bonds differ in their basis of interaction and bond energy?
Ionic bonds are based on the attraction of opposite charges and have a bond energy between 3-7 kcal/mol, whereas hydrogen bonds are formed by the sharing of a hydrogen atom and also have bond energy between 3-7 kcal/mol. Despite having similar bond energies, ionic bonds result from electrostatic attractions, while hydrogen bonds are due to polarity within molecules.
what is an ionic bond?
When one atom is so electronegative that it removes an electron from another atom to form an ionic bond
what is biochemical unity?
Biochemical unity: there are four kinds of macromolecules in living things, which are present in roughly the same proportions in all organisms, and have similar functions.
What Are the Chemical Structures and Functions of Proteins?
- Proteins are polymers of 20 different amino acids.
- Polypeptide chain: single, unbranched chain of amino acids.
- The chains are folded into specific three dimensional shapes defined by the sequence of the amino acids.
- Proteins can consist of more than one type of polypeptide chain.
What role do enzymes play among protein functions?
Enzymes are catalytic proteins that speed up chemical reactions in the body without being consumed in the process.
What are defensive proteins and give an example?
Defensive proteins are those that protect the body from foreign pathogens. Antibodies are a key example, as they bind to specific foreign particles, such as viruses and bacteria, to neutralize them and prevent disease.
are amino acids acidic or basic?
Amino acids have carboxyl and amino groups—so they function as both acid and base
How do hormonal and receptor proteins function in the body?
Hormonal and regulatory proteins control physiological processes by acting as messengers that coordinate the activities of different cell types. Receptor proteins receive and respond to molecular signals, initiating a cellular response to various stimuli, such as the presence of a hormone or a change in the environment.
What is the function of storage proteins?
Storage proteins store amino acids for later use.
What role do structural proteins play in an organism?
Structural proteins provide physical stability and support for cells and tissues.
How do transport proteins contribute to cellular function?
Transport proteins carry substances within the organism, such as hemoglobin, which transports oxygen in the blood.
What is the function of genetic regulatory proteins?
Genetic regulatory proteins control when, how, and to what extent a gene is expressed.
What is the significance of the alpha carbon in amino acids?
The alpha carbon atom is asymmetrical, making amino acids optically active and leading to two isomeric forms: D-amino acids and L-amino acids.
What are the two isomeric forms of amino acids and which one is found in organisms?
The two isomeric forms are D-amino acids (dextro, “right”) and L-amino acids (levo, “left”), with the L-form being the one found in organisms.
How are amino acids categorized?
Amino acids are grouped based on their side chains, or R-groups, which can have various functional groups.
What special role does methionine play in proteins?
Methionine initiates chains of amino acids, typically being the first amino acid in a newly synthesized protein.
How does proline affect the structure of proteins?
Proline causes kinks in chains of amino acids due to its unique structure, influencing the folding of proteins.
What is the function of cysteine in proteins?
Cysteine links
What is the role of cysteine in forming disulfide bridges?
The terminal -SH group of cysteine can react with another cysteine side chain to form a disulfide bridge (—S—S—), which is critical for protein folding.
covalent bond
Why are disulfide bridges important in proteins, and where are they most commonly found?
Disulfide bridges are important for stabilizing the three-dimensional structure of proteins and are most commonly found in extracellular proteins, which are exposed to more stress outside of the cell.
How are amino acids linked together in a protein?
Amino acids are linked together by peptide bonds formed during a condensation reaction, which is a covalent bond between the amino group of one amino acid and the carboxyl group of another.
What is the nature of the peptide bond in proteins?
The peptide bond is inflexible, meaning no rotation is possible around it, which contributes to the protein’s structure.
: What is the primary structure of a protein?
The primary structure of a protein is the sequence of amino acids that determines its higher levels of structure, including secondary and tertiary forms.
How does the amino acid sequence influence protein structure?
The sequence of amino acids dictates the secondary and tertiary structures of the protein, essentially determining how the protein will fold.
What does the diversity of proteins indicate about amino acid sequences?
The enormous number of different proteins that can be made from 20 amino acids indicates the vast array of functions and structures that proteins can have.
What defines the primary structure of a protein?
The primary structure of a protein is defined by its sequence of amino acids, which determines its higher-level structures and ultimately its function.
What are the two types of secondary structures commonly found in proteins?
The two common secondary structures are the alpha helix, a right-handed coil resulting from hydrogen bonding between N-H groups on one amino acid and C=O groups on another, and the beta pleated sheet, where two or more polypeptide chains align and are connected by hydrogen bonds.
What is the tertiary structure of a protein?
The tertiary structure is the overall three-dimensional shape of a protein, determined by interactions like disulfide bridges, hydrogen bonds, hydrophobic interactions, van der Waals forces, and ionic bonds.
How does the tertiary structure relate to protein functionality?
The tertiary structure’s intricate folding allows for a diversity of functional groups on the outer surfaces of the protein to interact with other molecules, enabling specific biological functions.
What demonstrates the information to specify protein shape is contained in the primary structure?
The fact that a denatured protein can refold into its normal tertiary structure upon cooling indicates that all information required for folding is contained within the primary sequence of amino acids.
What happens to a protein when it is denatured, and what does this demonstrate about protein structure?
When a protein is heated, its secondary and tertiary structures break down, a process known as denaturation. If the protein refolds to its normal structure upon cooling, it demonstrates that the primary structure contains all the information necessary to specify the protein’s shape.
What is the quaternary structure of a protein?
The quaternary structure of a protein results from the interaction of subunits through hydrophobic interactions, van der Waals forces, ionic bonds, and hydrogen bonds. Each subunit maintains its own unique tertiary structure within the larger complex.
