Atomic Structure & Chemical Bonds
How do the three subatomic particles contribute to the properties of an atom?
Protons determine the atomic number and identity of the element.
Neutrons contribute to atomic mass and can create isotopes.
Electrons determine the chemical behavior of the atom through their arrangement in orbitals.
Why is water considered a universal solvent?
Water's polarity allows it to dissolve many substances, especially ionic and polar molecules, making it essential for biochemical reactions and transport in organisms.
How does the sequence of amino acids determine a protein’s function?
The amino acid sequence determines the protein's folding and shape, which directly influences its function, such as enzymatic activity or structural support.
What structural differences exist between DNA and RNA?
DNA has a double helix structure, deoxyribose sugar, and thymine as a base. RNA is single-stranded, has ribose sugar, and uses uracil instead of thymine.
What makes lipids hydrophobic, and why is this property important in biological membranes?
Lipids are hydrophobic due to their nonpolar hydrocarbon chains, allowing them to form the bilayer of cell membranes, creating a selective barrier.
What differentiates an isotope from a regular atom of an element?
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons, leading to variations in atomic mass.
How do cohesion and adhesion contribute to capillary action in plants?
Cohesion (water molecules sticking to each other) and adhesion (water molecules sticking to other surfaces) enable water to move up plant vessels against gravity in a process called capillary action.
What roles do enzymes play in biochemical reactions?
Enzymes speed up reactions by lowering activation energy, enabling essential biological processes like metabolism, digestion, and DNA replication.
How does dehydration synthesis contribute to macromolecule formation?
Dehydration synthesis removes water molecules to form covalent bonds between monomers, creating larger macromolecules like proteins, nucleic acids, and carbohydrates.
How do phospholipids differ from triglycerides?
Phospholipids have two fatty acid tails and a phosphate group, while triglycerides have three fatty acids and serve as energy storage molecules.
How do ionic and covalent bonds differ in terms of electron sharing?
Ionic bonds form when electrons are transferred from one atom to another, resulting in oppositely charged ions.
Covalent bonds form when atoms share electrons to achieve stability.
What properties of water are essential for maintaining life?
High specific heat, high heat of vaporization, cohesion/adhesion, solvent properties, and ice being less dense than liquid water.
What are the four levels of protein structure, and why are they important?
Primary: Sequence of amino acids.
Secondary: Alpha-helices and beta-sheets due to hydrogen bonding.
Tertiary: 3D folding due to interactions between R groups.
Quaternary: Multiple polypeptide chains interacting.
These structures determine the protein's stability and function.
Why are polysaccharides essential for energy storage and structural support?
Polysaccharides like glycogen and starch store energy, while cellulose and chitin provide structural integrity to plant cell walls and exoskeletons.
Why are steroids considered lipids despite their unique structure?
Steroids have a hydrophobic carbon-ring structure, classifying them as lipids even though they differ structurally from fats and oils.
Explain the role of electronegativity in chemical bonding.
Electronegativity is an atom's ability to attract electrons in a bond.
Large differences in electronegativity lead to ionic bonds, while smaller differences result in polar covalent bonds.
Equal sharing of electrons forms nonpolar covalent bonds.
How does hydrogen bonding affect the density of ice compared to liquid water?
Hydrogen bonds cause water molecules in ice to arrange in a different structure, making ice less dense than liquid water.
How do peptide bonds form between amino acids?
Peptide bonds form through dehydration synthesis, where the carboxyl group of one amino acid bonds with the amino group of another, releasing water.
How do base-pairing rules influence DNA replication?
Complementary base-pairing (A-T and C-G) ensures accurate copying of genetic information during DNA replication.
What role do lipids play in energy storage compared to carbohydrates?
Lipids store more energy per gram than carbohydrates due to their dense hydrocarbon chains, making them ideal for long-term energy storage.
What are redox reactions, and why are they important in biological systems?
Redox (oxidation-reduction) reactions involve the transfer of electrons.
Oxidation is the loss of electrons, and reduction is the gain of electrons.
These reactions are crucial for processes like cellular respiration and photosynthesis.
Explain the significance of buffers in biological systems.
Buffers help maintain pH stability by absorbing or releasing hydrogen ions, preventing harmful fluctuations in biological systems like blood and cells.
How can environmental factors influence protein folding?
Factors like pH, temperature, and salinity can disrupt bonds stabilizing a protein’s structure, potentially leading to denaturation and loss of function.
What are the key components of a nucleotide?
A nucleotide consists of a five-carbon sugar (ribose or deoxyribose), a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, guanine, or uracil).
How do lipids contribute to cell signaling?
Lipids like steroid hormones (e.g., testosterone, estrogen) and phospholipids in cell membranes play crucial roles in cellular communication and signal transduction.