Chemistry Basics
Which two subatomic particles make up the atomic mass of an element?
Protons and Neutrons
What kind of bond holds the oxygen and hydrogen atoms together within a single water molecule?
Polar covalent bond
What type of bond links two monosaccharides into a disaccharide?
Glycosidic linkage
What type of bond holds amino acids together in a polypeptide chain?
Peptide bond
What structure surrounds all cells and regulates what enters/exits?
Plasma membrane (phospholipid bilayer)
Why are noble gases chemically unreactive?
They have full valence shells.
What property of water allows it to stick to glass in a graduated cylinder?
Adhesion
What type of reaction breaks down a polymer into monomers?
Hydrolysis
What type of bond connects the sugar of one nucleotide to the phosphate of the next in a nucleic acid strand?
Phosphodiester linkage
What are ribosomes made of, and what is their main function?
rRNA and proteins; protein synthesis
Compare ionic and covalent bonds in terms of electron behavior.
Ionic = transfer of electrons
Covalent = sharing of electrons
If [OH⁻] = 10⁻⁹ M, what is the solution’s pH?
pH = 5
Explain why saturated fats are usually solid while unsaturated fats are liquid at room temperature.
Saturated = straight chains, pack tightly
Unsaturated = cis double bonds create kinks, prevent packing
Which type of bond stabilizes an α-helix or β-pleated sheet?
Hydrogen bonds
What do prokaryotic cells lack that eukaryotic cells have?
Membrane-bound organelles
What property of an atom determines whether a covalent bond will be polar or nonpolar?
Electronegativity
Why do polar molecules dissolve in water, but nonpolar molecules do not?
Polar molecules form hydrogen bonds with water, while nonpolar molecules lack charges to interact with water.
Why are phospholipids classified as amphipathic molecules?
They contain hydrophilic (polar head) and hydrophobic (nonpolar tails) regions.
A DNA strand reads 5′-ATGCCGA-3′. What is its complementary strand?
3′-TACGGCT-5′
What are the infoldings of mitochondrial inner membrane called?
Cristae
What are isotopes?
Atoms having the same number of protons but different numbers of neutrons.
What would happen to the internal pH of cells if buffers were absent?
Even small additions of acids or bases would cause harmful pH swings.
Why can starch be digested by humans but cellulose cannot?
Enzymes recognize α-glycosidic bonds but not β-glycosidic bonds.
What part of a nucleotide is different between DNA and RNA?
The sugar (deoxyribose in DNA, ribose in RNA)
Which organelle is rich in enzymes that break down fatty acids and neutralize toxins like alcohol?
Peroxisome