Basic Chemistry & Bonding
Define an isotope and explain how it differs from a radioactive isotope
Isotopes have the same number of protons but different numbers of neutrons. Radioactive isotopes are unstable and emit radiation.
Name the monomer of proteins.
Amino acids.
Differentiate dehydration synthesis and hydrolysis.
Dehydration removes water to build larger molecules; hydrolysis adds water to break them apart.
Which organelle is called the 'post office' of the cell?
Golgi apparatus
Differentiate passive and active transport.
Passive transport requires no ATP and moves down the gradient; active transport requires ATP and moves against the gradient.
Explain the difference between ionic and covalent bonds.
Ionic bonds involve electron transfer; covalent bonds involve sharing electrons.
Compare saturated and unsaturated fats.
Saturated fats have no double bonds and are usually solid; unsaturated fats contain double bonds, have kinks, and are usually liquid.
The pH is logarithmic, meaning each unit represents a 10-fold change in H+ concentration.
Calculate: A solution changes from pH 7 to pH 4. By what factor has the H+ concentration increased?
1000 times.
Place these in order: Nucleus, Rough ER, Golgi, Vesicle, Cell membrane.
Nucleus → Rough ER → Golgi → Vesicle → Cell membrane
Why can small non-polar molecules diffuse directly through the membrane?
They dissolve in the hydrophobic lipid bilayer.
Water is a polar molecule. Explain why.
Oxygen is more electronegative than hydrogen and the bent shape creates unequal charge distribution.
Complete the chart: (bond type)
Carbohydrates–____;
Lipids–____;
Proteins–____;
Nucleic acids–____ .
Carbohydrates–___Glycosidic_;
Lipids–__Ester__;
Proteins–__Peptide__;
Nucleic acids–__Phosphodiester__ .
What is the role of buffers in the human body?
They resist sudden changes in pH and maintain homeostasis.
Explain why phospholipids naturally form a bilayer.
Hydrophilic heads face water; hydrophobic tails avoid water.
Compare channel proteins and carrier proteins.
Channels form pores; carriers change shape during transport.
Explain how the electron arrangement in carbon atoms enables them to form straight chains, branched chains, and rings.
Carbon has four valence electrons, allowing it to form four stable covalent bonds with many atoms, including other carbon atoms.
Explain why humans can digest starch but not cellulose.
Starch contains α-glucose linkages; cellulose contains β-glucose linkages that humans cannot digest.
Describe the induced-fit model.
The enzyme changes shape slightly as the substrate binds, improving catalysis.
Name three factors that affect membrane fluidity.
Temperature, cholesterol, and degree of fatty acid saturation.
Predict what happens to an animal cell in a hypertonic solution and explain why.
Water leaves by osmosis, causing the cell to shrink.
Describe two properties of water caused by hydrogen bonding and explain why each is important.
cohesion, adhesion, high specific heat, high heat of vaporization, universal solvent, ice floats.
State three structural differences between DNA and RNA.
Deoxyribose vs ribose;
Thymine vs uracil;
double-stranded vs single-stranded.
Compare competitive and non-competitive inhibition.
Competitive inhibitors bind the active site; non-competitive inhibitors bind an allosteric site and alter enzyme shape.
Describe how at least four organelles work together to produce and secrete a protein.
Nucleus → Rough ER/ribosomes → Golgi → Vesicle → Cell membrane
Describe how the sodium-potassium pump works.
Uses 1 ATP to move 3 Na+ out and 2 K+ into the cell.