Atom Structure, Molecules, & Bonds
What determines the chemical reactivity of an atom?
a. Number of protons
b. Number of electrons in the outermost (valence) shell
c. Total number of electrons
d. Number of neutrons
Number of electrons in the outermost (valence) shell
The tertiary structure of a protein is characterized by:
a. The sequence of amino acids
b. Multiple proteins interacting
c. Hydrogen bonding forming alpha helices and beta sheets
d. Complex folding giving the protein its final 3D shape
Complex folding giving the protein its final 3D shape
Frue of False: In cellular membranes, phospholipids are arranged with hydrophobic heads facing outward and hydrophilic tails inward.
False
Prokaryotic cells differ from eukaryotic cells in that they:
a. Have membrane-bound organelles
b. Lack a membrane-bound nucleus
c. Are typically larger and more complex
d. Contain mitochondria
Lack a membrane-bound nucleus
What is the main structural difference between DNA and RNA nucleotides?
DNA contains thymine; RNA contains uracil
Which type of chemical bond involves the sharing of electron pairs between atoms?
Hydrogen, Ionic, or Covalent
Covalent
What type of macromolecule are enzymes primarily classified as?
Protiens
Which transport process moves molecules against their concentration gradient and requires energy?
Active transport
Which cellular organelle is responsible for synthesizing ATP and contains its own DNA?
Mitochondria
What is the basic structure of a steroid?
Four-ring structure, 3 - 6 carbon rings, and 1 - 5 carbon ring.
What distinguishes isotopes of the same element?
Number of neutrons and mass number
Why do hydrogen bonds play a critical role in the structure of proteins and DNA?
They provide weak attractive forces that stabilize molecular shapes
What feature characterizes phospholipids and makes them essential to cell membranes?
Amphipathic, having both hydrophobic and hydrophilic regions
What is the function of lysosomes within the cell?
Breaking down old organelles, bacteria, and cellular debris
Why does the body need a buffer system, and what do buffers do?
Buffers stabilize pH by binding or releasing hydrogen ions. The body needs them to maintain homeostasis.
Why is water considered a polar molecule?
Electrons are shared unequally resulting in partial charges
What type of reaction links monomers into polymers in biological macromolecules?
Condensation (dehydration synthesis)
Describe the principle of osmosis.
Diffusion of water across a selectively permeable membrane
Explain the endosymbiotic theory?
Mitochondria and chloroplasts were once independent entities and were then engulfed to form a mutualistic relationship. It's why mitochondria and chloroplasts have their own DNA.
List the primary functions of proteins?
Support, Movement, Transport, Buffers, Hormone interaction, Receptors, Channels, Defence, Energy, and Metabolic regulation.
Strong acids in solution:
Almost completely dissociate and release hydrogen ions
What are the three main types of polysaccharides and their use?
Cellulose and chitin - structure
Starch - energy storage in plants
Glycogen - energy storage in animals
The sodium-potassium pump moves ions:
Against their concentration gradients using ATP
What are the three main cytoskeleton components and their primary function?
Microfilaments - shape and crawling
Intermediate filaments - stability and connecting cells
Microtubules - moving substances and centriole formation
What are the differences between a saturated fatty acid and an unsaturated fatty acid?
Saturated - animal products, solid at room temp, have single bonds
Unsaturated - plant products, liquid at room temperature, c=c kink due to double bond