BIO 120 Lecture Exam 2
⚡ METABOLISM
Q: What is metabolism?
A: The sum of all chemical reactions in a cell.
Q: What is anabolism?
A: Builds large molecules from small ones; requires energy (uses ATP).
Q: What is catabolism?
A: Breaks down large molecules; releases energy (makes ATP).
Q: What molecule is the cell’s energy currency?
A: ATP (adenosine triphosphate).
Q: Where is ATP’s energy stored?
A: In its high-energy phosphate bonds.
Q: Which process releases ATP — anabolism or catabolism?
A: Catabolism.
Q: Difference between aerobic and anaerobic respiration?
A: Aerobic uses oxygen and produces more ATP; anaerobic doesn’t and yields less ATP.
Q: What do enzymes do?
A: Speed up reactions by lowering activation energy.
Q: What happens to enzymes at high temperatures?
A: They denature (lose shape and function).
Q: What does denaturation mean?
A: Loss of protein’s 3D shape → loss of function.
Q: How does pH affect enzyme activity?
A: Extreme pH denatures enzymes and reduces activity.
🧬 DNA / RNA / PROTEIN SYNTHESIS
Q: What is a gene?
A: A segment of DNA that codes for a protein or trait.
Q: What is a genome?
A: All the genetic material in an organism.
Q: What is a chromosome?
A: A structure made of DNA that carries genes.
Q: What’s the monomer of DNA?
A: Nucleotide.
Q: Base-pair rules in DNA?
A: A–T, C–G.
Q: What bonds join base pairs?
A: Hydrogen bonds.
Q: What does “antiparallel” mean?
A: The two DNA strands run in opposite directions (5'→3' vs 3'→5').
Q: Which enzyme unzips DNA?
A: Helicase.
Q: Which enzyme adds nucleotides?
A: DNA polymerase.
Q: Which enzyme seals Okazaki fragments?
A: Ligase.
Q: What is semi-conservative replication?
A: Each new DNA has one old and one new strand.
Q: Which direction does DNA polymerase build in?
A: 5' → 3' direction.
Q: What is the central dogma?
A: DNA → RNA → Protein.
Q: What are the three types of RNA and their functions?
A:
mRNA: carries message from DNA.
tRNA: carries amino acids.
rRNA: part of ribosome structure.
Q: What is a codon?
A: 3-base sequence on mRNA coding for one amino acid.
Q: What is an anticodon?
A: 3-base sequence on tRNA complementary to mRNA codon.
Q: Define mutation.
A: A change in DNA sequence.
Q: Mutation changing one amino acid → ?
A: Missense.
Q: Mutation inserting or deleting bases → ?
A: Frameshift.
Q: Mutation making a stop codon → ?
A: Nonsense.
Q: Mutation that changes nothing → ?
A: Silent.
🌱 GROWTH & ENVIRONMENT
Q: What is a nutrient?
A: Substance needed for growth and metabolism.
Q: What are saprobes?
A: Feed on dead organic matter.
Q: What are parasites?
A: Live on or in host, causing harm.
Q: What are decomposers?
A: Break down dead material and recycle nutrients.
Q: What is osmosis?
A: Movement of water across a semipermeable membrane.
Q: Cell in isotonic solution — what happens?
A: Water moves equally, no net change.
Q: Cell in hypertonic solution — what happens?
A: Water leaves cell → shrinks (plasmolysis).
Q: Cell in hypotonic solution — what happens?
A: Water enters cell → swells/bursts.
Q: What is plasmolysis?
A: Cell membrane pulls away from wall due to water loss.
Q: What is a biofilm?
A: Community of microbes living together on a surface, protected by slime layer.
Q: Four bacterial growth phases?
A: Lag → Log → Stationary → Death.
Q: In which phase are antibiotics most effective?
A: Log phase (active growth).
Q: What happens to enzymes at high temperature?
A: Denature (lose function).
Q: What is an obligate acidophile?
A: Microbe that requires acidic conditions.
Q: Microbe that needs O₂ → ?
A: Obligate aerobe.
Q: Microbe that can’t survive O₂ → ?
A: Obligate anaerobe.
Q: Microbe that grows better with O₂ but can grow without → ?
A: Facultative anaerobe.
Q: Microbe that tolerates O₂ but doesn’t use it → ?
A: Aerotolerant anaerobe.
🧼 CONTROL OF MICROBIAL GROWTH
Q: What is sterilization?
A: Complete destruction of all microbes.
Q: What is disinfection?
A: Removal of most microbes (non-living surfaces).
Q: What is antiseptic?
A: Kills or inhibits microbes on living tissue.
Q: What is sanitization?
A: Reduces microbes to safe levels.
Q: What does bactericidal mean?
A: Kills bacteria.
Q: What does bacteriostatic mean?
A: Inhibits bacterial growth.
Q: What is sepsis?
A: Microbes or toxins present in blood/tissues.
Q: What is asepsis?
A: Absence of contamination.
Q: What is thermal death point?
A: Lowest temperature to kill all microbes in 10 min.
Q: Four major antimicrobial targets?
A: Cell wall, membrane, proteins, nucleic acids.
Q: What sterilizes with steam under pressure?
A: Autoclave.
Q: Conditions for autoclaving?
A: 121°C, 15 psi, 15–20 minutes.
Q: What is a surfactant?
A: Chemical that disrupts membranes, loosens microbes.
Q: Native vs denatured proteins?
A: Native = functional shape; Denatured = unfolded, nonfunctional.
🧬 GENE TRANSFER
Q: What is vertical gene transfer?
A: DNA passed from parent to offspring.
Q: What is horizontal gene transfer?
A: DNA exchanged between unrelated bacteria.
Q: What is transformation?
A: Uptake of free DNA from environment.
Q: What is transduction?
A: DNA transfer by a bacteriophage (virus).
Q: What is conjugation?
A: DNA (plasmid) transfer via sex pilus between bacteria.
Q: What is a plasmid?
A: Small circular DNA separate from chromosome.
Q: How do plasmids increase pathogenicity?
A: Carry antibiotic resistance or toxin genes.
Q: What is a recombinant organism?
A: One that has new genetic material from another source.