MIC 102 Exam Questions with Correct Answers

MIC 102 Exam Questions with Correct Answers What are the three main subgroups of Eukaryotes? - Answer-Algae, Protozoa, Fungi What subgroup does Algae and Protozoa make? - Answer-Protists DESCRIBE THE ROLE OF A PLASMA MEMBRANE AND A CELL WALL. - AnswerWhat's the difference between Basic & Differential Stain? - Answer-Basic Stain: Allows you to determine the basic structure of a bacteria (rod, etc) Differential Stain: Uses more than one stain -- most popular: the gram stain. Why would the cell wall be an important target for antibiotics? - Answer-Because the cell wall of Prokaryotes (like bacteria) has peptidoglycan, which is not found in Eukaryotes. The structure that defines the existence of a cell is the _____ - Answer-cell membrane Differences between Gram-Positive & Gram-Negative cells: - Answer-Positive: - during staining, it retains a dark purple stain after the decolorizer step - THICK. has 5 or more layers of peptidoglycan (which is why it stays purple. more layers.) -its peptidoglycan units - NAG & NAM are joined INdirectly via Pentaglycine bridge. Negative: - during staining, it eventually becomes colorless after the decolorizer step - has only 1-3 layers of peptidoglycan - its peptidoglycan units - NAG & NAM - are joined directly Archaea live in extreme conditions. What helps them accomplish this? - Answer-- having ether linkage (more stable instead of ester) - methylated groups - tighter bonds - monolayer instead of bilayer - stronger - inserting/fusing ring structures O2 & CO2 can easily pass through membrane via passive transport (aka diffusion) - Answer- If you have a high [solutes] inside the cell, water will rush in, pressure builds up, and bacterial cell may lyse. What can help prevent this? - Answer-Cell wall! - provides rigidity - antibiotics can "hurt" the cell wall, resulting in the cell to burst, bc most bacterial cells are found in hypotonic solutions (more solutes inside, less solutes outside) mycoplasmas, have a cell membrane with ______ - Answer-no outer layers. (rare) Gram-Negative bacteria have inner and outer leaflets in their outer membrane. Describe their composition. - Answer-Inner leaflet: contains phospholipid bilayer Outer leaflet: composed of LPS (lipopolysaccharide) Most bacterial cell walls are made up of _________ - Answer-peptidoglycan (or murein). -- which is basically a polysaccharide of repeating subunits of NAG & NAM for GRAM-NEGATIVE BACTERIA: In order for the cross-links between the repeating units N-acetylmuramic acid (NAM) & N-acetylglucosamime (NAG) to occur, what important step must happen? - Answer-The terminal D-Alanine group must be cleaved off in order for the cross-links to form How does Penecillin work? - Answer-It inhibits TRANSPEPTIDASE (which is the enzyme that forms the cross-links found in peptidoglycan, the structure base for the cell wall.) -- thus it weakens the cell wall **vancomyecin BINDS to terminal group What function does a "capsule" provide? - Answer-It prevents the bacterial cell (both + and -) from undergoing phagocytsosis by macrophages. (bad for us) Mycobacteria have _____ cell envelopes - Answer-Complex! (drawback -- harder for nutrients to get in) he inward-facing leaflet of the outer membrane includes - Answer-lipoproteins that connect the outer membrane to the peptide bridges of the cell wall -- w/out this lipoprotein cell wouldn't be able to divide The outward-facing leaflet consists of a special kind of phospholipid called ____, which has crucial medical importance because it acts as an ____ - Answer-- Lipopolysaccharide (LPS) - Endotoxin (pg.94) If the bacteria affecting someone is Gram Negative, you would prob want to give someone an antibiotic that ..... - Answer-Interfere with the GROWTH of the bacteria, but not kill it. Because if you kill it, the bacterial cell is going to release Lipid A (a toxin) which will cause even more problems. Flagella provide motility for bacteria. Types: Monotrichous Amphitrichous Lophotrichous Peritrichous ...how are they different - Answer-MONOtrichous - one flagellum AMPHItrichous - 2 flagellum (@ each end) LOPHOtrichous - 2 or more flagellum (@one end) PERITrichous - flagella surrounds entire cell ____ are involved in adherence, and appear as sticky projects. They also facilitate ____ - Answer-- Pilli - transfer of genetic material What are the three major structures found inside the bacterial cell membrane? - Answer-Nuclear Region Plasmids Ribosomes major targets for antibiotics: - Answer-cell wall ribosome Plasmids (end of lecture 2) - AnswerEssay Question 1: If you want to identify DNA polymerases like those used in polymerase chain reaction (PCR) for amplification of DNA, from which natural environment would you try to isolate the producers? Explain your answer. - AnswerWhat macronutrients are essential for microbes? (hint: they make protein, fat, carbs, & DNA!) -- what micronutrients? - Answer-- C, O, H, N, P, S - Mg, Fe, K - cobalt, copper, manganese, nikel, zinc, molybdenum Autotroph vs Heterotroph - Answer-Autotroph: Uses/fixes CO2 directly from the environment