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Bacterial Cell Structure and Function, Exams of Physiology

University of California-RiversidePhysiology

A comprehensive overview of the various structures and functions of bacterial cells. It covers topics such as the use of different microscopy techniques to observe bacterial cells, the composition and characteristics of the cell envelope, the different types of bacterial motility, the various metabolic classes of bacteria, the stages of microbial growth, and the mechanisms of bacterial growth control. The document also delves into the processes of dna replication, transcription, and translation in bacteria, as well as the regulation of gene expression and protein activity. Additionally, it discusses the challenges faced by gram-negative bacteria in transporting molecules across their cell membranes and the different secretion systems employed by these bacteria. A comprehensive understanding of the fundamental aspects of bacterial cell biology, making it a valuable resource for students and researchers in the field of microbiology.

Typology: Exams

2023/2024

Available from 08/28/2024

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BMSC 210 Midterm 1 Review | 100% Correct
Answers | Verified | Latest 2024 Version
Describe Koch's postulates and the significance of his experiment - ✔✔Koch's postulates: with the use of
anthrax provided a basis for Germ Theory.
the experiment: extract blood from diseased individual
grow culture
put culture into healthy individual, develop disease
extract this blood, culture it to show same results
Describe the importance of Louis Pasteur and the significance of his swan-neck flask experiment -
✔✔Disproved spontaneous generation (miasma)
the swan-neck made contamination- and growth- visible
Why are viruses not considered living? - ✔✔they do not perform metabolism and they are parasitic
(cannot grow on own), also missing cytoplasm
How do light microscopes work? What light microscopes did we learn about? - ✔✔Use of light to make
observation, can see live specimen
Brightfield: absorb and scatter light, use gram staining (due to lack of pigment), can observe motility
Darkfield: specimen deflect and scatter light
Phase-Contrast: very detailed, high contrast
Differential Interference Contrast: #D w/ use of 2 light beams
Fluorescence: use of fluorochromes, UV light, and excitation (confocal: 3D fluorescence)
How do electron microscopes work? What types have we learned about? - ✔✔Use of electrons and
magnets, higher mag/res, but specimen must be dead
TEM: go through specimen, can see inside
SEM: electrons bounce off
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BMSC 210 Midterm 1 Review | 100% Correct

Answers | Verified | Latest 2024 Version

Describe Koch's postulates and the significance of his experiment - ✔✔Koch's postulates: with the use of anthrax provided a basis for Germ Theory. the experiment: extract blood from diseased individual grow culture put culture into healthy individual, develop disease extract this blood, culture it to show same results Describe the importance of Louis Pasteur and the significance of his swan-neck flask experiment - ✔✔Disproved spontaneous generation (miasma) the swan-neck made contamination- and growth- visible Why are viruses not considered living? - ✔✔they do not perform metabolism and they are parasitic (cannot grow on own), also missing cytoplasm How do light microscopes work? What light microscopes did we learn about? - ✔✔Use of light to make observation, can see live specimen Brightfield: absorb and scatter light, use gram staining (due to lack of pigment), can observe motility Darkfield: specimen deflect and scatter light Phase-Contrast: very detailed, high contrast Differential Interference Contrast: #D w/ use of 2 light beams Fluorescence: use of fluorochromes, UV light, and excitation (confocal: 3D fluorescence) How do electron microscopes work? What types have we learned about? - ✔✔Use of electrons and magnets, higher mag/res, but specimen must be dead TEM: go through specimen, can see inside SEM: electrons bounce off

explain how gram staining works? - ✔✔1) stain with crystal violet (cells purple)

  1. add iodine (cells purple)
  2. de-colorize with alcohol (G- lose colour)
  3. counter-stain with safranin (G- stay purple, G+ pink) What is the cell envelope? What is it composed of? - ✔✔Cell envelope: layers around the cytoplasm
  • Cytoplasmic membrane: selectively permeable barrier
  • Cell Wall: prevent osmotic lysis and maintain shape Bacteria: made of peptidoglycan (lysozyme-sensitive) G+: thick, presence of techoic and lipotechoic acid, interbridge G-: thin so presence of outer membrane, presence of lipopolysaccharide (LPS)
  • S-Layer: outermost layer, protein mesh Bacteria: protection/adhesion archaea: act as cell wall (keep shape, prevent osmotic lysis)
  • Capsule & Slime Layer: sticky polysaccharide coat capsule: tight, strong attachment slime layer: loose what is the difference between Bacteria and Archaea cell walls? - ✔✔cell walls of bacteria are made of peptidoglycan which is lysozyme-sensitive; archaea are lysozyme insensitive what are acid fast bacteria? - ✔✔G+ w/ wax coat differentiate between G+ and G- bacteria - ✔✔G+: have thick peptidoglycan wall and interbridge presence of techoic and lipotechoic acid G-: have outer membrane presence of LPS

it is asymmetric division into a forespore and mother cell, before the lysis of the mother cell to a free endospore What is metabolism? - ✔✔the sum of all chemical reaction- anabolism (all biosynthetic reactions) and catabolism What are the metabolic classes? - ✔✔Phototroph: energy from light Chemotroph: energy from chemicals

  • chemooragnotroph: energy from organic chemicals chemoorganoheterotroph: carbon from organic compound
  • chemolithotroph: energy from inorganic chemicals chemolithoautotroph: carbon from CO describe the metabolic needs of a(n): photoautotroph chemoorganoheterotroph chemolithoautotroph - ✔✔photoautotroph: energy from light, C from CO chemoorganoheterotroph: energy from chemicals, use of organic chemicals, and carbon from organic compounds chemolithoautotroph: energy from chemicals, use of inorganic chemicals, C from CO who uses fermentation? how do you know this? - ✔✔chemoorganotrophs use fermentation recall that fermentation uses only organic compounds why is fermentation not classified as anaerobic respiration? - ✔✔no respiratory chain (no external electron acceptor) compare oxidative and substrate-level phosphorylation, Which is preferred and why? - ✔✔oxidative phosphorylation uses an external terminal electron acceptor and sub-lvl has an internal electron acceptor. Ox is preferred because it generates more ATP

True or false: both aerobic and anaerobic respiration can make use of both organic and inorganic compounds - ✔✔true differentiate between aerobic and anerobic respiration - ✔✔aerobic: oxygen as terminal electron acceptor anaerobic: terminal electron acceptor is not oxygen compare oxygenic and anoxygenic photorophic metabolism - ✔✔oxy: water is an electron donor, oxygen is waste product anoxy: water is not electron donor, no oxygen differentiate between differential and selective medium and give an example of each - ✔✔differential: distinguishes between types ex) pH indicator selective: selects for something specific ex) antibiotics describe the oxygen requirements of each: obligate aerobe facultative aerobe microaerobe obligate anaerobe aerotolerant - ✔✔ob a: need oxygen, performs a resp fac a: does best with oxygen (ox phos), performs a/an resp, ferm micro a: needs small amounts of oxygen, performs a resp ob an: oxygen lethal, performs an resp or ferm aerotolerant: can withstand oxygen but does not do better with it, performs fermentation

Define Minimum Inhibitory Concentration (MIC)? - ✔✔concentration of antimicrobial needed to stop growth What is the job of DNA polymerase? - ✔✔bond the new nucleotides together what is the job of DNA helicase? - ✔✔initiate replication by unwinding DNA at REPLICATION FORK Describe the process of DNA replication - ✔✔DnaA binds and opens at OriC helicase unwinds Primase makes primer DNA polymerase synthesizes DNA exonuclease removes primer DNA ligase seals nicks true or false: transcription yields RNA - ✔✔true What is a sigma factor? - ✔✔a protein that associates with RNA polymerase that facilitates binding to specific promoters what are two methods of transcription termination? - ✔✔1) Stem-Loop formation: inverted loop rich in GC, causes RNA polymerase to stop

  1. Rho dependant: causes RNA release In terms of replication, what are some similarities between bacteria and archaea? Archaea and Eukarya?
  • ✔✔BA: similar termination and processing (couples transcription and translation), polycistronic AE: similar RNA polymerase and promoters Define polycistronic - ✔✔more than one gene on an mRNA

Describe the Sec and Tat systems - ✔✔transport systems of protein secretion, initiated by a signal sequence Sec: transport unfolded proteins Tat: transport folded proteins why does G- pose a challenge in transporting proteins into it? How do you propose getting past this challenge? - ✔✔there is an extra membrane (periplasm)

  • use sec or tat system: attach signal sequence to get past membrane Knowing what you do about transport across membranes as well as membrane types, list the following bacteria from easiest to hardest in transporting molecules across the membrane - ✔✔G+ G- acid-fast Describe the following G- secretion systems: Type I Type II Type V - ✔✔Type I: ABC transporter, one step (similar to G+) Type II: sec and tat dependent (2 step), secrete from periplasm Type V: sec and tat dependent (2 step), secrete from periplasm, autotransporter (direct) Describe the following G- secretion systems: Type III Type IV Type VI - ✔✔Type III: syringe-like, inject proteins into eukaryotic cells Type IV: pilus-like, TRANSFER DNA Type VI: spear-likr, pierce membrane, bacteri-bacteria competition

What is a riboswitch? - ✔✔RNA that acts as a repressor and stops transcription describe attenuation - ✔✔rate of translation limits rate of transcription, resulting in premature termination ex. if too fast, stops describe the methods of regulating protein activity discussed in class - ✔✔feedback inhibition: product inhibits its production covalent modification: change in enzyme activity dye to small molecule ex. phosphorylation sigma and anti-sigma factors: if sigma factors recruit RNA polymerase, anti-sigma factors binding to sigma factors sequestor it (inactivate), but will degrade if stress is sensed what happens if you block: replication elongation segregation z-ring formation - ✔✔replication: no division elongation: cell w/ multiple chromosomes segregation: elongated cell w/ multiple chromosomes z-ring formation: elongated segregated cell recall that sporulation happens in the presence of stress as a protective mechanism, and that it requires a lot of energy. Where does it get this energy? - ✔✔cannibalize vegetative cells, lyses others with toxins to eat them What is biofilm formation? what are the steps? - ✔✔free planktonic cells become an attached community. done w/ quorum sensing

  1. attachment: few motile cells to a surface
  2. colonization: communication, growth
  3. development: of matrix
  1. dispersal: triggered by environmental factors what is a persistent cell? Why don't antibiotics kill it? - ✔✔Persistent cells are inactive (dormant) and antibiotics only kill active cells. Therefore, persistent cells do not die, but remain sensitive What controls transcription? When do they bind? - ✔✔Activators and repressors (block/allow DNA polymerase and sigma factors) A: before promoter R: after promoter (on operator)