Bacterial Growth, Metabolism and Respiration Flashcards
The bacteria that grow best in a low-oxygen environment are called?
-Anaerobe
-Aerobs
-Aerotolerant
-Microaerophile
Quiz question
Microaerophile
Microerophilic bacteria need oxygen as they can only do aerobic respiration however, normal atmospheric levels of O2 may inhibit them. Microaerophilic bacteria grow better under reduced oxygen (usually 5-10%) and increased CO2 (usually 10%).
Which one of the following statements about bacterial endospores is FALSE?
-They are highly resistant to heat and desiccation
-Sporulation is triggered by favourable growth conditions
-They produce calcium dipicolinate
-Spore shape and position is characteristic of species
-The spore’s outer protein coat is secreted by the mother cell
Quiz question
Sporulation is triggered by favourable growth conditions
Endospores are produced mainly by Gram-positive bacteria of the phylum Firmicutes, such as Bacillus and Clostridium. These types of bacteria have two phases to their life cycle, vegetative cells and endospores. When vegetative cells of these genera are exposed to harsh environmental conditions, they undergo a process called sporulation. The endospores generated are metabolically inactive and highly resistant to extreme conditions such as high temperatures, drying out, freezing, radiation, chemicals and many other environmental conditions that would easily kill a vegetative cell. The endospores have a peculiar structure, and the main components are an outer proteinaceous coat and core composed by DNA, ribosomes and large amounts of dipicolinic acid.
What is the role of FtsZ protein during the bacterial cell cycle?
-Promote elongation of the cell
-Promote chromosomal replication
-Forms a ring at the cell division site
-None of the above
Quiz question
Forms a ring at the cell division site
The FtsZ protein is a tubulin-like GTPase present in most of the major groups of bacteria. The FtsZ polymerize into a ring structure (Z-ring) on the inner part of the cytoplasmic membrane and initiate cell division.
What is the difference between simple and facilitated diffusion? Why cant bacteria only use diffusion to aquire nutrients?
Passive transport
Facilitated diffusion = pores or channels, hydrophilic molecules need channel/carrier proteins like glucose
Simple diffusion = small hydrophobic molecules
Explain how ion-coupled transport works
Active transport
Driven by electrochemical trans-memebrane proton gradient
Symport= co transport in same direction
Antiport= ion and substrates move in opposite direction
Explain how group translocation works
aka phosphotransferase system (PTS)
Substrate is phosphorylated during transport, and energy comes from the PEP being passed along chain of enzymes
How does ABC transport work?
ABC= ATP-binding cassette
Hydrolysis of ATP drives transport. Molecule binds to a binding protein, and then binds to top of channel. During ATP hydrolysis channel undergoes conformational change and lets molecule through
How do adaptaions in metabolic pathways allow bacteria to survive and proliferate within a host?
- Adaptation to varying supply of carbon sources in diff niches
- Glucongenesis and TCA cycle essential for E. coli UTI
Whats the difference between respiration and fermentation?
respiration= coupled redox reactions to move protons across membrane to then generate ATP (Krebs, ETC)
Fermentation= oxidises organic molecules. Does not use Krebs or ETC. Does NOT use oxygen.
- pyruvate broken down via NADH-> NAD+
Whats the difference between aerobic and anaerobic respiration?
Aerobic= Final electron receptor is oxygen (O2)
Anaerobic= final electron receptor is non-O2 inorganic compounds ie NO3, SO4 2, CO3 2
- less ATP than aerobic bc only part of Krebs works under anaerobic conditions
What bacteria is an example of how bacteria can adapt their metabolism during infection?
Mycobacterium tuberculosis.
- switch from carb based metabolism to lipid based because host cell lipids are essential carbon sources, and this way you avoid carbon loss during oxidation in the TCA cycle
What is binary fission?
Like how does it work
- cell elongates
- chromosome duplication
- septum wall grows inward and the chromosomes are pulled apart
- septum is synthesised and cell membrane start to seperate cell chambers
Whats the role of Fts and Min proteins during binary fission?
Fts = filamentous temperature sensitive
Fts proteins interact to form the Divisome-> the thingy that forms the septal ring that divides the cell during binary fission
Min proteins form a bipolar gradient that helps localize the Fts ring
What factors inhibit bacterial growth/bacterial cell cycle?
Heat shock, starvation, sporulation- inhibit going into S phase/ replication initation
Sudden starvation- inhibit S phase/ replication elongation
DNA damage, fast growth, sporulation- inhibit entering G2/ Z-ring formation
DNA damage- inhibits cell division
What are the steps in endospore formation and what enviromental factors triggers it?
- mother cell secretes protein coat (calcium dipicolinate) to protect spore, then lyses to release spore, spore germinates when conditions become favourable for growth
- sporulation triggered by adverse conditions
