Microbial Growth + Biofilms Flashcards
Which one of the statements is true?
1) Unlike all living things, microorganisms do not need sources of carbon and energy to grow.
2) Due to the PLASTICITY OF MICROBIAL GENOMES, bacteria have evolved ingenious strategies to find, acquire and metabolize wide source of food
3) Controlling bacterial cell growth is impossible; understanding how bacteria use food to increase cell mass and cell number can do only so much.
2 is true!
Like all living things, microorganisms DO need sources of carbon and energy to grow.
Understanding how bacteria use food to increase cell mass and cell number ENABLES US to control bacterial growth! It can even allow us to MANIPULATE them to make useful products!
Fill in the blanks:
Essential nutrients are those that MUST be supplied from the _____________.
______ nutrients are needed in large amounts (major elements in cell macromolecules and cations for protein function).
______ nutrients are needed in small amounts (trace elements needed 2 enzyme function).
Environment
Macro; Micro
(T/F) Majority, but not all, of Earth’s life-forms are carbon-based.
False. ALL of Earth’s life forms are carbon based!
Which organisms fix CO2 and assemble into organic molecules, and which ones use performed organic molecules to build biomass?
A) Photoautotrophs
B) Chemoorganoheterotrophs
C) Chemolithoautotrophs
D) Photoheterotrophs
All autotrophs fix CO2 and assemble into organic molecules and all heterotrophs use performed organic molecules (to make more).
Membranes separate insides and outside of a cell, what are the three ways SELECTIVE PERMEABILITY is achieved?
1) Substrate-specific carrier proteins (PERMEASES)
2) Dedicated NUTRIENT-BINDING PROTEINS that patrol the periplasmic space
3) Membrane-spanning PROTEIN CHANNELS/PORES (transporters)
What are three sources of energy that can cause a molecule to go against its concentration gradient (active transport)?
ATP
Proton motive force (PMF)
PEP (high energy molecules in bacteria)
What is the largest family of energy-driven transport systems?
ATP-binding cassette superfamily (ABC transporters)!
(T/F) ABC transporters are found in all three domains of life, and over 200+ different systems identified in eukaryotes for organic and inorganic compounds.
False! ABC transporters are found in all three domains of life, but over 200+ different systems identified in PROKARYOTES for organic and inorganic compounds.
Match the following terms regarding ABC transporters:
1) Gram-negatives
2) Gram-positives and Archaea
3) Uptake ABC transporters
4) Efflux ABC transporters
A) used as multi drug efflux pumps, throw drugs OUT of the cell
B) employ PERIPLASMIC BINDING PROTEINS
C) critical for transporting nutrients INTO the cell
D) employ substrate-binding proteins on EXTERNAL SURFACE OF CYTOPLASMIC MEMBRANE
Gram-negatives employ PERIPLASMIC BINDING PROTEINS
Gram-positives and Archaea employ substrate-binding proteins on EXTERNAL SURFACE OF CYTOPLASMIC MEMBRANE
Uptake ABC transporters critical for transporting nutrients INTO the cell
Efflux ABC transporters, used as multi drug efflux pumps, throw drugs OUT of the cell
Match the following steps of an uptake ABC transporter transporting a solute inside a gram negative cell:
1) Step 1
2) Step 2
3) Step 3
A) When the solute binds to the membrane transporter, conformational change activates ATPase.
B) After ATP hydrolysis, the dimer opens and releases the solute to the cytoplasm.
C) Solute binds to its cognate periplasmic binding protein, and the complex then binds to the membrane transporter
Step 1: Solute binds to its cognate periplasmic binding protein, and the complex then binds to the membrane transporter
Step 2: When the solute binds to the membrane transporter, conformational change activates ATPase.
Step 3: After ATP hydrolysis, the dimer opens and releases the solute to the cytoplasm.
(T/F) Microbes exist in complex, multispecies communities in nature and they can be grown together for detailed studies.
False!Microbes exist in complex, multispecies communities in nature but they have to be grown SEPARATELY in PURE CULTURE!
(T/F) After almost 140 years of trying, we have succeeded in culturing less than 1% of the microorganisms around us. The vast majority has yet to be tamed.
True!
Match the following culture media bacteria are grown in and what it is used for:
1) Liquid/broth
2) Solid (gelled with agar)
A) Useful for trying to SEPARATE MIXED CULTURES from clinical specimens or natural environments
B) Useful for studying the growth characteristics of a PURE CULTURE
1) Liquid/broth: Useful for studying the growth characteristics of a PURE CULTURE
2) Solid: Useful for trying to SEPARATE MIXED CULTURES from clinical specimens or natural environments
What are obligate intracellular bacteria? Give an example.
Bacteria that are unculturable! They absolutely require an eukaryotic host to survive and replicate.
Epidemic typhus fever bacteria (Rickettsia Prowazekii) can only grow within cytoplasm of eukaryotic cells and nowhere else.
*some can be cultured within host cell
Match the following terms regarding the growth cycle to their definition:
1) Growth
2) Binary fission
3) Septum
4) Generation time
A) Partition between dividing cells, pinches off between two daughter cells
B) Cell division following enlargement of a cell to twice its minimum size
C) Time required for microbial cells to DOUBLE in numbers; depends on NUTRITIONAL, GENETIC factors and TEMPERATURE
D) Increase in the number of cells
1) Growth: increase in the number of cells
2) Binary fission: cell division following enlargement of a cell to twice its minimum size
3) Septum: partition between dividing cells, pinches off between two daughter cells
4) Generation time: time required for microbial cells to DOUBLE in numbers; depends on NUTRITIONAL, GENETIC factors and TEMPERATURE
(T/F) During cell division, each daughter cell receives a chromosome and sufficient copies of all other cell constituents to exist as an independent cell.
True!
Briefly describe how cell division by septation occurs, also the role of FtsZ and Divisome.
After DNA synthesis terminates, a septum grows inward from the sides of the cell.
FtsZ circles around the septum and directs its growth (SEPTUM FORMATION). When FtsZ’s ring contracts, the cytoplasm of the two daughter cells separate.
Cell wall forms and the cell finally separates as individual cells.
Divisome is the protein complex that manages septation, which Ftsz is a part of.
What kind of cell division leads to equal products? How common is this?
BINARY FISSION; most bacteria
What kinds of cell division lead to unequal products?
Budding division from UNEQUAL CELL GROWTH or ASYMMETRIC GROWTH.
1) Simple budding - one side of the cell is new material, that one daughter cell is composed of.
2) Budding from hyphae
3) Cell division of stalked organism
4) Polar growth without differentiation of cell size
What are stalks, hyphae and appendages that budding bacteria form?
Cytoplasmic extensions
What is a closed culture? What is it also known as?
Culture with LIMITED NUTRIENTS. Also known as BATCH culture.
Match the phases of a bacterial growth curve of a closed culture:
1) Phase 1
2) Phase 2
3) Phase 3
4) Phase 4
A) Death/decline phase
B) Lag phase
C) Log phase
D) Stationary phase
Phase 1 - Lag phase
Phase 2 - Log phase
Phase 3 - Stationary phase
Phase 4 - Death/decline phase
Match the phases of a bacterial growth curve of a closed culture to their definition:
1) Lag phase
2) Log phase
3) Stationary phase
4) Death/decline phase
A) Exponential decrease in number of bacterial cells
B) No increase in number of living bacterial cells
C) Exponential increase in number of living bacterial cells
D) Plateau in number of living bacterial cells; RATE OF CELL DIVISION = RATE OF CELL DEATH
1) Lag phase: No increase in number of living bacterial cells
2) Log phase: Exponential increase in number of living bacterial cells
3) Stationary phase: Plateau in number of living bacterial cells; RATE OF CELL DIVISION = RATE OF CELL DEATH
4) Death/decline phase: Exponential decrease in number of bacterial cells
Why are log measurements used in bacterial growth curves?
Number of cells increase rapidly, and they double at the same amount of time in their best growth phase (log phase); log scale helps to visualize the complete curve.
When plotted on an ARITHMETIC SCALE (equal spacing for x and y values), the growth rate resembles a ________.
When plotted on a SEMILOGARITHMIC SCALE, (y-value are logarithmic, x-values are arithmetic), the growth rate appears _______.
Curve
Linear
What is a continuous culture?
What does the population in a continuous culture achieve? What does this allow study of?
Continuous culture - bacteria grown in a culture where the nutrients are not limited!
The bacterial population achieves a STEADY STATE. This allows DETAILED study of BACTERIAL PHYSIOLOGY.
