L1-3 Flashcards
(48 cards)
What are the six main categories of microbes?
Bacteria, Archaea, Fungi, Algae, Protozoa, Viruses
Which microbes are considered acellular?
Viruses
What distinguishes prokaryotes from eukaryotes?
Prokaryotes lack a nucleus and internal organelles, while eukaryotes have both.
What are the three domains in the Universal Phylogenetic Tree?
Bacteria, Archaea, and Eukarya
Which microbe is a common single-celled fungus?
Saccharomyces cerevisiae (budding yeast)
What is a distinguishing feature of Archaea?
They often inhabit extreme environments and have unique metabolic activities.
What staining method is used to classify bacteria by cell wall?
Gram staining
What is the size range of typical microbial cells?
1–10 µm for most, but can range from 0.5 µm to 750 µm
What gene is commonly used to classify bacterial diversity?
16S rRNA gene
What is binary fission?
A method of asexual reproduction where one cell divides into two identical daughter cells.
What is vertical gene transfer?
The transmission of genetic material from parent to offspring.
What are the three mechanisms of horizontal gene transfer?
Transformation, Conjugation, Transduction
What is transformation in bacteria?
Uptake and integration of free DNA into the bacterial chromosome. DNA cell must be competent
Includes Naked DNA
Transposons
plasmids
What is conjugation?
DNA transfer between bacteria via a pilus= bacterial mating , often involving plasmids, conjugative transporons
and intergrons .
What is transduction?
Transfer of bacterial DNA by a bacteriophage.
transduction can involve movement of phage DNA and host
cell DNA
Generalised transduction
(random DNA encapsulation)
Specialised transduction
(lysogenic integrated phage,
specific encapsulation of adjacent DNA
What experiment proved DNA is the material of transformation?
Avery-MacLeod-McCarty experiment using DNase
Why is horizontal gene transfer important?
It introduces genetic diversity and contributes to antibiotic resistance.
What is generation time?
The time required for a microbial population to double.
What are the five phases of microbial population growth?
Lag- adjustment of cell metabolism to new conditions,
Exponential- cell
growth at max.
rate possible in
the medium
chosen
, Deceleration- limiting supply of
one nutrient or
accumulation of
toxic metabolites, Stationary- no net growth,
at least one nutrient
depleted - possible growth
at expense of cell death
and lysis;
, Death- decline of viable
cells due to exhaustion of
energy or accumulation of
toxic byproducts.
5
What affects bacterial growth rate?
Species, nutrients, temperature, pH, and osmolarity
What is optical density (OD650)?
A light scattering method to estimate bacterial growth
What is the specific growth rate (μ)?
The rate of increase in cell number per unit time during exponential phase
What is a chemostat?
A continuous culture system where fresh medium is constantly added and culture removed
How do weak acids act as preservatives?
They lower intracellular pH by diffusing into cells and dissociating
