Microbiology Concepts from Brock Biology of Microorganisms

These flashcards cover core concepts, definitions, and facts from the lecture notes on microbiology, particularly focusing on cell types, growth, structure, and environmental effects.

What are the three domains of life defined by comparative ribosomal RNA sequencing?

Bacteria, Archaea, and Eukarya.

What type of bacteria have only a few layers of peptidoglycan?

Gram-negative bacteria.

What type of bacteria have several layers of peptidoglycan?

Gram-positive bacteria.

What is the primary function of the cytoplasmic membrane?

To act as a permeability barrier preventing leakage of cytoplasmic metabolites.

What is the process by which most microorganisms grow?

Binary fission.

What characteristic type of growth pattern do microbial populations show?

Exponential growth.

What are acidophiles?

Organisms that grow best at low pH.

What are alkaliphiles?

Organisms that grow best at high pH.

What is the cardinal temperature?

The minimum, optimum, and maximum temperatures at which an organism grows.

What types of metabolic processes do aerobes require?

Aerobic respiration.

What type of organisms can survive with or without oxygen?

Facultative organisms.

What is a major environmental factor controlling microbial growth?

Temperature.

What is a halophile?

Microorganisms that require high levels of salts for growth.

What are microaerophiles?

Aerobes that can use oxygen only at levels lower than atmospheric levels.

How can microbial growth be measured?

By the change in the number of cells over time.

What is the difference between direct counting and viable cell counts?

Direct counting measures total cells while viable cell counts measure only living cells.

What is required for the anaerobic growth of microorganisms?

Special techniques to prevent exposure to oxygen.

What toxic form of oxygen can be neutralized by catalase?

Hydrogen peroxide.

What are the two structural types of cells recognized?

Prokaryotic and eukaryotic cells.

What is the morphology of bacteria that are called spirochetes?

They have a spiral shape.

What barrier do halophiles maintain in order to grow?

Reduced water potential.

What do integral membrane proteins anchor to?

The cytoplasmic membrane.

What is the typical shape of cocci?

Spherical.

What phenomenon describes the growth pattern of microorganisms shown on a logarithmic scale?

Exponential growth.

How do gram-negative bacteria differ from gram-positive in terms of cell wall structure?

Gram-negative bacteria have an outer membrane and less peptidoglycan.

What are the two methods for measuring microbial growth from a dilution series?

Spread-plate and pour-plate methods.

What does the presence of peptidoglycan indicate in bacteria?

It suggests whether they are gram-positive or gram-negative.

What is a significant factor affecting microbial growth apart from temperature?

pH levels.

What is the relationship between enzyme activity and temperature in microorganisms?

Enzymatic reactions occur at maximal rates at optimum temperature.

What is the significance of establishing a standard curve in turbidity measurements?

To relate direct cell counts to turbidity values.

What do bacteria use to transport nutrients across their cytoplasmic membrane?

The proton motive force, phosphoenolpyruvate and ATP.

What do facultative anaerobes exhibit?

They can grow in both the presence and absence of oxygen.

What cell growth measurements assess only living, reproducing populations?

Viable cell counts.