Microbiology Exam One (Chapter 1, 3, 7)

Which domain contains organisms whose cell walls typically contain peptidoglycan?

Bacteria

Which statement correctly describes Archaea regarding peptidoglycan?

They lack peptidoglycan in their cell walls.

Which infectious agent consists solely of protein?

Prion

What is a viroid primarily composed of?

RNA

What is the major difference between prokaryotic and eukaryotic cells?

Eukaryotes have a membrane-enclosed nucleus.

Who used the swan-neck flask experiment to disprove spontaneous generation?

Louis Pasteur

What was the major conclusion from Pasteur's swan-neck flask experiment?

Microorganisms come from existing microorganisms rather than appearing spontaneously.

Who developed an antiseptic surgical system that reduced postoperative infections?

Joseph Lister

Robert Koch established a relationship between Bacillus anthracis and which disease?

Anthrax

What is the correct order of Koch's postulates?

1. Find organism 2. Isolate in pure culture 3. Inoculate host 4. Re-isolate organism

What is a major limitation of Koch's postulates?

Some microorganisms cannot be grown in pure culture.

Edward Jenner is associated with vaccination against which disease?

Smallpox

What is a spherical bacterial cell called?

Coccus

What are cocci arranged in chains called?

Streptococci

What are cocci arranged in grape-like clusters called?

Staphylococci

Which bacterial shape resembles a comma?

Vibrio

What term describes a bacterium that can vary in shape?

Pleomorphic

What is the primary function of bacterial ribosomes?

Protein synthesis

What is the size of bacterial and archaeal ribosomes?

70S

Which bacterial structure contains the chromosome?

Nucleoid

What are plasmids?

Extrachromosomal DNA molecules

What is a plasmid called that can integrate into the bacterial chromosome?

Episome

Which type of bacterium has a thick peptidoglycan layer?

Gram-positive

Which structure is characteristic of the Gram-negative outer membrane?

LPS (Lipopolysaccharide)

Lipid A is a component of which membrane structure?

LPS (Lipopolysaccharide)

Lipid A acts as what type of toxin?

Endotoxin

What color do Gram-positive bacteria appear after Gram staining?

Purple

What color do Gram-negative bacteria appear after Gram staining?

Pink/red

What is the main function of the bacterial cell wall?

Protection against osmotic stress and maintenance of cell shape

In which direction does passive diffusion move substances?

High to low concentration

Which process uses a carrier protein but does NOT require energy?

Facilitated diffusion

How does active transport move a substance relative to its concentration gradient?

Against its concentration gradient

What energy molecule do ABC transporters directly use?

ATP

In symport, in which direction do two substances move?

In the same direction

In antiport, in which direction do two substances move?

In opposite directions

Which transport mechanism chemically modifies a substance while it enters the cell?

Group translocation

Where does water move when a bacterial cell is placed in a hypotonic environment?

Into the cell

What process occurs when water moves out of a bacterial cell in a hypertonic environment?

Plasmolysis

Which bacterial structure is especially important for attachment to surfaces?

Fimbriae

What process requires sex pili?

Conjugation

What are the three major parts of a bacterial flagellum?

Filament, hook, basal body

What is a bacterium called that has flagella distributed across its entire surface?

Peritrichous

What type of movement does counterclockwise flagellar rotation produce?

Run

What is chemotaxis?

Movement in response to chemical attractants or repellents

What is the primary function of a bacterial endospore?

Survival under harsh conditions

What harsh conditions can bacterial endospores resist?

Heat, radiation, and desiccation

What is the correct sequence for an endospore returning to a vegetative cell?

Activation -> Germination -> Outgrowth

What is an organism that obtains energy from light called?

Phototroph

What is an organism that obtains carbon from CO2 called?

Autotroph

By what mechanism do most bacteria reproduce?

Binary fission

Which protein forms the Z ring during bacterial cell division?

FtsZ

What is the correct order of the major bacterial growth phases?

Lag -> Log/exponential -> Stationary -> Death

During which growth phase are bacteria adjusting to their new environment?

Lag phase

During which phase is bacterial population growth fastest?

Log/exponential phase

What causes a bacterial culture to enter stationary phase?

Nutrient limitation, toxic waste accumulation, and limited oxygen

What does generation time mean?

Time required for a population to double

If a culture starts with 100 cells, how many cells are present after 4 generations?

1,600 cells

What is an organism that grows best around neutral pH called?

Neutrophile

Which temperature group grows best between approximately 20°C and 45°C?

Mesophiles

What is an organism that strictly REQUIRES oxygen called?

Obligate aerobe

Which organism grows with or without O2, but better when O2 is present?

Facultative anaerobe

What oxygen level does a microaerophile require?

Lower concentrations of oxygen

Which enzyme helps bacteria protect themselves from reactive oxygen species?

Catalase

What term describes microorganisms attached to a surface?

Sessile

What term describes free-floating microorganisms?

Planktonic

What does EPS stand for in a biofilm?

Extracellular Polymeric Substance

What does quorum sensing allow bacteria to do?

Communicate in a density-dependent manner

AHL is an autoinducer associated primarily with which organisms?

Gram-negative organisms

What is a medium called in which every ingredient has a known chemical composition?

Defined/synthetic medium

Which agent is commonly used to solidify microbiological media?

Agar

What is the function of a selective medium?

Allows certain organisms to grow while inhibiting others

What is the function of a differential medium?

Distinguishes between different groups of microorganisms

How is MacConkey agar classified regarding selectivity and differentiation?

Both selective and differential

What group of bacteria does MacConkey agar select for?

Gram-negative bacteria

What metabolic property does MacConkey agar differentiate?

Lactose fermenters vs nonfermenters