BIOL 2041- (exam 1 part 2)

What is the difference between prokaryotes and eukaryotes?

Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have both.

Which domains contain prokaryotes?

Bacteria and Archaea.

Which domain contains eukaryotes?

Eukarya.

Do prokaryotes have membrane-bound organelles?

No.

Do prokaryotes have a nucleus?

No.

Do eukaryotes have a nucleus?

Yes.

Do eukaryotes have membrane-bound organelles?

Yes.

Which cells are generally smaller, prokaryotic or eukaryotic?

Prokaryotic cells.

Which cells generally divide by binary fission?

Prokaryotic cells.

Which cells divide by mitosis?

Eukaryotic cells.

Which cells contain 80S ribosomes?

Eukaryotic cells.

Which cells contain 70S ribosomes?

Prokaryotic cells.

What does the plasma membrane do?

Controls what enters and leaves the cell.

What is the cytoplasm?

The gel-like interior of the cell where cellular processes occur.

What is the nucleoid?

The region containing DNA in a prokaryotic cell.

What shape is bacterial DNA usually?

A single circular chromosome.

What are plasmids?

Small circular DNA molecules separate from the chromosome.

What are plasmids commonly used for?

Carrying genes such as antibiotic resistance genes.

What are ribosomes responsible for?

Protein synthesis.

What is the function of a bacterial cell wall?

Provides shape and protection against osmotic pressure.

Which molecule gives bacterial cell walls strength?

Peptidoglycan.

Do Archaea have peptidoglycan?

No.

Do animal cells have cell walls?

No.

Do plant cells have cell walls?

Yes.

What is the glycocalyx?

A sticky outer coating surrounding some bacteria.

What are the two forms of a glycocalyx?

Capsule and slime layer.

What is a capsule?

A well-organized glycocalyx firmly attached to the cell.

What is a slime layer?

A loose glycocalyx easily removed from the cell.

What are capsules used for?

Protection from phagocytosis and attachment to surfaces.

What is a biofilm?

A community of microorganisms attached to a surface.

What are fimbriae?

Short hair-like structures used for attachment.

What are pili?

Longer appendages used mainly for DNA transfer during conjugation.

What is conjugation?

Transfer of DNA between bacteria through a pilus.

What are flagella used for?

Motility.

What protein makes up bacterial flagella?

Flagellin.

What powers bacterial flagella?

The proton motive force.

What does monotrichous mean?

One flagellum.

What does amphitrichous mean?

One flagellum at each end.

What does lophotrichous mean?

A tuft of flagella at one or both ends.

What does peritrichous mean?

Flagella distributed over the entire cell.

What is bacterial chemotaxis?

Movement toward or away from a chemical stimulus.

What is a run?

Flagella rotate counterclockwise and the bacterium moves in a straight line.

What is a tumble?

Flagella rotate clockwise and the bacterium changes direction.

When does a bacterium perform longer runs?

When moving toward a favorable environment.

What is an endospore?

A dormant, highly resistant survival structure.

Do endospores function in reproduction?

No.

What genera commonly produce endospores?

Bacillus and Clostridium.

What triggers endospore formation?

Harsh environmental conditions.

What is the vegetative cell?

The active, growing bacterial cell.

What is binary fission?

The process by which prokaryotes reproduce.

Which stain differentiates bacteria based on cell wall structure?

The Gram stain.

Who developed the Gram stain?

Hans Christian Gram.

What color are Gram-positive bacteria after Gram staining?

Purple.

Why do Gram-positive bacteria stain purple?

Their thick peptidoglycan retains crystal violet.

What color are Gram-negative bacteria after Gram staining?

Pink.

Why do Gram-negative bacteria stain pink?

Their thin peptidoglycan loses crystal violet and takes up safranin.

Which bacteria have an outer membrane?

Gram-negative bacteria.

Which bacteria have teichoic acids?

Gram-positive bacteria.

What is lipopolysaccharide (LPS)?

A component of the Gram-negative outer membrane.

Which part of LPS is an endotoxin?

Lipid A.

Which bacteria are generally more resistant to antibiotics because of an outer membrane?

Gram-negative bacteria.

What is osmotic pressure?

The pressure caused by differences in water concentration across a membrane.

Why is the bacterial cell wall important during osmosis?

It prevents the cell from bursting.

What does isotonic mean?

Equal solute concentration inside and outside the cell.

What does hypotonic mean?

Lower solute concentration outside the cell; water enters the cell.

What does hypertonic mean?

Higher solute concentration outside the cell; water leaves the cell.

What happens to bacteria in a hypotonic environment?

Water enters the cell and the wall prevents bursting.

What happens to bacteria in a hypertonic environment?

Water leaves the cell causing plasmolysis.

What is plasmolysis?

Shrinkage of the cytoplasm due to water loss.

Which bacterial structure is targeted by penicillin?

The cell wall.

How does penicillin work?

It blocks peptidoglycan cross-linking, weakening the cell wall.

Why does penicillin selectively kill bacteria?

Humans do not have peptidoglycan cell walls.

What is the main function of peptidoglycan?

Provides rigidity and strength to bacterial cell walls.

True or False: Capsules help bacteria evade the immune system.

True.

True or False: Pili are primarily used for movement.

False.

True or False: Fimbriae are mainly used for attachment.

True.

True or False: Endospores are reproductive structures.

False.

True or False: Gram-positive bacteria have an outer membrane.

False.

True or False: Gram-negative bacteria contain lipopolysaccharide.

True.