Module 3 Friday p2: Prokaryotes

Flashcards about the structure, function, and reproduction of prokaryotic cells.

What are prokaryotic cells?

Simple, unicellular organisms without a nucleus or membrane-bound organelles; includes bacteria and archaea.

Where are prokaryotic microbes found?

Everywhere—soil, gut, pets, kitchen counters, etc. They thrive in diverse and extreme environments.

Why do prokaryotes reproduce so quickly?

Their small size allows for rapid reproduction through binary fission; short generation times.

How can some prokaryotes survive for centuries?

By forming endospores—protective structures that let them enter a dormant state until conditions improve.

What is the shape of Cocci bacteria?

Spherical

What is the shape of Bacilli bacteria?

Rod-shaped

What is the shape of Spirilla/Spirochetes bacteria?

Spiral-shaped

What is the function of the bacterial cell wall?

Provides structure, protection, and helps maintain shape. Prevents bursting in hypotonic environments.

What is peptidoglycan?

A mesh-like structure made of sugar polymers and polypeptides found in bacterial cell walls.

How do Gram-positive bacteria differ from Gram-negative bacteria?

Thick peptidoglycan layer, stains purple

How do Gram-negative bacteria differ from Gram-positive bacteria?

Thin peptidoglycan layer + outer membrane with lipopolysaccharides, stains pink

Why are Gram-negative bacteria harder to treat?

They have less peptidoglycan and an extra membrane, so common antibiotics targeting peptidoglycan are less effective.

Why are antibiotics that target peptidoglycan safe for humans?

Human cells don’t have peptidoglycan, so such antibiotics selectively target bacterial cells.

What is the function of a bacterial capsule or slime layer?

Helps bacteria stick to surfaces or each other, prevents dehydration, and protects against immune system attacks.

What is an endospore?

A dormant, armored form of a bacterium that can survive extreme conditions for centuries and reanimate later.

What are fimbriae?

Hair-like projections that allow bacteria to adhere to surfaces or each other to form colonies.

What is chemotaxis in bacteria?

Movement toward or away from chemical stimuli; often done using flagella.

How do prokaryotic flagella differ from eukaryotic flagella?

Structurally different; prokaryotic flagella are simpler and rotate like a propeller.

Do prokaryotes have membrane-bound organelles?

No. However, their membranes can fold to carry out metabolic functions.

Where is DNA located in a prokaryotic cell?

In a region called the nucleoid (not membrane-bound); DNA is typically circular.

What are plasmids?

Small, circular pieces of "bonus" DNA separate from the main chromosome. Often carry genes for antibiotic resistance.

How do prokaryotes reproduce?

By binary fission—a form of asexual reproduction where the cell clones itself and splits.

Why is genetic diversity important in prokaryotes?

Mutations and DNA exchange (via plasmids or appendages) allow adaptation and antibiotic resistance.

What is the clinical importance of microbiomes?

Gut microbes affect digestion, immunity, and possibly mental health. Microbial populations change with age, diet, and health.