BIO 2230 Study Guide – Microbiology Exam II (Flashcards)

Comprehensive practice questions covering prokaryotic and eukaryotic structures, fungal classification, protozoan life cycles, and the Endosymbiosis Theory based on Exam II lecture notes.

Compare the protein composition of prokaryotic and eukaryotic flagella.

Prokaryotic flagella are made of flagellin, while eukaryotic flagella are comprised of microtubules (tubulin) in a $9+2$ arrangement.

How does the mechanical movement of flagella differ between prokaryotes and eukaryotes?

Prokaryotic flagella rotate like a propeller, whereas eukaryotic flagella move with a whipping motion.

Explain the significance of flagellar rotation direction in prokaryotes.

Counterclockwise rotation moves the cell forward, while clockwise rotation causes the cell to tumble and change direction.

Which specific group of eukaryotes is known for possessing cilia?

The ciliates (Ciliophora).

What are the structural similarities between cilia and eukaryotic flagella?

Both are made of tubulin arranged in a $9+2$ microtubule pattern and both move with a whipping motion.

List the three major groups of parasitic worms known as helminths.

Nematodes (roundworms), trematodes (flukes), and cestodes (tapeworms).

Identify the vectors for Plasmodium and Trypanosoma.

Plasmodium is spread by Anopheles mosquitoes, and Trypanosoma is spread by the tsetse fly.

Identify the vectors for Borrelia and Yersinia pestis.

Borrelia is spread by ticks, and Yersinia pestis is spread by fleas.

What characterizes Rickettsias and chlamydias as 'obligate intracellular parasites'?

They must live and reproduce inside a host cell and cannot reproduce outside of living cells.

To which domain do Rickettsias and chlamydias belong?

Domain Bacteria.

Why are viruses excluded from being listed as living organisms?

They lack cells, cannot reproduce on their own, and cannot carry out metabolism without a host cell.

Contrast the cell membrane chemistry of Archaea and Bacteria.

Archaeal membranes contain ether-linked lipids, while bacterial membranes contain ester-linked lipids.

What is the primary difference between the cell walls of Bacteria and Archaea?

Bacteria possess peptidoglycan in their cell walls, while Archaea do not.

Define methanogens.

Methanogens are Archaea that produce methane gas.

How do the cell walls of Gram-positive and Gram-negative bacteria differ?

Gram-positive bacteria have a thick peptidoglycan cell wall with no outer membrane, while Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane.

What is the source of endotoxins in Gram-negative bacteria?

Endotoxins come from the lipopolysaccharide (LPS) located in the outer membrane.

Contrast the common shapes of Gram-positive and Gram-negative bacteria.

Gram-positive bacteria are commonly cocci (spheres), whereas Gram-negative bacteria are commonly bacilli (rods).

Describe the following bacterial arrangements: Diplococci, Streptococci, and Staphylococci.

Diplococci are pairs; streptococci are chains; staphylococci are clusters.

Where are periplasmic flagella located and what type of movement do they produce?

They are located in the space between the cell wall and outer membrane; their rotation causes the cell body to spin or flex in a corkscrew or undulating motion.

Contrast the lophotrichous and peritrichous flagellar arrangements.

Lophotrichous describes a tuft of multiple flagella at one or both ends; peritrichous describes flagella distributed randomly over the entire cell surface.

What are the primary structural polymers in the cell walls of Fungi and Algae?

The primary polymer in Fungi is chitin, and the main component in Algae is cellulose.

What are frustules?

Unique cell walls found in diatoms (photosynthetic protists).

Contrast a capsule with a slime layer within the context of a glycocalyx.

A capsule is an organized, dense layer, while a slime layer is an unorganized, loosely attached, and more fluid layer.

What are the primary functions of a bacterial glycocalyx?

Evading immune detection (virulence) and protection against dehydration.

Define pleomorphism and provide an example genus.

Pleomorphism is the ability to alter shape or size in response to stimuli; Mycoplasma (which lacks a cell wall) is a common example.

Who championed the Endosymbiosis Theory (EST)?

Lynn Margulis.

What does the Endosymbiosis Theory explain regarding the origin of mitochondria and chloroplasts?

It posits that an ancestral host cell engulfed independent bacteria (oxygen-consuming for mitochondria, cyanobacteria for chloroplasts) that were integrated rather than digested.

List four features of mitochondria and chloroplasts that support the Endosymbiosis Theory.

They possess circular DNA, bacterial-sized ribosomes, double-bounding membranes, and replicate via binary fission.

Define the roles of the Nuclear Envelope and the Nucleolus.

The Nuclear Envelope is a double membrane with pores that controls entry/exit; the Nucleolus is a dense region within the nucleus that builds ribosomes.

Compare the functions of the Rough ER and the Smooth ER.

Rough ER (RER) folds and modifies proteins using ribosomes; Smooth ER (SER) is ribosome-free and synthesizes lipids and detoxifies chemicals.

What are cisternae?

The flattened membrane sacs that form the structural compartments of the ER and Golgi.

Contrast lysosomes and phagosomes.

Lysosomes contain enzymes for digesting waste; phagosomes are temporary vesicles formed around engulfed foreign particles.

Define cristae, thylakoids, and grana.

Cristae are internal mitochondrial folds; thylakoids are disk-like sacs in chloroplasts; grana are stacks of thylakoids.

Contrast yeasts and hyphae.

Yeasts are unicellular fungi that reproduce by budding or fission; hyphae are long, thread-like tubular filaments.

What are dimorphic fungi?

Fungi species that can exist as both yeasts and hyphae structures.

Explain the difference between septate and non-septate hyphae.

Septate hyphae are divided by cross-walls (septa) into individual cells; non-septate hyphae are one continuous cell.

Define mycosis and list three examples.

Any infectious disease caused by fungus in human/animal tissue; examples include ringworm, thrush, and athlete's foot.

Compare the sexual spores of Zygomycota, Ascomycota, and Basidiomycota.

Zygomycota produce zygospores; Ascomycota produce ascospores (exactly 8 per cell); Basidiomycota produce basidiospores (exactly 4 per cell).

Which fungal group produces flagellated, swimming spores known as zoospores?

Chytridomycota.

Contrast algae and protozoa regarding nutrition and movement.

Algae are autotrophs (make food) and are usually stationary; protozoa are heterotrophs (ingest food) and actively move.

Define trophozoite and cyst in the protozoan life cycle.

A trophozoite is the active, motile, feeding stage; a cyst is a dormant, non-feeding, and highly resistant stage protected by a thick wall.

What is a zoonosis?

An infectious disease that naturally jumps from vertebrate animals to humans.

What is conjugation and what is its primary advantage?

The direct transfer of genetic material via a pilus; its advantage is genetic variation for environmental adaptation.

Identify the locomotion structures for Mastigophora, Sarcodina, and Ciliophora.

Mastigophora use flagella; Sarcodina use pseudopodia; Ciliophora use cilia.

Describe the anatomical differences between flukes (trematodes) and tapeworms (cestodes).

Flukes are leaf-shaped with an incomplete gut and two suckers; tapeworms are ribbon-like, segmented, lack a gut, and use hooks/suckers on the head.