Microbiology: Chapter 5 (Eukaryotic Cells & Microorganisms)

How do scientists think eukaryotic cells evolved from prokaryotic cells?

Through endosymbiosis, in which a larger ancestral cell engulfed smaller prokaryotic cells that survived inside it and eventually became organelles.

What is the endosymbiotic theory?

The idea that certain eukaryotic organelles originated when ancestral cells engulfed smaller prokaryotic cells that formed permanent relationships with the host.

What happened to the smaller cells after they were engulfed?

They remained inside the larger cell, performed specialized functions, and eventually became permanent organelles.

What organelles are thought to have originated through endosymbiosis?

Mitochondria and chloroplasts.

What are three pieces of evidence supporting the endosymbiotic theory?

Mitochondria and chloroplasts have their own circular DNA, contain prokaryote-like ribosomes, and can divide independently.

What additional evidence supports the endosymbiotic theory?

Their membranes and genetic characteristics resemble those of bacteria, and some antibiotics that affect bacteria also affect mitochondria.

What type of bacterium is thought to have become the chloroplast?

An ancient photosynthetic cyanobacterium.

What type of prokaryote is thought to have become the mitochondrion?

An aerobic bacterium.

How did the nucleus and endoplasmic reticulum likely develop?

They likely formed through inward folding or invagination of the cell membrane.

What is the nucleus?

The membrane-bound compartment that contains most of the cell's DNA and directs cellular activities.

What is the nuclear envelope?

The double membrane surrounding the nucleus.

What is the function of nuclear pores?

They regulate movement of materials such as RNA between the nucleus and cytoplasm.

What is the nucleolus?

The region where ribosome components begin to be produced.

What is chromatin?

DNA associated with proteins inside the nucleus.

What happens to chromosomes during mitosis?

They are duplicated and distributed between daughter cells.

What is the function of ribosomes?

They synthesize proteins.

What is the rough endoplasmic reticulum?

A membrane network covered with ribosomes that is primarily involved in protein synthesis.

Why does the rough endoplasmic reticulum look rough?

Ribosomes are attached to its surface.

What is the smooth endoplasmic reticulum?

A membrane network without attached ribosomes that is involved in lipid synthesis.

What is the Golgi apparatus?

A membrane-bound structure that processes and modifies proteins and lipids.

What is the function of vesicles?

They transport materials to and from different parts of the cell.

What can some vesicles contain?

Digestive enzymes used to break down materials inside or outside the cell.

What are mitochondria?

Organelles that serve as a central site of cellular metabolism and energy production.

Why are mitochondria called the "powerhouse" of the cell?

They produce much of the cell's usable energy through cellular respiration.

What evidence shows mitochondria have a bacterial origin?

They have circular DNA, prokaryote-like ribosomes, and can divide independently.

What are chloroplasts?

Organelles that carry out photosynthesis.

What evidence shows chloroplasts have a bacterial origin?

They have circular DNA and ribosomes similar to bacterial ribosomes.

What type of organism is thought to have given rise to chloroplasts?

An ancestral cyanobacterium.

What is the cytoskeleton?

A network of protein filaments that provides structural support and helps with movement, transport, and cell division.

What are the major functions of the cytoskeleton?

Structural support, cellular movement, intracellular transport, muscle contraction, and cell division.

What are eukaryotic locomotive appendages?

Flagella and cilia.

How do eukaryotic flagella differ from prokaryotic flagella?

Eukaryotic flagella are larger, membrane-bound, and move with a whip-like motion; prokaryotic flagella rotate.

How do eukaryotic cilia differ from eukaryotic flagella?

Cilia are shorter and usually occur in much greater numbers on a cell.

What is the function of eukaryotic flagella and cilia?

They provide movement.

What is the glycocalyx of a eukaryotic cell?

A carbohydrate-containing external coating involved in protection and attachment.

What is the function of a eukaryotic cell wall?

It provides structural support and helps maintain cell shape.

Which eukaryotic cells discussed in class have cell walls?

Plant and fungal cells.

What is the main structural material in plant cell walls?

Cellulose and lignin.

What is the main structural material in fungal cell walls?

Chitin.

Do animal cells have cell walls?

No. They have a cell membrane but no cell wall.

What are the major differences between prokaryotic and eukaryotic cells?

Eukaryotic cells have a nucleus, membrane-bound organelles, and greater internal compartmentalization; prokaryotic cells lack these features.

How do prokaryotic and eukaryotic cells differ in size?

Eukaryotic cells are generally larger than prokaryotic cells.

How do prokaryotic and eukaryotic cells differ in motility?

Prokaryotic flagella rotate, while eukaryotic flagella and cilia use a whip-like motion.

How do prokaryotic and eukaryotic cells differ in internal organization?

Eukaryotic cells are compartmentalized into membrane-bound organelles, while prokaryotic cells are not.

What is a helminth?

A multicellular parasitic worm.

What are the two major groups of helminths discussed in class?

Roundworms and flatworms.

What are roundworms?

Nematodes with an unsegmented body.

What are flatworms?

Worms with a flattened body that may be segmented or unsegmented depending on the group.

How are helminths commonly transmitted?

Many are transmitted through fecal contamination, ingestion, vectors, or direct contact with infectious stages.

How do helminths reproduce?

Most reproduce sexually using eggs and sperm.

What life stages can helminths have?

Embryo, larval, and adult stages.

What body systems or structures do helminths have?

They have specialized organs for reproduction, digestion, movement, and protection.

What are fungi?

Eukaryotic organisms that can exist as single cells or long filaments and have cell walls.

What are the two common microscopic forms of fungi?

Yeasts and molds.

What is a yeast?

A fungus that grows primarily as a single cell and can reproduce by budding.

What is a mold?

A filamentous fungus composed of long tubular structures called hyphae.

What are hyphae?

Long tubular fungal filaments.

What is a mycelium?

A network of interconnected hyphae.

What are the main characteristics of fungi?

They are eukaryotic, heterotrophic, have cell walls, and commonly grow as yeasts or filamentous forms.

How do fungi obtain nutrients?

They obtain nutrients from organic material in their environment.

How do fungi reproduce?

Primarily through spores, with both asexual and sexual reproduction occurring.

How does asexual fungal reproduction occur?

One parent produces genetically identical offspring through processes such as budding or spore formation.

How does sexual fungal reproduction occur?

Two parent cells or mating types fuse, producing genetically different offspring.

What is an important difference between fungal spores and bacterial endospores?

Fungal spores are reproductive structures, while bacterial endospores are survival structures.

What are the four major fungal groups discussed in the textbook?

Zygomycota, Ascomycota, Basidiomycota, and Chytridiomycota.

What type of sexual spores are associated with Zygomycota?

Zygospores.

What type of sexual spores are associated with Ascomycota?

Ascospores.

What type of sexual spores are associated with Basidiomycota?

Basidiospores.

What type of spores are associated with Chytridiomycota?

Motile zoospores.

What are examples of fungal diseases?

Athlete's foot, yeast infections, and fungal meningitis.

What other health effects can fungi cause?

Some can cause allergies, infections, or produce toxins.

What are some beneficial uses of fungi?

Baking, brewing, pharmaceutical research, drug production, food production, and decomposition.

What ecological role do fungi play?

They act as decomposers and break down organic material.

What are protists?

Eukaryotes that are not classified as fungi, animals, or plants.

What are the major protist groups discussed in class?

Algae and protozoa.

What are algae?

Eukaryotic organisms, usually unicellular or colonial, that photosynthesize using chlorophyll a.

What are protozoa?

Unicellular eukaryotes that lack tissues and share similarities in structure, nutrition, life cycles, and biochemistry.

What are major characteristics of algae?

They are photosynthetic, aquatic, and can be unicellular, colonial, filamentous, or multicellular.

What are examples of algae discussed in class?

Seaweed, dinoflagellates, diatoms, and Euglena.

What are important roles of algae?

They contribute oxygen, form the base of many aquatic food webs, and are major components of plankton.

Are algae generally pathogenic?

No. Most are not pathogenic, although some produce toxins.

What is red tide?

A harmful algal bloom, usually involving toxin-producing marine algae such as dinoflagellates.

Why is red tide medically important?

The toxins can contaminate seafood and cause serious food poisoning with neurological symptoms.

How can toxins from harmful algal blooms affect people?

Eating contaminated shellfish or fish can cause toxin-related illness.

Why isn't the term "red tide" always accurate?

Harmful algal blooms are not always red, so the term harmful algal bloom is more accurate.

How can people avoid illness from harmful algal blooms?

Avoid eating seafood from affected areas and follow local seafood and beach advisories.

What are the major characteristics of protozoa?

They are usually unicellular, heterotrophic, lack a cell wall, and most have structures for movement.

What structures can protozoa use for locomotion?

Flagella, cilia, or pseudopods.

What is a trophozoite?

The active, motile, feeding stage.

What is a cyst?

A resistant, dormant stage that allows survival during unfavorable conditions.

How do trophozoites and cysts differ?

The trophozoite is active, feeding, and motile, while the cyst is dormant and resistant.

How do protozoa reproduce?

They reproduce asexually through mitosis or multiple fission, and many can also reproduce sexually through processes such as conjugation.

What are the four protozoan groups discussed in class?

Mastigophorans, Sarcodina, ciliates, and Apicomplexa.

What are Mastigophorans?

Protozoa that use flagella for movement.

What disease is associated with Trypanosoma?

Sleeping sickness.

What are Sarcodina?

Protozoa such as amoebas that move using pseudopods.

What disease can Entamoeba cause?

Amoebiasis or amoebic dysentery.

What are ciliates?

Protozoa that use numerous cilia for movement and sometimes feeding.

What are Apicomplexa?

Parasitic protozoa that have an apical complex used to penetrate host cells.

What disease does Plasmodium cause?

Malaria.