Microbiology chap. 4 & 5

Eukaryotic Flagella

Long, sheathed cylinders containing regularly spaced microtubules used for cellular locomotion.

Eukaryotic Cilia

Locomotor structures similar in architecture to flagella, but smaller and more numerous.

Glycocalyx

The outermost layer composed of polysaccharides that comes into direct contact with the environment.

2 groups that do not have cell walls.

Protozoa and helminths.

Chitin

Polysaccharide fibers that make up the thick inner layer of fungal cell walls.

Eukaryotic Cell Membrane

A phospholipid bilayer embedded with protein molecules and sterols of various kinds.

Chromatin

The genetic material of the cell, composed of linear DNA and histone proteins.

Endoplasmic Reticulum

A series of membrane tunnels used in cellular transport and storage.

Rough Endoplasmic Reticulum

Endoplasmic reticulum that appears rough because ribosomes are attached to its membrane surface.

Smooth Endoplasmic Reticulum

Endoplasmic reticulum that processes nutrients and synthesizes and stores nonprotein macromolecules, such as lipids.

Golgi Apparatus

An organelle that modifies proteins and sends them to their final destinations.

Lysosomes

Vesicles that bud off the Golgi apparatus containing enzymes involved in intracellular digestion of food particles and protection against invading microorganisms.

Mitochondria

Eukaryotic organelles that generate energy for the cell.

Cristae

The folds on the inner mitochondrial membrane that hold the enzymes and electron carriers of aerobic respiration.

$80\text{S}$ Ribosomes

The size of eukaryotic ribosomes, which are freely scattered in the cytoplasm and cytoskeleton, and attached to the rough endoplasmic reticulum.

Yeasts

Round to oval fungal cells that reproduce asexually by budding.

Hyphae

Long, threadlike cells found in the bodies of filamentous fungi.

Fungal Saprobes

Fungi that obtain nutrients from the remains of dead plants and animals in soil or aquatic habitats.

Fungal Parasites

Fungi that grow on the bodies of living animals or plants, very few of which require a living host.

Mycelium

The woven, intertwining mass of hyphae that makes up the body or colony of a mold.

Fungal Spore Formation

The primary reproductive mode of fungi, which occurs through asexual or sexual spore formation.

Protozoa

Single-celled eukaryotic microorganisms that contain all of the major eukaryotic organelles and lack a cell wall.

Trophozoite

The motile, feeding stage of protozoa that requires ample food and moisture to stay active.

Protozoan Cyst

A dormant, resting stage of protozoa that occurs when environmental conditions become unfavorable and is resistant to heat, drying, and chemicals.

4 major groups of pathogenic protozoa

amoeboid, ciliated, flagellated, and apicomplexan protozoa.

Amoeboid Protozoa

A highlighted group of pathogenic protozoa that utilizes pseudopods for locomotion.

Apicomplexan Protozoa

A highlighted group of pathogenic protozoa that is categorized as nonmotile.

Helminths

Multicellular animals lacking cell walls that are equipped to some degree with organs and organ systems, including tapeworms, flukes, and roundworms.

Complete helminth life cycle

Fertilized egg, larval, and adult stages

Most developed organ system in pathogenic helminths

The reproductive tract

Where do disease-causing helminths spend part of their lives

The gastrointestinal tract

Nematodes

Roundworms characterized by elongated, cylindrical, and unsegmented bodies, whose sexes are separate and different in appearance.

Cestodes

Tapeworms; a group of flatworms that are generally hermaphroditic.

Trematodes

Flukes; a highlighted taxonomic group of flatworms.

Definitive Host

The final host in a helminth life cycle, in which adulthood and mating occur.

Hermaphroditic

Possessing both male and female sex organs within the same individual.

Obligate Intracellular Parasites

Infectious particles, such as viruses, that require a host cell to replicate and can infect bacteria, algae, fungi, protozoa, plants, and animals.

Viral Size Range

The diameter across viral particles, stated in the outline as about $20$ to $1{,}000\text{ nanometers}$.

Viruses

Not cells.

Do not fulfill characteristics of life.

Molecules on their surfaces give specificity for attachment to host cells.

Basic virus components

External capsid, core containing DNA or RNA, and sometimes one or two enzymes.

Capsid

The external protein shell surrounding the viral nucleic acid core.

Capsomeres

Identical protein subunits that bond together to assemble a viral capsid.

Nucleocapsid

The core complex composed of the viral capsid together with the nucleic acid.

Naked Virus

A virus that consists exclusively of a nucleocapsid and lacks a surrounding membrane envelope.

Viral Envelope

An external covering outside the capsid, usually composed of a modified piece of the host cell membrane acquired during budding.

Viral Spikes

Surface molecules projecting from the nucleocapsid or envelope that allow viruses to dock with host cells.

Helical Capsid

A capsid structure formed by rod-shaped capsomeres bonded together into hollow discs resembling a bracelet; rigid when naked and flexible when enveloped.

Icosahedral Capsid

A capsid structure forming a three-dimensional, $20$-sided figure with $12$ evenly spaced corners.

Are capsomeres arranged identically in all icosahedral viruses.

No. Their arrangements vary from one virus to another.

How does a virus acquire its envelope during budding.

A piece of host cell membrane surrounds the capsid during release.

Genome

The sum total of genetic information carried by an organism. Contains DNA or RNA, but not both.

Viral DNA

Can take single-stranded or double-stranded; double-stranded DNA may be linear or circular.

Viral RNA

Usually single-stranded, although double-stranded forms occur.

Positive-Sense RNA

Viral single-stranded RNA that is immediately ready to undergo translation into proteins.

Negative-Sense RNA

Viral RNA that cannot be translated directly and must serve as a template to make messenger RNA first.

Segmented RNA

A viral genome arrangement in which individual genes exist on separate pieces of RNA.

Reverse Transcriptase

An enzyme carried by retroviruses that synthesizes DNA from an RNA template.

Fit required for viral absorption.

An exact fit between the virus and a specific host molecule.

Host Range

The specific spectrum of host cells that a particular virus is capable of adsorbing to and invading.

Viral penetration by endocytosis.

The cell engulfs the entire virus and encloses it in a vacuole or vesicle.

Direct Fusion

A mechanism of viral entry wherein the viral envelope merges directly with the host cell membrane to release the nucleocapsid inside.

DNA virus replication and assembly.

In the host cell nucleus.

RNA virus replication and assembly.

In the cytoplasm.

Release of nonenveloped and complex viruses.

They are released when the host cell lyses, or ruptures.

Release of enveloped viruses.

Budding from membranes of the cytoplasm, nucleus, endoplasmic reticulum, or vesicles.

Cytopathic Effects (CPEs)

Virus-induced structural damage to host cells that alters their microscopic appearance.

Carrier Relationship

A persistent host-cell interaction in which the cell harbors a virus without being immediately lysed.

Provirus

A viral state during persistent infection where viral DNA becomes incorporated into the host organism's DNA.

Latent viruses under various stimuli.

Can periodically become activated.

Oncoviruses

Mammalian viruses capable of initiating tumors, estimated to cause $20\text{ percent}$ of cancers.

Transformation

The phenotypic effect and alteration of host cells induced by oncogenic, or cancer-causing, viruses.

Bacteriophage

A virus that infects bacteria; a name that translates literally to 'bacteria eating.'

Prophage

An inactive, latent state of bacteriophage DNA integrated into the bacterial host chromosome during a temperate phage infection.

Lysogeny

A condition in which the host bacterial chromosome carries and maintains integrated bacteriophage DNA.

How can phage genes change a bacterium’s toxin or enzyme production.

They can cause production of toxins or enzymes that the bacterium would not otherwise have.

Lysogenic Conversion

The acquisition of a new trait or phenotypic characteristic by a bacterium from its temperate phage.

Viral Cultivation

The process of propagating viruses to isolate and identify clinical specimens, prepare vaccines, and research viral structure, multiplication, genetics, and effects on host cells.