Microorganisms Lecture Notes Review

Flashcards generated from lecture notes on Microorganisms, covering characteristics, structures, disease transmission, and interventions.

Describe the nucleus in prokaryotic cells.

No true nucleus; DNA is in a nucleoid region

Describe the nucleus in eukaryotic cells.

Has a true, membrane-bound nucleus

Give examples of prokaryotic cells.

Bacteria and Archaea

Give examples of eukaryotic cells.

Animals, plants, fungi, protists

What type of cell division occurs in prokaryotic cells?

Binary Fission

What type of cell division occurs in eukaryotic cells?

Mitosis and Meiosis

What structures are only found in eukaryotic cells?

Nucleus and Membrane-bound organelles (mitochondria, ER, Golgi)

Which statement describes prokaryotic cells?

Prokaryotic cells are found in coccus form in both pairs and clusters.

Which statement describes eukaryotic cells?

The nuclei of eukaryotic cells are surrounded by complex nuclear membranes.

Which statement describes eukaryotic flagella?

Eukaryotic flagella are flexible, whip-like structures.

Which statement describes the endomembrane system?

It includes the Golgi apparatus, lysosomes, and vesicles.

What is a cell wall?

a structure in the cell envelope of some cells that helps the cell maintain its shape and withstand changes in osmotic pressure

What is cytoplasm?

The gel-like material composed of water and dissolved or suspended chemicals contained within the plasma membrane of a cell

Define cell morphology

cell shape, structure, and arrangement, as viewed microscopically

What is osmosis?

diffusion of water across a semipermeable membrane

Define osmotic pressure

the force or pressure generated by water diffusing across a semipermeable membrane, driven by differences in solute concentration across the membrane

What is a prokaryotic cell?

a cell lacking a nucleus bound by a complex nuclear membrane

What is a eukaryotic cell?

has a nucleus surrounded by a complex nuclear membrane that contains multiple, rod-shaped chromosomes

Define ribosome

a complex intracellular structure that synthesizes proteins

What is the cytoskeleton?

an internal network that supports transport of intracellular components and helps maintain cell shape

What is the nucleus?

a membrane-bound structure of eukaryotic cells that houses the DNA genome

What is the nuclear membrane/envelope?

a structure defining the boundary of the nucleus composed of two distinct lipid bilayers that are contiguous with each other and with the endoplasmic reticulum

Define nucleolus

a dense region within the nucleus where ribosomal RNA biosynthesis occurs and preribosomal complexes are made

What is the Eukaryotic Ribosome (80S) composed of?

composed of 60S and 40S subunits

Define free ribosome

eukaryotic 80S ribosome found in the cytoplasm; synthesizes water-soluble proteins

Define membrane-bound ribosomes

80S eukaryotic ribosome attached to rough endoplasmic reticulum

Define endomembrane system

a series of organelles (endoplasmic reticulum, Golgi apparatuses, lysosomes, and transport vesicles) arranged as membranous tubules, sacs, and disks that synthesize many cell components

What is the endoplasmic reticulum (ER)?

part of the endomembrane system that is an interconnected array of tubules and flattened sacs with a single lipid bilayer that may be either rough or smooth, important in synthesizing proteins and lipids

What are transport vesicles?

Membranous sac that carries molecules between various components of the endomembrane system

What is the Golgi apparatus?

An organelle of the endomembrane system, composed of a series of flattened membranous disks, called dictyosomes, each having a single lipid bilayer, that are stacked together; important in the processing of lipids and proteins

Define extracellular matrix:

material composed of proteoglycans and fibrous proteins secreted by some eukaryotic cells that lack cell walls; helps multicellular structures withstand physical stresses and coordinates signaling from the external surface of the cell to the interior of the cell

Function of peptidoglycan cell wall (prokaryotic cells)

Provides shape and protection; unique to bacteria

What is the function of Fimbriae (prokaryotic cells)?

Hair like structures used for attachment

Define endospores

dormant, highly resistant structures formed by certain bacteria to survive harsh conditions

Characteristics of Gram-positive cell walls

thick peptidoglycan layer, retains crystal violet stain (purple), no outer membrane

Characteristics of Gram-negative cell walls

thin peptidoglycan layer, has an outer membrane with lipopolysaccharides, stains pink/red with safranin

Function of the plasma membrane (prokaryotic and eukaryotic cells)?

Controls movement of substances in/out of the cell

Function of the cytoplasm (prokaryotic and eukaryotic cells)?

Gel-like fluid where cellular components are suspended

What is the bacterial ribosome 70S composed of?

Composed of 50S and 30S

What is a capsid?

A protein coat surrounding a virus's nucleic acid. It protects the viral genome and helps the virus attach to and enter host cells.

What are the benefits of Fungi?

decomposition antibiotic production, food production, and research tools

Are protozoa multicellular or unicellular?

Unicellular

Are helminths more complex?

Yes, they are multicellular animals with organ systems and complex life cycles, often requiring multiple hosts and environmental stages for development

How is Guinea worm disease caused by the nematode Dracunculus medinesis transmitted?

Transmitted by drinking water contaminated with infected water fleas

Why are plasmids important to the survival of organisms?

Plasmids carry genetic material, apart from the genome, that can benefit the organism.

Which statement describes bacteria?

Some bacteria have cell walls composed of mycolic acid.

Define acellular

Not made of cells

Define bacteria

Any of various unicellular prokaryotic microorganisms typically (but not always) having cell walls that contain peptidoglycan

Define pathogens

A disease-causing microorganism

Define 70S ribosomes

a ribosome composed of 50S and 30S subunits

What is a vegetative cell?

a cell that is actively growing and dividing, and does not contain an endospore

Define cell envelope

the combination of external cellular structures that collectively contain the cytoplasm and internal structures of a cell

Define fluid mosaic model

refers to the ability of membrane components to move fluidly within the plane of the membrane, as well as the mosaic-like composition of the components

Define peptidoglycan

The polymer of alternating N-acetylmuramic acid (NAM) and N- acetylglucosamine (NAG) subunits linked together by peptide chains; a major constituent of bacterial cell walls

Define S-layer

Cell envelope layer composed of protein covering the cell walls of some bacteria and archaea; in some archaea, may function as the cell wall

Define pili

Long protein extensions on the surface of some bacterial cells; specialized F or sex pilus aids in DNA transfer between cells

What is a complex virus?

Virus shape that often includes intricate characteristics not seen in the other categories of capsid

Define hyphae

Tubular, filamentous structures that makes up most fungi

Define thallus

Body of fleshy fungi that commonly co-occurs with HIV infection; the microbes move to the lymphatic system in the groin

Define budding yeasts

Yeasts that divide by budding off of daughter cells

Define ascocarps

Cup-shaped fruiting bodies of an ascomycete fungus

Define ascus

Structure of ascomycete fungi containing spores

Define basidia

small club-shaped structures of basidiomycete fungi where basidiospores are produced

What is a polar tubule?

tube-like structure produced by spores of parasitic Microsporidia fungi that pierces host cell membranes

Define spores

Specialized cells that may be used for reproduction or specialized to withstand harsh conditions

Define phytoplankton

Photosynthetic plankton

What is a trophozoite?

A life cycle phase in which protists are actively feeding and growing

What are cysts?

Microbial cells surrounded by a protective outer covering

Define plasmalemma

Protist plasma membrane

What is a cytostome?

A protozoan cell structure that is specialized for phagocytosis

Define contractile vacuoles

Organelles found in some cells, especially in some protists, that take up water and then move the water out of the cell for osmoregulatory purposes

What is mitosis?

Period of the cell cycle during which the duplicated chromosomes are separated into identical nuclei; includes prophase, prometaphase, metaphase, anaphase, and telophase

What is meiosis?

A two-stage nuclear division process that results in four genetically distinct gametes

Define pathogenicity.

The ability of a microorganism to cause disease

Define virulence

The degree or severity of the disease caused by microorganisms

Define median infection dose

The number of microbial cells or virions required to cause infection in 50% of a test population

Describe opportunistic pathogens

It only causes disease when a person’s defenses are weakened

Describe opportunistic pathogens

It only causes disease when a person’s defenses are weakened

What is the key difference between a primary pathogen and an opportunistic pathogen?

Primary pathogens can infect anyone, whereas opportunistic pathogens can cause disease if the host is immunocompromised.

How can disease expression be described?

Signs and symptoms associated with illness can be a result of many things, including an immune response.

What is the correct understanding of the median infectious dose?

It is the number of pathogenic cells required to cause active infection in 50% of inoculated animals.

Define virulence factors

Molecules or traits produced by pathogens that enhance their ability to cause disease

What are adhesins?

Surface molecules that allow pathogens to bind to specific receptors on host cell surfaces

What is antigenic variation?

Refers to a pathogen’s ability to alter its surface proteins so that the immune system cannot recognize it effectively.

What is antigenic shift?

A sudden and major change, usually caused by gene reassortment between different viral strains, resulting in new viral subtypes.

Describe the virulence of Giardia lamblia (protozoan pathogens)

Uses a ventral adhesive disc supported by microtubules to stick to intestinal cells.

Describe the virulence of Plasmodium falciparum (protozoan pathogens)

Displayed on infected RBC surfaces, causes clumping and vessel wall adherence, which blocks blood flow.

Describe the virulence of worms (helminths)

Secretes proteases that degrade skin proteins to enter bloodstream.

Which structure aids in the evasion of phagocytosis by preventing immune cells from adhering to pathogens?

Capsule

Which group contains a pathogen that adheres to host cells by using a large adhesive disc?

Protozoans

Which phenomenon is NOT found only in viruses?

Capsule formation

Function of Nucleoid (prokaryotic cells)

Region containing the prokaryotic DNA, not membrane bound

What is the function of plasmids (prokaryotic cells)?

Small, circular DNA molecules independent of chromosomal DNA, often carry antibiotic resistance genes

What is the function of Ribosomes(70S) (prokaryotic cells)?

Smaller than eukaryotic ribosomes, responsible for protein synthesis

What is the function of Fimbriae (prokaryotic cells)?

Hair like structures used for attachment

What is the function of the Capsule (in some) (prokaryotic cells)?

Protects against phagocytosis

Which virulence factor aids in the adherence of bacterial pathogens to a host?

Coagulase

Which situation is an indirect result of endotoxin release?

Inflammation and fever are initiated

Which characteristic is true of endotoxins?

Endotoxins cause fevers

What is the definition of Exoenzymes?

Secrete chemicals, cell surface receptors, or extracellular structures that damage cells in the host.