N236: Introductory Concepts in Microbiology

Biology

The study of living things

Microbiology

The study of microscopic organisms

Living microbes

Bacteria, algae, protozoa, fungi (CELLULAR)

Non-living microbes

Viruses, viroids, prions (ACELLULAR)

Prokaryotes

Cells that do not contain nuclei (bacteria)

Eukaryotes

Cells that contain nuclei

Pathogens

Microbes that cause disease

Non-pathogenic organisms

Microbes that do not cause disease or infection (97% of microbes)

Microbiologist

Someone who studies microscopic organisms

Medical microbiology

Involves the study of the prevention, diagnosis, and treatment of infectious diseases

Microbiome

All of the microorganisms in a particular environment

Physical microbiome environments

Soil, ocean, atmosphere

Biological microbiome environments

Plants, animals, humans

Human microbiota

All of the microbes living in and on the human body

What does the human microbiota do?

Helps protect us against pathogens, and aids in the breakdown/synthesis of nutrients

Microbiota colonization

Babies are first colonized during birth --> the human microbiota expands throughout life

Opportunistic pathogens

Normal human microbiota that can cause infections when they travel somewhere they do not belong

Example: UTI

How does antibiotic therapy affect microbiota?

Antibiotics can kill harmless bacteria along with the intended target bacteria

Antibiotic-associated diarrhea

Loose, watery diarrhea that occurs over 3 times per day as a result of taking antibiotics

Saphrophytes

Microorganisms that feed off dead animals, insects, and leaves

Probiotics

Live microbes that are digested --> can restore and supplement the intestinal microbiota

Taxonomy

The science of classifying organisms

Taxa

Groups of organization into which organisms are classified

Taxonomic ranks (7)

Kingdom, Phylum, Class, Order, Family, Genus, Species

Five Kingdoms of Life

1. Monera

2. Protista

3. Fungi

4. Plantae

5. Animalia

Generic Name

Indicates the organism's genus and is written in upper case letters

Example: Homo

Specific Name

Indicates the organism's species and is written in lower case letters

Example: sapiens

Anton van Leeuwenhoek

Father of microbiology, invented the microscope and was the first to observe bacteria and protozoa

Animalcules

A microscopic "animal"; first observed by Anton van Leeuwenhoek

Louis Pasteur

A French chemist who discovered that life could exist in the absence of oxygen

Aerobes

Bacteria that require oxygen to grow

Anaerobes

Bacteria that grow in the absence of oxygen and are destroyed by oxygen

Pasteurization

A process of heating food/drinks to a temperature that is high enough to kill harmful bacteria

Swan-neck flask experiment

Pasteur proved that microbes cannot be spontaneously generated from nonliving things

Robert Koch

A German physician and microbiologist who developed methods for fixing and staining bacteria on a glass microscope slide

Koch's Postulates

A set of rules that proves that specific microorganisms cause specific diseases

Postulate 1

Microorganism must always be found in similarly diseased animals but no healthy ones

Postulate 2

The microorganism must be isolated from a diseased animal and grown in a pure culture

Postulate 3

The isolated microorganism must cause the original disease when inoculated into a healthy animal

Postulate 4

The microorganism can be re-isolated from the experimentally infected animal

Obligate Intracellular Pathogens

Pathogens, such as viruses, that can only grow when inside cells --> violates postulate 2

Species-specific pathogens

Pathogens that are unable to infect certain species --> violates postulate 3

Microscope

A device that magnifies images of structures that are too small to see with the naked eye

Resolving power

The ability of an microscope to show two objects as separate

What is the resolving power/resolution of the human eye?

0.2 millimeters (mm)

How many inches in a meter?

39.37 inches

How big are bacteria?

1-10 micrometers long

How big are viruses?

10-30 nanometers (SO SMALL)

Simple microscope

A microscope that contains only one lens (3-20x naked eye)

Compound microscope

A light microscope that has more than one lens (1,000x naked eye)

Photomicrograph

Photograph of an image seen using a compound microscope

Electron Microscopes

A powerful microscope that uses beams of electrons (not light) to produce images

Transmission electron microscope

A microscope that uses an electron beam to study the internal structure of cells

Scanning electron microscope

A microscope that uses an electron beam to study the external structure of cells

Electronmicrograph

Photograph of an image seen using an electron microscope

Cytology

The study of the structure and function of cells

Cell membrane

A semipermeable membrane that controls which substances can enter or leave the cell

Cytoplasm

The portion of the cell outside the nucleus

Cytosol

Fluid portion of cytoplasm

Nucleus

Control center of the cell where the DNA is stored

Nucleoplasm

Gelatinous fluid inside the nucleus

Chromosomes

DNA molecules and proteins inside the nucleoplasm

Nuclear membrane

A membrane that controls what goes in and out of the nucleus

Nucleolus

A sphere in the middle of the nucleus that produces ribosomes

Endoplasmic reticulum

An organelle composed of several convoluted folded membranes that form passageways for proteins/materials to travel within the cell

Rough ER

Section of the ER that contains ribosomes

Smooth ER

Section of the ER that does NOT contain ribosomes

Ribosomes

Organelles that synthesize proteins

Golgi complex

Organelle that packages and distributes proteins

Lysosomes

An organelle that contains digestive enzymes

Peroxisomes

Organelles that contain catalase which speeds up breakdown of H2O2

Mitochondria

POWERHOUSE OF THE CELL, organelle that is the site of ATP production

Plastids

Organelles that carry out photosynthesis in plants

Cytoskeleton

A network of long protein strands in the cytosol that helps support the cell structure

Cell wall

A rigid structure that surrounds the cell membrane protects the cell

Flagella

A whiplike tail that one-celled organisms use to swim

Cilia

The hair-like projections on the outside of cells that allow the cell to move

9+2 arrangement

Eukaryotic flagella + cilia have 9 pairs of microtubules that form a circle around two lone microtubules

Prokaryotic chromosome

A single, circular DNA molecule that is found in the cytoplasm of prokaryotes

Plasmid

A small ring of DNA that carries accessory genes separate from those of the bacterial chromosome

Cytoplasmic particles

Small ribosomes in prokaryotes, which synthesize proteins

Prokaryotic cell wall

A rigid, chemically complex wall that protects the prokaryotic cell and helps maintain its shape

Peptidoglycan

A protein-carbohydrate compound that makes the cell walls of bacteria rigid

Cell-wall deficient bacteria

Some bacteria lose their ability to produce cell walls

Pleomorphism

Cell-wall deficient bacteria can change their size and shape

Gram +

Bacteria with a thick peptidoglycan layer --> stains purple

Gram -

Bacteria with a thin peptidoglycan layer --> does not stain

Glycocalyx

A bacterial capsule that is made of a fuzzy coat of sticky sugars

Slime layer

A glycocalyx that is loosely attached to the cell wall --> helps bacteria slide/glide

Capsule

A glycocalyx that is firmly connected to the cell wall --> protects bacteria from phagocytosis

Prokaryotic Flagella

A tail that propels the cell through its liquid environment (NOT arranged in 9+2 for prokaryotes)

Monotrichous bacteria

Bacteria with single flagellum

Lophotrichous bacteria

Bacteria with multiple flagella at one end

Amphitrichous bacteria

Bacteria with a flagellum at each end

Peritrichous bacteria

Bacteria with flagella all over their surface

Pili

Appendages that allow bacteria to attach to each other and to transfer DNA

Spores

Dormant, non-reproductive structures that are highly resistant to cold and heat damage; capable of generating new organisms

Terminal spores

Endospores that are found at the end of a bacterial cell

Subterminal spores

Spores that form between the center and the end of a bacterial cell

Binary fission

A form of asexual reproduction in which one prokaryotic cell divides to form two identical cells