ABIO 314 Microbiology Test 1

What is microbiology?

The study of the dominant form of life on earth, and the effect that microbes have on our planet and all of the living things that call it home

What kinds of organisms do microbiologists study?

Microorganisms, AKA microbes, which are life forms too small to be seen by the human eye.

What are microorganisms

A diverse group of generally minute simple life forms that include bacteria, archaea, algae, fungi, protozoa, and viruses

How are microorganisms diverse?

They are diverse in form, function, their habitats, and their physiology. Microorganisms can reside in almost all environments capable of supporting life. Some are single while others are multi-cellular

Contrast the biomass and number of cells of microbes to all other form of life on earth

Microorganisms are major fraction of earth's biomass

How long has microbial life been present on earth?

Microorganisms are the oldest form of life presiding our earth for near 3.8 and 4.8 billion years ago

Where are microbes found?

everywhere

What is the limiting factor to microbial life?

Temperature, Microbes are only capable of living in an evironemnt with a hospitable temperature. That being said, the range of suitable temperatures is quite large. Mircobes can not live in a volcano, for example, but can live very close to one.

How do microbes benefit society?

-produce many of our foods, beverages, medications, and vitamins

- required for normal human health (normal flora)

- can be taken in probiotic form

- used to clean out water through biodegredation

- used to clean up toxic wastes through bioremediation

What is the Human Microbiome?

the collection of all the microorganisms living in association with the human body. Most of these are not harmful or beneficial to the humans. Live on the surface and effect human life in terms of infectious disease, food, etc.

Contrast microorganisms to plants/animals

Microbes surround plants and animals, which were found on earth about 0.5 billion years ago.

What are three properties of microbial cells

Growth, evolution, metabolism

Growth

Nutrients from the environment are converted into new cellular materials to form new cells. (number not size)

Evolution

cells evolve to display new properties. Phylogenetic trees capture evolutionary relationships

What are four properties of some microbial cells

differentiation, communication, genetic exchange, motility

differentiation

some cells can form new cell structures such as spores

communication

cells interact with each other my chemical messengers

genetic exchange

cells can exchange genes by several mechanisms

motility

some cells are capable of self-propulsion

What is the three domain system?

Bacteria, Archaea, Eukarya

Who is the scientist responsible for developing the 3 domain system

carl woese

what is the marker gene used to develop the 3 domain system?

ribosomal rRNA structure gene - found relationships can be deduced by comparing the genetic information that's common to all organisms

What do all bacteria have in common?

They are prokaryotes that are usually undifferentiated single cells. They are 30 major phylogenetic lineages

what do all Archaea have in common?

They are prokaryotes that are less morphologically diverse than bacteria. Mostly undifferentiated cells with 5 well-described phyla. Associated with extreme environments. Lack any known parasites/pathogens of plants and animals

what do Bacteria and Archaea have in common

no membrane enclosed organelles, no nucleus, singular chromosome

What is the endosymbiont hypothesis?

The origin of mitochondria and chloroplast is from an endosymbiont, where an anicent archaea engulfed a bacteria and adopted it's structure.

How to write a bacteria species name?

Genus name and specific epithet. The whole name is italicized. The genus name is italisized and the specific epithet is not.

Who was the first person to directly observe bacteria?

Anton Van Leeuwenhoek

Where did the first observed bacteria originate from?

Scrapings from his teeth

Anto Van Leeuwenhoek

Made the first microscope to confirm the thread count of textiles. Found bacteria instead. Decided to observe his dental plaque and confirm his clean, healthy teeth

Robert Hooke

publishes drawings of fungus. Was first to describe microbes (fruiting structure of molds)

Louis Pasteur

created flasks with long curved necks and filled them with a nutrient-rich broth to test whether microorganisms come from the air. He found no growth in the broth, confirming his hypothesis that something living presides within the air. He also discovered alcohol fermentation, disproved the theory of spontaneous generation which lead to new sterilization methods and food preservation. He also developed the vaccine for anthrax, fowl cholera, and rabies

Joseph Lister

provided indirect evidence that microorganisms were agents of disease. He developed a surgery system to prevent microorganisms from entering wounds of his patients and found greater survival rates.

Robert Koch

He established the relationship between Bacillus antracis and anthrax using criteria that are now known as Koch's postulates. Hew developed agar, petri dish, and a method for isolating microorganisms

What is the germ theory of disease?

The theory that specific microscopic organisms are the cause of diseases

Koch's Postulates Definition

series of guidelines used to identify the microorganism that causes a specific disease

List all of Koch's postulates

1. The suspected pathogen must be present in all cases of the disease and absent from all cases of healthy animals

2. The suspected pathogen must be grown in pure culture

3. Cells from a pure culture of the suspected pathogen must cause disease in a healthy animal

4. the suspected pathogen must be reisolated and shown to be the same as the original

When and why are Koch's postulates not useful or practical?

Some organisms can not be grown in a pure culture, using humans to test for disease is unethical, and moleculer and genetic evidence may replace the limits imposed by Koch's postulates

What are three important properties for imaging bacteria with a microscope?

Magnification, contrast, resolution

magnification

make the object seem larger

contrast

ability to distinguish object from background

resolution

measure the closest distance between two points

what is the bending of light by a lens called?

refraction

what is resolution

the quantitative measure of the closest distance between two points at which they are clearly sperate entities

How is refraction defined?

using an objective lens with a larger numerical aperture and use shorter wavelength of light to improve the resolution with a light microscope

What is contrast?

The ability to distinguish organisms from their background in a microscope

What are two general ways to improve contrast?

Optique technique and stain samples

optique technique

Dark-feild, phase contrast, and brightfield

stain samples

chromogenic stains and fluorescence stains

What does Bright field look like?

Regular background and no illuminating light

What does phase contrast look like?

regular background wiht illuminating light

what does dark-field microscope look like?

darker background illuminating light and organelles

What is the main function of staining a microbial specimen?

straining improves contrast. Stains bind to specific cellular materials and can be used to highlight certain cellular materials during microscopy

What is a differential stain?

The use of two or more dyes that react differently with different kinds/parts of bacteria.

What property does the Gram stain use to differentiate bacteria?

these stains use the cell wall structure to differentiate bacteria

What is gram positive bacteria?

thick cell walls with large amounts of peptidoglycan. Retains crystal violet stain

What is gram negative bacteria?

outer cell membrane, thin peptidoglycan layer, and cell membrane. Stains pink

Does the gram stain work on archaea

No because they do not contain peptidoglycan in their cell walls which need to be present

What are the two components of a Fluorescent in situ hybridization probe?

1. Reporter component - fluorescent tag

1. specificity component - recognizes a gene or gene product such as DNA sequence, RNA sequence, or protein to bind to.

Compare and cotnrast fluorescent dyes and fluorescent proteins

Fluorescent dyes offer higher photostability and brightness compared to fluorescent proteins and do not require a maturation time. However, dyes are usually targeted to proteins of interest by antibody conjugates or peptide tags. This requires the fixation of cells, which renders measurement of genetic circuit dynamics impossible.

What is the main advantage fluorescent proteins

proteins contain fluorescent amino acids such as tryptophan, tyrosine, and phenylalanine. As a result, they also offer photostability and brightness and do not require fixation of cells

what are the two main types of electron microscopy?

Transmission Electron Microscope and Scanning Electron Microscopy

transmission electron microscope

to view cells and cell structure at higher magnification and resolution levels. Also used to limit or reduce scatter caused by electrons for clearer image

scanning electron microscopy

gives a 3d image of the cell

why is resolution hier with electron microscopy than with light microscopy?

the resolution is higher in electron microscopy because the wavelength of electrons is shorter than light

coccus (cocci)

spherical shaped bacteria

coccobacillus

short round rod, pill shaped

vibrio

curved rod, comma shaped

Baccilus

Long rod shaped bacteria

Spirillium/spirilla

zig zag shaped bacteria

Spirochetes

long, slender spiral-shaped bacteria

stalked bacteria

thin extensions of the cell wall from the main cell body

Diplococci

Spherical bacteria that grow in pairs and cause diseases such as pneumonia.

staphylococci

a group of about 30 species of bacteria that form irregular groups or clusters resembling grapes

streptococci

Pus-forming bacteria arranged in curved lines resembling a string of beads. They cause infections such as strep throat and blood poisoning.

tetrad

4 cocci in a square

what is the importance of the surface to volume ratio for a bacterial cell?

a surface to volume ratio controls how fast a cell grows, shapes, and can exchange nutrients and get rid of waste

an increase in the radius of a spherical cell yields what effects in the surface to volume ratio?

when radius increases, surface to volume ratio decreases

what is the function of the plasma membrane?

permeability barrier, protein anchor, energy conservation and consumption

what are the 5 bacterial macronutrients?

C, H, N, O, P, S

What are micronutrients and howare they different from macronutrients?

macronutrients are often requred in larger amounts, while micronutrients are required in trace amounts

what are three kinds of ways that molecules can enter bacteria cell through the membrane?

passive diffusion - not energy dependant

facilitated diffusion - not energy dependant

active transport - energy dependant

what are the two main types of bacterial cell walls?

gram positive (thick peptidoglycan on outermost layer and sometimes teichoic acid)

gram negative cell wall ( think layer of peptidoglycan surrounded by an outer membrane)

what is a peptidoglycan?

A rigid layer that provides strength. a mesh like polymer of identical subunits forming long strands composed of modified gluocse and amino acids

What is lipopolysaccharide?

a type of polysachharide molecule that is covalently bound to lipids

why is it important to medical microbiology?

LPS is one of the conserved microbial structures responsible for activating the innate immune response

what kind of bacteria have lipopolysaccharide?

gram negative

function of lipopolysaccharides

create a permeability barrier, contribute to negative charge of the cell, acts as an endotoxin

what is the function of porins

proins are transmembrane proteins that allow for non-specific transport of solutes

where are porins located?

in the outer membrane of gram negative bacteria cells

what is an aquaporin?

water channel protein in a cell

what is the function of the cell wall?

the function of the cell wall is to protect against osmotic lysis

teichoic acid

acid molecules embedded in the cell walls of gram positive bacteria. Their main function is to provide flexibility to the cell wall by attracting cations such as calcium and potassium

How does penicillin kill bacteria?

penicillin targets cell wall synthesis, leaving the cell susceptible to osmotic lysis

what is the glycocalyx?

a stickly or slimy material on the outermost layer of the cell that is composed of proteins or polysaccharides (capsule and slime layer)

what are the functions of the glycocalyx?

aid in attachments to solid surface ( biofilms and animals)

What are inclusions?

They are reserve deposits found in both pro- and eukaryotes.

examples of inclusions

storage inclusions for carbon, phosphate, amino acids, and glycogen

gas vacuoles, magnetosomes

pilli

think filamentous structures made of proteins that extend from the cells, enable the cell to stick to srufaces (longer and fewer than fimbriae)

fimbriae

short type of pilli that mediate attachments, enable the cell to stick to surfaces