Week 1: Intro, Chemical principles, and prokaryotes

Define Microbiology

the study of microorganisms (too small to be seen with naked eye)

What sorts of functions do microbes play?

• Environmental (decomposers and generate O2)

• Industrial (produce chemicals like vinegar)

• Manufacturing (products)

• Medical (hormones and proteins)

• Food (fermentation)

How is microbial nomenclature expressed?

Genus. species (the specififc epithet)

What are the 4 types of microorganisms?

• bacteria

• fungi

• viruses

• protozoa

Who devised the 3 domain system?

Carl Woese

Who discovered that living things are composed of “little boxes” (cells) and marked the beginning of cell theory?

Robert Hooke

Define cell theory

all living things are composed of cells

Who observed the first microbes and termed them “animalcules”?

Anton van Leeuwenhoek

Define spontaneous generation

the hypothesis that life arises from nonliving matter; a “vital force” is necessary for life

Who was the first to challenge spontaneous generation by filling jars with meat?

Francesco redi

Who was the first to demonstrate that microbes are present in the air with his curved flask experiment?

Louis Pasteur

Name a few more discoveries of Pasteaur

• Fermentation by microbes

• Microbes spoil food and beverages

• Bacteria that use oxygen turn wine to vinegar

• Adding enough heat to kill organisms but not cook can make foods last longer

Define the germ theory of disease

the theory that disease was caused by microbes

What are koch’s postulates?

a set of four scientific rules to prove that a specific microbe causes a specific disease

Who was the first to start vaccinating people with cowpox to fight small pox?

Edward jenner

Define antibiotic

chemicals made by fungi or bacteria that kill microbes

define chemotherapy

treating disease with chemicals

Who accidentally discovered the first antibiotic (penicillin)

Alexander flemming

What are some problems that could arise from antimicrobial chemicals?

• Overuse leads to resistance

• Some drugs (like antivirals) are toxic

True or false: most microbes are pathogenic towards humans

false; pathogenic bacteria make up a small percent of all microbes

This macromolecule is used for cell structure and energy storage; most are isomers

carbohydrtes

Compare monosaccharides, disaccharides, and polysaccharides.

• Monosaccharide = simple sugar w/ 3-7 carbon atoms

• Disaccharides = two monosaccharides joined in a dehydration

synthesis

• Polysaccharides consist of tens or hundreds of monosaccharides

  joined through dehydration synthesis

This macromolecule is insoluble in water, makes up important biological membranes, and acts as energy storage

Lipids

What is the difference between saturated and unsaturated fatty acids?

• saturated have no double bonds

• unsaturated has atleast one double bond

What is the name of the complex lipid (composed of a glycerol, 2 fatty acids, and a phosphate group) that makes up cell membranes?

phospholipids

This macromolecule is essential in cell structure and function and is comprised of amino acids

proteins

What do amino acids contain?

Amino acids contain a carbon that has an attached

• Carboxyl group (-COOH)

• Amino group (-NH2)

• R group (side group)

What is a peptide bond and how is it formed?

Peptide bonds are between amino acids and are formed by removal of water (dehydration)

describe the four levels of protein structure

• The Primary Structure is a polypeptide chain

• The Secondary structure occurs when the amino acid chain folds and coils in a regular helix or pleats

• The Tertiary structure is the three-dimensional structure of a protein.

• The Quaternary structure is the relationship of several

folded polypeptide chains, forming a protein

This macromolecule is what comprises DNA and RNA

nucleic acids

Explain the difference between nucleotides and nucleosides

• Nucleotides consist of a pentose (deoxyribose or ribose), a phosphate group, and a nitrogen-containing (purine or pyrimidine) base

• Nucleosides consist of a pentose and a nitrogen-containing base

DNA (Deoxyribonucleic acid) contains four bases? What are they called and which of those bases always pair with each other?

• Adenine hydrogen bonds with Thymine

• Cytosine hydrogen bonds with Guanine

RNA (Ribonucleic acid) has a difference in bases compared to DNA, what are those differences?

RNA is single stranded, it contains ribose not deoxyribose, and it contains Uracil (which bonds with Adenine) instead of Thymine

What are the three main shapes of bacterial cells?

• Bacillus (rod-shaped)

• Coccus (spherical-shaped)

• Spiral (Vibrio, Spirillum, Spirochete)

Describe the different arrangements of bacterial cells

• Pairs: diplococci

• Clusters: staphylococci

• Chains: streptococci

• Groups of four: tetrads

• Cubelike groups of eight: sarcinae

What is the difference between gram positive and gram negative bacterial cells?

Gram-positive (monoderm) has only a single plasma membrane, a and a thick peptidoglycan layer (purple stain) with teichoic acids

Gram-negative (diderm) has an outer membrane enclosing a thinner peptidoglycan layer (pink stain), periplasmic space, and an inner membrane

What is a bacterial cell wall made of and what is its function?

It is made of peptidoglycan and it gives the cell shape/rigidity, prevents osmotic lysis, and acts of a point of anchorage for flagella

• can also contribute to pathogenicity

What is the composition and characteristics of peptidoglycan?

• Polymer of a repeating disaccharide in rows:

• N-acetylglucosamine (NAG)

• N-acetylmuramic acid (NAM)

• Rows are linked by polypeptides

What do teichoic acids do in gram-positive bacteria?

• Lipoteichoic acid links cell wall to plasma membrane

• Wall teichoic acid links the peptidoglycan

• Carry a negative charge

• Regulate movement of cations

What is the outer membrane of gram negative bacteria made of?

polysaccharides, lipoproteins, and phospholipids

What is a lipopolysaccharide (LPS)?

a large molecule made of a lipid and a polysaccharide that forms the outer membrane of Gram-negative bacteria

What is a porin?

proteins that form channels through the plasma membrane

What are the functions of the periplasm?

• Digestion by hydrolytic enzymes

• Transport by proteins

In summary, a gram-positive cell wall has…

• Thick peptidoglycan layer

• Peptidoglycan that contains teichoic acid

• No outer membrane around peptidoglycan

In summary, a gram-negative cell wall has…

• Thin peptidoglycan layer

• No teichoic acid

• Outer membrane around peptidoglycan with LPS

These atypical cell walls are made of a waxy lipid (mycolic acid) and are bound to mycobacterium (stained with carbolfuchsin)

acid fast cell walls

What is the name of the bacterium that has no cell wall?

Mycoplasma

____ hydrolyzes bonds in peptidoglycan

lysozome

_______ inhibits peptide bridges in peptidoglycan

penicillin

What is a gram-positive cell called when it loses its cell wall?

protoplast

What is a gram-negative cell called when it loses its cell wall?

spheroplast

true or false: protoplasts and spheroplasts are susceptible to osmotic lysis

true

What is the glycocalyx? What are the two types?

viscous and gelatinous secretion external to cell wall made of polysaccharides and/or polypeptides

• Capsule: neatly organized and firmly attached

• Slime layer: unorganized and loose

What are the main functions of the glycocalyx?

• Can contribute to virulence

• Capsules prevent phagocytosis

• Prevent dehydration

• Aids in adhesion

• Is a source of nutrients

• Extracellular polymeric substance helps form biofilms

What is a biofilm?

• Microbes attach to solid surfaces and grow into masses

• They will grow on rocks, pipes, teeth, other organisms

• Biofilms are often resistant to antibiotics or other stressors

Define a flagella

Filamentous appendages external of the cell used to propel bacteria (made of flagellin)

Name the five types of flagella (or lack of)

• Monotrichous: A single flagellum attached to one end (pole) of the cell.

• Amphitrichous: A single flagellum (or a tuft of flagella) located at both opposite ends of the cell.

• Lophotrichous: A cluster or tuft of multiple flagella emerging from one or both poles.

• Peritrichous: Multiple flagella distributed evenly all over the entire surface of the cell.

• Atrichous: Bacterium without a flagellum

What are the three parts of a flagella?

• Filament: outermost region

• Hook: attaches to the filament

• Basal body: consists of rod and pairs of rings; anchors flagellum to the cell wall and membrane

How do bacteria use flagella to move? What is the process called and how does it work?

Run and Tumble:

• Run: flagella rotate counterclockwise to propel bacterium

• Tumble” flagellum switch directions to clockwise motion to change direction

Axial filaments are found in _______ and move in a ______ fashion

spirochetes; corkscrew

Compare and contrast: fimbrae and pili

Fimbrae are short hair-like appendages that are thinner than flagella, hundred per cell, and function in adhesion

Pili are longer than fimbrae, only a few per cell, function by grabbing and retracting to pull cell

• both are found only on gram-negative bacteria and made of protein called pilin