why is microbiology important? - jfriel - jessica friel's...

1

Introduction to Microbiology

Why is Microbiology Important?

• Diarrhea

• Pneumonia

• Tuberculosis

• Malaria

• Hepatitis B

• Measles

• Tetanus

• AIDS

• Whooping cough

• Amebiasis

• Schistosomaisis

Top Causes of Death

Photosynthesis and Nitrogen How Microbes Shape Our Planet

•Microbes are the main forces that drive the structure and content of the soil, water, and atmosphere

- produce gases such as CO2, NO, and CH3 that regulate the temperature of the earth

- the enormous underground community of microbes influence weathering, mineral extraction, and soil formation

- bacteria and fungi live in close associations with plants that help them obtain nutrients and protect them against disease

2

Microbes and the Planet

•Microbes are ubiquitous- found in the Earth’s crust, polar ice caps,

oceans, and the bodies of plants and animals

- occur in large numbers

- live in places where other organisms cannot survive

FoodBreadCheeseMilk ProductsAlcoholic BeveragesSpoilage/PreservativesPlant and Animal Disease

Antibiotics

• Penicillins

• Tetracyclines

• Erythromycin

Molecular Biology

Gene cloningGenetic engineeringMetabolism research

History of Microbiology

History of Microbiology• The study of microbes originated ~300 years ago

• Prior to microbiology, many believed people that got sick were being punished for their transgressions

• Before 1900, one of every two (50%) of children died before reaching 10

• Walk through older cemeteries and many graves belong to children

• Imagine having one of your 2 children dead before age 10

3

History of Microbiology1660‐ Robert Hooke observes plants under simplemicroscope (coins term “cell” due to resemblance ofplant cells to monks' cells)


Antonie van Leeuwenhoek was a linen merchantwho needed to analyze hiscloth fibers and becamecurious about otherspecimens like rain waterand tooth plaque. To hissurprise he found “movinganimalcules”!

1676‐ the first to observemicrobes (up to 300X)

History of Microbiology:Spontaneous Generation

Spontaneous Generation or Abiogenesis: Early belief that some forms of life could arise from vital forces present in nonliving or decomposing matter.

Biogenesis: All living things arise from other living things.

• Two of the most popular experiments to prove biogenesis:

– Francisco Redi—meat and maggots

– Louis Pasteur—S‐shaped flask


• 1688 Francesco Redi‐ published experiments to disprove spontaneous generation

In 1859, Pasteur devises the S‐ shaped flask to disprove the theory of spontaneous generation. Microbes are everywhere (air) and will grow in broth

unless killed by boiling and prevented from entering broth


Vigorous heat is applied to produce

broth free of live cells (sterile).

Intact: Microbe Growth Does Not Occur

Neck intact; airbornemicrobes are

trapped at base,and broth is sterile.

Exposed: Microbe Growth Occurs

Neck on secondsterile flaskis broken;

growth occurs.

1796‐ Edward Jenner demonstrates that inoculation with cowpox material provides humans with immunity to smallpox (origin of vaccines)


4


• 1847‐1850‐ Ignaz Semmelweiswas the first to test whether disinfecting hands can prevent disease

• 1867‐Joseph Lister tested the effectiveness of disinfecting medical equipment using aseptic techniques

Louis Pasteur:

• 1857‐Fermentation is caused by microbes

• 1861‐Completes S‐shaped flask experiments that disprove spontaneous generation

• 1862‐Introduces pasteurization to prevent spoilage

• 1881‐Develops anthrax vaccine for animals


Robert Koch:

• Studied anthrax and hypothesized that it may be caused by bacteria

• 1876‐ Proved that microbes cause disease (cause & effect link)

• Invented agar plates

• Developed Koch’s postulates

• Germ theory of disease uses these postulates


GERM THEORY‐diseases are caused by germs and not because you have sinned or done something wrong.

1. The suspected pathogen must be found in every case of the disease.

3. Inoculation of a sample of the culture into a healthy, susceptible animal must produce the same disease.

2. The suspected pathogen must be isolated in pure culture.

Koch’s Postulates

4. The suspected pathogen must be recovered from the inoculated animal.

• 1910‐ Paul Ehrlich introduces first chemotherapeutic for syphilis (searched for “magic bullets”)

• 1928‐1940s‐ Alexander Fleming accidentally discovers penicillin

History of Microbiology Scientific Method: Another Development in Microbiology

Modified from:

5

Scientific Method: In Action

You are a researcher in the late 1800s and observe that some bacteria, such as Bacillus anthracis, are very hard to kill

Modified from:


You hypothesize that Bacillus anthracis can withstand high temperatures not tolerated by other bacteria such as Staphylococcus aureus.

Modified from:


From this hypothesis you predict: If Bacillus anthracisand Staphylococcus aureusare subjected to increasing temperatures then Bacillus anthracis will be able to survive after treatment of higher temperatures than Staphylococcus aureus.

Modified from:


You expose both bacteria to increasing temperatures and observe that Bacillus anthracis can withstand higher temperatures than Staphylococcus aureus.

Modified from:

Scientific Method: In ActionYour hypothesis was supported. Now you have made another observation: that Bacillus anthracis can withstand higher temperatures than Staphylococcus aureus.

Now you can make another hypothesis: Bacillus anthracisis able to protect itself from high temperatures by changing its morphology.

And the cycle continues…

Modified from:

Classification

6

Microorganismsvary in size ‐1μm to 200 nm

Characteristics of Microorganisms

• Prokaryotic – no nucleus and organelles

– Relatively simple in structure BUT complicated in function

• Eukaryotic – nucleus and organelles

– organelles are small, double‐membrane‐bound structures that perform specific functions in a cell and include the nucleus, mitochondria, and chloroplasts

• Caryo: Greek for kernel

Prokaryote Eukaryote

The Cell

• Fundamental characteristics of a cell (life)• Growth

• Reproduction and heredity (all have DNA)

• Metabolism(digest nutrients and build cell parts

• Motility and/or irritability(Response to molecules)

• Protection and Storage (Cell wall or membrane)

• Nutrient transport (cell membrane regulates transport and draws nutrients in and expels wastes and other chemicals)

Bacteria appeared approximately 3.5 billion years ago

7

Taxonomy

• Grouping organisms

• Why is it important to be able to classify things in microbiology?

– Allows to identify things correctly

– Communicate about species of microrganisms

– Identify disease causing agent so you can treat

Advent of molecular biology caused scientists to rethink the 5 kingdom classification model.

Now six kingdoms

The basis of the Domain system is based off of rRNAsequence information

Domains• Based on genetic similarities:

– Archaea: (oldest cells‐ archaic) cells that live in extreme environments, high salt, heat, etc, NO peptidoglycan, no organelles

– Bacteria: true bacteria, peptidoglycan in cell wall, no organelles

– Eukarya: have a nucleus & membrane bound organelles (ER, Golgi, mito/chloro)

Viruses‐ Living or Not?• Depends on who you ask‐ I say not living, most biologist agree with this. Why:- Do not have cell structures

- Cannot replicate without using host replication machinery

- For this class they are not living!!

• Because viruses are not living they are not included in the Kingdom system

Pathogens: What Domain and Kingdom?

• Helminthes:

8


• Protists:


• Viruses:


• Fungus:


• Bacteria:

All Levels of Classification

Domain……………………….Did

Kingdom……………………..King

Phylum……………………….Philip

Class……………..…………..Come

Order………………………….Over

Family………………………...For

Genus…………………………Great

Species……………………….Soup?

Notice how inclusive a kingdom is, and how

less inclusive a genus and species isEukaryotic, heterotrophic and mostly multicellular

Possess notochord, dorsal nerve cord, pharyngeal slits (if only in embryo)

Possess hair, mammary glands

Digital dexterity, large cerebral cortex, slow reproductive rate, long life span

Large brain, no tail, long upper limbs

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Primates

Family: Hominoidea

Genus: HomoErect posture, large cranium, opposable thumbs

Species: sapiensHumans

Genus: ParameciumPointed, cigar-shaped cells withmacronuclei and micronuclei

Species: caudatumCells cylindrical, long, and pointed at one end

Cells rotate while swimming and have oral grooves

Elongated oval cells with cilia in the oral cavity

Single cells with regular rows of cilia; rapid swimmers

Only protozoa with cilia

Includes protozoa and algae

Kingdom: Protista

Phylum: Ciliophora

Class: Hymenostomea

Order: Hymenostomatida

Family: Parameciidae

9

Classification

• Helpful to figure out how closely related organisms are

• Very helpful when identifying and treating disease.

• For example, can you treat all diseases the same?

• What if you gave a patient a drug that killed worms or insects could you also harm the human cells?

When cell type is similar to host…

• Much more difficult to treat diseases that are similar to animal cells

– Animalia parasites

– Fungal parasites

– Viruses (replicate inside our cells)

Nomenclature• In order to accurately classify things we need to accurately name them

• Scientists use Binomial (or scientific) nomenclature which uses 2 names:– Genus – Homo, always capitalized– species ‐ sapiens, lowercase

• Both italicized or underlined

• Ex. Homo sapiens (H. sapiens)

Nomenclature

• Escherichia coli: Named by Dr. Escherich, found in colon

• Staphylococcus aureus: Looked like a cluster of grapes (staphylococcus) and was golden yellow (aureus)

• Saccharomyces cerevisiae: Myc‐fungi who eat sugar (saccharo) and make cerveza (beer)

The Chemistry of Biology

Macromolecules: Superstructures of Life

•Macromolecules: very large molecules

•Four main macromolecules- carbohydrates- lipids- proteins - nucleic acids

•Monomers: subunits of macromolecules

•Polymers: chains of various lengths made up of monomers

10

•Generally represented by the chemical formula (CH2O)n

•Monosaccharides and disaccharides are specified by combining a prefix that describes some characteristic of the sugar with the suffix –ose.

O

O

O

O

Polysaccharide

Monosaccharide

Disaccharide

O

O

CH2

CH2

© H Lansdown/Alamy (RF)

Carbohydrates

•Contribute to structural support and protection

•Serve as nutrient and energy stores

•Agar: polysaccharide used in preparing solid culture media for microbes

•Peptidoglycan: polysaccharides linked to peptide fragments; found in bacterial cell walls

•Lipopolysaccharide: complex of lipid and polysaccharide responsible for symptoms of fever and shock

•Glycocalyx: outer surface of many cells; functions in attachment or as a receptor that receives external stimuli

Polysaccharides

Peptidoglycan is composed of both carbohydrates and

peptides

In most cells, tryglycerides are stored in long‐term concentrated form as droplets or globules

Lipids: Fats, Phospholipids, and Waxes

• Hydrophilic (“water‐loving”) region from the charge on the phosphoric acid‐alcohol “head” of the molecule

•Hydrophobic (“water‐fearing”) region in the long, uncharged “tail” of the molecule formed by fatty acids

OC C

OO

H

H

O

O

P OO

RO

Variable alcohol group

Polar lipid molecule

(a)

Phosphatepolar head

(b)

Water Water

(2) Phospholipid bilayer

Glycerol

Water

(1) Phospholipids in single layer

Chargedhead

HCH

HCH

HCH

HCH

HCH

HCH

HCH

HCH

HCH

HCH

HCH

HCH

HCH

HCH

HCH

HCH

HCH

HCH

HCH

HCH

HCH

HCH

HCH

HCH

HC

HCH

CH

Fattyacids

Nonpolartails

These lipids naturally assume single and double layers (bilayers), which contribute to their biological significance in membranes

Membrane LipidsView of a Membrane Bilayer of Lipids

H C

C

C C

Cellmembrane

Protein

Cholesterol

Glycolipid

Phospholipids

Site forester bondwith a fattyacid

Cholesterol

HO

CH2

CH2

CH2

CH2

CH

CH3 CH3

CHH2C C

H2C

CH3

CH3

CH3CH

CH

HC

HC CH

H2C

H2

11

•Predominant organic molecule in cells

•Amino acids: building blocks of proteins

•Peptide: a molecule composed of short chains of amino acids

•Polypeptide: contains an unspecified number of amino acids but usually has more than 20 and is often a smaller subunit of a protein

ProteinsProtein Structure and Diversity

•Primary structure (1°): the type, number, and order of amino acids in the chain

•Secondary structure (2°): arises when functional groups exposed on the outer surface of the molecule interact by forming hydrogen bonds

- alpha helix

- beta‐pleated sheet

Protein Structure and Diversity

•Tertiary structure (3°): created by additional bonds between functional groups

•Quaternary structure (4°): formed when more than one polypeptide forms a large, multiunit protein

•Each protein develops a unique shape with a distinctive surface pattern

•Creates a functional diversity required for thousands of cellular activities

•Enzymes: protein catalysts for chemical reactions in cells

•Antibodies: complex glycoproteins with specific attachment regions for bacteria, viruses, and other microorganisms

•Native state: the functional three‐dimensional form of a protein

•A protein becomes denatured if the protein structure is disrupted for some reason

Protein Bonding and Folding

Enzymes• Biological catalysts that lower activation energy

• Very Efficient:• Enzymes can catalyze reactions up to 10 billion times

faster• There is a high turnover rate. One enzyme can be

recycled many times (depending on the enzyme).

• Very Specific:• 1 enzyme for 1 substrate, similar to 1 key for 1 lock,

difficult to open any car in the parking lot with your key

Enzymes

• Enzymes have specific active sites that bind to specific substrates

12

• In order for bonds to be formed or broken, there has to be a minimal amount of energy available. This minimal amount of energy is termed “activation energy.”

Enzymes Catalyze Reactions The Nucleic Acids

•DNA: contains the special coded genetic program with detailed and specific instructions for each organism’s heredity

•RNA: “helper” molecules responsible for carrying out DNA’s instructions and translating the DNA program into proteins

The Nucleic Acids

The Double Helix of DNA•Formed by two very long polynucleotide strands linked by hydrogen bonds between complementary pairs of nitrogen bases

RNA: Organizers of Protein Synthesis•Contains ribose instead of deoxyribose and uracil instead of thymine

•Three major types:- messenger RNA (mRNA)- ribosomal RNA (rRNA)- transfer RNA (tRNA)

ATP: The Energy Molecule of Cells

•Adenosine triphosphate (ATP)

•high‐energy compound that give off energy

•This releases energy to do cellular work

why is microbiology important? - jfriel - jessica friel's...

Documents