Microm 410 Exam 1

What is defined as the "Microbial World", and what organisms does it contain?

-Organisms 1mm or smaller in size

-Eukaryotes:

Fungi

Protozoa

Multicellular Parasites

-Prokaryotes:

Bacteria

Archaea

What is significant about Deinococcus radiodurans?

It is an early prokaryote, and can survive doses of radiation 3000x the lethal human dose

What are stromatolites?

Stacks of bacterial living together, dating back ~3.5-3.8 billion years of age.

When was the Great Oxidation Event, and who caused it?

2.4 billion years ago

Caused by cyanobacteria

When were plant cells first discovered?

In 1665, by Robert Hooke, using a 20x magnification

When was the Microbial World discovered?

In 1677 by Antoni van Leeuwenhoek, with a 100x magnification.

Looked at plaque, rain/pond water.

Found bacteria, protozoa, RBC

What is the Germ Theory of Disease?

Microorganisms are responsible for infectious diseases - Pasteur, 1857

What are Koch's Postulates?

1. Microbe is always present in diseased host, and absent in healthy.

2. Microbe is grown in pure culture, with no other microbes present.

3. Pure microbe is introduced into healthy host, and causes sickness.

4. Same microbe is re-isolated from now-sick individual.

What are Koch's Postulates used as?

They are used as a criteria for establishing a causative link between an infectious agent and a disease.

What are the key differences between prokaryotes and eukaryotes?

Eukaryotes have a cytoplasmic cell membrane, and nucleus, and organelles

What is the significance of the 16S rRNA?

It can be used as a molecular clock, as it is highly conserved, and can find the branching point between two organisms.

What traits do all living organisms share in Chromosomal Material?

All have double-stranded DNA

What traits do all living organisms share in RNA Transcription?

All have a common ancestral RNA Polymerase

What traits do all living organisms share in Translation?

Universal genetic code

Common ancestral rRNAs and elongation factors

What traits do all living organisms share in Protein?

Common ancestral functional domains

What traits do all living organisms share in Cell Structure?

Aqueous cell compartment enclosed by a membrane

What did Schimper propose, and when?

Proposed in 1883 that chloroplasts were cyanobacteria living inside plant cells

What are some traits Mitochondria and Chloroplasts share with Prokaryotes?

Circular DNA

No Histones

70S Ribosomes

Growth via Binary Fission

What are polysaccharides?

Sugar polymers, mostly joined by alpha-1,4-glycosidic bonds

Where are lipids most important in a cell?

As components making up cell membranes

What are nucliec acids?

Nucleotide polymers, joined by Phosphodiester bonds between 3' and 5' carbons of the deoxyriboses

What are proteins?

Amino acid polymers, joined by peptide bonds at the N and C ends

What prokaryotic structures can be located on the cellular envelope?

Flagella

Pili

Outer membrane

Capsule

Wall

Periplasm

Cell membrane

What prokaryotic structures can be located in the nucleoid?

DNA

What structures make up the cytosol?

1,000 proteins

60 tRNAs

Glycogen

What structures make up the polysomes?

18,000 ribosomes

55 proteins

3 tRNAs

1,000 mRNAs

What is the size range of Prokaryotes?

Mycoplasma: 0.1-0.3 um

Thiomargarita namibiensis: 700-750 um

What are the common shapes of prokaryotes?

Filimentous Rods (Bacilli)

Rods (Bacilli)

Spirochetes

Cocci in pairs (diplococci)

Cocci in chains

Vibrio

Stalk

What is the meaning of pleomorphic?

No defined shape

What are three common arrangements of prokaryotic cells?

Chains

Packets

Clusters

What is Gram Staining?

A crystal violet dye is injected to bacteria.

Gram-positive: Retain crystal violet stain because of thicker cell wall

Gram-negative:Dye is not retained.

What are the steps to perform a gram stain?

1. Add methanol to fix cells to surface, air dry.

2. Add crystal violet stain (1 min)

3. Add iodine, which binds to stain gram positive cells (1 min)

4. Wash with ethanol (20 s)

5. Add safarin counterstain (to stain gram negative) (1 min)

What are other differential stains?

Acid-fast Stain: Carbolfuchsin used to stain Mycobacterium

Spore Stain: malchite green used to detect spores of Bacillus and Clostridium

Negative Stain: Colors the background, making capsules more visible

How thick is the phospholipid membrane?

6-8 mm

What are three key functions of the cell membrane?

1. Site of energy generation

2. Key location of important proteins

3. Permeability barrier/location of transport functions

What is the structure of bacterial phospholipids?

Fatty acids attached to glycerol backbone via ester linkage

Phospholipids vary on basis of fatty acids and groups attached to phosphate head group

When is the fluidity of a membrane increased?

FA tail length is shorter

FA tails are polyunsaturated

What are planar molecules that provide membrane stability?

Eukaryotes: Sterols, cholesterol

Bacteria: Hopanoids, hopanes

What is the composition of phospholipids in Archaea?

Ether links between the glycerol and fatty acids

Hydrocarbons are branched terpenoids

Diethers are condensed in the middle together

Can form a lipid monolayer

What is the importance of a cell wall?

Provides rigidity to cell, allowing resistance to osmotic/ionic changes, and turgor pressure

Has role in shape determination

Provides a barrier against toxic chemical and biological agents

Site of action of commonly used antibiotics treating bacterial infections

Component of cell wall is responsible for infection symptoms

How is the cell wall of gram-positive bacteria structured?

A thick peptidoglycan layer surrounds the membrane.

How is the cell wall of gram-negative bacteria structured?

An inner and an outer membrane with a thick periplasm between. The periplasm is packed full of proteins, and there is a thin peptidoglycan layer in the middle.

Which prokaryotes lack a cell wall?

Mollicutes group of Bacteria

L-forms of bacteria

Some Archaea (Thermoplasma)

What are some properties of the mollicuties group?

No cell wall

Sensitive to osmotic lysis

Resistant to antibiotics directed at cell wall biosynthesis

Pleomorphic

Have sterols in membrane

Some are parasites of plants/animals

Which prokaryotes contain peptidoglycan?

All bacteria, except for Planctomyces and Chlamydia

Which prokaryotes lack peptidoglycan?

All cell-walled Archaea

C. trachomatis

What is C. trachomatis?

An intracellular parasite, leading cause of blindness in the world.

How much of a gram-positive bacteria's cell wall is made of peptidoglycan?

~40-90%

How much of a gram-negative bacteria's cell wall is made of peptidoglycan?

~5-10%

What is the basic subunit of peptidoglycan?

N-Acetylglucosamine (NAG), linked to N-acetylmuramic acid (NAM) by a beta-1,4 glycosidic linkage.

NAM has a lactic acid attached, which has 4 additional AA attached

One of these is meso-DAP, where cross-linked peptidoglycans attach.

How are new peptidoglycans synthesized?

1. Make subunit

2. Get it across membrane via a flippase

3. Insert it into existing peptidoglycan via glyosylase.

ADD CARD FOR LONG PEPTIDOGLYCAN SYNTHESIS EXPLANATION

How are peptidoglycan strands cross-linked?

DAP of one strand attaches to the terminal D-ala of the other, displacing a single D-ala group by transpeptidase.

What are some ways that bacteria can gain antibiotic resistance?

Inactivate antibiotic b-lactamase (penicilinase)

Change chemistry of target site (preventing antibiotic binding)

Limit access of antibiotic to target site

What links peptidoglycan and the cell membrane?

Teichoic Acid

What is the function of Teichoic Acid?

Provide structural integrity

-Can link with terminal D-ala of NAM

Can act as a receptor for bacteriophage

What is the purpose of the overall negative charge in Teichoic acids?

Negative charge allows it to chelate Mg2+ and Ca2+ ions

How are Teichoic acid subunits connected?

By phosphate diester, can be linked to NAM

What specific porins do Gram-Negative Cell Envelopes have?

LamB - maltose and maltodextrins

Tsx - Uptake of Nucleosides

What is Lipopolysaccharide?

A major antigenic determinant of Gram-negative bacteria.

Made of up to 200 sugars

What are the differences between Archaeal cell walls and prokaryote cell walls?

Archaea use NAT instead of NAM, links to NAG by a beta 1,3 linkage.

No lactic acid between NAT and peptides

What is the S-layer?

A Protein cell wall component

Found in many archaea, some bacteria

A selectively permeable membrane

Scaffold to attach other proteins

What is a capsule layer?

A polysaccharide layer outside of the cell wall

What is a true capsule?

A discrete layer deposited outside the cell wall

What is a slime layer?

A less discrete structure or matrix embedding the cells

What are the possible chemical compositions of Capsule/slime layers?

Polysaccharide in composition

Glycoprotein in composition

How can the type of capsule be identified?

Chemical analysis

Serotyping via:

-Antibodies

-Immunoglobins

-Antigen

-Antogenic determinant/epitope

How is dextran synthesized?

From sucrose by S.mutans

Involved in plaque formation

What is the structure of dextran?

Complex, branched glucose polymer

What are the uses of dextran?

Energy Reserve

Attachment Factor

Antithrombotic agent in microsurgery

Lubricant in eye drops

Size-exclusion chromatography matrix

What things can Capsule/slime layer protect against?

Dessication

Avoiding Phagocytosis

What are some examples of capsule/slime layer contributing to pathogenesis?

Streptococcus pyogenes - Sore throat

Streptococcus pneumoniae - pneumonia

Yersinia pestis - plaque

Bacillus antracis - anthrax

Neisseria meningitidis - meningitis

By what method do motile prokaryotes generally swim?

Via rotary flagella

What is the distribution of flagella in Peritrichous cells?

Flagella randomly distributed around the cell.

Rotate together in a bundle behind the swimming cell.

What is the distribution of flagella in Lophotrichous cells?

Flagella at the end(s)

What is the distribution of flagella in monotrichous cells?

A single flagellum

How is the energy generated in gram-negative flagellum?

Energy required provided by proton motive force

What is the structure of eukaryotic flagella/cilia?

Many cilium around the cell

Each cilium contains 11 microtubules, forming a ring around the edge of a cell, with one in the middle.

How do spirochetes move?

Endoflagella are enclosed in a space beneath the outer membrane.

They rotate beneath this to create the corkscrew swimming motion of spirochetes.

What are gas vesicles?

Small gas-filled structures made of protein, conferring buoyancy on cells.

What is the structure of gas vesicles?

Two proteins arranged to form a gas-permeable, but watertight, structure

What is a Magnetosome?

A bacteria that is sensitive to magnetic fields.

What materials make magnetosomes magnetic?

Magnetite

Greigite

Iron Pyrite

What is the purpose of magnetic sensitivity in Magnetosomes?

Help find oxic-anoxic interface in freshwater systems

Moves parallel to magnetic field

Moves faster as field strength increases

What are the five things necessary for growth/maintenance?

1. Reducing Power (NADH, NADPH, FADH2, FMNH)

2. Biochemical Energy (ATP)

3. Electrochemical Energy (PMF)

4. 12 key Organic Precursor Molecules

5. Source of C1 (Methyl) Groups

What is chemoorganotrophy?

Energy produced by breaking down organic compounds

What is chemolithotrophy?

Energy produced by oxidizing inorganic compounds (H2, NH4+, H2S)

What is phototrophy?

Energy produced by harvesting light

What are the details of generating energy via respiration?

Energy generated through ETC

ETC is a series of REDOX reactions

Electron donor feeds high E electrons to ETC

Terminal electron acceptor receives e- at the end

What are the details of generating energy via fermentation?

Oxidation of organic compounds is coupled directly to ATP production

What are important energy-rich molecules in Biological systems?

Phosphoenolpyruvate

Adenosine triphosphate

Glucose 6-phosphate

Acetyl-CoA

Acetyl phosphate

What is oxidation?

Loss of an electron

What is reduction?

Gain of an electron

How much energy does NADH carry compared to ATP?

Two or three times as much

What is the reduced form of NADH?

NADH

What is the oxidized form of NADH?

NAD+

How many hydrogen atoms are needed to convert NAD+ to NADH? Where does the required energy come from?

Two hydrogen atoms are consumed

The energy comes from food molecules

What is the reduced form of FADH2?

FADH2

What is the oxidized form of FADH2?

FAD

How many electrons and protons does FAD require to be reduced?

Two electrons and two protons