Microbio Exam 1

Define microbe

Single organisms too small to see with the naked eye

Can eukaryotes be microbes?

Yes (protists, fungi, animals)

Do microbes contain nucleic acid?

Yes

True or false: all microbes replicate and evolve

True

Give 4 examples of places where microbes live

Soil. freshwater, seawater, and sediments

Where are microbes first thought to have evolved?

Oceans on the deep-sea floor near thermal vents

What is the current definition of prokaryotic species?

• Share high degree of similarity in several independent traits

• 98.7% or greater 16S rRNA gene sequence identity

• 70% or greater DNA-DNA hybridization

• Share multiple phenotypes

What are the key purposes of microbes?

• Nutrient production and energy flow

• Decomposition

• Symbiotic relationship with humans, animals, and plants

What are three main types of microscopy?

• Light microscopy

• Scanning probe microscopy

• Electron microscopy

How is total magnification calculated?

The product of all lens magnification

Define resolution

The ability to distinguish between object and background or other neighbors

What are the two properties that are most important for visualizing samples by light microscopy?

Magnification and resolution

What is the limit of light microscopy?

0.2 um (200nm)

What are the two types of bright field microscopy?

Wet mount and differential stains

Where does light come from in dark fiel microscopy?

From the sides

What does phase contrast microscopy rely on?

Phase ring which enhances differences in light phase

Can differential interference contrast microscopy distinguish internal features of cells?

Yes

Describe the light used in confocal microscopy?

Pin point focused light of only one wavelength

What are fluorophlores?

Small structures found in dyes and proteins, absorb light energy of a specifc wavelength and re-emits light at a longer wavelength

Does laster scanning confocal microscopy give depth information to 3D structures?

Yes

What is the effect of STORM/PALM on fluorophores?

Only activate or excite a small percentage of them at one time

What are two key uses of STORM/PALM?

• Track molecule movement over time

• Precise localization of fluorophores

What are the largest bacteria known?

• Epulopiscium fishelsoni

• Thiomargarita namibiensis

• Thiomargarita magnifica

What is the smallest idependently-replicating bacteria known?

Mycoplasma (can cause pneumonia and pelvic inflammatory disease)

What size and shape is preferable in an unstable environment?

Small and cocci

What is the benefit of cocci shape in stable low nutrient environments?

Slow growth and maximal diffusion throughout the cell (high S/V ratio)

What shape is favored in liquids or semi-solids?

Red and helical

What does the suffix “-coccus” indicate?

Spherical

What does “vibrio” indicate?

Curved rod shape

What does the suffix “-bacillus” or “-bacter” indicate?

Rod shaped

What does the suffix “-spira” or “-spirillum” indicate?

Spiral shaped

What does the prefix “azoto-” indicate?

Nitrogen-fixing

What does the prefix “nitro-” indicate?

Nitrogen cycle

What does the prefix “cyano-” indicate?

Blue/green (usually photosynthetic)

What does the prefix “rhodo-” indicate?

pink/red/purple (often photosynthetic)

What does the prefix “photo-” indicate?

Photosynthetic

What does the prefix “hydrogeno-” indicate?

Hydrogen cycle

What does the prefix “methano-” indicate?

CO2/methane cycle

What does the prefix “ferro-” indicate?

Iron

What does the prefix “sulfo-” indicate?

Sulfur cycle

What does the prefix “thio-” indicate?

Sulfur cycle

What does the prefix “phospho-” indicate?

Phosphate

Can external forces change the shape of some organisms?

Yes

What is the difference in layers for G+ and G- cell walls?

G- cell walls have 3 layers while G+ have 2

What is the extra layer in G- cell walls?

Outer membrane, a lipopolysaccharide rich outer envelope

____ linkages are between head groups and fatty acids in BACTERIA?

Ester

Do most cytoplasmic membranes lack or contain sterols in BACTERIA?

Lack

What are the linkages between isoprenoid chains and glycerol backbones in ARCHAEA?

Esther

Are monolayers more or less fluid than bilayers?

Less fluid

In what environments is less fluidity favorable?

Extreme conditions like high heat

What are functions of cytoplasmic membranes?

• Prevents leakage and diffusion into the cell

• Anchors proteins

• Provides barrier allowing for proton motive force

• Regulates transport into the cell

• Regulates transport out of the cell

Is diffusion passive or active transport?

Passive

Uniporters, symporters, and antiporters work in what type of transport?

Simple active transport

Are ABC transporters ATP-dependent?

Yes

How many secretion systems in bacteria?

9

Where are proteins secreted in bacteria?

Into the periplasmic space, outside the cell, or into neighboring cells

Describe the structure of peptidoglycan

Repeated subunits of NAG and NAM bound by B-1,4 linkages. Cross-linked together via peptide bonds. Studded with proteins

Which kind of bacteria has a thick peptidoglycan layer?

G+

Is peptidoglycan found in archaea or eukaryotes?

No

What are the main functions of peptidoglycan?

• Cytoskeleton gives structure to cell

• Anchors proteins (G+/G-) and lipoteichoic acids (G+)

• Acts as mesh

• Connects cytoplasmic membrane to outer membrane

Does peptidoglycan retain crystal violet?

Yes

What are the three general types of archaeal cell walls?

• S-layer

• Pseudomurein

• Other polysaccharides

What is the correct order of Gram staining?

Crystal violet, iodine, ethanol, safranin

What dictates virus shapes?

• Nucleic acid

• Proteins

• Host cell envelopes

• No peptidoglycan

• No cell walls

What nutrients are required for most microbes?

• Carbon

• Hydrogen

• Nitrogen

• Oxygen

• Phosphorus

• Sulfur

What is the chemical formula for a cell?

C6H12O3N

Is iron a macro or micronutrient?

Micronutrient

What are the three transport systems for orgnanic carbon?

• Permeases (for sugars)

• High-affinity uptake systems (for amino acids)

• Uptake or competence (for nucleotides)

What kind of organisms can convert CO2 into organic carbon?

Autotrophs

Is N2 in the air bioavailable to bacteria?

No

What is NH4?

Nitrogen-fixing bacteria

What is NO2-?

Nitrifying bacteria

What is N2 converted to for consumption?

NH4 or NO2-

Can others (not bacteria) acquire nitrogen from inorganic or organic sources?

Yes

What reaction is mediated by nitrogenase enzyme?

N2 —> NH3

What reaction is mediated by glutamate dehydrogenase in ammonia channels?

NH3+a-ketoglutarate —> glutamate

How do bacteria acquire iron?

• Siderophores

• High affinity molecules

• Diffused into environment

• Uptake systems

What is the advantage to secreting siderophores into the extracellular milieu?

It will help sister microbes (the same species) grow

Can most or some microbes do glycolysis?

Most

What is glycolysis?

Glucose (C6) to 2 pyruvate (C3)

Some microbes can do fermentation, which converts ___ to ____ and/or ___.

Pyruvate, lactic acid, ethanol

What is aerobic respiration and what is it done through?

Pyruvate to CO2 through TCA, e- transport chain

What is the electron acceptor in aerobic respiration?

O2

What is anaerobic respiration and what is it done through?

Pyruvate to CO2 through TCA, e- transport chain

What are the electron acceptors in anaerobic respiration?

SO4, NO2, NO3, etc.

True or false: transferring of e- can lead to work

True

Can glycolysis be aerobic or anaerobic?

Yes

What are the net products of glycolysis?

2-3 ATP + 2 pyruvates + 1-2 NAD(P)H

__ ATPs are produced per glucose in fermentation

2

How many ATPs per glucose in respiration?

34-38

In the TCA cycle, 1 glucose molecule generates:

6 CO2, 8NAD(P)H, 2 FADH2, 2 GTP

True or false: oxidized e- carriers are essential for electron transport

False, reduced carriers are

The TCA cycle generates precursors to…

amino acids, nucleotides, fatty acids

The proton motive force makes the inside of the membrane electrically ____.

Negative

What does ATP synthase (ATPase) do?

Converts proton motive force into ATP

What are the two componenets of ATP synthase?

F1 and F0

What is F1?

Multiprotein extramembrane complex that faces the cytoplasm

What is F0?

Proton-conducting intramembrane channel

What is chemotrophy?

Energy comes from breaking bonds in chemical compounds

What is phototrophy?

Energy comes from light