Exam 2

Units 4, 5, and 6

Name the 4 macromolecules

Proteins, lipids, carbs, and nucleic acids

What do nucleic acids aid in?

Replication, transcription, and translation of DNA

In prokaryotes, flagella rotates from

Basal body

Atrichous

No flagella

All cocci are

Atrichous

Monotrichous

1 flagella

Amphitrichous

Tuft at each end

Lophotrichous

2 or more at each end

Peritrichous

Distributed over the entire cell

What are flagella made of an anchored to?

Flagellin, cell walls and membranes

Flagellin protein H antigen is used to

Distinguish subspecies, like E. coli 0157:H7 for food borne epidemics

Axial filaments are found on

Spirochetes

Many gram negative bacteria have pili whose purpose is to

Adhere to surfaces, colonize a cell, conjugation (transfer DNA)

Cell wall is absent in

Mycoplasma sp. which causes walking pneumonia

Cell wall is semi-rigid and complex whose purpose is to

Provide shape Protect cell membrane Anchor flagella Prevent rupture of cell in hypotonic solutions

Cell wall is composed of

PG, which is made of the sugars NAG and NAM, and the proteins tetra peptide side chain and peptide cross bridge

Gram positive cell wall has many layers of

PG, like staph.

Bacterial cell membrane

Is a phospholipid bilayer

Gram negative cell wall (E. coli)

Consists of 1 or few layers. Composed of an outer membrane with a lipid later that acts as a barrier (enzymes. detergents, and antibiotics) and a periplasmic space. Susceptible to mechanical breakage.

Cell membrane is a phospholipid bilayer with

No sterols and is less rigid than the cell membrane in eukaryotes. It’s selectively permeable.

Cell membrane is the site of

ATP synthesis in bacteria with no mitochondria.

Cytoplasm is made of

80% water, proteins, carbs, lipids, and inorganic ions

Cytoplasm is

Thick, aqueous, semitransparent, and elastic

True or False: Cytoplasm cytoskeleton was recently discovered, composed of microtubules and filaments, similar to eukaryotic cells

True

Nucleoid (nuclear area, no nucleus)

Bacterial DNA is double stranded and circular 1 chromosome with 3-5k genes on it NO nuclear membrane or histone proteins Attached to the cell membrane

Plasmids (optional)

Small, circular, double stranded DNA Not connected to the chromosome 5-100 genes on it Replicated independently of chromosomal DNA. Can be gained or lost with no harm to the cell

Ribosomes

70 Svedberg 10k+ present Eukaryotes are around 80 Svedberg

What do antibiotics inhibit in regards to protein synthesis?

Ribosomes

Inclusions

Cells accumulate certain nutrients Metachromatic granules contain phosphate or ATP

Reserve deposits

Pockets within the bacteria, can hold glycogen, lipids, sulfur, gas, and enzymes

Endospores in bacteria are

NOT for reproduction

Endospores

Protect the cell from adverse environmental conditions. Found in Clostridium and Bacillus sp.

Sporulation

The process of forming endospores within the vegetative cell

Germination

If the cell goes back to the vegetative state when the endospores are no longer needed

Stain used to locate endospores involves

Malachite green and heat

Spore coat is made of

PG, Ca++, and dipocolinic acid

Endospores location

Terminal, subterminal, or central

When mature what happens to the endospores?

Cell ruptures and lacks endospores

Capsule is made of

Glycocalyx, a mucopolysaccharide

\___ to cell wall

External

Capsule stain is

India ink, a negative stain of the background

Microbes with a capsule

Pasturella multocida (dog bite) S. Pneumoniae H. Influenzae (bacterial eye infection, babies get a vaccine for it at 2 months, used to be the leading cause of meningitis)

Cocci

round, atrichous cells

Vibrio

Curved

Spirillium (rigid or flexible)

Rigid

Spirochetes (rigid or flexible)

Flexible

Binary fission

Cell elongates and DNA replicates → new cell begins to form → cells separate

Lag phase

Preparing for growth, not actively replicating

Log phase

Logarithmic increase in population

Stationary phase

Microbial deaths balance production of new cells

Death phase

Logarithmic decrease in population

Genetic recombination

Exchange of genes between 2 DNA molecules to from a new combination of genes on a chromosome

How is antibiotic resistance developed?

Bacteria of the same species pick up genes from each other

Transformation

DNA, plasmid, enters through the pores of the cell membrane or cell wall

Conjugation

Cell-to-cell contact, opposite mating strains and pili

F+

Pili and plasmids (donor)

F-

No pili or plasmids (recipient)

HFR

High frequency of recombination. Plasmid becomes integrated into bacterial chromosome.

Transduction

Virus or bacteriophage is involved Virus acts as a vector by transporting bacterial DNA from the donor bacterial cells to the recipient bacterial cells

Psychrophiles

Cold loving around 15 C, not a human pathogen Location: polar area, deep ocean

Mesophiles

Moderate temp, 25-40 C Most common, very adaptive Common cause of food spoilage and disease

Thermophiles

Heat loving, around 50-60 C Location: sunlit areas and hot springs

Bacteria pH

neutral 6.5-7.5

Mold pH

acidic 5-6

Osmotic pressure

The force with which a solvent (water) moves  across a semi-permeable membrane from a solution of low solute concentration to high solute concentration

Osmophiles

Like hypertonic conditions, also happen to be halophiles Location: oceans and salt mines

Saccarophiles

Sugar loving Found in compost piles and grain silos

Autotrophs are

self feeders, source of Carbon is light

Heterotrophs

Feed on others

Nitrogen, Sulfur, and Phosphorus is needed for

Protein synthesis, DNA, RNA, and ATP

Trace elements of … are needed in enzymatic reactions, found in water and culture media

Fe++, Zn++, Cu++

Vitamins and amino acids can be

Synthesized or obtained from environment

Strict aerobe (pseudomonas sp.)

Oxygen is the final electron acceptor Pseudomonas is an infection of the skin or RT (2nd/3rd degree burns)

Strict anaerobe (Clostridium sp.)

Organic compounds are the final electron acceptor 2 pathways: anaerobic respiration or fermentation

Facultative aerobe/anaerobe (E. coli)

Can live in the presence or absence of oxygen

Microaerophilic (Neiserria gonnorrhoeae)

Tolerates small amounts of oxygen

Culture media general requirements

Proper food elements, temperature, oxygen (available or not), moisture, pH, and sterility

Agar

Solely a solidifying agent Polysaccharide, dissolves at 100 C, solid at 42 C Derives from algae or marine seaweed

General Characteristics - Viruses are

Obligate Intracellular Parasites (OIP)

General Characteristics - Viruses were first discovered by Iwanowski as

Tobacco Mosaic Virus (TMV)

Name all 4 characteristics viruses must meet

Protein coat that surrounds nucleic acid Has structures that allow it to transfer the viral nucleic acid to the host Uses host cell machinery to multiply Contains DNA OR RNA, never both

True or False: Viruses have few or no enzymes of their own

True

Host range cells are

Determined by the host cell attachment sites.

Host cells can be

Plants, animal, fungi, protozoa, and bacteria

Virus is in the… range and needs an … microscope

20-1000 nanometer range, electron

Outer coat

Capsid Made of proteins referred to as capsomeres

Inner Core

Nucleic acid Animal viruses: ds and ss DNA, ss and ds RNA Bacteriophages: dsDNA

Viral Structure - Envelope (some have)

Made of proteins, lipids, or carbs Surrounds capsid

Viruses that lack an envelope are referred to as

Naked viruses

Spikes (some have)

Made of carbs and proteins Attaches to envelope (if it has one) Helps virus attach to host Sometimes used to ID viruses, like the flu, by arrangement

Structure types

Helical, polyhedral, enveloped, and complex

Naked helical virus

No envelope, rope-like, think ebola

Naked polyhedral virus

No envelope, nucleic acid inside

Complex viruses are all

Bacteriophages

Growing bacteriophages

Grow host bacteria in Petri plates, inoculate with bacteriophage

What do you look for when growing bacteriophages?

Plaque formation, if the bacteriophage attacks the bacteria, it will leave a mark

Growing animal virus

Living animals (suitable host, limited by host range, expensive)

Embryonated eggs (influenza virus, convenient)

Cell cultures (preferred, grow cells in monolayers, requires skill)

Identification methods

Electron microscope (assuming it can be easily identified) Serologically (viral antigens, rotavirus; viral antibodies, HIV and Rubella) Molecular methods (nucleic acid analysis)

Do all viruses have to be identified?

No

Viral Multiplication - Bacteriophages

They can go through 2 cycles, lytic or lysogenic