Lecture: Unit 3 exam – Flashcards

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question

 

 

Compared to eucaryotic cells

(human cells)

prokaryotic cells are...

answer
  • of very ancient origin (survivors, ↑danger to humans)
  • smaller (↑ability to hide from immune system)
  • simpler (↑survival, ↓energy requirement, take less to repair)
  • more abundant
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(continued)

Compared to eucaryotic cells

(human cells)

prokaryotic cells are...

answer

 

have no nucleus

(DNA unprotected in cytoplasm~BUT~we can't attack w/abx all the time since human DNA also targeted)
have no organelles

(Activities hard to target since all happens within cytoplasm)
have a single chromosome

(vs- human's 46 chromosomes)

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(continued)

Compared to eucaryotic cells

(human cells)

prokaryotic cells are...

answer

Much more sophisticated in terms of:

 

~ adaptation capabilities

~ cell envelope structure

      (≥ 7 layers VS humans' 1 layer)

~ mechanisms for motility

~ mechanisms for adhesion

question

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State the definition of a bacterium:

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A microorganism whose body is procaryotic (unicellular).

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; The term "bacteria" is plural.

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Define appendage:

answer

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A component which project from the body.

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Questions to ask...

How many appendages does M/O have?

How will this affect me?

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FLAGELLA - EXTERNAL

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Flagella are mainly present in M/Os of which shapes?

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Mainly present in bacilli ; spirilla

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FLAGELLA - EXTERNAL

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What are the 3 purposes of flagella?

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;~ motility

or

~ chemotaxis (to detect a specific chemical)

or

~ phototaxis (ability to detect light)

Note: psychrophiles are negatively phototactic and only like cold and absence of light.

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FLAGELLA - EXTERNAL

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What is the composition of a flagellum?

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answer

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A flagellum is comprised of:

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BODY (anchors)

HOOK (moves, spins)

FILAMENT (can regenerate if cut)

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FLAGELLA - EXTERNAL

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Is the body attached to the microorganism, or IS IT the M/O?

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The body is attached to the M/O.

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FLAGELLA - EXTERNAL

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Each bacterial species has specific # and arrangement of flagella...

answer

~ Monotrichous

(one flagellum)

~ Lophotrichous

(2 flagella, usually opposite sides of M/O)

~ Amphitrichous

(flagella fanned out in 2 groups opposite sides of M/O)

~ Peritrichous

(flagella all around M/O)

question

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What are 2 methods to determine if a microorganism is motile?

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answer

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SEMISOLID STAB

(colony visible distinctly separate from stab line)

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HANGING DROP SLIDE

(technically possible BUT not a good method since M/O dies from heat quickly and isn't stained)

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Chemotaxis and Phototaxis

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Determined by trial and error, reading can be +/-

 

Chemical/different types of light placed on opposite end of slide, watch for movement,

done one chemical at a time.

 

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FLAGELLA: INTERNAL

 

Is an internall flagellum an appendage?

answer

 

No, it is not an appendage.

 

It is never used for chemotaxis or phototaxis.

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FLAGELLA: INTERNAL

 

a/k/a "periplasmic" are found in:

answer

 

 

Internal/Periplasmic flagella

found mostly in spirochetes.

 

 

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FLAGELLA - INTERNAL

 

Location and purpose

answer

 

Located within cell envelope between cell wall and cell membrane.

 

Purpose: varied & precise movement

(↑ risk of infection to host)

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PILI

singular: "pilus"

answer

 

Present only in Grm-

but not in ALL Grm-

 

Questions to ask...

Is M/O Gm+ or Gm-? Does M/O have pilus?

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PILUS

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Long, tube-like structure,

originates from one bacterium and attaches to another.

 

Both ends of tube are open.

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Pili are used during Conjugation.

Explain...

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Conjugation is called Transformation in lab.


Pili are used in this process, which isn't the same as Reproduction, and is more of an Association between M/Os.

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During conjugation/transformation,

a PLASMID comes into play.

What is a plasmid?

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An excised or copied piece of DNA which is transferred from a donor bacterium to a recipient bacterium through the pilus.

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1st TYPE OF CONJUGATION of Prokaryotic Cells

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during shift from favorable to unfavorable environment...

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Donor bacterium knows the other cannot tolerate; - environment, builds pilus, copies its strong genes (plasmids), sends plasmids to recipient bacterium via pilus, both bacteria survive.


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2nd TYPE OF CONJUGATION of Prokaryotic Cells

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Donor bacterium knows the other cannot tolerate; - environment, builds pilus, EXCISES its strong genes (plasmids), sends plasmids to recipient bacterium via pilus, DONOR DIES.

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example: MRSA is highly transformed

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APPENDAGES: Fimbrae

answer

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~ have bristle-like proteins, stick out all over surface;

;;; of M/O

~ adhesive

~ linked to process of infection

;;; (due to length of association with host's system

     through adhesion)

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CELL ENVELOPE COMPOSITION

 

Glycocalyx

 

 

 

answer

~ outermost layer of cell envelope

 

~ composition varies (usually polysaccharides)

 

~ thickness varies

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CELL ENVELOPE COMPOSITION

 

2 most common types of Glycocalyces

answer
  1. SLIME LAYER: loosely bound, prevents water & nutrient loss, making M/O stronger, less leaky. (This is less threatening than M/O with capsule.)
  2. CAPSULE: tightly bound & sticky (can't be removed by meds), protects against WBCs due to adherence
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examples of ENCAPSULATED microorganisms...

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Streptococcus pneumoniae

(eats holes in simple squamous epithelium of alveoli and capillaries, then blood pools into alveolar regions. This is "fluid in the lungs".)


Haemophilus influenzae

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Bacillus anthracis

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CELL WALL ; PEPTIDOGLYCAN

in Gram + M/Os because...

answer

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Peptidoglycan is the most important component of the cell wall, as it's very rigid and prevents collapse/bursting, helps maintain shape.

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How many

PROKARYOTIC CELL MEMBRANES

is common and why?

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5 cell membranes are common because of selective permeability (into/out of cell body).

 

Composition varies - some resemble human cell membranes.

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CELL ENVELOPE COMPOSITION

 

List main components...

answer
  1. Glycocalyx
  2. Cell wall
  3. Cell membrane
  4. Cytoplasm (chromosome, plasmids, ribosomes, storage bodies, endospores)
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CHROMOSOME

within prokaryotic cell's cytoplasm

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  1. one double helix, loose, no nucleus
  2. looped or linear shape
  3. DNA is coiled
  4. contains ;250,000 genes
  5. genes used for many purposes, mainly protein synthesis (ie, enzymes)

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What to Sulfa medications target?

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DNA

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Define PLASMID

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COPY of a small segment of DNA

~or~

EXCISED SEGMENT of DNA

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Unique features of Plasmids

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They are intended for donation

or have just been received.

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Only Gram - bacteria use plasmids*

*but not all Gram- M/Os do it*

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1st of 2 Purposes of PLASMIDS

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To impart Resistance, survival.

;;; (accomplished by plasmid type "Pr")

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question

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Describe how Plasmids

impart resistance

from one M/O to another.

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;; An environment has become unfavorable.

;; M/O#1 is OK (resistant) and M/O#2 isn't OK 

    (susceptible).

Here the plasmid is usually a copy (not excised).

    This plasmid's purpose: resistance "Pr"

;; Plasmid sent via Pilus (singular) from M/O#1 to

;;;; the other.

;; M/O#2 is now resistant, no longer susceptible.

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2nd of 2 Purposes of PLASMIDS

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To improve Abilities (not linked to resistance)**

**accomplished by "Pa" plasmids

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Describe how one M/O improves abilities of another M/O by donating a plasmid.

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;; An environment is favorable.

;; Both M/Os are OK (resistant).

;; Here the Abilities plasmid (Pa) contains genes

;;; that M/O#2 doesn't have.

    ***Plasmid's purpose: PLANNING ONLY (not survival)

;; Plasmid sent via Pilus (singular) from M/O#1 to

;;;; the other.

;; M/O#2 now has NEW ABILITIES.

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Most effective way of killing M/Os?

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Target the Ribosomes with medication.

why?

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Because it's where Proteins are synthesized.

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Prokaryotic Ribosomes

>>where located? size?

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Prokaryotic ribosomes float in the cytoplasm and are

smaller/less dense (70S) than

eucaryotic ribosomes (80S).


S= Svedberg Unit (a unit of mass)

 


 

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Why does medication target

prokaryotic ribosomes successfully?

answer




MAJORITY OF MEDS work by killing 70S ribosomes because of ↓ risk of damage to humans (80S eucaryotic).

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STORAGE BODIES

of prokaryotes

2 types

answer

INCLUSIONS used for basic nutrients

Dedicated inclusions - 1 type of nutrient (ie, carbs).

General inclusions store variety of nutrients.

 

GRANULES have variety of purposes.

Pigment Granules (S. marcescens) purpose unknown

Gas Granules - one purpose: float for survival

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The process of SPORULATION

produces what?

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ENDOSPORES

a/k/a

"SPORES"

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The ONLY type of

prokaryote capable of sporulation is:

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BACILLI are the only type

capable of sporulation.

 

(example: B. anthracis)

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When does a bacillus undergo the process of sporulation?

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When it is near death.

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Describe 4 Stages of Sporulation

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1) chromosomes are replicated

    (some M/Os make 10, some make 1,000)


2) envelope of nearly dead M/O is used to envelope

    new chromosomes


3) spores are released


4) spores eat & grow to match size of original

 

 

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Define SPORE

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Spore = a copied chromosome

a/k/a "clone" that is wrapped in pieces of the M/O's old envelope

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In sporulation the ORIGINAL MICROORGANISM is referred to as...

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VEGETATIVE FORM

not not not

"parent cell"

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Name the 3 types of Appendages

for prokaryotic cells

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Flagella, Pili, Fimbrae

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Prokaryotic Cell Envelope

is composed of what?

answer

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Glycocalyx (1 layer), Cell Wall (1 layer)

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Cell Membranes (5 or more layers)

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(remember bacteria have ; 7 layers/covers)

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Name the 4 structures found in Cytoplasm of prokaryotic cells.

answer

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Chromosomes

Plasmids

Ribosomes

Storage Bodies

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Range of size of Bacteria

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0.2 microns (;m) - Bacilli

to

250 microns (;m)- Spirochetes

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Implications of small size of bacteria...

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Bacteria can hide from the immune system.


Bacteria can fit everywhere/harm everywhere.

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What gain is there in bacteria having certain shapes?

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SURVIVAL

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COMMON SHAPES (types) of Bacteria

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Coccus - roundish (not perfect sphere);;

;;; Bacillus - rod, elongated (found where nutrients

;;; are dispersed, long shape ; ability to eat)

Coccobacillus - elongated but still round

;;; Vibrio - crescent moon shape (always in

;;; windy environment, hanging)

Spirillum - spiral shaped

;;; Spirochete - spiral, highly coiled

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define

PLEIMORPHISM

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definition: Changing shape/morphing.

**MOST microbes are created with

1 shape and remain so.

**A few, Pleimorphic, species

can have more than one shape.

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Most Pleimorphs have changed shape because of what?

answer

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access to NUTRITION

(if nutrients in Env. disperse, M/O has to elongate to increase reach)

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A 2nd type of Pleimorph has changed shape because:

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HEREDITY

just because this M/O

can change shape

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Name 2 Pleimorphic bacteria

answer

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Rhizobium

Corynebacterium

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Arrangements of Bacterial cells

~a LIFESTYLE~

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Some bacteria live as Independents (E. coli)

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Others live in Association,

but not necessarily for protection or sharing.

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7 types of

Bacterial cell Arrangements

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;Diplococci: 2 paired cocci

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Tetrads: always cocci, 4 together

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Sarcinae: cocci clustered in multiples of 8

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7 types of

Bacterial cell Arrangements

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(continued)

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Streptococci: cocci living in a straight chain (a/k/a serial arrangement)

**causes a wound that is wide but superficial

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Staphylococci: cluster of cocci,

NOT in multiples of 8

**wound deep

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7 types of

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Bacterial cell Arrangements

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(continued)

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Diplobacilli: side by side contact of bacilli

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Streptobacilli: straight chain of bacilli

example: B. megaterium (a large, rare strep)

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ID of Bacteria

is based on 6 criteria.

Name them...

answer

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1); morphology (shape, size, arrangement)
2); Gram status
3); presence of specific structures;;

;;;;; (internal/external appendages, storage bodies)
4);; colony characteristics (streak plate)

5); biochemical reactions

6); nucleic acid composition (DNA analysis)


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Bacteria with unusual traits

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#1 - Obligate Intracellular Parasite

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Obligate intracellular parasites must live inside a cell, eats it from inside out.

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Immune system can't see since it's hidden in cell. Best defense is vaccination.

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Bacteria with unusual traits

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#1 - Obligate Intracellular Parasite

Rickettsias - 3 examples

answer

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Mammal host;Arthropod (lice, ticks);Human

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Rocky mountain spotted fever

(destroys connective tissue)

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Typhus will go into all human cells

(not fastidious)

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Bacteria with unusual traits

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#1 - Obligate Intracellular Parasite

Chlamydias - 3 examples

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Eye infection from environment.

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STD (human transmission)

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Ornithosis (infection from pet bird)

question

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Bacteria with unusual traits

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#2 - Cell Wall deficient bacteria

Mycoplasmas

answer

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Mycoplasma:

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With no cell wall, M/O releases sterols (alcohol) when it's threatened.

(ie, Atypical Pneumonia eats alveoli while releasing sterols. LETHAL)

 

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Bacteria with unusual traits

 

 

 

#3 - Photosynthetic bacteria

 

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Photosynthetics:

  • Cyanobacteria
  • Green & Purple Sulfur bacteria
  • Myxobacteria fruiting bodies
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What contains every known fact about every known bacteria?

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Bergey's Manual of

Systemic Bacteriology

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explain

Evolutionary-VS-Phenetic Relationships

in Classification

answer

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Evolutionary: scientists want the M/O name to include ALL characteristics (too complex)

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Phenetic: scientists want to name according to morphology (size, shape, etc.) ONLY (too simplistic)

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