Cumulative questions for final exam Flashcards

List the major contributors to field of microbiology and what they did.

Francesco Redi: performed an experiment to
disprove spontaneous generation using decaying meat

Louis Pasteur: swan-neck flasks
show that spontaneous generation does not occur;
microbes are responsible for fermentation; invented pasteurization;
proposed the germ theory

Robert Koch: proved that a bacterium causes anthrax.
***developed pure culture techniques

Alexander Fleming: discovered the first
antibiotic, Penicillin, that killed Staphylococcus aureus

Ignaz Semmelweis : suggested hand
washing to prevent transmission of puerperal fever/ childbed fever

Joseph Lister: used a chemical
disinfectant to prevent surgical wound infections

Spontaneous generation vs. Biogenesis

Spontaneous: The idea that organisms like flies, mice, and worms,
could just "pop up" or grows vital force that forms life
from non-living matter Biogenesis: A theory that says
living organisms arise from preexisting life

Differences between prokaryotic and eukaryotic Microorganisms.

Eukaryote: complex organelles, nucleus, membrane bound organelle,
nuclear membrane, animal, no peptidoglycan, some can reproduce
asexual Prokaryote: no nuclear membrane, no mitochondria,
don't have a nucleus (membrane-bound organelles), no cytoskeleton,
structurally different flagella, lack of cilla, have stored bodies
& vesicles, always unicellular, asexual Similarities:
Both contain DNA, has a cell membrane, has cytoplasm, has ribosomes,
and cell wall (eukar-(plant) only).

gram stain

differential stain -very useful for identifying and classifying
bacteria as either gram negative or gram positive.1. primary
stain --> crystal violet: stains the bacteria purple2.
mordant ---> grams iodine: mixes with the crystal violet to form a
complex 3. decolorizing agent ---> ethyl alcohol: washes the
primary stain off some bacteria, others are unaffected4.
secondary stain: safranin stains the decolorized bacteria red
Gram positive: those that retain the primary stain and do not
decolorize easily -purplebacillusS. epidermis
Gram Negative: those that decolorize easily-pinkE. coli

endosymbiotic theory

1. Larger cell engulfs smaller one;smaller one survives and
beginsan endosymbiotic association.2. Smaller prokaryote
becomesestablished in its host'scytoplasm and
multiplies;it can utilize aerobicmetabolism and
increaseenergy availability for the host3. Ancestral
eukaryotic celldevelops extensive membranepouches that
become theendoplasmic reticulum andnuclear
envelope.4. Photosynthetic bacteriaare also
engulfed;they develop intochloroplasts.5. The first
eukaryotic cells haveemerged

Why are antibiotics with a very broad spectrum of activity not as
useful as one might first think?

Because they are affective against more than one group of bacteria.
They destroy many normal microbiota of the host.

Identify at least one reason why it is so difficult to target a
pathogenic virus without damaging the host's cells

At the cellular level, eukaryotic cells resemble the human cell (much
more closely than the bacterial cell).

Describe why an illness caused by a gram negative bacterium is
treated differently than one caused by a gram positive bacterium.

gram negative bacterium has a thin peptidoglycan layer and an outer membrane
gram positive has a thick peptidoglycan layer and no outer membrane
***b/c it has a gram (-) & more likely to be resistant due to
the peptidoglycan and outer membrane.

Process of identifying an unknown microorganism

ELISA test - Enzyme Linked ImmunoSorbant Assay
-detects and measures antibodies in your blood
** this test can determine if you have antibodies related to
certain infectious conditions
Direct (researcher is looking for the antigen)
1. looking for antigen
2. antibody is absorbed to a small well in a special plate
3. if the correct antigen is present= it will bind with the antibody
4. enzyme linked antibody specific for test antigen is added and
binds to the antigen
5. if the test is + for the presence of the antigen, the fluid in
the well will turn a different color
6. this color change indicated that the antigen is present
- involves 2 binding processes of primary antibody & secondary antibody
1. looking for the antibody
2. antigen is absorbed to the well
3. enzyme linked anti-HISG is added ad. binds to bond antibody

oxygen requirements for bacteria


Serial dilutions and plate counts.

Serial dilutions: used by starting with the original sample and then
taking a certain amount out of the first one and placing it to the
next tube. Then take the same amount out of the second tube and put it
into the third tube. etc.-counting bacteria: direct methods
Plate counts: After incubation, count colonies on plates that
have 25�250 colonies (CFUs). The more diluted the sample is before
placing it onto the agar will result in fewer colonies that will
grow; making it easier to count after incubation.

Cellular respiration

1. Glycolysis produces ATP and reduces NAD+ to NADH while oxidizing
glucose to pyruvic acid. In respiration, the pyruvic acid is converted
to the first reactant in the Krebs cycle. (2 ATP)2. The Krebs
cycle produces ATP and reduces NAD+ and FADH2 while giving off CO2.
The NADH and FADH2 from both processes carry electrons to the electron
transport chain. (2 ATP)3. In the electron transport chain, NADH
becomes NAD+, electrons travel through carriers and the protons exit
the carriers into the Inter-membrane Space. Oxygen becomes present,
which creates water, and the protons enter through ATP synthase to
create ADP ---> ATP. The energy of the electrons is used to produce
a great deal of ATP. (32 ATP)Total of 36 ATP.

Central Dogma � generally how it is done with bacteria.

� identifies the flow of genetic material (DNA->RNA->protein)
� Types of RNA�mRNA: (Messanger RNA)
translated in codons (3 nucleotides); start codon (AUG)
--tRNA: (transfer RNA) small RNA molecules
carry amino acids to the ribosome to turn into a polypeptide
rRNA: (Ribosomal RNA): does not make
proteins instead makes polypeptides (assembles as amino acids)

Ways genes can be transferred between bacteria

Transformation (INDIRECT): entails the transfer of naked DNA and
requires no special vehicle. Conjunction (DIRECT):
requires the attachment of two related species and the formation of a
bridge that can transport DNA. Transduction (INDIRECT):
the transfer of DNA from one bacterium to another via a bacterial virus.

Antibiotic modes of action on bacteria

1. Inhibition of cell wall synthesis2. Inhibition of protein
synthesis3. Inhibition of nucleic acid replication and
transcription4. Injure to plasma membrane5. Inhibition of
synthesis of essential metabolites

How does antibiotic resistance occur?

when bacteria change in some way that reduces or eliminates the
effectiveness of drugs, chemicals, or other agents designed to cure or
prevent infections. The bacteria survive and continue to multiply
causing more harm. Bacteria can do this through
several mechanisms.
1. Altered metabolic pathway (Sulfonamides - SFA).2.
Antibiotic inactivation.3. Active export of antibiotic.

Lysogenic verses lytic cycle of viruses.

lytic cycle: has 5 stages (attachment, penetration,
biosynthesis, maturation, and release).

attachment: phage
attaches to tail fibers to host cell penetration: lysozyme opens
cell wall; tail sheath contracts to force DNA to cell biosynthesis: production of
phage DNA and proteins maturation: assembly of
phage particles release: phage causes lysis
& death of host

-phage attaches to host cell & injects DNA-phage DNA
circulates & enters lysogenic cycle-phage DNA integrates
within bacterial chromosome by recombination, becoming a
prophage- lysogenic bacterium reproduces normally
-occasionally prophage may exercise from bacterial chromosome by
another recombination event

Result: prophage DNA
incorporated in host DNA = phage conversion= specialized transduction

Classifying infectious diseases (epidemic, endemic, etc)

endemic: an infectious disease that exhibits a
relatively steady frequency (constant) over a long time
period in a particular areaex: lyme disease

sporadic: occasional cases are
reported at irregular intervalsex: tetanus & diphteria

epidemic:Disease acquired by many hosts in a given
area in a short time
ex: chlamydia & gonorrhea

Innate immunity vs. the adaptive immune system. Be able to describe
components of each and compare them

innate: defense against any pathogen that we have at
birth or soon after. Components: -
physical epithelial barriers- phagocytic leukocytes-
dendritic cells- natural killer cells- circulating plasma proteins

adaptive: induces resistance to a specific pathogen

Components: -
B cells= mature in red bone marrow - T cells= mature in the thymus

How can an untreated infection by Streptococcus pyogenes
cause long term health issues like arthritis and heart disease?

Arthritis: damaged heart valves= occurs 3 weeks
after pharyngitis has subdivided=reaction b/w streptococcal M
protein; heart muscle= rheumatic fever

Heart disease: cause permanent heart damage
signs: fever,
painful, tender joints, red hot swollen joints, painless nodules
beneath the skin