UNIT 8: MICROBIOLOGY STUDY Guide with Test Objectives
Learning Objectives
1. Define microbiology. The study of microbes (bacteria, archaea, viruses, unicellular eukaryotes)
2. Compare and contrast prokaryotic cells and eukaryotic cells.
a. Eukaryotic cells are larger and more advanced. They have distinct, membrane-bounded organelles,
including the nucleus that contains DNA.
b. Prokaryotic cells do not have specific structures that perform a specific task within the cytoplasm. The
DNA is visible throughout the cell. Ribosomes are present but do not have membranes.
3. List the main benefits of bacteria.
a. Help eliminate planet’s waste by decomposing organic material
b. Enable us to digest our food by absorbing nutrients
c. Make air breathable by changing nitrogen from one form to another in the nitrogen cycle
d. Plays a role in making drugs, foods, and vitamins
4. List the harmful roles of bacteria.
a. Spoil food
b. Produce harmful or damaging toxins
c. Cause shortage of oxygen in lakes when “blooms” occur
d. Cause diseases
5. Describe the different shapes and arrangements of bacteria.
a. coccus- spherical
b. bacillus- rod-shaped
c. spirillum- spiral-shaped
6. Identify the shape and arrangement of bacteria based on its scientific name.
a. Colonies are described according to how individual bacteria are grouped together.
b. Not grouped for survival; Usually only cocci or bacilli form colonies
c. Named according to their shape and number
i. Colony with 2 bacteria DIPLOii. Colony that forms a string of bacteria STREPTOiii. Colony that forms a cluster formation STAPHYLO7. LABEL and IDENTIFY the key structural features of bacteria and describe their function.
a. nucleoid region- area where genetic material is found; contains a single, large circular strand of DNA
needed for cell growth, survival, and reproduction
b. plasmid- a small, circular, double-stranded DNA molecule that
is distinct from a cell's chromosomal DNA
c. cell wall- provides support, shape, and regulates amount of
water absorbed by cell; found outside of plasma membrane
d. capsule- sticky outer layer that surrounds cell of some
prokaryotes, protecting surface
e. ribosomes- small, cellular structure that synthesizes proteins
f. flagella- long appendages that rotate to allow movement
8. Explain the process of asexual reproduction in bacteria (binary fission).
See picture to the right.
a. Process where one cell divides to form two identical cells
9. Describe the three methods of
genetic variation that occur in
bacteria.
a. Conjugation: A temporary
union of two organisms for the
purpose of DNA transfer.
b. Transformation: The transfer
of a DNA segment from a
nonfunctional donor cell to
that of a functional recipient
cell.
c. Transduction: The process in
which infection by a virus
results in DNA being transferred from one bacterium to another.
i. This type of virus is called a bacteriophage.
10. Describe the roles of viruses and bacteria in causing diseases.
How do pathogens cause disease?
After infection/exposure, the pathogen rapidly multiplies during the incubation period.
 Tissue destruction
o Pathogen obtains nutrition from host cells, destroying them in the process
 Toxin release
o Pathogens release poisonous substances, causing the cells to malfunction
Examples:
Bacterial disease- treatable with antibiotics; some preventable with vaccines
 vaccines stimulate the immune system to produce antibodies
 antibiotics can block the growth and development of bacteria
1. Streptococcus infections (Strep throat)- releases toxins into blood which can cause scarlet fever
2. Diphtheria * can be prevented with vaccine
• infects tissues of the throat, releasing toxins into blood where they destroy tissues
leading to breathing problems, heart failure, paralysis, and/or Death
Viral disease• Viral infections can be prevented with vaccines, but the vaccine must be given before an infection
begins**
• Viral diseases cannot be treated - only the symptoms of viruses can be treated
• Antibiotics do not work on viruses
1. AIDS (Acquired Immune Deficiency Syndrome)
2. common cold
3. Smallpox **
4. Influenza (Flu)
5. Warts (host cell transforms into wart cell)
11. Describe the purpose of endospore formation and its role in bacterial survival.
a. Bacteria need moisture, rely on temperature, pH and nutrition to grow.
b. During unfavorable growth conditions, the bacteria forms an ENDOSPORE to protect the nucleoid region;
surrounded by many layers of hardened material that allow for dormancy.
12. Distinguish the virus from cells according to its structure and means of reproduction.
a. Structure: nucleic acid core (RNA or DNA) and capsid
i. They are not classified as cells. They are unable to reproduce without a host cell.
b. Reproduction: requires host cell
 Lytic Cycle: the activity of a virulent virus
1. If the virus does not affect a certain type of cell, the virus is nonvirulent for that cell type.
2. During the lytic cycle, the virus invades the cell, uses the resources of the host cell to produce
multiple copies of the viral nucleic acid, destroys the host cell, and releases new viruses into
the environment.
Attachment >> Entry >> Replication & Transcription >> Assembly >> Release
 Lysogenic Cycle
1.
The virus enters the cell & remains inactive (latent).
2.
The viral genome incorporates into the host genome.
3.
The virus can be activated by various stimuli.
•
Example: herpes simplex virus a.k.a. cold sores
13. Categorize Protists by animal-like, plant-like, or fungus-like.
Protozoans
Algae
• Animal-like
• Protists divided into phyla
based on their means of
locomotion.
• Examples: amoeba,
paramecium
•
• Plant-like
• Protists divided into phyla based on
their habitat, organization, and cell
wall.
• Examples: euglena, kelp, diatoms,
dinoflagellates
Water Molds; Slime Molds
• Fungus-like
• heterotrophic/saprophytic/decomposers
• Protists divided into phyla based on the
their complex life cycles
• Contain cellulose in their cell walls
• motile
Protists are a very large, diverse group of organisms, including the plant-like protists (algae), fungi-like protists, and
the animal-like protists (protozoans).
– Protozoans refer to the animal-like protists that are aquatic and motile (able to move on its own).
• Pathogens
• Amoebic dysentery caused by parasite (Entamoeba histolytica) from Phylum Sarcodina
• Malaria caused by parasite (Plasmodium) from Phylum Sporozoa
• African sleeping sickness caused by parasite (Trypanosomiasis) from Phylum Zoomastigina;
infection spread by vector, tsetse fly
– ALGAE
• Phytoplankton
• Green Algae- Largest Algal phyla; Unicellular, Multicellular, or Colonial
• Dinoflagellates- unicellular, two flagella; some have Bioluminescence (glow) as a defense
mechanism
• Diatoms- Unicellular; Highest producers of oxygen; cell wall is made of silicon dioxide
(principle component of glass)
• Multicellular algae
• They have no true tissues. Its body is called a thallus which is the basic unit of an alga.
• Brown algae- example, seaweed, kelp
• Red Algae
• Golden Algae
14. IDENTIFY an amoeba, euglena, and paramecium by their cellular structures, shape, locomotion, and
organization.
Key Cellular
Structures
Amoeba
Euglena
Paramecium
Pseudopodia
Endoplasm
Ectoplasm
Food vacuole
Flagella
Chloroplasts
Pellicle
Eyespot
Cilia
Pellicle
Macronucleus
Micronucleus
Trichocysts
Oral groove, Mouth pore,
gullet, Anal pore
Ectoplasm, endoplasm
Cyst
Shape
Locomotion
Special Features
(Type of Protist,
Eating Behavior)
No shape
Unicellular
Pseudopodia
Movement of
endoplasm towards cell
membrane
Protozoan
(Animal-like)
Eats by phagocytosis
using pseudopods to
engulf food
Oval
With tail
Unicellular
Oval with cilia all around it
Flagella rotates to
create movement
Cilia
Plant-like Protists
Autrotrophic
(Photosynthesis) and/or
Heterotrophic
(Absorbing food from
environment)
Protozoan
(Animal-like)
Cilia sweeps food into its
oral groove (mouth pore,
gullet, food vacuole)
15. Summarize how some protozoans react to adverse conditions.
a. Amoeba- forms a cyst (a structure similar to a spore that is formed as part of the life cycle of some
organisms or when conditions become unfavorable)
b. Paramecium – exhibits avoidance behavior by moving away from negative or unpleasant stimuli;
exhibits defensive strategies by shooting filaments from trichocysts to entangle a predator or make
themselves look bigger