BIO 251 COMPREHESIVE EXAM QUESTIONS AND
ANSWERS GUARANTEE A+
✔✔List the 4 steps that must be taken to prove the cause of an infectious disease
(Koch's postulates) - ✔✔1. The suspected causative agent must be found in every case
of the disease and be absent from healthy hosts.
2. The agent must be isolated and grown outside the host.
3. When the agent is introduced to a healthy, susceptible host, the host must get the
disease.
4. The same agent must be found in the diseased experimental host.
✔✔Describe the 4 major processes of living cells - ✔✔- Growth: increase in size
-Reproduction: increase in number
-Responsiveness: ability to react to environmental stimuli
-Metabolism: controlled chemical reactions of organism
✔✔***Compare and contrast prokaryotic and eukaryotic cells - ✔✔Prokaryotic:
-No nucleous, lack internal membrane
- less than 1um (micrometer) and 70s
-two types: bacteria, archaea (lives in extreme conditions)
Eukaryotic:
-Has nucleous, internal membrane bound organelles
- 10 to 100 um (micrometer) and 80s
-more complex
-has mitochondria
-comprised of algae, protozoa, fungi, animals, and plants
✔✔Describe glycocalyces
1. Capsule
2. Slime layer - ✔✔Glycolcalyces: gelatinous, sticky substance surround the outside of
the cell. Composed of polysaccharide or rarely polypeptides or both.
Capsule: composed of organized repeating units of organic chemicals
-Firmly attached to cell surface
-Protects cells from drying out
-May prevent bacteria from being recognized and destroyed by host
Slime Layer: sticky layer that allows prokaryotes to attach to surfaces
-loosely attached to cell surface
-water soluble
-protects cells from drying out
✔✔Discuss the structure and function of bacterial flagella - ✔✔Responsible for
movement
, Structure:
-Composed of filament, hook, and basal body
-Flagellin protein (main protein)
-Filament capable of rotating 360 degrees
✔✔List and describe 4 bacterial flagellar arrangements - ✔✔1. Monotrichous - single
flagella
2. Lophotrichous - multiple flagella on one end of bacteria
3. Amphitrichous - flagella on both ends
4. Peritrichous - flagella everywhere
✔✔**Describe chemotaxis - ✔✔is the movement of an organism in response to a
chemical stimulus and direct their movements according to certain chemicals in their
environment.
Run: movement toward favor (counter clockwise)
Tumble: rotate away (clockwise)
✔✔Compare and contrast the structures and functions of fimbriae, pili, and flagella -
✔✔Fimbriae - sticky bristlelike projections (used for biofilms). Used by bacter to adhere
to one another, to hosts and environment. Shorter than flagella and may have
hundreds.
Pili - Long hollow tubes composed of pilin. Longer than fimbriae but shorter than
flagella. One or two per cell, and used as grappling hooks.
Flagella: has flagellin (protein) and capable of rotating 360 degrees. Uses chemotaxis to
run or tumble
✔✔Describe the sugar and peptide portions of peptidoglycan - ✔✔-Most bacteria have
cell walls composed of peptidoglycan; a few lack a cell wall entirely.
-Peptidoglycan composed of sugars, NAG and NAM
-NAG and NAM, polymers are connected by tetrapeptide crossbridges
-Bridges may be directly linked to one another or bridges may be joined by short
connecting chains of amino acids
-Aminos attach to NAM
-Penicillin destroy bridges on NAM (ex. NAM/NAG)
✔✔*Compare and contrast the cell walls of Gram-positive and Gram-negative bacteria
in terms of structure* - ✔✔Gram Positive Cell Walls:
*Relatively thick layer of peptidoglycan*
* Contains unique polysaccharides called teichoic acids
- Some covalently linked to lipids, forming lipoteichoic acids that anchor peptidoglycan
to cell membrane
*Retains crystal violet dye in Gram staining procedure appears purple*
ANSWERS GUARANTEE A+
✔✔List the 4 steps that must be taken to prove the cause of an infectious disease
(Koch's postulates) - ✔✔1. The suspected causative agent must be found in every case
of the disease and be absent from healthy hosts.
2. The agent must be isolated and grown outside the host.
3. When the agent is introduced to a healthy, susceptible host, the host must get the
disease.
4. The same agent must be found in the diseased experimental host.
✔✔Describe the 4 major processes of living cells - ✔✔- Growth: increase in size
-Reproduction: increase in number
-Responsiveness: ability to react to environmental stimuli
-Metabolism: controlled chemical reactions of organism
✔✔***Compare and contrast prokaryotic and eukaryotic cells - ✔✔Prokaryotic:
-No nucleous, lack internal membrane
- less than 1um (micrometer) and 70s
-two types: bacteria, archaea (lives in extreme conditions)
Eukaryotic:
-Has nucleous, internal membrane bound organelles
- 10 to 100 um (micrometer) and 80s
-more complex
-has mitochondria
-comprised of algae, protozoa, fungi, animals, and plants
✔✔Describe glycocalyces
1. Capsule
2. Slime layer - ✔✔Glycolcalyces: gelatinous, sticky substance surround the outside of
the cell. Composed of polysaccharide or rarely polypeptides or both.
Capsule: composed of organized repeating units of organic chemicals
-Firmly attached to cell surface
-Protects cells from drying out
-May prevent bacteria from being recognized and destroyed by host
Slime Layer: sticky layer that allows prokaryotes to attach to surfaces
-loosely attached to cell surface
-water soluble
-protects cells from drying out
✔✔Discuss the structure and function of bacterial flagella - ✔✔Responsible for
movement
, Structure:
-Composed of filament, hook, and basal body
-Flagellin protein (main protein)
-Filament capable of rotating 360 degrees
✔✔List and describe 4 bacterial flagellar arrangements - ✔✔1. Monotrichous - single
flagella
2. Lophotrichous - multiple flagella on one end of bacteria
3. Amphitrichous - flagella on both ends
4. Peritrichous - flagella everywhere
✔✔**Describe chemotaxis - ✔✔is the movement of an organism in response to a
chemical stimulus and direct their movements according to certain chemicals in their
environment.
Run: movement toward favor (counter clockwise)
Tumble: rotate away (clockwise)
✔✔Compare and contrast the structures and functions of fimbriae, pili, and flagella -
✔✔Fimbriae - sticky bristlelike projections (used for biofilms). Used by bacter to adhere
to one another, to hosts and environment. Shorter than flagella and may have
hundreds.
Pili - Long hollow tubes composed of pilin. Longer than fimbriae but shorter than
flagella. One or two per cell, and used as grappling hooks.
Flagella: has flagellin (protein) and capable of rotating 360 degrees. Uses chemotaxis to
run or tumble
✔✔Describe the sugar and peptide portions of peptidoglycan - ✔✔-Most bacteria have
cell walls composed of peptidoglycan; a few lack a cell wall entirely.
-Peptidoglycan composed of sugars, NAG and NAM
-NAG and NAM, polymers are connected by tetrapeptide crossbridges
-Bridges may be directly linked to one another or bridges may be joined by short
connecting chains of amino acids
-Aminos attach to NAM
-Penicillin destroy bridges on NAM (ex. NAM/NAG)
✔✔*Compare and contrast the cell walls of Gram-positive and Gram-negative bacteria
in terms of structure* - ✔✔Gram Positive Cell Walls:
*Relatively thick layer of peptidoglycan*
* Contains unique polysaccharides called teichoic acids
- Some covalently linked to lipids, forming lipoteichoic acids that anchor peptidoglycan
to cell membrane
*Retains crystal violet dye in Gram staining procedure appears purple*
