Biol 2420 Chapter 3 Review Questions and Correct Answers
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Course
BIO 2420
Institution
BIO 2420
Differentiate Prokaryotes from Eukaryotes. Prokaryotes: No Nucleus or Histones, No membrane bound organelles. Bacteria/ Archea
What two taxa (domains) are prokaryotes divided into? Bacteria are divided into two groups based on what? Archae and Bacteria. Bacteria= divided in 2 based on gram stain r...
Biol 2420 Chapter 3 Review Questions
and Correct Answers
Differentiate Prokaryotes from Eukaryotes. ✅Prokaryotes: No Nucleus or Histones, No
membrane bound organelles. Bacteria/ Archea
What two taxa (domains) are prokaryotes divided into? Bacteria are divided into two
groups based on what? ✅Archae and Bacteria.
Bacteria= divided in 2 based on gram stain reaction
Know the basic shapes of prokaryotic organisms. ✅Coccus(Round)
Bacillus(Rod)
Vibrio(Curve rod)
Coccobacillus(Short Rod)
Spirilla(Spiral)
Spirochete(Long, loose helical spiral)
define pleomorphism ✅variation in size and shape in a single species caused by
variation in cell wall structure
What are the different arrangements of cocci and what determines a particular
arrangement? ✅Coccus arrangement caused by split in # of planes.
Diplococcus(2)
Tetrad(4)
Streptococcus(chain of coccus)
Staphlycoccus(Cluster)
Why are cells small? Explain how surface-to-volume ratio affects the size of cells.
✅important for nutrient uptake
What is the function of the bacterial flagellum? ✅Bacterial locomotion, attachment to
surfaces
Parts of Bacterial Flagellum ✅filament, hook, basal body.
Define these terms which describe flagellar arrangements - monotrichous,
lophotrichous, amphitrichous, and peritrichous ✅Mono: single flagellum
Lopho: bunches or tufts
Amphi: Both poles of cell
Peritrichous: dispersed randomly
What is chemotaxis? ✅Bacteria Movement based on chemicals.
, Name and describe the structure is used by spirochetes for movement? ✅Multiple
flagella FORM axial fibril (Periplasmic flagella) winds around cell exhibits flexing and
spinning movements.
Besides the bacterial flagellum and axial filament of spirochetes, what are two other
types of motility? ✅Twitching: cells are in contact with each other
Gliding: smooth movements
Describe the structure and functions of fimbriae. Know the functions of pili (ex. F-pili),
and how they differ from fimbria. ✅Fimbrae: used for attachment. (fine hair-like)
bristles extending from cell SA helps in adhesion) Type 4 used for motility.
Pili: use for attachment and genetic exchange during conjugation.
cell envelope ✅includes plasma membrane, cell wall, and glycocalyx
Know the composition and functions of capsules and slime layers. ✅composed of
polysaccharides, proteins or both.
FUNCTION: avoid phagocytosis, dessication//used for adhesion (biofilms)//Used for
exclusion of viruses and chemicals.
What is the main difference between slime layer and capsule? ✅Capsules are bound
more tightly to the cell and denser and thicker than a slime layer/.
Encapsulated bacterial cells generally have greater pathogenicity.
What are the functions of Bacteria cell walls? ✅A rigid structure that lies just outside
the cell plasma membrane.
-Maintain shapes of bacterium
-help protects from toxic materials and osmotic lysis
-May contribute to phatogenecity.
Know the structure of Gram positive and Gram negative cell walls, noting the
differences between the two. Understand the structure of peptidoglycan, which is found
in both cell wall types and how it differs between the two types. ✅Gram Positive:
Peptidoglycan thick and contains teichoic acid and lipoteichoic acid.
Gram Negative: Peptidoglycan thin and has an outer membrane with a periplasmic
space. porins, murein lipoproteins.
What is the importance of the lipopolysaccharide of the Gram negative cell wall? ✅-
contribute to negative charge on cell surface.
-helps stabilize outer membrane structure (lipid A)
-creates permeability barrier)
-protection form host defenses (O antigen)
-Can acts as an endotoxin stimulates hemorrhaging, fever and shock (Lipid A).
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