Lab 3 Structure & BIO250
L
Microscopy
Student Name:
Access Code (located on the underside of the lid of your lab kit): AC-3BMK7G
Pre-Lab Questions
1. What determines if a bacterial cell is Gram-positive or Gram-negative?
The Gram classification of bacteria relies on the structure of their cell
walls. Gram-positive bacteria have a thick peptidoglycan cell wall,
while Gram- negative bacteria have a thin peptidoglycan cell wall
surrounded by an outer membrane. This difference in cell wall
structure explains the distinct staining patterns observed in Gram
staining, a common method for differentiating between these two
bacterial groups.
2. In this lab, both viruses and prions were introduced as acellular organisms.
Do some research and describe one other type of acellular organism. What
characteristics about this organism classify it as acellular?
In addition to viruses, viroids represent another type of acellular
organism. These minuscule entities are comprised of circular RNA
molecules and exclusively infect plants. Notably, viroids lack any
proteins or other cellular components, distinguishing them from
viruses and further exemplifying the diversity of acellular entities.
3. Bacteria have many different shapes that often determine their class.
Research and form a hypothesis on the evolutionary reasons for so many
different bacterial morphologies. The diverse array of bacterial shapes, or
morphologies, likely stems from evolutionary adaptations to various
environments and competitive pressures.
, Lab 3 Structure & BIO250
L
Microscopy
For instance, rod-shaped bacteria excel in traversing liquid
environments, while spherical bacteria possess enhanced resilience
in harsh conditions.
4. Do a search online or look in your textbook for 1-2 antibiotics that affect Gram-positive bacteria
and list them. On what part of the cell do the antibiotics usually work? List one or two
antibiotics that affect Gram-negative bacteria? On what part of the cell do the antibiotics usually
work? (Be sure to cite your sources in your answer.)
Antibiotics for Gram-Positive Bacteria Penicillin and vancomycin, two
common antibiotics, target the bacterial cell wall, preventing its
formation and leading to bacterial destruction. Antibiotics for
Gram- Negative Bacteria Ciprofloxacin and aminoglycosides
disrupt bacterial DNA replication and protein synthesis,
respectively, halting bacterial growth and reproduction.
5. Why do you think it is important to identify a bacterial disease in a patient before
prescribing any antibiotic treatments? (Be specific.)
Antibiotics are specifically designed to combat bacteria. While they offer
effective treatment for bacterial infections, excessive use can trigger
adverse effects and promote antibiotic resistance.
EXPERIMENT 1: Staining
Data Tables
Table 1: Experiment 1 Staining Observations
Stain Used: Crystal Violet
L
Microscopy
Student Name:
Access Code (located on the underside of the lid of your lab kit): AC-3BMK7G
Pre-Lab Questions
1. What determines if a bacterial cell is Gram-positive or Gram-negative?
The Gram classification of bacteria relies on the structure of their cell
walls. Gram-positive bacteria have a thick peptidoglycan cell wall,
while Gram- negative bacteria have a thin peptidoglycan cell wall
surrounded by an outer membrane. This difference in cell wall
structure explains the distinct staining patterns observed in Gram
staining, a common method for differentiating between these two
bacterial groups.
2. In this lab, both viruses and prions were introduced as acellular organisms.
Do some research and describe one other type of acellular organism. What
characteristics about this organism classify it as acellular?
In addition to viruses, viroids represent another type of acellular
organism. These minuscule entities are comprised of circular RNA
molecules and exclusively infect plants. Notably, viroids lack any
proteins or other cellular components, distinguishing them from
viruses and further exemplifying the diversity of acellular entities.
3. Bacteria have many different shapes that often determine their class.
Research and form a hypothesis on the evolutionary reasons for so many
different bacterial morphologies. The diverse array of bacterial shapes, or
morphologies, likely stems from evolutionary adaptations to various
environments and competitive pressures.
, Lab 3 Structure & BIO250
L
Microscopy
For instance, rod-shaped bacteria excel in traversing liquid
environments, while spherical bacteria possess enhanced resilience
in harsh conditions.
4. Do a search online or look in your textbook for 1-2 antibiotics that affect Gram-positive bacteria
and list them. On what part of the cell do the antibiotics usually work? List one or two
antibiotics that affect Gram-negative bacteria? On what part of the cell do the antibiotics usually
work? (Be sure to cite your sources in your answer.)
Antibiotics for Gram-Positive Bacteria Penicillin and vancomycin, two
common antibiotics, target the bacterial cell wall, preventing its
formation and leading to bacterial destruction. Antibiotics for
Gram- Negative Bacteria Ciprofloxacin and aminoglycosides
disrupt bacterial DNA replication and protein synthesis,
respectively, halting bacterial growth and reproduction.
5. Why do you think it is important to identify a bacterial disease in a patient before
prescribing any antibiotic treatments? (Be specific.)
Antibiotics are specifically designed to combat bacteria. While they offer
effective treatment for bacterial infections, excessive use can trigger
adverse effects and promote antibiotic resistance.
EXPERIMENT 1: Staining
Data Tables
Table 1: Experiment 1 Staining Observations
Stain Used: Crystal Violet
