BIOL 1409 LAB 17. MICROBIOLOGY (BACTERIA &
PROTISTA) study guide
Objectives:
Describe the basic structures of a bacterial cell.
State the three domains of life.
Name the shape of a given bacteria specimen.
Be able to grow and count bacteria cultures
State the domain of cyanobacteria.
Be able to identify the cyanobacteria examples viewed in lab.
State the domain of the protista.
Be able to recognize the protista specimen viewed in lab.
Identify protista as photosynthetic or heterotrophic.
Introduction:
I. KINGDOM BACTERIA
Bacteria evolved some 600 million years ago and were probably
responsible for the production of the earth's atmosphere (cyanobacteria).
Bacteria were discovered in the 17th century after the development of the
microscope. Bacteria are prokaryotes that, along with several other
distinctions, have peptidoglycan in their cell wall. These unicellular
organisms are incredibly diverse and involved in all ecological processes
across every ecosystem. Though most are too small to see with the naked
eye and thus easily overlooked, some bacteria, such as the myxobacteria
(in the order Myxococcales), collaborate to produce multicellular structures.
In Figure 1 we have a few phyla for Bacteria with their representative
organisms.
, BIOL 1409 LAB 17. MICROBIOLOGY (BACTERIA &
PROTISTA) study guide
Figure 1: Chlamydia, Spirochetes, Cyanobacteria, and Gram-positive bacteria are described in
this table.
Characteristics of Prokaryotes
There are many differences between prokaryotic and eukaryotic cells.
However, all cells have four common structures: a plasma membrane that
functions as a barrier for the cell and separates the cell from its
environment; cytoplasm, a jelly-like substance inside the cell; genetic
material (DNA and RNA); and ribosomes, where protein synthesis takes
place. As shown in Figure 2, prokaryotes come in various shapes, but many
fall into three categories: cocci (spherical), bacilli (rod-shaped), and spirilla
(spiral-shaped).
, BIOL 1409 LAB 17. MICROBIOLOGY (BACTERIA &
PROTISTA) study guide
Figure 2: Bacteria three distinct shapes: coccus (spehrical), bacillus (rod-shaped) and
spirillum (spiral-shaped) (left to right). (Credit a: modification of work by Janice Haney Carr,
Dr. Richard Facklam, CDC; credit c: modification of work by Dr. David Cox, CDC; scale-bar
data from Matt Russell)
Prokaryotes are unicellular organisms that lack organelles or other internal
membrane-bound structures. Therefore, they do not have a nucleus but
instead generally have a single chromosome—a piece of circular, double-
stranded DNA located in an area of the cell called the nucleoid as shown in
Figure 3. Most prokaryotes have a cell wall outside the plasma membrane.
Recall that prokaryotes are divided into two different domains, Bacteria and
Archaea, which together with Eukarya, comprise the three domains of life.
Bacterial cells lack a membrane bound nucleus. Their genetic material is
naked within the cytoplasm. Ribosomes are their only type of organelle. The
term “nucleoid” refers to the region of the cytoplasm where chromosomal
DNA is located, usually a singular, circular chromosome. Bacteria are usually
single-celled, except when they exist in colonies. These ancestral cells
reproduce by means of binary fission, duplicating their genetic material and
then essentially splitting to form two daughter cells identical to the parent. A
wall located outside the cell membrane provides cell support and protection
against mechanical stress or damage from osmotic rupture and lysis. The
major component of the bacterial cell wall is peptidoglycan or murein. This
rigid structure of peptidoglycan, specific only to prokaryotes, gives the cell
shape and surrounds the cytoplasmic membrane. Flagella are long, hair-like
structures that extend from the plasma membrane and are used to move an
entire cell.
PROTISTA) study guide
Objectives:
Describe the basic structures of a bacterial cell.
State the three domains of life.
Name the shape of a given bacteria specimen.
Be able to grow and count bacteria cultures
State the domain of cyanobacteria.
Be able to identify the cyanobacteria examples viewed in lab.
State the domain of the protista.
Be able to recognize the protista specimen viewed in lab.
Identify protista as photosynthetic or heterotrophic.
Introduction:
I. KINGDOM BACTERIA
Bacteria evolved some 600 million years ago and were probably
responsible for the production of the earth's atmosphere (cyanobacteria).
Bacteria were discovered in the 17th century after the development of the
microscope. Bacteria are prokaryotes that, along with several other
distinctions, have peptidoglycan in their cell wall. These unicellular
organisms are incredibly diverse and involved in all ecological processes
across every ecosystem. Though most are too small to see with the naked
eye and thus easily overlooked, some bacteria, such as the myxobacteria
(in the order Myxococcales), collaborate to produce multicellular structures.
In Figure 1 we have a few phyla for Bacteria with their representative
organisms.
, BIOL 1409 LAB 17. MICROBIOLOGY (BACTERIA &
PROTISTA) study guide
Figure 1: Chlamydia, Spirochetes, Cyanobacteria, and Gram-positive bacteria are described in
this table.
Characteristics of Prokaryotes
There are many differences between prokaryotic and eukaryotic cells.
However, all cells have four common structures: a plasma membrane that
functions as a barrier for the cell and separates the cell from its
environment; cytoplasm, a jelly-like substance inside the cell; genetic
material (DNA and RNA); and ribosomes, where protein synthesis takes
place. As shown in Figure 2, prokaryotes come in various shapes, but many
fall into three categories: cocci (spherical), bacilli (rod-shaped), and spirilla
(spiral-shaped).
, BIOL 1409 LAB 17. MICROBIOLOGY (BACTERIA &
PROTISTA) study guide
Figure 2: Bacteria three distinct shapes: coccus (spehrical), bacillus (rod-shaped) and
spirillum (spiral-shaped) (left to right). (Credit a: modification of work by Janice Haney Carr,
Dr. Richard Facklam, CDC; credit c: modification of work by Dr. David Cox, CDC; scale-bar
data from Matt Russell)
Prokaryotes are unicellular organisms that lack organelles or other internal
membrane-bound structures. Therefore, they do not have a nucleus but
instead generally have a single chromosome—a piece of circular, double-
stranded DNA located in an area of the cell called the nucleoid as shown in
Figure 3. Most prokaryotes have a cell wall outside the plasma membrane.
Recall that prokaryotes are divided into two different domains, Bacteria and
Archaea, which together with Eukarya, comprise the three domains of life.
Bacterial cells lack a membrane bound nucleus. Their genetic material is
naked within the cytoplasm. Ribosomes are their only type of organelle. The
term “nucleoid” refers to the region of the cytoplasm where chromosomal
DNA is located, usually a singular, circular chromosome. Bacteria are usually
single-celled, except when they exist in colonies. These ancestral cells
reproduce by means of binary fission, duplicating their genetic material and
then essentially splitting to form two daughter cells identical to the parent. A
wall located outside the cell membrane provides cell support and protection
against mechanical stress or damage from osmotic rupture and lysis. The
major component of the bacterial cell wall is peptidoglycan or murein. This
rigid structure of peptidoglycan, specific only to prokaryotes, gives the cell
shape and surrounds the cytoplasmic membrane. Flagella are long, hair-like
structures that extend from the plasma membrane and are used to move an
entire cell.
