14: ALGAE
- Page ID
- 157076
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\( \newcommand{\dsum}{\displaystyle\sum\limits} \)
\( \newcommand{\dint}{\displaystyle\int\limits} \)
\( \newcommand{\dlim}{\displaystyle\lim\limits} \)
\( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)
( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\id}{\mathrm{id}}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\kernel}{\mathrm{null}\,}\)
\( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\)
\( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\)
\( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)
\( \newcommand{\vectorA}[1]{\vec{#1}} % arrow\)
\( \newcommand{\vectorAt}[1]{\vec{\text{#1}}} % arrow\)
\( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vectorC}[1]{\textbf{#1}} \)
\( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)
\( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)
\( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)-
-
Identify and compare the major structural forms of algae, unicellular, filamentous, and colonial, using prepared microscope slides of representative species such as Ceratium, Diatoms, Spirogyra, and Volvox.
-
Explain the ecological and medical relevance of algae, including their roles in toxin production, nutrient cycling, and contributions to biotechnology and public health.
-
BACKGROUND
The kingdom Protista includes a diverse range of aquatic organisms, many of which are microscopic. Within this kingdom are two major groups of interest in microbiology: protozoa (animal-like protists) and algae (photosynthetic, plant-like protists). This section focuses on algae—their structure,
classification, and how they differ from both plants and bacteria.
Algae are single-celled or simple multicellular, eukaryotic organisms that perform photosynthesis. They inhabit both freshwater and marine environments and use chloroplasts containing the pigment chlorophyll (a molecule that captures light energy to produce organic compounds). Although algae share several characteristics with plants, such as photosynthesis and the presence of a cell wall, they lack the specialized tissues found in higher plants.
Historically, organisms were often classified by outward characteristics like color and habitat. As a result, some photosynthetic bacteria were mistakenly labeled as algae. For example, cyanobacteria were once called “blue-green algae” due to their color and photosynthetic ability. However, we now know that cyanobacteria are prokaryotes—cells without a nucleus or membrane-bound organelles—while true algae are eukaryotic. Cyanobacteria perform photosynthesis using bacteriochlorophyll, which is chemically distinct from plant chlorophyll, and they lack the internal structures that define eukaryotic cells.
While algae and plants are both eukaryotic and photosynthetic, algae do not have the tissue specialization seen in plants. Algae may be unicellular, form simple filaments, or grow as colonies, but all the cells are generally similar in structure and function. In contrast, plants have differentiated tissues such as roots, stems, and leaves.
Unicellular Algae
Unicellular algae exist as independent, free-floating cells. One of the most ecologically important types is the diatom. Diatoms are enclosed within a hard silica shell, or test, composed of two interlocking halves. These microscopic organisms glide using a thin extension that protrudes through a slit in the test. Diatoms play a crucial role in aquatic ecosystems by forming the base of the food web and producing significant amounts of oxygen. Their fossilized remains accumulate as diatomaceous earth, which is mined and used in water filtration systems, abrasives, and insecticides.
Filamentous Algae
Filamentous algae consist of long, unbranched chains of cells. These cells remain connected after division, forming visible strands in aquatic environments. All cells within the filament are structurally and functionally similar.
An excellent example of filamentous algae is Spirogyra, recognized by its internal spiral chloroplasts.
Since the cells are not specialized, any fragment of the filament can detach and grow independently,
giving these organisms a high capacity for dispersion and colonization.
Colonial Algae
Colonial algae form groups of similar cells arranged in sheets, clusters, or spheres. While each cell maintains individual function, they may coordinate activities such as movement and reproduction. Colonies can reproduce by forming smaller internal daughter colonies. Volvox is a well-known colonial algae that forms spherical colonies composed of thousands of cells, each with flagella that allow the colony to rotate and move through water. When stained, Volvox colonies may appear in vibrant colors, aiding in microscopic visualization.
Medical Significance of Algae
While algae are not typically pathogenic to humans, they do have medical and public health relevance. Certain species of marine algae can produce toxins that accumulate in shellfish, leading to serious human illnesses when consumed. For example, Gonyaulax and related dinoflagellates can produce neurotoxins responsible for paralytic shellfish poisoning (PSP).
Additionally, cyanobacteria (though not algae) can form harmful algal blooms (HABs) in freshwater systems. These blooms release toxins that can affect the liver, nervous system, and skin, posing health risks to humans and animals that come into contact with contaminated water.
On a more positive note, algae also contribute to biotechnology and medical research. Species such as Chlorella and Spirulina are cultivated as nutritional supplements due to their high protein, vitamin, and mineral content. Algal polysaccharides like agar and carrageenan, derived from red algae, are widely used in microbiological media, pharmaceuticals, and cosmetics as stabilizers and gelling agents. Understanding the role of algae in both environmental systems and medical contexts is essential for allied health professionals, especially those working in public health, clinical microbiology, or environmental safety.
MATERIALS
Prepared slides of the following:
- Ceratum
- Diatoms
- Volvox
- Spirogyra filamentous algae
-
METHODS/PROCEDURES
1. Observe each of the above organisms listed at 10x only.
The following is to be completed during lab then turned in on Canvas as a PDF
*If you are using an iPad or tablet you will need to take screen shots of your competed work, save the screenshots as one PDF then submit them on Canvas by the due date designated on Canvas.
*You can also print out the entire exercise to bring to lab with you. If you choose to complete the lab on paper, take pictures of the completed results and conclusions sections only, save them as one PDF, then submit to Canvas by the due date designated on Canvas.
ALGAE
NAME ______________________
EXPECTATIONS
Fungi are eukaryotes. Based on that, what differences do you expect to see between fungal cells and bacterial cells when viewed under the microscope?
RESULTS
CONCLUSIONS
1. Identify one example of each type of algal growth form that you observed today:
Unicellular: _____________________________________________________________________________________________________
Filamentous: ___________________________________________________________________________________________________
Colonial: ________________________________________________________________________________________________________
2. What visible features helped you distinguish between unicellular, filamentous, and colonial algae? Provide at least two distinguishing characteristics.
3. Some algae and cyanobacteria produce toxins. Describe one way these organisms can impact human or environmental health.
4. Based on your observations, which organism(s) appeared to have the most complex structure? What features led you to that conclusion?