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General
Biology
BIOL 109 Lecture 6Cell Structure and Function
# 7
> Unit 5/ Concept 28
# Protists 28 Learning Objectives
At the end of this lecture the student will be able to:
> A Preview of Cell Biology
Define Protists as living small and its four supergroups .
Identify Excavata , the protists with unique flagella.
Demonstrate the highly diverse group of protists (SAR).
Understand Archaeplastida with its two clades .
Demonstrate Unikonta supergroup Briefly. Enrichment Link:
Chagas Disease: Life cycle of the parasite:
https://www.youtube.com/watch?v=XPN 4Zob 9f5s
Plasmodium, The Malaria Parasite:
https://www.youtube.com/watch?v=plFnRYYREXU
Foraminifera: Hard on The Outside, Squishy on the Inside:
https://www.youtube.com/watch?v=mEml 7kTDHqY
Green Algae:
https://www.youtube.com/watch?v=O 916 JANPv 2IStructural and Functional Diversity in Protists
Protist is the informal name of the group of mostly unicellular
eukaryotes .
Single -celled protists can be very complex , as all biological
functions are carried out by organelles in each individual cell.
Most protists are unicellular , but there are some colonial and
multicellular species.
> Unit 5/ Concept 28
Four Supergroups of Eukaryotes
One hypothesis divides all eukaryotes (including protists ) into four
supergroups :
- Excavates
- SAR
- Archaeplastida
- Unikonta
Starting with the four Supergroups , we will divide the rest into different
levels called clades . A Clade is defined as a group of biological taxa (as
species) that includes all descendants of one common ancestor.
> Unit 5/ Concept 28
Diplomonads
Parabasalids
Euglenozoans
> Stramenopiles Alveolates Rhizarians
> algae
> Green
> Amoebozoans Opisthokonts
> Excavata
Diatoms
Golden algae
Brown algae
Dinoflagellates
> SAR
Apicomplexans
Ciliates
Radiolarians
Forams
Cercozoans
Red algae
Chlorophytes
Charophytes
Plants
Slime molds
Tubulinids
Entamoebas
Nucleariids
Fungi
Choanoflagellates
Animals
> Unikonta Archaeplastida
> 2018 Pearson Education Ltd.
Unit 5 / Concept 28
Proposed phylogenetic
tree of eukaryote .
Protist groups are
indicated by yellow
boxes
Some protists are more
closely related to plant,
fungi or animals than
to other protists
Protists, the most nutritionally diverse of all eukaryotes,
include:
Photoautotrophs , which contain chloroplasts.
Heterotrophs, which absorb organic molecules or ingest
larger food particles.
Mixotrophs , which combine photosynthesis and
heterotrophic nutrition.
Some protists reproduce asexually, while others reproduce
sexually , or by the sexual processes of meiosis and
fertilization.
> Unit 5/ Concept 28
Excavates
Include protists with modified mitochondria and protists with unique
flagella .
The clade Excavata is characterized by its cytoskeleton .
Some members have a feeding (excavated) groove on one side of their
body .
This controversial group includes the Diplomonads , Parabasalids , and
Euglenozoans.
> Unit 5/ Concept 28
Diplomonads
> Excavata
Parabasalids
Euglenozoans
SAR
Archaeplastida
Unikonta
> 2018 Pearson Education Ltd.
Excavates
Unit 5 / Concept 28
Excavates
Diplomonads and Parabasalids
These two groups lack plastids , have modified mitochondria , and most live in
anaerobic environments .
Diplomonads
Have modified mitochondria called mitosomes
Derive energy from anaerobic biochemical pathways
Have two equal -sized nuclei and multiple flagella
Are often parasites, for example, Giardia intestinalis (also known as Giardia
lamblia )
> Unit 5/ Concept 28
# Medical importance of
# Giardia lamblia
Giardia lamblia , a flagellated protozoan, is an important cause of
diarrhea .
Direct person -to -person transfer can occur during sex.
Infection may also be acquired by contaminated food and water Excavates
Parabasalids :
Have reduced mitochondria called hydrogenosomes that generate
some energy anaerobically.
Include Trichomonas vaginalis , the pathogen that causes yeast
infections in human females .
> Unit 5/ Concept 28
> Excavates
> Diplomonads ,
> Parabasalids ,
> Euglenozoans (the kinetoplastids and euglenids )
# Medical importance of
# Trichomonas vaginalis
Trichomoniasis can increase
the risk of getting or spreading
other sexually transmitted
infections .SAR
SAR is a highly diverse group of protists defined by DNA similarities
SAR is a monophyletic supergroup named for the first letters of its three major
clades: Stramenopiles , Alveolates , and Rhizarians
> 2018 Pearson Education Ltd.
Unit 5 / Concept 28
> Excavates
> SAR
> Archaeplastida
> Unikonta
SAR
Stramenopiles
The clade Stramenopila includes important phototrophs as well as several
clades of heterotrophs .
Most have a hairy flagellum paired with a smooth flagellum .
Stramenopiles include diatoms , golden algae , and brown algae.
> Unit 5/ Concept 28
Stramenopiles
Alveolates
Rhizarians SAR
Stramenopiles
Diatoms
Diatoms are unicellular algae with a unique two -part , glass -like wall of
hydrated silica.
Unit 5 / Concept 28
> Stramenopiles
> diatoms ,
> golden algae ,
> brown algae
SAR
Alveolata
Members of the clade Alveolata have membrane -bounded sacs (alveoli)
just under the plasma membrane.
The function of the alveoli is unknown.
The alveolates include:
Dinoflagellates
Apicomplexans
Ciliates
> Unit 5/ Concept 28
Stramenopiles
Alveolates
Rhizarians SAR
Alveolata
Dinoflagellates
Dinoflagellates have reinforced cellular plates with two flagella , one apical and
one in a groove within the plates.
They are abundant components of both marine and freshwater phytoplankton.
They are a diverse group of aquatic phototrophs, mixotrophs, and heterotrophs .
Toxic red tides are caused by dinoflagellate blooms.
> Unit 5/ Concept 28
> Alveolates
> Dinoflagellates
> Apicomplexans
> Ciliates
Red tide
Flagella SAR
Rhizarians
Many species of rhizarians are amoebas.
Amoebas are protists that move and feed by pseudopodia , extensions of
the cell surface.
Rhizarian amoebas differ from amoebas in other clades by having
threadlike pseudopodia .
Rhizarians include radiolarians, forams , and cercozoans
> Unit 5/ Concept 28
Stramenopiles
Alveolates
Rhizarians Excavata
SAR
> Archaeplastida
Red algae
Chlorophytes
Charophytes
Green algae
Plants
Unikonta
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Red algae and green algae are the closest relatives of plants
Unit 5 / Concept 28
>
Archaeplastida
Red algae:
6,000 known species of red algae (rhodophytes, from the Greek rhodos , red)
most are multicellular.
Reddish , owing to the photosynthetic pigment phycoerythrin , which masks
the green of chlorophyll.
> Unit 5/ Concept 28
Archaeplastida
> Red algae
> Green algae
Archaeplastida
Green algae:
Green algae are named for their grass -green chloroplasts .
The two main groups are chlorophytes and charophytes .
Chlorophytes present large size and great complexity and live mostly
in fresh water ( Ulva and Caulerpa ).
Charophytes are most closely related to land plants.
> Unit 5/ Concept 28
Archaeplastida
> Red algae
> Green algae
> Ulva Caulerpa
The Economic importance of Algae
Algae constitute the link of food chain.
Algae is useful in fish culture.
Algae is useful in sewage treatment plants.
Algae is used in space research The Economic importance of Algae .
Algae is used as food and fodder.
Algae is used as fertilizers.
Algae is used as medicine. Unikonta
The supergroup Unikonta includes animals, fungi, and some
protists
This group includes two clades: the amoebozoans and the
opisthokonts (animals, fungi, and related protists )
> Unit 5/ Concept 28
Excavata
SAR
Archaeplastida
Slime molds
Tubulinids
Entamoebas
Nucleariids
Fungi
Choanoflagellates
Animals
> Unikonta
> 2018 Pearson Education Ltd.
Unit 5 / Concept 28
Unikonta
Amoebozoans
Amoebozoans are amoebas that have lobe - or tube -shaped,
rather than threadlike, pseudopodia.
They include:
- Slime molds
- Gymnamoebas
- Entamoebas
> Unit 5/ Concept 28
Unikonta
Amoebozoans
Slime molds
Includes species that were once thought to be fungi because they possess hyphae
and their fruiting bodies.
They contribute to the decomposition of dead vegetation, and feed on bacteria,
yeasts, and fungi. Thank you