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LSCI 230 Study Guide - Midterm Guide: Asymmetric Cell Division, Osmoregulation, Apicomplexa


Department
Life Sciences
Course Code
LSCI 230
Professor
Mira Ovechestcky
Study Guide
Midterm

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Lecture 11: Taxonomy in Eukaryotes Part II
Caulobacter
*Notes: This is clarification for previous
lecture on Caulobacter:
1. Caulobacter has an asymmetric cell division
each cell cycle where you have a stalked
mother cell that produces morphologically
distinct progeny
A) So you have a daughter swarm cell that
can’t reproduce at first.
B) And a daughter non-motile stalk cell
2. Mother cell produces only one set of
offspring per cell cycle
3. If conditions are favorable, the stalked daughter can undergo another cycle of DNA
replication and cell division meaning it will become a new mother cell
4. Swarmer must undergo an obligate period of growth and differentiation before beginning
a new cycle
A) So we got a swarmer cell that has to go through a period of growth and differentiation
then eventually it’ll become a stalk cell.
**Key: Understand that there is morphologically distinct progeny a swarm cell and a stalk
cell
Phylogeny of the Eukarya
1. Gunna finish of eukarya then later go into fungi
Alveolates
1. Some members of the Alveolates are the ciliates,
dinoflagellates, and apicomplexans
2. Alveolates are characterized by the presence of alveoli,
which are sacs underneath the cytoplasmic membrane
A) Alveoli may function to help cells maintain osmotic
balance
B) In Paramecium: you have a contractile vacuole which
does the same thing as alveoli (maintain osmotic balance)

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Alveolates: Ciliates (a subgroup)
1. Ciliates are called this because they possess cilia
at some stage of their life
2. The most widely distributed genera is
Paramecium → (first pic)
3. Ciliates use cilia for motility and to obtain food
4. Ciliates have two nuclei (a macronucleus and
micronucleus)
A) Macronucleus is the place for transcription and
translation
B) But, both nucleus carries identical genetic
information
C) Micronucleus is what is used during sexual
reproduction
5. So during conjugation (sexual reproduction), the two paramecia (a ciliate) exchange
micronuclei aka exchange of genetic info
6. Some ciliates are animal parasites and some are animal symbionts (found in the rumen or
reproductive tracts of animals).
A) Second pic shows yeast cells so it shows just how much larger a paramecia cell is.
Paramecium feeding
1. Shows a video of paramecium feeding
Alveloates: Dinoflagellates (another subgroup)
1. Dinoflagellates are diverse marine and freshwater
phototrophic organisms
Thus, these are primary producers
2. Some are free-living and others live symbiotically with
corals
3. They have two flagella with different insertion points on
the cell
A) So they got a Transverse flagellum (top)
B) Longitudinal flagellum (bot)

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**Know that what distinguishes dinoflagellates is that they have 2 flagella
**For the exam know the unique features of each of the organisms
Toxicity of dinoflagellates
1. Some dinoflagellates species can secrete neurotoxins.
2. In warm and polluted waters, dinoflagellates can
reach very high numbers.
A) So high that you can get these red tides, which is a
very dense suspensions of these cells (top)
3. These are associated with human poisoning (paralytic
shellfish poisoning).
A) For example there can be an accumulation of toxic
dinoflagllates in mussels leads to paralytic shellfish
poisoning
Alveolates: Apicomplexans (another subgroup)
1. Apicomplexans are obligate parasites of animals
A) Ex: Plasmodium falciparum the agent that
causes malaria
B) Toxoplasma gondii
causes toxoplasmosis (in
cats
2. Apicomplexans have a complex life cycle:
Basically has a bunch of stages no need to
know in details just know the stages
A) Sporozoite (transmission)
B) Gametocyte (sexual reproduction)
C) Other stages
3. Apicomplexans contain apicoplasts, which are
degenerate chloroplasts that lack pigments and phototrophic capacity, but still carry many
anabolic pathways.
4. Apicomplexans cause severe diseases such as malaria (Plasmodium), toxoplasmosis
(Toxoplasma), and coccidiosis (Eimeria).
Phylogeny of the Eukarya
1. Now another group of eukarya Stramenopiles
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