PARA Lecture 3- 08/28/26

Species

a group of individuals with similar properties allowing them to interbreed with one another, produce fertile offspring, and that do not regularly interbreed with other species

Dioecious

species is comprised of separate male and female individuals

Monoecious

species has functional reproductive organs of both sexes (hermaphroditic) and are capable of self-fertilization or cross-fertilization

Metagenomics

sequencing of genetic materials from mixed samples to see which organisms are present

Taxonomy

the science of identification, description, and naming of organisms

What is the issue with Darwin’s model of the tree of life

Did not consider horizontal gene transfer, only considered vertical gene transfer

What improvement did the modernized tree of life make

charts both vertical and horizontal gene transfer

What is the debate over the domains of life

2 domains- bacteria and archaea/eukarya vs. 3 domains- bacteria, archaea, and eukarya

With recent discoveries of archaea, like Asgard archaea with eukaryotic-like features, it has been argued that origins of Eukarya are within Archaea

How common is parasitism in Archaea

Seems to be rare in archaea- the only known parasitic archaea is Nanoarchaeum equitans which parasitizes a larger archaea, Ignicoccus sp.

Archaea typical environments

many are extremophiles but becoming clear they’re more ubiquitous

How many overall phyla of bacteria are there

30

Dr. Maggie’s fav name of a species lol

Borrelia burgdorferi- causes lyme disease

How many bacterial lineages contain human pathogens

8

What does the SAR supergroup stand for

Stramenopiles, Alveolata, Rhizaria

Stramenopile key characteristic

also called heterokonts because many produce flagella of 2 different shapes in their motile phase

What organisms do stramenopiles include

• free-living species like diatoms and golden algae

• parasitic species like water molds or oomycetes (Phytophthora infestans caused Irish potato famine)

What do alveolata include

ciliates, dinoflagellates, and apicomplexa

Rhizaria key features

mostly unicellular- some produce pseudopods and some are spore-forming

What type of species are Rhizaria (free living or not)

most Rhizaria are free-living, some are parasitic

What are metamonada

a large group of flagellated, microscopic eukaryotes

Metamonada key characteristics

• Lack mitochondria- with evidence that they used to have mitochondria since they have mitosomes

• They are anaerobic- mostly aerotolerant anaerobes

What are Discoba grouped by

this group is united by sequence similarity of multiple genes but lack many morphological similarities

Kinetoplastids

Group within Discoba that possess a single mitochondria that contains a kinetoplast

Kinetoplast

dense network of circular mitochondrial DNA

Example of Archaea parasitism

The only parasitic archaea is Nanoarchaeum equitans which parasitizes Ignicoccus sp. N. equitans cannot synthesize its own lipids and hijacks host functions to survive.

Example of intracellular bacterial parasites

Chlamydia and Rickettsia

Example of bacterial parasites that are a combination of free-living and parasitic

Spirochetes

Stramenopile example

Phytophthora infestans- causes blight, irish potato famine

Alveolata examples

• Ciliate- Balantidium coli, causes GI symptoms

• Dinoflagellate- Oodinium, causes gold dust/velvet disease in fish

Rhizaria example

Phytomyxea- plant parasite, example clubroot on cauliflower

Matamonada examples

• Giardia Lamblia

• Trichomonas vaginalis

Discoba example

Naegleria fowleri- “brain-eating” amoeba

Naegleria fowleri mechanism

Aquatic, swimmers snuff into nasal chambers, move through small passages in cribriform plate and get into brain, phagocytose brain cells, primary amebic meningoencephalitis

3 stages of Naegleria Fowleri

trophozoite, flagellated form, and cyst

Kinetoplastid example

Trypanosoma