🧬 Bacteria and Archaea Diversity
What are the two domains of prokaryotic life?
Bacteria and Archaea
What theory explains how mitochondria originated?
The endosymbiotic theory.
Are protists a monophyletic, paraphyletic, or polyphyletic group? How do we know?
Paraphyletic
What are the main characteristics of fungi?
Eukaryotic, heterotrophic, have chitin cell walls, and absorb nutrients externally.
Name one difference between Bacteria and Eukarya.
In bacteria, no nucleus, circular chromosomes, no complex RNA polymerase, no histone proteins with DNA
Name one piece of supporting evidence that the mitochondria evolved through endosymbiosis.
Mitochondria and chloroplasts ~ size of an average bacterium.
Both replicate by fission, as do bacteria
Both have double membranes, consistent with the engulfing mechanism.
Both have some genes (in circular DNA) that code for their own replication and transcribe their own genomes.
Mitochondiral and chloroplast gene sequences are much more closely related to bacterial sequences than to nuclear DNA sequences of eukaryotes.
What does it mean to be an autotroph? What does it mean to be a heterotroph?
Autotrophs produce their own food from inorganic substances, while heterotrophs obtain their food by consuming other organisms.
What is a hypha, and what structure do many hyphae form?
A threadlike filament; collectively they form the mycelium.
What is the name of the process where bacteria can exchange DNA without reproducing?
Lateral gene transfer
According to endosymbiosis, what benefit did the host cell and the engulfed bacterium provide each other?
The host got more efficient energy production; the bacterium got protection and nutrients.
What group of protists includes the parasite that causes malaria?
Apicomplexa (Plasmodium falciparum).
What is the function of mycorrhizae in plants?
Mycorrhizal fungi form mutualistic relationships with plant root cells, aiding nutrient and water absorption.
Name the three types of extremophiles and their environments.
Halophiles (salt), thermophiles (heat), acidophiles (acidic pH).
What evidence supports the idea that mitochondria and chloroplasts were once free-living bacteria?
They have circular DNA, replicate by fission, and have double membranes like bacteria.
Why is studying protists important for understanding evolution?
They provide insight into the early evolution of eukaryotes and the origins of multicellularity.
Explain the difference between Basidiomycota and Ascomycota fungi.
Basidiomycota produce spores in club-shaped basidia; Ascomycota produce spores in sac-like asci.
How does lateral gene transfer affect our understanding of relatedness of organisms?
Lateral gene transfer complicates our understanding organismal relatedness by transferring genes between distantly related species. Trees are no longer vertical and no longer show evolutionary history.
Differentiate between primary and secondary endosymbiosis, giving an example of each.
Primary: a prokaryote engulfed by a eukaryote (e.g., origin of mitochondria).
Secondary: a eukaryote engulfed another eukaryote (e.g., origin of chloroplast).
Compare the seven major eukaryotic groups — name three and describe one key trait for each.
Stramenopila: two hairy flagella
Alveolata: Flattened sacs in cell called alveoli
Rhizaria: No cell walls, thin projections for eating
Amoebozoa: No cell walls, large lobes for moving
Plantae: photosynthetic with chloroplasts from primary endosymbiosis.
Excavata: Feeding grove, no mitochondria
Opisthokonta: includes animals & fungi; single posterior flagellum.
Describe the ecological and evolutionary importance of fungal symbioses (lichens, mycorrhizae, parasitic fungi).
They influence nutrient cycling, plant evolution, ecosystem stability, and even biodiversity through symbiosis and disease.