Eukaryotic Organisms Flashcards
What is phylogeny
The evolutionary history of a group of organisms that can be inferred indirectly from nucleotide or AA sequence data
How are global phylogenies investigated
Certain genes/ proteins are globally distributed
What is the most widely used phylogenetic marker
Small subunit ribosomal RNA (SSUrRNA) gene
Where is the SSUrRNA gene found
In all cellular life forms
How are genes/proteins sequences made into gene trees
Choose gene of interest, identify homologous, align sequences and calculate gene tree
What is the difference in the SSUrRNA gene in prokaryotes and eukaryotes
16S rRNA in prokaryotes 18S rRNA in eukaryotes
What size is the SSUrRNA gene in plastids and mitochondria (pointing to bacterial origins)
12s
What are the features of the SSUrRNA gene
Functionally constant, sufficiently conserved, can be cloned with degenerate primers and generate informative aligners, used in environmental surveys
What is used to complement the SSUrRNA gene phylogenies
Protein coding genes
What are the features of mitochondria, chloroplast/plastids
- small genomes that encodes rRNA and proteins
- protein synthesis machinery e.g.ribosomes, tRNA
What makes up mammalian mitochondria
- 2 ribosomal RNAs
- 22 tRNAS
- 13 essential genes that encodes rRNA subunits of the oxidative phosphorylation enzyme complexes
What encodes the vast majority of mitochondrial proteins
The nuclear genome
What is the archezoa hypothesis
Suggest that the nucleus came first, prior the mitochondrion acquisition through endosymbiosis
What are the advantages of metagenomic surveys
- resolve important nodes in the tree of life
- refine our understanding of the host cell that evolved into a eukaryotes
- refine the phylogenetic relationships between major lineages of eukaryotes
What is the evidence for mitochondria- like organelles in Archezoa
Electron microscopy data of Trichomonads, Microsporidia and Giardia
What are hydrogensomes
Organelles that produce hydrogen, produce ATP by substrate level phosphorylation, and have a genome with a mitochondrial signature. Nuclear genomes that encode reduced fractions of mitochondrial proteins
What are mitosomes
Small organelles (<100nm) with no evidence of ATP producing ability and no genome. Nuclear genomes encode reduced mitosomal/ mitochondria, proteins set
What does phylogenetic analysis determine mitosomes and hydrogensomes to be
Double membrane bound organelles in archezoa that are homologous to mitochondria
What is a homologue
The same organ/organelle under every variety of form and function
Did the nucleus or the mitochondria come first in evolution
We do not know as an archaeological cell could have been the host cell for the mitochondrial endosymbiosis rather than a eukaryote
What are plastids
Double membrane bound organelles contains pigment or food e.g. chloroplast
How have many species come to possess plastids
Through primary, secondary or tertiary endosymbiosis
What is the difference between extracellular and intracellular parasites
Intracellular parasites need to penetrate their host cells to complete their life cycle, extracellular parasites thrive on and in tissues without entering host cells e.g. mucosal surfaces
