W4L2 -Endosymbioysis Flashcards
Mitochondria: Number in a cell? (1)
Cells may contain either: (1) Single, large mitochondrion; or (2) Several mitochondria
Mitochondria: Structure? (4)
- Outer membrane
- Highly convoluted inner membrane
- Matrix: Enclosed by inner membrane. Contains molecules to generate ATP
- Cristae: Inward projections. Contains enzymes, ribosomes, DNA.
Mitochondria: Function? (1)
Aerobic respiration of all eukaryotic cells
Mitochondria: Genes? DNA and Ribosomes. (2)
Circular DNA Chromosomes
Small, bacterial-sized ribosomes: Can translate own proteins from their genome (DNA)
Mitochondria: Cell division? (1)
Binary fission (Similar to bacteria)
Mitochondria: Lists of similarity to bacteria (4)
Electron transport chain and turbine ATPase of inner membrane of the mitochondria are the same as the plasma membrane of bacteria
Circular DNA chromosome
Ribosome size
Binary Fission
Mitochondria: Link to Endosymbiosis (1)
Originated as symbiotic aerobic bacteria
Mitochondria: Originated as symbiotic aerobic bacteria. How and why? (3)
- Initially, host eukaryote is only capable of glycolysis (1 glucose = 2 ATP) and produces pyruvate.
- By detaining endosymbiont aerobic bacterium (α-proteobacteria), eukaryote gives pyruvates to aerobic bacteria, which generates ATPs via. aerobic respiration
- Fitness advantage for both (Bacteria will not die; Host have more ATPs)
Chloroplasts: Number in a cell? (1)
Cells may contain either one or many chloroplasts per cell
Chloroplasts: Structure? (3)
Outer membrane
Inner membrane that forms a complex internal network of lamellae/thylakoids
- Photosynthetic pigments located at lamellae/thylakoids
Chloroplasts: Function? (1)
Photosynthesis (Convert light to chemical energy)
Chloroplasts: Link to Endosymbiosis (1)
Orignated as symbiotic, photosynthetic, bacteria (Cyanobcateria)
Chloroplasts: Orignated as symbiotic, photosynthetic, bacteria (Cyanobcateria) . Why and how? (2)
- Host already had mitochondrial endosymbiont
- Fitness advantage for both
- Host: Glucose supply
- Cyanobacterium: Not dead, CO2 (From mitochondria respiration)
Cyanobacteria: When and where were they found? (1)
Arose 3.5 billion years ago found in stromatolites
Cyanobacteria: What could they do? (1)
Photosynthesise
Cyanobacteria: Function compared to plastids (Plants)? (1)
Molecular machinery in photosynthetic cyanobacteria is identical to molecular machinery in plastids
What is the theory of Endosymbiosis? (1)
Complex organelles are derived from relict (old) symbionts
Endiosymbiosis: Implications on the tree of life? (2)
Mitochondria: We are a chimera of two lineages (Eukaryotes + α-proteobacteria)
Chloroplasts: Algae and plants are chimeras of at least 3 organisms (Host, Mitochondrion, Plastid)
Evidence for Endosymbiotic Origin of Mitochondria and Chloroplasts? (6)
- Organelles appear morphologically similar to bacteria
- Surrounded by an outer membrane similar to a cell membrane while their inner membrane invaginates to form lamellae or cristae
- Mitochondria and chloroplasts are semi-autonomous, retaining their own genome (DNA, RNA, proteins).
- Mitochondria and chloroplasts retain their own machinery for synthesizing proteins, including ribosomes
- Mitochondria and chloroplasts metabolism is like existing prokaryotic organisms (cyanobacteria for chloroplast and a purple bacterium for mitochondrion)
- Some chloroplasts still have the bacterial peptidoglycan wall between the inner and outer membranes (e.g., cyanophora)
Evolutionary timeline: Mitochondria vs Chloroplasts? (2)
Mitochondria were acquired only once, at the very beginning of eukaryotic evolution (no eukaryotes lacking mitochondria are known)
Chloroplasts were acquired after mitochondria, and only in the lineage that lead to plants and algae
What makes the world go around?
Photosynthesis:
CO2 and H2O > O2 and Sugar
Respiration:
O2 and Sugar > CO2 and H2O
