ch. 9 evolution of eukaryotes

Question 1

Explain why cyanobacteria are important from an evolutionary perspective.

Answer 1

Cyanobacteria evolved to make oxygenic photosynthesis, fixed carbon (carbon fixation) through Calvin cycle, and broke down glucose using ETC

Question 2

Consider the two bacterial Domains, Archaebacteria and Eubacteria, which form an endosymbiotic union to give rise to the eukaryotes.
a. Which specific lineage evolved into mitochondria? What benefit does it get from the
symbiosis? What goodies does it give to its host?

Answer 2

Purple non-sulfur bacteria evolved into mitochondria. The benefit it got from symbiosis is a cell wall that guaranteed it food (pyruvate, ADP+Pi, and even more NADH) from its Archaebacteria host, so it was able to produce ATP by using forwad Krebs and ETC. The goodies it gives its host is lots of ATP.

Question 3

Consider the two bacterial Domains, Archaebacteria and Eubacteria, which form an endosymbiotic union to give rise to the eukaryotes.
b. Which specific lineage evolved into chloroplasts? What benefit does it get from the symbiosis? What goodies does it give to its host?

Answer 3

Cyanobacteria evolved into the chloroplast. The benefit it got from symbiosis was the protection from phagocytosis from the archaebacteria. The goodies that it gave its host was food made by photosynthesis that it allowed to occur in the cell.

Question 4

Loss of the cell wall in the Archaebacteria has important consequences.
a. What are the negative consequences of the lack of cell wall.

Answer 4

Disadvantage was the loss of the cell wall that put archaebacteria at risk of lysing from osmosis

Question 5

Loss of the cell wall in the Archaebacteria has important consequences.
b. Name two very different positive consequences of the lack of cell wall.

Answer 5

1. allows DNA replication to occur at multiple points of origin
2. cells can capture food through phagocytosis or endocytosis

Question 6

Loss of the cell wall in the Archaebacteria has important consequences.
c. How did the loss of the cell wall lead to a symbiotic relationship with Eubacteria?

Answer 6

Loss of cell wall led to symbiotic relationship with Eubacteria because archaebacteria started taking in living cells as food. In an archaebacterium, only glycolysis can occur, so it was making only 2 ATP’s at a time. Purple bacterias can make up to 18x ATP made in glycolysis since glycolysis, ETC, and Krebs were able to occur in it. Therefore, it became a mutually beneficial relationship since purple bacteria benefitted from archaebacterias pyruvate.

Question 7

Be able to draw the cladogram of the three domains, Eubacteria, Archaebacteria, and Eukaryota, including the two “cross-over” events that initiated the Eukaryota

Answer 7

Eubacteria is at top left of branch and Eukaryotes are on top right branch. There is a node on branch to Eukaryotes that leads to Archaebacteria. There are two arrows from Eubacteria branch to Eukaryote branch labeled cyanobacteria and purple bacteria.

Question 8

Make a sketch to help you describe aerobic metabolism in the dark in Eukaryotes. Starting
with glucose outside the cell, use arrows between labeled processes put circles around each process) and indicate all inputs and outputs (indicate which outputs are the most important). Start by drawing a cell with its cytosol (Archaebacterial host), and a large mitochondrion (symbiont) as we did in the lecture exercise last week. Pay close attention to the membranes separating these two regions. Don’t forget to resolve the host’s NAD+ problem without fermentation. Map onto your sketch in its proper place: phagocytosis, outer membrane, inner membrane, intermembrane space, glucose, glycolysis, pyruvate, Krebs cycle, NADH/FADH2, NAD+, FAD+, electron transport chain, protons, proton pump, ATP, ADP + Pi

Answer 8

glycolysis, forward Krebs, ETC, reverse proton pump, run the cell (ATP to ADP)

if with fermentation just add it right next to glycolsis in outer membrane