16.a/b/d Ednosymboisis+rise oxygen+horizontal gene transfer

Question 1

Before oxygen how photosynthetic organisms lived

Answer 1

Photosynthetic organisms used light energy to extract hydrogen atoms and electrons from compounds such as hydrogen sulphide, In turn these hydrogen atoms and electrons were used to fix co2 into carbohydrates.

Question 2

What did cyanobacteria develop (2)

Answer 2

the remarkable ability to oxidize a molecule that was much more abundant: water.

This gave them a ecological advantage and they thrived,

Question 3

Compared to Eukaryotes
archaea and bacteria showed…….

Answer 3

archaea and bacteria show remarkable biochemical flexibility and thrive in harsh environments inhabitable to eukaryotes

Question 4

a hypothesis for why bacteria and archaea have remained simple:

Answer 4

Increased complexity requires increased energy production and eukaryotic cells can generate huge amounts of it.

Question 5

Descendants (Mitochondria and chloroplasts) (3)

Answer 5

Mitochondria and chloroplasts are actually descended from free living prokaryotic cells.

Mitochondria from aerobic bacteria

chloroplast from cyanobacteria.

Question 6

Symbiosis

Answer 6

a mutually advantageous relationship

Question 7

6 lines of evidence suggest that both chloroplasts and mitochondria have distinctly prokaryotic characteristics not found in other eukaryotic organelles

Answer 7

1. Morphology (similar shape and she of prokaryotic cells)
2. Reproduction (Just like free living prokaryotes, daughter cells arise by cell division through binary fission)
3. Genetic info ( Both contain separate DNA like prokaryotes that are circular. DNA in the nucleus are linear)
4. transcription/ translation (Both include a complete transcription and translation machinery, Contain ribosomes and tRNA)
5. electron transport (similar to free living prokaryotic cells, both has electron transport chains and enzyme ATP synthase which generate chemical energy)
6. sequence analysis (belong on the bacterial branch of the tree of life)

Question 8

All eukaryotes have mitochondria while plants and algae have both________ suggest that

Answer 8

mitochondria and chloroplasts

suggests that endosymbiosis occurred in stages which the events leading to the evolution of mitochondria occurring first. Once eukaryotic cells were able to aerobic respiration, some become photosynthetic after taking up cyanobacteria.

Question 9

Endosymboisois resulted in eukaryotic cells gaining the ability to

Answer 9

generate large amounts of energy,

Question 10

By overcoming an energy production barrier, eukaryotes could (2)

Answer 10

support a larger genome that codes from greater number of proteins and support a wider variety of genes (sexual reproduction, cell cycle, endomembrane trafficking, the nucleus, multicellularity)

Question 11

Vertical Gene transfer

Answer 11

Inheritance from one generation to the next

Question 12

Horizontal gene transfer

Answer 12

Genetic info (DNA) moves between unrelated organism

Question 13

Tell me what happened after endosymbiosis inside the eukaryotic cell (4)

Answer 13

1. Following initial endosymbiosis event, the early eukaryotic cell would have contained two distinct compartments, each with its own genome (the nucleus and the early mitochondrion)
2. these compartments each contained DNA instructions for molecules required for their own structure and function such as RNA and protein)
3. Some of the genes were lost as they are redundant as the nucleus already has genes that encode proteins with the same function.
4. Many of the genes in the mitochondrion and chloroplast were relocated to the nucleus through horizontal gene transfer.

Question 14

Outcome of horizontal gene transfer

Answer 14

Not a change in gene function, only change in location.

Question 15

host cell and nuclear genome came from

Answer 15

the archaea