week 6 - eukaryotic cells

Question 1

Eukaryotes vs prokaryotes

Answer 1

size
euk: 10-100 um
prok: 0.2-2.0 um

nucleus
euk: true nucleus with nuclear membrane
prok: nucleoid

DNA
euk: multiple chromosomes with histone arrangements
prok: single chromosome, no histones

ribosomes
euk: 80s (40s and 60s with 18s rRNA)
prok: 70s (50s and 30s with 16s rRNA)

organelles
euk: membrane enclosed, lysosmes, Golgi complex, ER, mitochondria, chloroplasts
prok:

plasma membrane
euk: sterols and carbohydrates
prok: no carbohydrates, generally lack sterols

Question 2

endosymbiosis
what

Answer 2

• Theory to explain how eukaryotes gained mitochondria and chloroplasts
• ## Predicting they were once free-living prokaryotes

Question 3

endosymbiosis
when

Answer 3

About 2 billions years ago

Question 4

endosymbiosis
which organisms

Answer 4

• Mitochondria –> alpha-proteobacteria phylum
• Chloroplasts –> Cyanobacteria phylum

Question 5

endosymbiosis
selection

Answer 5

The symbiotic relationship was then selected for and lead to a the expansion of Eukaryotic diversity
o Gave cell selective advantage
o protected inside another cell / ability to produce ATP
o Indicated that they were once separate organisms that come together

Question 6

secondary endosymbiosis

Answer 6

• Evidence for more complicated endosymbiosis
  o Engulfed another eukaryote
  o Remnants of this in the nucleus

Question 7

some eukaryotes have:

Answer 7

• Chloroplasts
  o Plants, algae, some protists
• Cells walls
  o Entirely different from prokaryotic cell walls
• Smaller membrane bound compartments
  o Lysosomes, peroxisomes etc.
• Cilia and flagella
  o Entirely different from prokaryotic flagella Evolved differently
  o How they produce the movement is different (motors move in a different way)
  o Composition is different
  o But same solution

Question 8

diversity of eukaryotes

Answer 8

• Plants and animals
• Fungi
  o Yeasts, moulds, mushrooms
• Algae
• Protists