Chapter 25

Question 1

Eukaryotes came when?

Answer 1

Between 2.1-1.8 billion years after O2 accumulated in atmosphere

Question 2

Hypothesis for origin of eukaryotes

Answer 2

Endosymbiosis
Nuclear membrane came from infolding
Mitochondria and chlorophsts arose from endosymbiosis

Aerobic heterotrophic prokaryote engulfed= mitochondrion
Photosynthesis prokaryote engulfed= plastid

Question 3

What evidence supports endosymbiosis

Answer 3

• Mitochondria and chloroplasts have their own DNA
• inner membranes of both organelles have enzymes and transport systems the same as living prokaryotes
  -mitochondria and plasmids have ribosomes to transcribe/translate
  -these ribosomes are similar to prokaryotes
  -mitochondria and plastids divide in similar way to certain prokaryotes (both contain circular DNA molecules
  -

Question 4

Serial symbiosis

Primary symbiosis

Secondary symbiosis

Answer 4

Involves the engulfing of Cyanobacteria by primitive eukaryotes to form the lineages of protists, the green algae, and the red algae

Involves the engulfing of either red or green algae cells by another eukaryotes

Question 5

Lateral gene transfer

Answer 5

Endosymbiosis prokaryotes are believed to have relinquished certain genes to the nucleus of their host cells in a process known as endosymbiotic gene transfer

Question 6

Origin of multi cellular animals

Answer 6

May have evolved from colonial forms but different jobs from different parts allows for better efficiency

Diversity explosion at beginning of Cambrian period (540 Mya)

Question 7

Phylogenetic hypothesis

Answer 7

The relationship between 4 major supergroups of eukaryotes on earth today

• Excavata
• SAR
• Archaeapastida
• Unikonta

Question 8

Excavates

Answer 8

-presence of excavated feeding groove on one side of body

Diplomonads: lack mitochondria
Parabasalids:reduced mitochondria
Euglenozoans:diverse group with para flagellate rod
-euglenids
-kinetoplasts: large mass of DNA inside large mitochondrion

Question 9

SAR

Answer 9

Stramenopiles, alveolates, rhizarians

Question 10

Stramenopiles

Answer 10

Protists that have two different flagella, one whiplike and one tinsel
Also called heterokonts
Includes diatoms, dinoflagellates, brown algae and ciliated protozoans

Question 11

Alveolates

Rhizarians

Answer 11

Membrane enclosed sacs (alveoli) under plasma membrane

Includes amoebas

Question 12

Archaeplastids

Answer 12

Formed by primary symbiosis of blue green algae and the pro-eukaryotes
Red algae still have some Cyanobacteria characteristics
Green algae have given rise to all land plants

Question 13

Red algae

Answer 13

Multicellular seaweeds with red photosynthetic pigment “phycoerythrin”

Question 14

Green algae

Answer 14

Chlorophyta are extremely diverse group of freshwater and marine algae.
Sexually reproduce with bi-flagellated gametes

Question 15

Origin of land plants

Answer 15

Green algae called charaphyta are closely related to land plants.

Question 16

Unikonta

Answer 16

Means one flagellum

Two major clases: amoebozoa (some molds) and the opisthokonts (fungi, animals, choanoflafellates)

Question 17

Amoebozoans example

Answer 17

Tubulinids - lobe like pseudopodia

Include amoeba and slime molds that feed on decaying organic matter by phagocytosis

Question 18

Protists effects on human and animals

Answer 18

Important contributors to productivity on ecosystems
And
Pathogenic effects (disease)