Origin of Eukaryotes

Question 1

Oldest fossil record of Eukaryotic cells dates back to:

Answer 1

1.8 BYA

Question 2

Ways Eukaryotes differ from prokaryotes:

Answer 2

1. DNA in linear chromosomes in a membrane-bound organelle
2. membrane-bound organelles such as mitochondria and chloroplasts
3. generally much larger
4. Cytoskeleton (internal network of proteins)
5. have dynamic membranes that facilitate movement and feeding
6. Sexual reproduction promotes genetic diversity

Question 3

Meiosis

Answer 3

creates unique gametes (chromosomal recombination)

Question 4

fertilization

Answer 4

fuses gametes at random creating unique combinations of alleles

Question 5

endosymbiont theory

Answer 5

mitochondria and plastids (chloroplasts and related organelles) were formerly small prokaryotes living within larger host cells

Question 6

endosymbiosis

Answer 6

a relationship between two species in which one organism lives inside the cell of another organism

Question 7

endosymbiont

Answer 7

a cell that lives within a host cell

Question 8

Process of serial endosymbiosis

Answer 8

1. ancestral prokaryote calls developed structures gradually by infoldings of the plasma membrane
2. Ancestral prokaryote cells took into endosymbiotic aerobic, heterotrophic prokaryote
3. One ancestral heterotrophic eukaryote lineage engulfed a photosynthetic prokaryote

Question 9

Ancestral prokaryote cells took into endosymbiotic aerobic, heterotrophic prokaryote

Answer 9

likely enguphed an alpha bacteria (uses oxygen and organic material to generate energy) which eventually became mitochondrion

Question 10

Primary Endosymbiosis

Answer 10

prokaryotic cells are taken up as endosymbionts by prokaryotic or eukaryotic cells

Question 11

Secondary endosymbiosis

Answer 11

eukaryotic cells are taken up as endosymbionts by other eukaryotic cells

Question 12

Mitochondria genomes are most similar to the genomes of

Answer 12

alpha proterobacteria

Question 13

Chloroplast genomes are most similar to the genomes of

Answer 13

cyanobacteria

Question 14

Mitochondria and Chloroplast proof of being endosymbiots

Answer 14

1. Mitochondria and chloroplasts have
small, circular DNA (like prokaryote
circular genomes), which they
replicate, transcribe, and translate
independently of nuclear DNA.

2. The organelle’s inner membranes
   are homologous to plasma
   membranes of prokaryotes
3. These organelles and
   prokaryotes divide by binary
   fission.
4. The organelle ribosomes (sites of
   protein synthesis) are more
   similar to prokaryotic than
   eukaryotic ribosomes.
5. The organelles resemble
   prokaryotes in size and structure.

Question 15

Multicellularity evolved independently ______

Answer 15

multiple times

Question 16

Oldest multicellular organism

Answer 16

1.2 BYA small algae

Question 17

Disparities between molecular phylogenies can be explained by the occurrence of _____

Answer 17

horizontal gene transfer

Question 18

Protist

Answer 18

taxonomically diverse group of mostly unicellular eukaryotes

Question 19

Protist is not a monophyletic group because

Answer 19

it excludes plants, animals, and fungi

Question 20

Most eukaryotes are:

Answer 20

protists and most protists are unicellular

Question 21

____ are the most diverse Eukariotic group

Answer 21

protists

Question 22

Photoautotrophs

Answer 22

use chloroplasts to fix inorganic carbon using light energy (e.g. algae and phytoplankton)

Question 23

Chemoheterotrophs

Answer 23

absorb organic molecules or ingest larger food particles

Question 24

Mixotrophs

Answer 24

combine photoautotrophic (photosynthesis) and chemoheterotrophic nutrition.

Question 25

Protist diversity has origins in ______

Answer 25

endosymbiosis

Question 26

The plastid-bearing lineage of
protists that arose from ____
endosymbiosis evolved into
photosynthetic protists: ______

Answer 26

primary, red and green algae

Question 27

Plastid genome DNA of red algae and
green algae closely resemble DNA of
______

Answer 27

cyanobacteria

Question 28

On at least three occasions during
eukaryotic evolution, red and green
algae underwent secondary endosymbiosis, in which they:

Answer 28

were
ingested by a heterotrophic
eukaryote