Ch. 27 Eukaryotes

Question 1

what are eukaryotes?

Answer 1

unicellular (fungi, protista)

multicellular (plants, animals)

Question 2

what are prokaryotes?

Answer 2

can be unicellular or multicellular

-bacteria or archaea

Question 3

what are heterotrophs?

Answer 3

eat food from other organisms/plants

cannot make own food

Question 4

what are autotrophs?

Answer 4

can make own food from simple organic substances

Question 5

define phagocytosis

Answer 5

engulf, package, transport and digest
food particles
-ex. amoebas do this

Question 6

define pinocytosis

Answer 6

the ingestion of liquid into a cell by the budding of small vesicles from the cell membrane.

Question 7

why is there so much more

diversity in size, shape, types of eukaryotes than prokaryotes?

Answer 7

• Membrane dynamics
• Compartmentalized metabolism
• Genome organization
• Genetic diversity by means of sex
• Life cycles

Question 8

what is the life cycle of animal cells?

Answer 8

subset of haploid cells – meiosis – gametes – fertilization

1 multicellular phase: diploid

Question 9

what is the life cycle of plant cells?

Answer 9

2 multicellular phases

1 haploid and 1 diploid

Question 10

when does the cell cycle differ?

Answer 10

-Cell cycle differs when the organism reproduces sexually or asexually

• Sexually reproducing eukaryotes alternate states.
• Differences are most obvious in the proportion of time spent as haploid versus diploid

Question 11

define endosymbiosis

Answer 11

symbiosis in which one of the symbiotic organisms lives inside the other

Question 12

what evidence of endosymbiosis do we see in plant cells?

Answer 12

chloroplasts in plant cells most closely resemble certain photosynthetic bacteria (cyanobacteria)

• machinery of cyanobacteria closely resembles how thylakoid membranes organize machinery of chloroplasts
• processes of photosynthesis in both are almost identical
• chloroplasts have their own separate membranes
• chloroplast DNA is closely related to cyanobacteria rather than the DNA of their host

Question 13

define symbiont

Answer 13

organisms that lives in closely evolved association with another species

Question 14

define symbiosis

Answer 14

interaction between two different organisms living in close physical association, typically to the advantage of both.

Question 15

what are 3 cases in which organisms use chloroplast endosymbiosis?

Answer 15

red algae
green algae
photosynthetic amoeba

Question 16

what is a characteristic of chloroplast endosymbiotic DNA?

Answer 16

No longer need a big genome since they are not independent (free-living)
• Some genes migrated to the host nucleus

Question 17

do we see endosymbiosis associated with mitochondria? if so, what are mitochondria most closely related to?

Answer 17

yes
proteobacteria
(except for a few extreme types in oxygen poor environments)

Question 18

characteristic of eukaryotic cells that lack mitochondria

Answer 18

even eukaryotic cells that do not have mitochondria have traces of mitochondrial DNA in their genome

-many eukaryotic cells that do not have mitochondria have “hydrogenosomes” which generate ATP by anaerobic processes (allows them to function in oxygen poor environments)

Question 19

hypotheses of the origins of eukaryotic cells/their DNA components

Answer 19

• Nuclear genes of eukaryotes are loaded with other organism genes.
• Probably multiple horizontal gene transfer events.

Question 20

what are protists?

Answer 20

organisms having a nucleus but lacking other features specific to plants/animals/fungi
(usually microscopic eukaryotes and seaweeds)

Question 21

what is algae?

Answer 21

photosynthetic protists

may be microscopic single celled organisms OR big visible clumps of seaweed

Question 22

what is protozoa?

Answer 22

heterotrophic protists
(almost always single celled organisms)
-have remarkable diversity!!

Question 23

what are the 7 major superkingdoms of eukaryotes?

Answer 23

1. opisthokants
2. amoebozoans
3. archaeplastids
4. stramenopiles
5. alveolates
6. rhizarians
7. excavates

Question 24

in which superkingdom do most eukaryotic species fall under?

Answer 24

opisthokanta
75% of species
(1.8 million species discovered so far)

Question 25

which groups are in the opisthokant superkingdom?

Answer 25

- animals (complex multicellularity) - choanoflagellates - fungi (complex multicellularity)

Question 26

what are choanoflagellates?

Answer 26

``` •type of opisthokant - 150 species • All unicellular protists • All have microvilli ring with a single flagellum • Closest genome to animals! ```

Question 27

what are microsporidia?

Answer 27

- very closely related to fungi - group of unicellular opisthokants - parasites that live inside of animal cells - only spores can live outside of host environments - have no mitochondria/golgi apparatus/flagella - cause illness and health problems in humans

Question 28

what are some characteristics of the superkingdom amoebozoa?

Answer 28

-group of eukaryotes with amoeba like cells that move and gather food by means of pseudopodia

Question 29

what are plasmodial slime molds?

Answer 29

type of amoebozoa - coenecytic (multinucleotide cells, replicate nucleus but no cytokinesis) - plasmodia generate sporangia (stalked structures that produce spores for dispersal in order to reproduce) - often seen as lace like structures to the naked eye "Weird creatures that form zygotes that repeatedly go through mitosis but no cell division (coenocytic cells = a single cell with many nuclei)… this forms the plasmodia which builds the sporangia, a reproductive body"

Question 30

what are cellular slime molds?

Answer 30

type of amoebozoa -live most of life as solitary amoeboid cells feeding on bacteria in soil. when starved, release cylic AMP signals to aggregate cells into a large chemical clump "Soil amoeboid-style living. When starved of food (bacteria), form aggregations called a slug. Slug can form sporangia"

Question 31

what are some characteristics of the superkingdom archaeplastida? what are the 3 groups of archaeplastids?

Answer 31

- photosynthetic organisms, superkingdom form which land plants arose - descended from protists and acquired photosynthesis from endosymbiotic cyanobacterium 1. glaucocystophytes 2. red algae 3. green algae

Question 32

glaucocystophytes

Answer 32

-fresh water -single-celled -the highest number of features linking to the ancestral cyanobacteria endosymbiont -Peptidoglycan and biliprotein pigments that are photosynthetic

Question 33

red algae

Answer 33

- 5000 spp - mostly marine - walls of cellulose, chlorophyll a, and biliproteins - Used in toothpaste, ice cream and agar.

Question 34

green algae

Answer 34

-8,000 spp -some are fresh water -land plants originate here -Green Algae Diversity: differences in form, chlorophyll a and b, 2-membrane chloroplasts, phytoplankton, worldwide

Question 35

characteristics of the superkingdom stramenopila?

Answer 35

-Giant kelp, algae, and protozoans (photosynthetic) -free-living and parasitic -Odd flagellum with stiff hairs, some with second flagellum that is not hairy

Question 36

what are some types of stramenopila?

Answer 36

- Diatoms - most diverse stramenopiles (used in beer/responsible for 25% of worlds PSN) - brown algae

Question 37

characteristics of the superkingdom alveolata? what are the 3 types?

Answer 37

-Dinoflagellates (“whirling whip”): Most are SW spp. But a few spp are common in FW, lots with chloroplasts, some endosymbionts with coral especially (zooxanthellae). Ex. Red Tides -Ciliates: cilia, lots of parasitic spp, not generally parasitic to humans (ex. paramecium) -Apicomplexans (parasites, only gametes locomote): Ex. Plasmodium falciparum (MALARIA) 655,000 human deaths in 2011 alone

Question 38

what is the fossil record of protists?

Answer 38

1.8 billion years • Oldest Eukaryote is in Australian rocks • 1200 million year old multicellular red algae in Canada • 750 million year old rock in Arizona has diverse amoebazoans