Module 4: Protista and the Origin of Eukaryotes

eukaryotic characteristics that are different from prokaryotes

-DNA and cytoplasm is separated by a nuclear envelope -cytoplasm contains membrane-bound compartments with specialized metabolic functions (mitochondria, chloroplasts, endoplasmic reticulum, Golgi complex) -highly specialized contractile proteins that move cells and internal parts

process of endosymbiosis theory

-areobic bacterium with an anaerobic eukaryote -eukaryotic cell engulfs the bacterium -bacterium survives -endosymbiosis both benefit (pyruvate and O2 is given to the aerobic bacterium and ATP is given to the anaerobic bacterium)

supporting evidence for eukaryotes and serial endosymbiosis

-similarities in inner membrane structures and functions -both have their own circular DNA -prokaryotic ancestors of mitochondria and plastids probably gain entry to the host cell as undigested prey or internal parasites -horizontal gene transfer may have contributed to large genomes and complex cellular structures of eukaryotic cells

the origin of the nuclear envelope

1. ancestor of eukaryotes; chromosomes and plasma membrane 2. infoldings of membrane 3. eukaryotic cell; nucleus, endoplasmic reticulum

eukaryotes

Almost all protists are

eukaryotic organisms including fungi, plants, and some protists do have cell walls, but the cell walls are composed of different biomolecules than those of prokaryotes.

Describe one difference in cellular structure or metabolism between prokaryotes and eukaryotes.

false (Protists have a diversity of ways they generate energy and gain resources, which includes photosynthesis.)

If an organism is capable of photosynthesis, it is not a protist.

All photosynthetic eukaryotes have mitochondria

In the Endosymbiotic Theory for the origin of eukaryotes, the final step was the engulfing a functional cyanobacterium to produce photosynthetic eukaryotes ("plants"). Why is this stage considered the final step in the sequence of eukaryote evolution?

Only early Earth was intensely bombarded by large space debris.

In what way were conditions on the early Earth of more than 3 billion years ago different from those on today's Earth?

sporozoites

Malaria results from a mosquito injecting the _______________ of Plasmodium into the human blood stream.

cyanobacteria aquatic animals algae eukaryotes (Cyanobacteria appear in the fossil record as early as 2.5 billion years ago (between the Archaean and Proterozoic eons), and are largely responsible for oxygenating Earth's oceans and atmospheres (thus making multicelluar and eukaryotic life possible). The first eukaryotic fossils appear near the beginning of the Proterozoic, the first algae appear during the middle of the Proterozoic, and aquatic animals (sponges) appear near the end of the Proterozoic. Eukayrotic life rapidly diversified during the Cambrian explosion.)

Select all of the groups in the list below that appear prior to the Cambrian diversification ("Cambrian explosion") around 542 mya.

Oxygen

The appearance of abundant multicellular organisms coincided with increased levels of _________ in the Earth's atmosphere.

origin of cyanobacteria < origin of mitochondria < origin of chloroplasts < origin of multicellular eukaryotes < origin of fungal-plant symbioses

What is thought to be the correct sequence of these events, from earliest to most recent, in the evolution of life on Earth? Use "<" to mean "occurred before". origin of mitochondria origin of multicellular eukaryotes origin of chloroplasts origin of cyanobacteria origin of fungal-plant symbioses

algae

What type of plant-like protist produces much of the oxygen in the atmosphere?

oxygenation of atmosphere

Which major event (or events) likely allowed eukaryotes to evolve?

ingesting and digesting prey decomposing dead organic matter being parasitic photosynthesis mutualistic symbioses

Which of the following describe ways in which some protists can obtain energy?

Its members have DNA that floats in the cytosol

Which of the following is not a true statement about the kingdom Protista?

It is able to produce oxygen in the light.

You have found a new eukaryote. What line of evidence would support your hypothesis that the organism is a photosynthetic protist?

animal-like protists

all heterotrophs classified by the 4 ways they move

heterotrophs protista

amoeboids ciliates zooflagellates sporozoans plasmodial slime molds cellular slime molds water molds

flagellum

back and forth wave motion whip-like tail(s) animal-like protists

autotrohps protista

green, brown, red, diatoms, dinoflagellates euglenoids

false

he Kingdom Protista is a convenient grouping of closely related, well-characterized unicellular eukaryotic taxa.

sessile

no locomotion or movement

earliest eukaryotes were prokaryotes

nuclear membrane then mitochondria (animals and fungi; first endosymbiosis), then chloroplasts (plants; second endosymbiosis)

pseudopodia

projection of cytoplasm that sticks out like a foot (false foot) animal-like protists

cilia

tiny beating hair-like structures coordinate movement between individual cilia animal-like protists