Protists 1

Question 1

what does the protist fossil record show

Answer 1

Oldest fossil protist 1.2 bya, red alga

Protists display numerous evolutionary adaptations resulting in widely different organisms

There are also recent radiations (aka bursts of new species and groups)

Question 2

what are the four stages of eukaryote evolution from prokaryotes

Answer 2

Four stages:

1. loss of prokaryote cell walls and replaced with new types of cell wall
2. Elaboration of internal membrane systems e.g nuclear envelope
3. Development of intracellular trafficking system for molecules
4. endosymbiosis leading to phtosynthetic cyanobacteria becoming chloroplast and alpha-protobacteria becoming mitochondria

Question 3

what is endosymbiosis

Answer 3

Endosymbiosis:

evidence: chloroplast and mitochondria share features with prokaryotes

• circular DNA not in a nucleus
• some very similar enzymes
• similar ribosomes

Chloroplasts have been derived just once

the engulfment of a prokaryote = primary endosymbiosis

some marine protists acquired photosynthesis from absorbing a eukaryotic cell

either red algal or green algal cell, both of which have their own nucleus

Question 3

how do protists get their nutrition

Answer 3

• Autotrophs
  
  • like algae consume light
• Heterotrophs
  
  • ingestive heterotrophs consume particles and cells
  • Absorptive heterotrophs absorb molecules

Question 4

what is basic protist phylogeny

Answer 4

I. Supergroup Excavata

1. Diplomonads

II. Supergroup SAR

1. Stramenopiles

i.Diatoms

ii. Brown algae

iii. Oomycetes

2. Alveolates

i.Dinoflagellates

ii.Apicomplexans

III. Supergroup Unikonta

1. Amoebozoans

IV. Supergroup Archaeplastida

1. Rhodophyta
2. Chlorophyta

Question 5

what are some ways protists drive selection

Answer 5

Heterotrophic protists eat other organisms like other protists. They can also be parasites weakening another species’ fitness

They are massive drivers of selection, responsible for killing off species

Question 6

describe supergroup Excavate

Answer 6

Supergroup Excavata

• Asymmetric in shape, have a feeding furrow on one sideDiplomonds:
  • lack chloroplasts and a cell walls
  • don’t use ATP or mitochondria
  • have mitosomes and hydrogenosomes that are smaller
  • anaerobic use iron-sulphur chemistry
  • Ex Giardia:
    
    • infects hikers who drink in mountain streams

Question 7

how is the SAR clade grouped

Answer 7

Supergroup SAR Clade (Stramenopiles, Alveolates, and Rhizarians)

• united on the basis of whole-genome sequencing. very diverse, very controversial

Question 8

what are Diatoms like

Answer 8

• Diatoms
  
  • have glass cell walls made of amorphous silica dioxide
  • Glass is made of thermodynamically unstable stuff. Sorta solid, sorta liquid.
  • silica dioxide shells take less energy to produce, so diatoms have more energy for growth making them the fastest growing protists
  • 2-500 um in size
  • the binary fission that diatoms undergo leaves one daughter cell smaller than the parent due to the way their cell walls work. To overcome the progressive restriction this causes the zygote enters another form called an auxospore which is large and has silica bands instead of a full cell
  • so sex resets the size

Question 9

What are brown algae like

Answer 9

• Brown Algae
  
  • largest seaweeds
  • multicellular
  • BC is a kelp hotspot with over 30 species
  • bullwhip kelp aka mermaid’s bladder, ribbon kelp, bladder wrack, or Ihqyaama

Question 10

what is primary endosymbiosis

Answer 10

Far in the past one cell (probably a bacteria) entered into the cell of another organism (probably an Archean)

The bacteria was an aerobic organism who uses oxygen to make energy. The exterior organism didn’t digest the smaller one and found its energy production useful.

The smaller organism over time became the mitochondria in Eukaryotes.

A similar process occurred with an organism like a cyanobacterium becoming a chloroplast.

Question 11

what does Endosymbiosis show, and what are some results

Answer 11

Endosymbiosis shows that when opportunity presents itself in nature then a series of random events usually leads to an organism or population using it.

Mitochondria and chloroplast have two membranes

Endosymbiosis led to changes in the atmosphere and allowed Eukaryotes to grow bigger cells and eventually became multicellular

Mitochondrial DNA is inherited from the mother.

Question 12

what is secondary endosymbiosis

Answer 12

• sometimes an organism that arose from endosymbiosis can be absorbed by another cell
• ex Red alga was absorbed to make dinoflagellates, Apicomplexcans, and Stramenopiles
• and green alga was absorbed 2 different times to make the line of Euglenids and the line of Chlorarachniophytes

Question 13

what is the record for number of genomes in one cell

Answer 13

Cryptomonas gyropyronoidosa

1. Cell nucleus
2. Mitochondria - PE
3. Red Alga nucleus - SE
4. Chloroplast in the red alga
5. Grellia numerosa bacteria
6. Megaira polyxenophila bacteria
7. Mankyphage virus in the M. polyxenophila

Question 14

what are hotspots

Answer 14

• places where a great deal of evolution is occuring
• high # of species
• 44% of plants
• 35% of animal diversity

Ex New Caledonia

• plants - ex 14 species of Aravcarie (conifers)
• Animal - ex Blue Kagou (endemic bird)

Endemic = one found in one place

When a species line the blue kagou goes extinct all its parasite species go extinct

Hotspots cover 3% of earth’s surface but hold 50% of plant species

Question 15

how do hotspots lead to discovery and extinction

Answer 15

~4000 species of plants and fungi are discovered a year

hotspots are major sources of discovery byt they are also threatened by human activity.

Question 16

how is diatom reproduction scuffed

Answer 16

In diatoms their glass outer shell is made of a big and a small side. when they divide the new shell forms inside the old one. meaning one division has to be smaller.
the progressive restriction of the glass shell is overcome periodically after fertilization when the zygote enters another form called an auxospore. which is a larger cell with silica bands not the normal shell.