Lecture 4/5: Protists Flashcards
(29 cards)
Antoni van Leeuwenhoek
- developed hand held microscope
- allowed to view entire new biosphere previously hidden
- viewed a diverse group of unicellular organisms
What are protists classified as?
eukaryotes (mostly single-celled)
What do eukaryotes have that prokaryotes (archaea and bacteria) don’t?
A nucleus enclosed within the nuclear membrane
Is it true that some protists are more closely related to plants/fungi/animals than other protists?
Yes, True
Biologists now only use the term protists to refer to…
eukaryotes that aren’t plants/fungi/animals
What’s the diversity of protists?
- very difficult to give key traits to protists, b/c so diverse
- most are unicellular but still some colonial/multicellular species
- single celled protist are considered the simplest eukaryotes, yet their internal cellular level are very complex
What are some styles of acquiring nutrition that protists use? (Photoautotrophs, Heterotrophs, Mixotrophs)
PHOTOAUTOTROPHS:
-> use photosynthesis
HETEROTROPHS:
-> absorb organic molecules, ingest larger food particles
MIXOTROPHS:
-> use both photosynthesis and heterotrophic nutrition
Photosynthesis rundown / eqn
- organism uses light energy to convert carbon dioxide and water into carbohydrates and oxygen
- needed for carbon fixation
CO2 + H2O + light energy -> carbohydrate + O2
Explain Carbon fixation
process of when carbon dioxide is converted into sugars
Have protists always been able to photosynthesize?
No, they developed it. It is a process that has been passed around organisms during the diversification of eukaryotes
What bacteria was the first to use oxygenic photosynthesis?
cyanobacteria
Explain endosymbiotic theory (simple)
- theory explains how eukaryotes evolved
- suggesting that some of the cell’s organelles (mitochondria and chloroplasts) were once free-living
- but then, these organelles were swallowed/entered into larger cells
- instead of being digested, they underwent symbiosis, where the organelle provided energy and the host cell provided protection
- over millions of years these bacteria became permanent parts of the cell
- supported by the fact that mito and chloro have their own DNA and reproduce independently within the cell
Protists live in almost any environment that contains…
liquid water
What eukaryotic organism shares traits from both plants and animals?
Euglenoids
Where could I find a Euglenoid?
fresh water ponds, soil, ditches (can only see with a microscope)
What do euglenoids feed on?
bacteria or algae, make their own food by photosynthesis, or absorb nutrients from the water by osmosis
What is a unikonta?
- supergroup of eukaryotes that includes a range of protists, animals and fungi
- ‘unikonta’ meaning one flagellum
- many are amoebas (any organisms that moves/feeds by extending out its plasma membrane, aka false foot)
- separated into 2 groups
What are the ‘false foot’ by ameoba also known as?
pseudopods
What are the two groups that unikonta is split into?
- Amoebazoans: contains only protists
- Opisthokonts: includes fungi/animal kingdoms
What are the 3 taxa that comprise Archaeplastida (another supergroup of eukaryotes)?
- Chloroplastida (green algae/land plants)
- Rhodophyta (red algae)
- Glaucophyta
Why are rhodophyta (red algae) red?
b/c of the presence of the pigment phycoerythrin. it reflects red light and absorbs blue light
Why is the red pigment helpful for red algae?
b/c blue light penetrates water to a greater depth than light of longer wavelengths, and these pigments allow the algae to photosynthesize and live at somewhat greater depths than most other algae
Which group of algae is the most diverse?
green algae (more than 7000 species)
What does paraphyletic mean?
(of a group of organisms) descended from a common evolutionary ancestor or ancestral group, but not including all the descendant groups.
