Bot-Lec (Sem-1) - Chapter 5: Protists

Kingdom Protista

Kingdom Protista

composed of simple eukaryotic organisms; most are aquatic; exhibit remarkable diversity where sizes range from single cells to large multicellular organisms

Chlamydomonas

unicellular, photosynthetic protist; a motile organism with two flagella and a cup-shaped chloroplast

locomotion

the ability to move from place to place

pushing out cytoplasmic extensions; flexing individual cells; waving cilia; lashing flagella

means of locomotion

photosynthetically; heterotrophically

how protists obtain nutrients

free-living

organism that does not depend on another for food or a place to live

symbiotic relationships

close, prolonged associations between two or more different organisms of different species that may, but do not necessarily benefit the members.

mutualism

symbiotic relationship in which both species benefit from the relationship

parasitism

symbiotic relationship in which one organism lives on or inside another organism and harms it

termites

have a mutualistic relationship with intestinal protozoa in order to digest cellulose

lichen

symbiotic association between a fungus and a photosynthetic organism (algae or cyanobacteria)

phylogeny

evolutionary history of a species

molecular data

evidence of phylogenetic relationships; for gene that codes for small subunit ribosomal RNA in different eukaryotes; for other nuclear genes (many of which code for proteins) in various protists

rRNA (ribosomal RNA)

an organelle that contains most of the RNA in the cell and that is responsible for ribosome function; used in classifying organisms in phylogenic analysis; faster replication

nuclear genes

genes located on chromosomes found in the cell nucleus of eukaryotic cells; preferred for phylogeny

elevated evolution rate (sequence); biparental inheritance; multiple independent loci

reasons why nuclear genes are preferred for phylogeny

loci

point on the chromosome where the gene is found

ultrastructure

evidence of phylogenetic relationships; fine details of cell structure revealed by electron microscopy; often similar among protists that comparative molecular evidence suggests are monophyletic and evolved from a common ancestor

monophyletic

ALL descendants came from one common ancestor

Euglenoid (Euglenophyta)

mostly freshwater, flagellated, unicellular protist that moves by an anterior flagellum and is usually photosynthetic; Euglena sp.

eyespot

A light-sensitive organelle that helps it react to light in certain protozoa

Dinoflagellates (Dinophyta/Pyrrophyta)

unicellular, biflagellated, typically marine protist; usually photosynthetic; brown pigment fucoxanthin, and is an important component of plankton; causes red tides (HAB: Harmful Algal Bloom)

eutrophication

excessive richness of nutrients in a lake or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life and death of animal life from lack of oxygen

Pyrodinium bahamense

causes Paralytic Shellfish Poisoning (PSP); can lead to hypoxia; caused by high salinity + temperatures

hypoxia

lack of oxygen

Gymnodinium catenatum

causes Neurotoxic Shellfish Poisoning (NSP); caused by high salinity + temperatures

fucoxanthin

a brown carotenoid pigment occurring in and generally characteristic of the brown algae, diatoms, and dinoflagellates

water mold (Oomycota)

a protist with a body consisting of a coenocytic mycelium and with asexual reproduction by motile zoospores and sexual reproduction by oospores

coenocytic

hyphae without septa

mycelium

mass of hyphae

diatom (Bacillariophyta)

usually a unicellular protist, covered by an ornate siliceous shell and containing the brown pigment fucoxanthin; important component of plankton in both marine and fresh water; used to make sandpaper

plankton

weak swimmers; carried by water current

bioluminescence

the production of light by living organisms

silica

component of diatom shell

golden alga (Chrysophyta)

a protist that is biflagellated, unicellular, and photosynthetic, and contains the brown pigment fucoxanthin

brown alga (Phaeophyta)

a predominantly marine; photosynthetic protist that is multicellular and contains the brown pigment fucoxanthin

Laminaria; Fucus; Ectocarpus; Sargassum (lusay)

brown algae

blade; stipe; holdfast

parts of brown algae: leaf; stem; root

Macrocystis pyrifera

giant kelp; multicellular brown algae; has gas-filled floaters which allows buoyancy

red alga (Rhodophyta)

diverse group of photosynthetic protists that contain the pigments phycocyanin and phycoerythrin

Polysiphonia; Kappaphycus; Gracilaria; Bosiella

red alga

phycocyanin

blue pigment

phycoerythrin

red pigment

green alga (Chlorophyta)

diverse group of protists that contain the same pigments as land plants (chlorophylls a and b and carotenoids)

Micrasterias; Spirogyra; Volvox; Ulva (sea lettuce); Codium fragile (dead man's fingers); Chara (stonewort)

green alga

Chara sp. (stonewort)

closely related to plants; distributed in fresh water

chlorophyll alpha

the key light-capturing pigment that participates directly in the light reactions

chlorophyll beta

an accessory pigment

carotenoids

an accessory pigment, either yellow or orange, in the chloroplasts of plants; by absorbing wavelengths of light that chlorophyll cannot, carotenoids broaden the spectrum of colors that can drive photosynthesis

isogamy; anisogamy; oogamy

reproduction in green algae

isogamy

production of equal-sized gametes

anisogamy

sexual reproduction by the fusion of dissimilar gametes

oogamy

large non-motile egg, smaller motile sperm

plasmodial slime mold (Myxomycota)

a protist whose feeding stage consists of a multinucleate, amoeboid plasmodium

Physarum polycephalum

plasmodial slime mold; bright yellow

amoeboid

cell that moves and engulfs debris with pseudopods

plasmodium

causes malaria

conjugation

process in which paramecia and some prokaryotes exchange genetic information

cellular slime mold

a protist whose feeding stage consists of a unicellular, amoeboid organism that aggregates to form a pseudoplasmodium during reproduction

pseudoplasmodium

a slightly motile aggregation of cells that produces fruiting bodies, which in turn produce spores