PROTISTA III
Red Algae
Green Algae
Streptophytes
Keeting et al. 2005 Trends in Ecology & Evolution
Volume 20, Issue 12, Pages 670-676
THE EUKARYOTIC TREE OF LIFE
Plantae
Chlorophyll a
Chlorophyta
Rhodophyta
PLANTAE ORIGIN
Primitive archea-like cell with
or without nuclear membrane
Prochloron-like prokaryote
Chlorophyll a
Prokaryote with respiration
(can make ATP from oxidation of organic
substrates)
PHYLUM
RHODOPHYTA
red algae
Coralline Red Alga
Keeting et al. 2005 Trends in Ecology & Evolution
Volume 20, Issue 12, Pages 670-676
THE EUKARYOTIC TREE OF LIFE
Rhodophyta
• Pigments:
• chlorophyll a
• carotenoids and phycobilins
• Photosynthetic reserve: Floridean starch (a highly
branched starch)
• Cell Wall composition: cellulose, calcium, pectin
• Reproductive Mobility: None
• Habitat: mostly marine and rare fresh water species
Phycoerythin reflects red light and absorbs blue light. Because blue light penetrates
water to a greater depth than light of longer wavelengths, these pigments allow red
algae to photosynthesize and live at somewhat greater depths than most other algae.
Some rhodophytes have very little phycoerythrin, and may appear green or bluish from
the chlorophyll and other pigments present in them.
Boldia-local freshwater species
Red algae actually
has 3 “generations”
2=n
3=2n
1=2n
Most red algae have a complex life
history with three phases:
tetrasporophyte, gametophyte,
and carposporophyte.
Economic importance
Agar: a polysaccharide from the red algae Gelidium gracilaria found
in the far east and Mediterranean. Primary medical use is for
growth of bacteria.
Food: In Asia, rhodophytes are important sources of food, such as
nori. The high vitamin and protein content of this food makes it
attractive, as does the relative simplicity of cultivation, which
began in Japan more than 300 years ago.
Reefs: Some rhodophytes are also important in the formation of
tropical reefs, an activity with which they have been involved for
millions of years; in some Pacific atols, red algae have contributed
far more to reef structure than other organisms, even more than
corals. These reef-building rhodophytes are called coralline algae,
because they secrete a hard shell of carbonate around
themselves, in much the same way that corals do.
The red alga genus Hypnea is a source of carageenan, a common food additive
Irish moss (Chondrus crispus) from Nova Scotia – The most common red alga and a source of
carageenans
Tie for 1st place in Science
photography contest
Prior to WW2, the Japanese produced all of our agar for medical use.
With the start of WW2, a search began for American based seaweed and the
carageenan industry was born
FOOD APPLICATIONS:
Beer/Wine/ Vinegar -accelerates and improves clarity.
Chocolate Milk Drink -stabilizes and improves viscosity.
Ice cream -prevents ice crystals formation.
-enhances excellent mouthfeel.
Flans/Dessert Gel-enhances flavor release and excellent mouthfeel
Sauces and Dressings -thickens and improves viscosity.
Even the pimento in your martini olives is from a pimento-algae sludge
PROCESSED MEAT
Beef Patty -substitutes fat, retains moisture and increase yield.
Luncheon Meat -prevents fat separation serves as a meat extender.
Poultry and Ham -controls dehydration of frozen poultry, enhances
juiciness and increase yield.
NON-FOOD APPLICATIONS
Petfood
Canned meat and fish -gelling and stabilizing agent. Moist, solid
petfood -binder.
Toothpaste-stabilizer.
Air freshener-gelling agent.
Carageenan has anti-viral properties against human HPV and cold virus
PHYLUM
CHLOROPHYTA
(green algae)
Keeting et al. 2005 Trends in Ecology & Evolution
Volume 20, Issue 12, Pages 670-676
THE EUKARYOTIC TREE OF LIFE
Green Algae
Pigments:
chlorophyll a and b, occasionally c
carotenoids and phycobilins
Photosynthetic reserve: starch
Cell Wall composition: polysaccharides
Reproductive Mobility: Varied numbers of flagella
Habitat: Marine and rare fresh water species
Class Ulvophyceae
Ulva
Ulva life cycle is sporic meiosis (aka alternation
of generations)
The complete life cycle pattern has three kinds of organisms
(1) Sporophyte
(2) Female gametophytes
(3) Male gametophytes
also see lab book
Generalized Life Cycles
The life cycle alternates between haploid and diploid phases (alternation of
generations)
The haploid phase begins after cells undergo the cellular process of meiosis
The diploid phase begins after haploid cells fuse
Unlike higher plants, the haploid and diploid stages are usually free living
REQUIRED LIFE CYCLE
Gametophyte n
Gametophyte n
meiosis
mating
Sporophyte 2n
Zygote 2n
Ulvophyceae
Class Chlorophyceae
Volvox
Chlorophyta - Volvox
A colonial green alga
- Volvox
Individual cells are connected by cytoplasmic threads
Asexual reproduction forms by
invaginating and forming daughter
colonies
Motile colonies due to the
presence of flagella
Sexual reproduction: Volvox
Some of the enlarged cells that grow into
daughter colonies become eggs instead
packets of sperm are produced elsewhere in
the colony and swim to the egg
fertilization produces a zygote.
zygotes go through a dormancy period then
undergo meiosis and release haploid
zoospores
Asexual
Sexual
Hydrodictyon
Colonial Non-motile organism: the water net
Hydrodictyon is coenocytic
STREPTOPHYTA
A clade consisting of the land plants plus their
closest relatives, the charophytes.
Keeting et al. 2005 Trends in Ecology & Evolution
Volume 20, Issue 12, Pages 670-676
THE EUKARYOTIC TREE OF LIFE
Chlorophyta
Land plants (embryophytes) evolved from streptophyte
green algae, a small group of freshwater algae ranging
from scaly, unicellular flagellates (Mesostigma) to
complex, filamentous thalli with branching, cell
differentiation and apical growth (Charales). Streptophyte
algae and embryophytes form the division Streptophyta,
whereas the remaining green algae are classified as
Chlorophyta
Class Charophyta
Spirogyra
Zygnema
Coleochaete
Chara
The early freshwater adaptation of streptophyte algae was a major advantage
for the earliest land plants, even before the origin of the embryo and the
sporophyte generation.
Spirogyra sp
filamentous
ornate chloroplasts
large nuclei
reproduction by conjugation-”scaleriform”
Spyrogyra sp.
Life cycle of spirogyra
Conjugation bridge
Meiosis, only one of
the cells germinates
Zygnema sp.
Distinguishing factor is the
presence of stellate
chloroplasts rather than ribbonlike chloroplasts
Coleochaete (fresh water)
Coleochaete and Chara are most like higher plants
zygotes remain attached to the parental thallus
Node and internode
Chara
Antheridia and oogonia
Freshwater algae
Chara oogonium (left) and antheridium (right). Chara is characterized by whorls of
branches along the main axis, grey-green color and a garlic or skunk-like odor. Sperm cells
resemble those of mosses.
Image is from
Carolina Biologicals
“Unseen world”
screensavers
END