6/2/2010
Examples of Autotrophic Protists
Euglena and Laminaria
Euglena sp. (Euglenids)
• Unicellular!
• One or two flagella that emerge from a pocket at one end of the cell
Figure 28.8!!
Long flagellum
Eyespot
Light shield so
only specific light
hits the detector
Nucleus
Euglena (LM)
5 µm
Light detector
Contractile vacuole
Osmoregulation
Plasma membrane
Chloroplast
Pellicle
Protein bands that provide
strength and flexibility
1
6/2/2010
Nutrition, Movement and Regulation
• Mixotrophs
– Lose chlorophyll in dark (become absorptive)
• Movement: Flagellar or euglenoid (shape change)
– Positive phototaxis (due to light detector)
• Osmoregulation
Os o egu at o
– Euglena are hypertonic to their environment (have more solutes and particles)
– Contractile vacuole
Brown Algae (Laminaria sp.)
•
•
•
•
Largest and most complex algae (“Seaweed”)
Multicellular (not a plant! Has “plant‐like” parts)
Marine environments
Kelp: Giant seaweed!
p
2
6/2/2010
Human Uses of Seaweeds
• Foods, thickeners (gel like), lubricants
Terms needed to understand Laminaria life cycle
•
•
•
•
Haploid (n): containing one set of chromosomes
Diploid (2n): containing two sets of chromosomes
Gamete: a haploid reproductive cell (ie: egg and sperm)
Zygote: the diploid product of the union of gametes (ie: fertilized egg)
fertilized egg)
• Sporophyte: Multicellular diploid structure, produces haploid spores
• Spore (zoospores): haploid cell with flagella, can make a multicellular haploid structure
• Gametophyte: multicellular haploid structure, produces gametes
Alternation of Generations
• Alternate between two multicellular forms:
1. Sporophyte (“seaweed”)
– Diploid (2n) individual
– Produces haploid (n)
P d
h l id ( ) spores (zoospores!)
(
!)
2. Gametophyte
– Haploid (n) individual
– Produces gametes that fuse together (fertilization) to form a diploid zygote
3
6/2/2010
Fig. 28-16!,!!
Divides number of
chromosomes in half
10 cm
Sporophyte
(2n)
MEIOSIS
Zoospore
Female
Gametophytes
(n)
Male
Egg
Sperm
Key
Haploid (n)
Diploid (2n)
Fig. 28-16!,!!
10 cm
Sporophyte
(2n)
MEIOSIS
Zoospore
Female
Developing
sporophyte
Mature female
gemetophyte
(n)
Zygote
(2n)
Gametophytes
(n)
Male
Egg
FERTILIZATION
Sperm
Key
Haploid (n)
Diploid (2n)
Summary
• Euglena
– Major components, nutrition, movement (+phototaxis), osmoregulation
• Laminaria
a
a a ((Brown Algae)
o
gae)
– Multicellular, marine, kelp, parts: blade, stipe, holdfast
• Human uses of seaweed
• Alteration of generations
– Haploid / diploid parts of figure, structures (note: do not have to know “sporangia” that is labeled in the book)
4