20-3 plantlike protists: unicellular...
Post on 29-Apr-2018
227 Views
Preview:
TRANSCRIPT
Slide
1 of 33
Copyright Pearson Prentice Hall
20-3 Plantlike Protists:
Unicellular Algae
20-3 Plantlike Protists:
Unicellular Algae
Slide
2 of 33
Copyright Pearson Prentice Hall
Plantlike protists contain chlorophyll and carry out
photosynthesis.
Plantlike protists are commonly called “algae.”
Algae are sometimes classified with the plants.
20-3 Plantlike Protists:
Unicellular Algae
Slide
3 of 33
Copyright Pearson Prentice Hall
The four phyla of unicellular algae are:
• euglenophytes
• chrysophytes
• diatoms
• dinoflagellates
20-3 Plantlike Protists:
Unicellular Algae
Slide
4 of 33
Copyright Pearson Prentice Hall
Chlorophyll and Accessory
Pigments
Chlorophyll and accessory pigments allow
algae to harvest and use the energy from
sunlight.
20-3 Plantlike Protists:
Unicellular Algae
Slide
5 of 33
Copyright Pearson Prentice Hall
One trait used to classify algae is the type of photosynthetic pigments they contain.
Some algae have different forms of chlorophyll—a, b, and c—that absorb different wavelengths of light.
Accessory pigments absorb light at different wavelengths than chlorophyll, giving algae a variety of colors.
Chlorophyll and Accessory
Pigments
20-3 Plantlike Protists:
Unicellular Algae
Slide
6 of 33
Copyright Pearson Prentice Hall
Euglenophytes
Euglenophytes are plantlike protists that
have two flagella but no cell wall.
20-3 Plantlike Protists:
Unicellular Algae
Slide
7 of 33
Copyright Pearson Prentice Hall
Euglena
Euglenophytes
Gullet
Flagella
Eyespot
Pellicle
Contractile vacuole Carbohydrate
storage bodies
Chloroplast
Nucleus
20-3 Plantlike Protists:
Unicellular Algae
Slide
8 of 33
Copyright Pearson Prentice Hall
Two flagella emerge from
a gullet in the cell. The
longer of the flagella
spins so it pulls the
organism rapidly through
the water.
Euglenophytes
Gullet
Flagella
20-3 Plantlike Protists:
Unicellular Algae
Slide
9 of 33
Copyright Pearson Prentice Hall
Near the gullet is a
reddish pigment known
as the eyespot, which
helps find sunlight to
power photosynthesis.
Euglenas can also live as
heterotrophs.
Euglenophytes
Eyespot
20-3 Plantlike Protists:
Unicellular Algae
Slide
10 of 33
Copyright Pearson Prentice Hall
Euglenas store
carbohydrates in small
storage bodies.
Euglenophytes
Carbohydrate
storage bodies
20-3 Plantlike Protists:
Unicellular Algae
Slide
11 of 33
Copyright Pearson Prentice Hall
Euglenas do not have
cell walls. Instead, they
have an intricate cell
membrane called a
pellicle.
The pellicle folds into
ridges, each supported
by microtubules.
Euglenas reproduce
asexually by binary
fission.
Euglenophytes
Pellicle
20-3 Plantlike Protists:
Unicellular Algae
Slide
12 of 33
Copyright Pearson Prentice Hall
Chrysophytes
Members of the phylum Chrysophyta
are a diverse group of plantlike protists
that have gold-colored chloroplasts.
20-3 Plantlike Protists:
Unicellular Algae
Slide
13 of 33
Copyright Pearson Prentice Hall
Chrysophytes
The cell walls of some chrysophytes contain the
carbohydrate pectin rather than cellulose, and others
contain both.
Chrysophytes store food in the form of oil rather than
starch.
They reproduce both asexually and sexually.
Most are solitary, but some form threadlike colonies.
20-3 Plantlike Protists:
Unicellular Algae
Slide
14 of 33
Copyright Pearson Prentice Hall
Diatoms
Diatoms produce thin, delicate cell walls
rich in silicon (Si)—the main component of
glass.
The walls are shaped like the two sides of a
petri dish or flat pillbox, with one side fitted
snugly into the other.
20-3 Plantlike Protists:
Unicellular Algae
Slide
15 of 33
Copyright Pearson Prentice Hall
Dinoflagellates
Dinoflagellates
About half of the dinoflagellates are
photosynthetic; the other half live as
heterotrophs.
20-3 Plantlike Protists:
Unicellular Algae
Slide
16 of 33
Copyright Pearson Prentice Hall
Dinoflagellates
Dinoflagellates have two flagella that fit in grooves
between two thick plates of cellulose that protect the
cell.
Most dinoflagellates reproduce asexually by binary
fission.
Many dinoflagellates are luminescent. When they are
agitated, they give off light.
20-3 Plantlike Protists:
Unicellular Algae
Slide
17 of 33
Copyright Pearson Prentice Hall
Ecology of Unicellular Algae
Ecology of Unicellular Algae
Plantlike protists are important to freshwater and
marine ecosystems because they make up the
base of the food chain in many aquatic
ecosystems.
20-3 Plantlike Protists:
Unicellular Algae
Slide
18 of 33
Copyright Pearson Prentice Hall
Ecology of Unicellular Algae
Phytoplankton constitute the population of small,
photosynthetic organisms found near the surface of
the ocean.
Phytoplankton carry out half of Earth’s
photosynthesis. In addition, they provide nourishment
for many organisms.
20-3 Plantlike Protists:
Unicellular Algae
Slide
19 of 33
Copyright Pearson Prentice Hall
20-4 Plantlike Protists: Red,
Brown, and Green Algae
20-3 Plantlike Protists:
Unicellular Algae
Slide
20 of 33
Copyright Pearson Prentice Hall
20-4 Plantlike Protists: Red, Brown,
and Green Algae
The three phyla of algae that are largely multicellular
are:
• red algae
• brown algae
• green algae
20-3 Plantlike Protists:
Unicellular Algae
Slide
21 of 33
Copyright Pearson Prentice Hall
Red Algae
Red algae are able to live at great depths due to their efficiency in harvesting light energy.
Red algae contain chlorophyll a and reddish accessory pigments called phycobilins.
Phycobilins absorb blue light, enabling red algae to live deep in the ocean.
20-3 Plantlike Protists:
Unicellular Algae
Slide
22 of 33
Copyright Pearson Prentice Hall
Brown algae contain chlorophyll a and c, as well as a brown accessory pigment, fucoxanthin.
Brown Algae
20-3 Plantlike Protists:
Unicellular Algae
Slide
23 of 33
Copyright Pearson Prentice Hall
Brown Algae
Brown algae are the largest and most complex of the
algae.
All are multicellular and most are marine, commonly
found in cool, shallow coastal waters of temperate or
arctic areas.
20-3 Plantlike Protists:
Unicellular Algae
Slide
24 of 33
Copyright Pearson Prentice Hall
Brown Algae
Brown Alga Structure
Blades
Bladder
Stipe
Holdfast
20-3 Plantlike Protists:
Unicellular Algae
Slide
25 of 33
Copyright Pearson Prentice Hall
Brown Algae
Fucus, a common brown
alga, is made up of a
holdfast, stipes,
bladders, and blades.
The holdfast attaches the
alga to rocks.
Holdfast
Blades
20-3 Plantlike Protists:
Unicellular Algae
Slide
26 of 33
Copyright Pearson Prentice Hall
Brown Algae
The body of Fucus
contains:
a flattened stemlike
structure called a stipe,
leaflike structures called
blades, and
gas-filled bladders that
keep the alga afloat and
upright.
Blades
Bladder
Stipe
20-3 Plantlike Protists:
Unicellular Algae
Slide
27 of 33
Copyright Pearson Prentice Hall
Green Algae
Green algae share many characteristics with plants, including their photosynthetic pigments and cell wall composition.
20-3 Plantlike Protists:
Unicellular Algae
Slide
28 of 33
Copyright Pearson Prentice Hall
Green Algae
Green algae live in fresh and salt water, and moist
land areas.
Many species live most of their lives as single cells.
Others form colonies, groups of similar cells that are
joined together but show few specialized structures.
A few are multicellular and have specialized
structures.
20-3 Plantlike Protists:
Unicellular Algae
Slide
29 of 33
Copyright Pearson Prentice Hall
Reproduction in Green Algae
The life cycles of many algae include both a diploid and a haploid generation.
Switching between haploid and diploid stages during a life cycle is known as alternation of generations.
Many alga also shift between sexual and asexual reproduction.
20-3 Plantlike Protists:
Unicellular Algae
Slide
30 of 33
Copyright Pearson Prentice Hall
Reproduction in Green Algae
Reproduction in Chlamydomonas
• The unicellular Chlamydomonas spends most of
its life in the haploid stage.
20-3 Plantlike Protists:
Unicellular Algae
Slide
31 of 33
Copyright Pearson Prentice Hall
Reproduction in Green Algae
Reproduction in Ulva
• The life cycle of the green alga Ulva involves
alternation of generations.
• Ulva are gametophytes, or gamete-producing
plants.
20-3 Plantlike Protists:
Unicellular Algae
Slide
32 of 33
Copyright Pearson Prentice Hall
Ecology of Algae
Ecology of Algae
• Algae produce half of Earth’s oxygen through photosynthesis.
• Algae is found in sushi, ice cream, and other foods.
• Chemicals from algae are used to make plastics, waxes, transistors, deodorants, paints, lubricants, and artificial wood.
• Agar thickens nutrient mixtures in scientific labs.
top related