Download Diversity of Living Things Part 3

Diversity of Living Things Part 3
Kingdom Protista
Protists
• Organisms in the kingdom Protista appeared
about 1.5 billion years ago. For the first 2
billion years, only prokaryotes were living.
But the protists (eukaryotes) were very
different. They are 10 times larger than
prokaryotes, have many chromosomes, have
organelles with their own membranes.
Origins of Eukaryotes
• Endosymbiosis: relationship in which single•
•
celled organism lives within the cells of another
organism
Membrane bound organelles likely developed
from the folded cell membrane of ancestral
prokaryotic cell.
Consider:
– Mitochondria and chloroplasts have 2 membranes
that are similar to ancestral prokaryotes
– They have their own DNA
– They reproduce on their own by binary fission
– Same size as prokaryotic cells.
Animal-like Protists
• Some protists used to be classified under the
animal kingdom and were called protozoans.
They are like animals because they eat or
ingest material from their surroundings.
• Heterotrophs
• Zooflagellates, Amoebas and Ciliates
Zooflagellates
• Zooflagellates have one or more flagella.
Some are heterotrophic and feed on other
protists. Others live as parasites on animals
(some are even human pathogens)
• Sleeping sickness is caused by a parasitic
zooflagellate and can be fatal. Found in
Africa.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Amoeba
• Amoebas are single-celled protozoans with no real
body shape. They can make temporary projections
called pseudopods to move and feed.
– Eat small organisms by endocytosis where particles of food
are sealed off in food vacuoles in the cytoplasm
– Some are parasitic: amoebic dysentery: in tropical regions.
They feed on intestinal walls can cause bleeding. They
form protective cysts so they do not get digested.
Ciliates
• Ciliates are protozoans that are covered in cilia.
– have a rigid outer covering called a pedicle/pellicle that maintains
their shape.
– Aquatic
– Heterotrophic
– Salt and fresh water
– A freshwater ciliate called a Paramecium is the most common
– They beat their cilia to move and to bring food into their oral
grooves.
– Once the food enters the oral groove, the membrane pinches off
and forms a food vacuole, where it travels into the cytoplasm and
joins with a lysosome that breaks down the food.
– After the ciliate has digested the food, the unwanted is
discharged through the anal pore.
– Paramecia, like other ciliates, have two types of
nuclei: a large macronucleus and one or more smaller
micronuclei.
– Reproduction through binary fission (sometimes
through conjugation they can use sexual reproduction)
•
•
•
•
Fungus-like Protists
heterotrophic
decomposers
live in cool and damp habitats
3 major phyla:
– acellular slime moulds
– cellular slime moulds
– water moulds
• Sporozoans are protists that make spores.
– non-motile and parasitic
– most known: Plasmodium that cause malaria and spend part of
their life cycle within human red blood cells. When the red blood
cell bursts open the parasites’ toxins fill the bloodstream causing
fever and chills. Some types can be fatal.
Plant-like Protists
• 24 000 species of protists that contain
chlorophyll and undergo photosynthesis
• Multicellular protists differ from plants in that
the zygote of the alga is on its own and
unprotected, whereas a plant zygote is
protected by the parental cells, and they differ
because they do not have tissues.
• Euglenoids and algae
Euglenoids
– Unicellular flagellates
– The Euglena propels through water by it’s
flagellum
– In sunlight it is autotrophic and in the dark it will
start to lose its chlorophyll and feeds as a
heterotroph on dead organic material
Algae
• Algae have chloroplasts as well.
– Some are single-celled, others live in colonies, others
multicellular.
– 6 main groups, but we’ll only study 3:
• diatoms are yellow-brown in colour and have glass-like shells made of
silica
• dinoflagellates single-celled and have 2 flagella. Most are photosynthetic
but some are heterotrophs. Move in a spinning motion and they can be
luminescent (give off light). They reproduce asexually. They can create
red tides with their blooms, which can be bad because they produce toxins
• green algae can be single-celled or colonial. They have two flagella and
live in fresh water. They have cellulose in their cell walls and we think
that plants originated from them.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Fungi
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Characteristics
• Heterotrophic eukaryotic organisms
• Saprobes (absorb their food from decaying matter)
• Release digestive enzymes into their immediate
environment that break down the decaying matter, then
they absorb the digested food through their cell wall
• Different from slime moulds because they absorb through
endocytosis
• Bodies consist of filaments called hyphae , which grow to
form a tangled mess of filaments called mycelium.
Hyphae have cell walls that contain chitin (not cellulose).
Reproduction
• Most species reproduce both sexually and asexually with
spores. (single reproductive cells with a haploid number
of chromosomes)
• Fungi with spores that are in a caselike structure care
called sporangium and are in the division Zygomycota
• Fungi with spores in a saclike structure area called an
ascus and are in the division Ascomycota.
• Fungi with spores that form in a clublike structure are
called a basidium and are in the division Basidiomycota.
Life Cycles
• Complicated because nuclei are haploid (single set of
chromosomes)
• Spores are haploid and germinate to produce hyphae.
• + and - hyphae fuse to form dikaryotic cells (one cell with
2 nuclei)
• Because large and makes a fruiting body (mushroom)
• basidia form on the underside and haploid dikaryotes fuse
into a zygote
• The zygote undergoes meiosis producing four haploid
spores.
Symbiotic Relationships
• Lichens are a symbiotic relationship between a fungus and
either an alga or a cyanobacterium. The alga provides
nourishment by photosynthesis and the fungus provides the
water, minerals and protection from dryness.
• Mycorrhizae is the symbiotic relationship between a
fungus and the roots of a plant. The fungus mycelium
form a web over the plants and passes the plant water,
while the plant provides amino acids and sugars to the
fungus
Plant Kingdom
Plants
 Scientists believe that the earliest plants came
from algal-like ancestors.
 Plants are eukaryotic and multicellular, their cell
walls have cellulose in them.
 Plants develop from embryos that are protected
by tissues of the parent plant.
 Include mosses, ferns, conifers, flowering plants.
 Life cycles vary among the different plant groups.
Alternation of Generations
 Plants go through an alternation of generations where one
generation is haploid (1n) and the other is diploid (2n)
which are called the gametophyte and sporophyte
generations.
 A plant produces haploid spores that undergo cell division
and grow into a new plant (gametophyte), which is haploid.
These haploid plants eventually produce gametes, which
fuse together to make a diploid zygote. The zygote then
grows into a diploid sporophyte plant.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Non-Vascular Plants
 Bryophytes include mosses, liverworts and hornworts.
 They lack true roots, stems and leaves and do not
have special tissue that transports materials.
 Usually only a few cm tall and grow in moist
environments
 Can grow in soil, on rock, dead trees and even on
buildings.
 Liverworts can reproduce asexually through
vegetative reproduction
 Bryophytes reproduce sexually when the sperm
from the male swims from the male reproductive
organ to the female (why we need moist
environments).
 They produce spores instead of seeds
Vascular Plants
 Tracheophytes have conducting tissues called
xylem and phloem that transport materials
throughout the plant.
 Are divided into two groups: spore-producing and
seed-producing plants.
Spore Producing
 Spore-producing plants like the club mosses and
horsetails mostly grow in marshes and the edges
of streams. Ferns are much more common and
usually found in shady and wet environments.
 The leaves of ferns are called fronds and the
underground stems are called rhizomes. They
produce spores in sporangia on the underside of the
fronds. Spores grow into the gametophyte and then
the sperm fertilize the eggs to produce the sporophyte
again.
Seed Producing
 Seed-producing plants have highly
specialized organs like leaves, stems, and
roots. Two types: ones that produce cones,
and others that produce flowers. In both,
sexual reproduction occurs via pollination.
 Gymnosperms and Angiosperms
Gymnosperms
 Gymnosperms make cones and include conifers,
gnetae, ginkgos, cycads.
 Make 2 different types of cones: male (pollen
cones) and female (seed cones).
 After fertilization, the zygote (ovum and sperm)
makes a seed.
Angiosperms
 Angiosperms are flowering plants and the seeds
are contained in a protective wall that develops
into a fruit.
 the ovum is inside the pistil (female part) and
must be fertilized by a sperm cell contained
inside the pollen grain. Once it is fertilized, the
zygote develops into an embryo in a seed.