Diversity of Eukaryotes
CHAPTERS 3 and 4
The Mind-Boggling Diversity of Life
• The Eukarya domain contains four kingdoms
– Protista
– Plantae
– Fungi
– Animalia
• Eukaryotes evolved sometime after
prokaryotes populated the Earth
The Dawn of Eukarya
• Key evolutionary features of eukaryotes:
– Presence of a nucleus
– Membrane-bound internal compartments
– Larger cell size
– Sexual reproduction
– Multicellular (not all are though)
Eukaryotes Have Subcellular
Compartmentalization and Larger Cells
• Eukaryotic DNA
is in a nucleus
• Increased
complexity
allows
eukaryotes to
function with
greater
efficiency
• Eukaryotes are
thousands of
times larger in
volume than
prokaryotes
Sexual Reproduction Increases Genetic
Diversity
• Sexual
reproduction
increases genetic
diversity by
producing offspring
that are different
from each other
and from both
parents.
Protista: The First Eukaryotes
Protista: The First Eukaryotes
• The protists include any
organism that do not fit into the
other kingdom classifications
– simple organization
– No specialized tissues
– Single cellular
– Mobile- flagella, cilia, or
pseudopodia
Protista: The First Eukaryotes
• Live in almost
any environment
that contains
liquid water
• Many protists,
such as the
algae, are
photosynthetic
Protists are Autotrophs, Heterotrophs,
or Mixotrophs
• What is an autotroph?
What is a producer?
• What is an
heterotroph? What is
a consumer?
• What is an
mixotrophs?
Protists are Autotrophs, Heterotrophs,
or Mixotrophs
• Algae are autotrophic
producers that use energy
from sunlight to carry out
photosynthesis and release
oxygen gas as a by-product
Protists are Autotrophs, Heterotrophs,
or Mixotrophs
• Heterotrop
hic protists
rely on
other
organisms
for energy
Protists are Autotrophs, Heterotrophs,
or Mixotrophs
• Mixotrophs obtain energy from a variety of
sources, depending on environmental
conditions
– Photosynthesize in light
– Hunt in dark
Euglena viridis
Some Protists Are Pathogens
• Some of the best-known protists are diseasecausing pathogens
– Malaria
--- Giardia
Fungi: A World of Decomposers
Fungi
• Fungal cells have a
protective cell wall that
can produce chitin to
help protect the cell
• Fungi can be
multicellular or singlecelled species
• DNA comparisons show
that fungi are more
closely related to
humans than to plants!
Fungi
• Fungi can be
multicellular or
single-celled
species
• The body of a
multicellular
fungus is called
the mycelium and
is made up of
many mycelial
strands of hyphae
Fungi Play a Key Role as Decomposers
• Fungi are
heterotrophs that
decompose organic
materials
• Fungi are the most
important
decomposers on land
Fungi Can be Dangerous Parasites
• Parasitic fungi grow on the
tissue of living organisms
Athlete's Foot
Ring “worm”
Yeast
Lichens and Mycorrhizae:
Collaborations between Kingdoms
• Symbiosis is the process of two organisms
working together in close association
• Fungi have formed beneficial relationships
with members of almost every kingdom
Lichens Contain a Fungus and a
Photosynthetic Microbe
• A lichen is a positive
association between:
– a photosynthetic
microbe (algae or
cyanobacteria) and
a fungus
• Lichens are pioneers of
barren environments,
helping to facilitate soil
formation
Mycorrhizae are Beneficial Associations
between a Fungus and the Plant Root
• Mycorrhizae are beneficial
associations between a fungus
and the plant root
• Plant gets more water with
Mycorrhizae
• Mycorrhizae gets sugars from
plant
Plantae
Plantae
• Plants are multicellular autotrophs that use
specialized organelles called chloroplasts to
carry out photosynthesis
Plantae
• Bryophytes
– earliest land
plants
– mosses, liverwort,
and hornwort
• Gymnosperms
– conifers
• Angiosperms
– flowering plants
Plants Had to Adapt to Life on Land
• In order to
evolve on
land, plants
developed a
waxy cuticle
that prevents
them from
drying out
Plants Had to Adapt to Life on Land
• Stomata are
pores that
open and close
to allow the
carbon dioxide
needed for
photosynthesis
to enter the
leaves
Plants: Vascular System
• Vascular tissue:
– Phloem
• Transports food
molecules like sugar
• Flows down
– Xylem
• transports water and
dissolved nutrients
• Flows up
Gymnosperms
• Gymnosperms were the first plants to
evolve pollen and seeds
– The evolution of seeds contributed
to their success
• Pollen
– contains sperm cells
– dry and powdery
– produced in great quantities
• Seed
– plant embryo and a short
supply of food encased in a
protective seed coat
Male Cone
Female Cone
Angiosperms
• Angiosperms produce
flowers and fruit
• Most abundant and
diverse group of plants
• Contain both male and
female structures
• Bright petals, odors,
and sugary nectar are
used to attract
pollinators
Plants Are the Basis of Land Ecosystems
and Provide Many Valuable Products
• Nearly all
organisms
on land
depend on
plants for
food
Plants
• Plants have value when left in nature as well
– Preventing runoff and erosion
– Recycle carbon dioxide from the atmosphere
– Produce oxygen to breath