Download Cell Structure and Function

Bacteria, Archaea, &
Protista
Chapter 24
What you need to know!
• Different Domains of unicellar organisms
• How chloroplasts and mitochondria
evolved through endosymbiosis
• Protista is no longer considered an
independent kingdom. They are part of
the Eukaryotes domain and are very
diverse.
• How Chloroplasts and mitochondria
evolved through endosymbiosis
Domains
• Bacteria
• Archaea
• Eukarya
Characteristics of Prokaryotes
(both domains)
•
•
•
•
No membrane bound organelles
Smaller ribosomes
Haploid (no meiosis)
Can have plasmids (horizontal gene
transfer)
• Can have flagella (made of flagellin not
tubulin)
• Evolved all metabolic pathways on earth
– Photoautotroph, chemoautotroph,
photoheterotroph, chemoheterotroph
• Classified based on: metabolism then
shape then staining
• Cell walls (different molecular make-up)
• Reproduce via binary fission
Eubacteria Characteristics
• Identified by shape: cocci (sphere), bacilli
(rod), spirilla (spirals)
• Distinguished by staining method
– Gram positive = outer cell wall
– Gram negative = inter cell wall (between 2
membranes)
• Cyanobacteria (formerly blue/green algae):
photosynthetic, some fix nitrogen
• Chemosynthetic bacteria: autotrophs, some
fix nitrogen
– Nitrogen Fixing Bacteria: heterotrophs, mutualistic
with plants, live in modules
• Endospores: DNA packed into cell wall for
long term hybernation/survival
Types of Archaeabacteria
• Methanogens: anaerobic,
chemoheterotrophic (obligate anaerobes),
produce methane; found in: deep-sea
hydrothermal vents, mud, swamps, guts of
cows, and termites
Extremophiles:
• Extreme Halophiles: aerobic, heterotrophic,
or anaerobic, photosynthetic (with pigments),
live in high salinity (Salt Lake, Dead Sea)
• Extreme Thermophiles: chemosynthesis,
autotrophs, live in high heat (150 – 180
degrees F)
Horizontal Gene Transfer
A process in which genes are
transferred from one genome to
another by methods other than
reproduction:
• Transformation: uptake of foreign
DNA
• Viral infection
– Transduction: viruses (accidentally)
transfer non viral genes from their
maker to their host
• Conjugation: Exchange of
transposable elements (plasmids)
from source to target
• Fusions of organisms
endosymbiotic hypothesis
Protista ≠ Kingdom
Characteristics
• Protists are eukaryotes
• Can be unicellular, colonial or multicellular
• Predecessor to other eukaryotes: plants,
fungi, and animals.
• Eukaryotic fossils date back 1.8 billion
years
• Some of the most complex cell structures
found
• Special organelles: contractile organelle
(primitive excretion, H20 balance), eye
spots (primitive sight), anal pores (primitive
waste excretion)
Endosymbiotic Hypothesis
Metabolism
• Protists are the most nutritionally diverse of
all eukaryotes:
• Most protists are aerobic, with mitochondria
for cellular respiration.
• Some protists are photoautotrophs with
chloroplasts.
• Still others are heterotrophs that absorb
organic molecules or ingest larger food
particles.
• A few are mixotrophs (heteroautotrophs),
combining photosynthesis and
heterotrophic nutrition
Specifics
• Absorptive, protists (fungus-like)
• Protozoa - ingestive, animal-like protists
• Algae - photosynthetic, plant-like protists.
Features:
• Flagella: Protists have a flagella or cilia
during some time in their life cycles.
• The eukaryotic flagella are extensions of
the cytoplasm with a support of a
microtubule system (made from tubullin)
• Cilia are shorter and more numerous than
flagella.
Reproduction
•
•
•
1.
2.
3.
4.
5.
protists can reproduce asexually or
sexually
Many protists form resistant cells (cysts)
that can survive harsh conditions.
Protists are the first group to show
“alternation of generation”:
Most protists are haploid organisms (n),
called gametophytes
Gametophytes produce gametes
Gametes fuse to form a zygote
The Zygote develops into a sporophyte
(not the main organisms)
The Sporophyte produces haploid spores
that germinate into gametophytes
Habitat
Protists are found almost anywhere there is
water:
• Oceans, ponds, and lakes, but also damp
soil, leaf litter, and other moist terrestrial
habitats.
• Protists are also important parts of the
plankton, communities of organisms that
drift passively or swim weakly in the
water.
• Phytoplankton (including planktonic
eukaryotic algae and prokaryotic
cyanobacteria) are the bases of most
marine and freshwater food chains.
Lifestyle
• Many protists are symbiots that inhabit the
body fluids, tissues, or cells of hosts.
• These symbiotic relationships span the
continuum from mutualism to parasitism
(malaria, giardia)
Euglena
• Part of phytoplankton
• mixotrophic
• Base of marine and fresh
water food webs
Amoebas
• Pseudopods, extensions
of the cytoplasm
• Capturing prey,
locomotion
• Heterotrophic
Radiolarians
• Skeleton
pseudopods to
increase surface
area
Foraminiferans
• Beautifully shaped
calcium carbonate or
silica shelled protists
Paramecium
• Coordinated movement
through ciliates
• Complex organelles:
contractile vacuole for
osmoregulation (pumping
out water)
Malaria (protozoan)
• transmitted by infected
mosquito
Phylum Crysophyta/Diatoms
• Abundant in plankton and
sediments
• Have silica shells
• Top and bottom shells fit
together like boxes
Well Known Members
• Infamous:
• Giardia
• Trypanosomes
• Malaria
• Cute
• Paramecium
• Amoeba
• Mistaken as other organisms
• Brown, green, and red algae
• Giant Kelp
Critical Vocabulary
• Obligate aerobes: need oxygen
environment to live
• Obligate anaerobes: need an oxygen free
environment to live (absolutely no oxygen)
• Facultative anaerobes: can survive w/ or
w/out oxygen