Transcript chapt05_lecture

Chapter 5
Lecture
Slides
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FLIPBOOK REVIEW
• Using five pieces of overlapping paper create a flipchart
that summarizes the information from notes, the
textbook section on the Microbial World. The title on the
flipchart is Ocean- The Microbial World. The following
ten headings will appear on the ten tabs of your
flipchart: Classification system, Prokaryotes, Bacteria,
Archaea Bacteria, Prokaryote Food, Unicellular Algae,
Diatoms, Dinoflagellates, Foraminiferans, and Fungi.
Under the tabs of each section you will summarize in a
couple of paragraphs the main characteristics of each
microbial group or organisms and their importance.
Marine Bio
Section 2
The Microbial World
Chapter Opener
Viruses
• Non-cellular infectious agents that have
two basic characteristics:
– Not capable of reproduction without a host
cell
– Structure:
•Nucleic acid core- can be DNA or RNA
•Capsid (Protein coat)- consists of
numerous protein subunits organized
into rod-like or many sided shape.
Protein coat also contains specific
proteins that bind with receptors on
host cells (great at mimicry!!) Many
Figure 05_01
Viruses
• Notable Types of Viruses:
• Retroviruses- store genetic information in
the form of nucleic acid known as RNA
• Lysogenic viruses – reproduce by inserting
their DNA into the DNA of the host cell
• Bacteriophages – viruses that infect
bacteria
Viruses
• Viruses in the Marine Community:
– They are common in marine waters
– They can infect bacteria, plankton, fish, sea
turtles and marine mammals
– Lysis (bursting) of viral infected cells spills
contents and releases large amounts of
organic matter that can be utilized by other
organisms (dissolved organic matter or DOM)
Prokaryotes
• Archea and Bacteria
• Characteristics of Archean and Bacterial Cells:
– Prokaryotic- no nucleus
– Single chromosome (normally circular)- some also
with plasmids
– Most with cell wall
– Great metabolic diversity
Prokaryotes
• Archea –
– Ancient organisms – fossils found that date
back 3.8 billion years
– Some live in very extreme environments
– Variety of metabolic types
– Widely distributed in the marine community
– They can tolerate wide ranges in temperature,
salinity and even desiccation (drying out)
– Can be found in many areas including near
hydrothermal vents and salt flats (very
extreme environments)Left off 2/22/10
Prokaryotes
• Special Features of Bacteria:
• A variety of shapes including spirals,
spheres, rods and rings
• Cell wall structure is semi-rigid, but
permeable; most with cell wall
• Size is normally microscopic, but a few are
large
• Wide variety of metabolic types
• Very abundant worldwide
Prokaryotes
• Special Features of Bacteria:
– A very important job of bacteria in the marine
community: break down dead organic matter.
– Forms detritus- minute particles of organic matter
now available as nutrition for other organisms
– Cyanobacteria are a group of photosynthetic bacteria
– Stromalites, massive calcareous mounds formed by
cyanobacteria, have been found that are billion years
old
Figure 05_04
Prokaryotes
• Metabolic diversity:
• Photosynthesis – derive energy from light
• Chemosynthetic – derive energy from
chemical compounds
• Heterotrophs – derive energy from organic
matter by respiration(like us)
Diatoms
• Diatoms:
– Photosynthetic
– Yellow-brown color in life is a result of
photosynthetic pigments, chlorophyll A and C
and carotenoids
– Shell of silica called a frustule
– Most important primary producer on Earth
– Mostly solitary and unicellular
– Some can form colonies
Frustule
http://craticula.ncl.ac.uk/EADiatomKey/ima
ges/fig_1_frustule.jpg
http://www.astrographics.com/GalleryPrint
s/Display/GP2131.jpg
http://www.ucmp.berkeley.edu/chromista/
diatoms/diatomthecae.gif
Diatoms
• Diatoms
– Around half of the 12, 000 known species are marine
– Most are planktonic
– Store excess energy as an oil which also aids in
buoyancy
– Tiny pores in shell used for gas/nutrient exchange
– Some produce a toxin, known as domoic acid, that
can accumulate in the tissues or organisms that eat
diatoms such as shellfish and small fish
– Larger organisms that eat these shellfish or small fish
can become ill or die from this accumulated toxin
Diatoms
• Diatoms Continued
– Mainly reproduce by cellular division (a form of
asexual reproduction)
– In this type of reproduction, the cell divides and each
result cell gets one-half of the frustule.
– This cell now must secrete the other half of the
frustule (smaller piece)
– Due to this, diatoms get smaller each time they
reproduce
– To restore normal size, they must either sexual
reproduce or cast off the frustule and secrete an
entire new frustule
Dinoflagellates
• Dinoflagellates
– Most species live in marine environment
– Mostly photosynthetic, some can ingest particles
– Each species has unique shape reinforced by plates of
cellulose
– Two flagella in grooves on body that produce motion
– Also reproduce by cellular division
– Some are bioluminescent
Figure 05_08
Dinoflagellates
• Dinoflagellates
– Zooxanthellae are important dinoflagellates
that live in a symbiotic relationship with
corals, sea anemones and other organisms
(many of these host organisms have little or
no growth without their symbiotic partner)
Algal Blooms
• Diatoms and dinoflagellates can go
through periods of rapid growth known as
“blooms”
• This is a result of high levels of nutrients
in the water
• These blooms can be harmful to marine
organisms and even people at times
Protists
• Dinoflagellates
– A few species lack chloroplasts and live as parasites
in marine organisms
– Some species can reproduce in larger numbers and
produce “Red Tide”
– Pfiesteria is a dinoflagellate that produces very
serious toxins that can cause massive fish kills, harm
shellfish and impair the nervous system in humans.
– Pfiesteria was discovered near the Outer Banks in
North Carolina
Red Tide
• There are no known ways that humans
can control it, but many scientists around
the world are studying red tide at present.
It's important to remember that red tide
has happened before and the marine
environment has always recovered.
WATCH OUT-Whoa
• Three common signs of a red tide
bloom are:
• discolored water
• dead fish
• breathing difficulty.
Protists
• A few more species of phytosynthetic
plankton:
– Silicoflagellates
• Star-shaped internal skeleton of silica
• Two flagella of varying lengths
– Coccolithophores
• Ornate shells of calcium carbonate
Protozoa
• Foraminiferans (forams)
– Exclusively found in marine community
– Found on sandy or rocky bottoms
– Shells of calcium carbonate
– Can be important contributors of calcareous
material on coral reefs or sandy beaches
– Pseudopods (false feet) extend through pores
in the shell where they are used to capture
minute food particles such as phytoplankton
Protozoa
• Radiolarians
– Planktonic, mostly microscopic, although a
few can reach large sizes
– Shell of silica
– Like forams, they use pseudopods that extend
through pores in the shell where they are
used to capture minute food particles such as
phytoplankton
Protozoa
• Ciliates
– Cilia present for locomotion
– Most live as solitary cells
– Some build shells made of organic
debris
– May live on hard substrate
– Some are planktonic
Fungi
• Eukaryotic and mostly multicellular
• Heterotrophic
• Most of the 1500 species of marine fungi
are microscopic
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BIOLUMINESCENT FUNGIIII
Fungi
• Like bacteria, many fungus break down
dead organic matter into detritus
• Some fungus live in symbiosis with
cyanobacteria, these are known as lichens
• Marine lichens often live in wave-splashed
areas of rocky shorelines and other hard
substrate
Most Important Characteristics
of Marine Microbes