Protists

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Protists

• Abdulhafez A Selim, MD, PhD
• ASELIM_at_KFUPM.EDU.SA

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• Simple Eukaryotic Organisms.
• Unicellular.
• Live in aquatic environments.

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Protists cellular structure
Single Cell
Colony
Multicelluar organism
coenocytes
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Protists feeding methods
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Protists feeding methods

• An autotroph (from the Greek autos self and
  trophe nutrition) is an organism that produces
  organic compounds from carbon dioxide as a carbon
  source, using either light or reactions of
  inorganic chemical compounds, as a source of
  energy. An autotroph is known as a producer in a
  food chain.

• A heterotroph (Greek heterone (an)other and
  trophe nutrition) is an organism that requires
  organic substrates to get its carbon for growth
  and development. A heterotroph is known as a
  consumer in the food chain.

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Autotroph or heterotroph?
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Protists, how they live?
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Symbiosis

• Symbiosis (pl. symbioses)(from the Greek words
  syn with/plus and bio life) is an interaction
  between two organisms living together in more or
  less intimate association or even the merging of
  two dissimilar organisms that bond and interact
  as a living element. The term host is usually
  used for the larger (macro) of the two members of
  a symbiosis. The smaller (micro) member is called
  the symbiont (plural symbionts), or alternately,
  symbiote (plural symbiotes). When a microscopic
  symbiont lives inside the cells of a host, it is
  referred to as an endosymbiont.

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Protists, reproduction.
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Protists, movement
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Protists, movement
A cilium (plural cilia) or undulipodium (pl.
undulipodia) is an organelle found in eukaryotic
cells. Cilia are thin, tail-like projections
extending approximately 5-10 micrometers outwards
from the cell body. There are two types of cilia
motile cilia, which constantly beat in one
direction, and non-motile cilia, which typically
serve as sensory organelles.
A flagellum (plural, flagella) is a long, whip
like projection composed by microtubes. They help
propel cells and organisms in a whip like motion.
The flagellum of eukaryotes usually moves with an
S motion, and is surrounded by cell membrane.
Pseudopods or pseudopodia (false feet) are
temporary projections of eukaryotic cells. Cells
having this faculty are generally referred to as
amoeboids.
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Phylogenetic relationship

• How it was determined?
• Ultrastructure (electron microscopy cell
  structure)
• Molecular data (DNA sequence similarity)

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Protists DNA Bar code
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Protists, Protozoa, Amoeba
Amoebic dysentery

• Amoebic dysentery is transmitted by contaminated
  water, and is well known as a "traveler's
  dysentery" because of its prevalence in
  developing nations, although it is occasionally
  seen in industrialized countries. Liver
  infection, and subsequent amoebic abscesses can
  occur. It can be treated with metronidazole or
  related azole drugs.

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Protists, Protozoa, Forams

• The Foraminifera, or forams for short, are a
  large group of amoeboid protists with
  reticulating pseudopods, fine strands that branch
  and merge to form a dynamic net.
• They typically produce a shell, or test, which
  can have either one or multiple chambers, some
  becoming quite elaborate in structure.
• About 250,000 species are recognized, both living
  and fossil. They are usually less than 1 mm in
  size, but some are much larger, and the largest
  recorded specimen reached 19 cm.

Psuedopods

• The form and composition of the test is the
  primary means by which forams are identified and
  classified. Most have calcareous tests, composed
  of calcium carbonate, which generally takes the
  form of interlocking microscopic crystals, giving
  it a glassy or hyaline appearance.
• Openings in the test, including those that allow
  cytoplasm to flow between chambers, are called
  apertures.

fossil
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Uses of Forams

• Because of their diversity, abundance, and
  complex morphology, fossil foraminiferal
  assemblages are useful for biostratigraphy, and
  can accurately give relative dates to rocks.
• Before more modern techniques became available,
  the oil industry relied heavily on microfossils
  such as forams to find potential oil deposits.
• Calcareous fossil foraminifera are formed from
  elements found in the ancient seas they lived in.
  Thus they are very useful in paleoclimatology and
  paleoceanography.
• They can be used to reconstruct past climate by
  examining the stable isotope ratios of oxygen
  The ratio of 18O to 16O is used to tell the
  temperature of the surrounding water of the time
  solidified, indirectly.
• Geographic patterns seen in the fossil records of
  planktonic forams are also used to reconstruct
  ancient ocean currents.
• Because certain types of foraminifera are found
  only in certain environments, they can be used to
  figure out the kind of environment under which
  ancient marine sediments were deposited.
• For the same reasons they make useful
  biostratigraphic markers, living foraminiferal
  assemblages have been used as bioindicators in
  coastal environments, including indicators of
  coral reef health.
• Because calcium carbonate is subsceptible to
  dissolving in acidic conditions, Foraminifera may
  be particularly affected by changing climate and
  ocean acidification.

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Ocean currents
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Protists, Protozoa, Actinopods

• Radiolarians have many needle-like pseudopods
  supported by bundles of microtubules, called
  axopods, which aid in flotation.
• The nuclei and most other organelles are in the
  endoplasm, while the ectoplasm is filled with
  frothy vacuoles and lipid droplets, keeping them
  buoyant.
• Often it also contains symbiotic algae,
  especially zooxanthellae, which provide most of
  the cell's energy.

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Actinopods, Radiolarians, Ecology

• Radiolarians They are found as plankton
  throughout the ocean, and because of their rapid
  turn-over of species, their tests are important
  diagnostic fossils

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zooflagellates
ZAAACF
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Protists, Protozoa, Zooflagellates Trypanosoma

• Trypanosoma is a notable genus of trypanosomes, a
  monophyletic1 group of unicellular parasitic
  protozoa.
• The name is derived from the Greek trypaô
  (boring) and soma (body) because of the way the
  organisms move.
• Different species infect a variety of different
  vertebrates, including humans, causing the
  trypanosomiasis diseases, e.g. sleeping sickness.
• Most species are transmitted by invertebrates
  such as biting insects.
• Trypanosoma undergo a complex lifecycle which may
  include several different morphological forms
  especially in the species which are transmitted
  by invertebrates.
• They may go through a variety of different forms
  in the invertebrate host, but in the vertebrate
  host the cells take a characteristic form called
  a trypomastigote, where the flagellum is runs
  from the posterior to the anterior of the cell
  and is connected by an undulating membrane.

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Trypanosoma Life Cycle
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Protists, Protozoa, Zooflagellates Giardia,
Giardiasis

• Giardia lamblia (formerly also Lamblia
  intestinalis and also known as Giardia duodenalis
  and Giardia intestinalis) is a flagellated
  protozoan parasite that infects the
  gastrointestinal tract and causes giardiasis.
• Infection causes giardiasis, a type of
  gastroenteritis that manifests itself with severe
  diarrhea and abdominal cramps. Other symptoms can
  include bloating, flatulence, fatigue, nausea,
  vomiting and weight loss. In some patients,
  vomiting or nausea is the major symptom. The
  symptoms usually manifest themselves about seven
  to ten days after ingestion. Giardia is a major
  cause of intestinal disease worldwide and the
  most frequent non-bacterial cause of diarrhea in
  North America. Nonetheless, the basic biology of
  this parasite is poorly understood.

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Giardiasis, Prophylaxis

• Filter use or boiling is recommended for water
  purification of drinking water in wilderness
  conditions.
• Treatment of drinking water for Giardia typically
  involves some form of high efficiency filtration
  and/or chemical disinfection such as chlorination
  or ozonation. Treatment is necessary throughout
  North America.

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Ciliates
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Zooflagellates, choanoflagellates

• The choanoflagellates are a group of flagellate
  protozoa.
• They are considered to be the closest relatives
  of the animals, and the last unicellular
  ancestors of animals are thought to have
  resembled modern choanoflagellates.
• Each choanoflagellate has a single flagellum,
  surrounded by a ring of hairlike protrusions
  called microvilli, forming a cylindrical or
  conical collar (choanos in Greek).

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Ciliates, reproduction

• Unlike other eukaryotes, ciliates have two
  different sorts of nuclei a small, diploid
  micronucleus (reproduction), and a large,
  polyploid macronucleus (general cell regulation).
  
• polyploid macronucleus is generated from the
  micronucleus by amplification of the genome and
  heavy editing.
• Division of the macronucleus occurs by amitosis,
  the segregation of the chromosomes is by a
  process, whose mechanism is unknown.
• This process is by no means perfect, and after
  about 200 generations the cell shows signs of
  aging.
• Periodically the macronuclei must be regenerated
  from the micronuclei. In most, this occurs during
  sexual reproduction, which is not usually through
  syngamy but through conjugation. Here two cells
  line up, the micronuclei undergo meiosis, some of
  the haploid daughters are exchanged and then fuse
  to form new micro- and macronuclei.

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Protists, Algae
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Eugelnoids

• The euglenids (also spelled euglenoids) are one
  of the best-known groups of flagellates, commonly
  found in freshwater especially when it is rich in
  organic materials, with a few marine and
  endosymbiotic members.
• Many euglenids have chloroplasts and produce
  energy through photosynthesis, but others feed by
  phagocytosis or strictly by osmosis.
• Euglenids are distinguished mainly by the
  presence of a pellicle, which is composed of
  proteinaceous strips underneath the cell
  membrane, supported by dorsal and ventral
  microtubules. This varies from rigid to flexible,
  and gives the cell its shape, often giving it
  distinctive striations.

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Eugelnoids

• Euglena green algae can create green and opaque
  water problems in aquariums. Euglena can grow due
  to high Nitrate, Phosphate levels or direct
  sunlight. Decreasing phosphate and Nitrate by
  patial water change and moving the aquarium to
  shade can help in solving the problem.

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Dinoflagellates

• The dinoflagellates are a large group of
  flagellate protists.
• Most are marine plankton, but they are common in
  fresh water habitats as well their populations
  are distributed depending on temperature,
  salinity, or depth.
• About half of all dinoflagellates are
  photosynthetic.
• Being primary producers make them an important
  part of the aquatic food chain.
• Some species, called zooxanthellae, are
  endosymbionts of marine animals and protozoa, and
  play an important part in the biology of coral
  reefs.
• Other dinoflagellates are colorless predators on
  other protozoa, and a few forms are parasitic
  (see for example Oodinium, Pfiesteria).

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Dinoflagellates, Ecology

• Dinoflagellates sometimes bloom in concentrations
  of more than a million cells per millilitre. Some
  species produce neurotoxins, which in such
  quantities kill fish and accumulate in filter
  feeders such as shellfish, which in turn may pass
  them on to people who eat them. This phenomenon
  is called a red tide, from the color the bloom
  imparts to the water.
• Some colorless dinoflagellates may also form
  toxic blooms, such as Pfiesteria.
• It should be noted that not all dinoflagellate
  blooms are dangerous.
• Bluish flickers visible in ocean water at night
  often come from blooms of bioluminescent
  dinoflagellates, which emit short flashes of
  light when disturbed.

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Dinoflagellates, Caution

• Red Tide is more specifically produced when
  dinoflagellates are able to reproduce rapidly and
  copiously on account of the abundant nutrients in
  the water.
• Although the resulting red waves are a miraculous
  sight, they, again, contain toxins that not only
  affect all marine life in the ocean but the
  people who consume them as well. A specific
  carrier is shellfish. This can introduce both
  non-fatal and fatal illnesses.
• Human inputs of phosphate further encourage these
  red tides, and consequently there is a strong
  interest in learning more about dinoflagellates,
  from both medical and economic perspectives.

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zooflagellates
ZAAACF
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• The ookinetes penetrate and escape the midgut,
  then embed themselves onto the exterior of the
  gut membrane. Here they divide many times to
  produce large numbers of tiny elongated
  sporozoites.
• These sporozoites migrate to the salivary glands
  of the mosquito where they are injected into the
  blood of the next host the mosquito bites. The
  sporozoites move to the liver where they repeat
  the cycle.

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Plasmodium, Malaria

• The life cycle of Plasmodium is very complex.
  Sporozoites from the saliva of a biting female
  mosquito are transmitted to either the blood or
  the lymphatic system1 of the recipient.
• The sporozoites migrate to the liver and invade
  hepatocytes. The so-called latent or dormant
  stage of the Plasmodium sporozoite in the liver
  is called the hypnozoite.
• From the hepatocytes, the parasite replicates
  into thousands of merozoites, which then invade
  red blood cells. Here the parasite grows from a
  ring-shaped form to a larger trophozoite form. In
  the schizont stage, the parasite divides several
  times to produce new merozoites, which leave the
  red blood cells and travel within the bloodstream
  to invade new red blood cells.
• Most merozoites continue this replicative cycle,
  but some merozoites differentiate into male or
  female sexual forms (gametocytes) (also in the
  blood), which are taken up by the female
  Anopheles mosquito. In the mosquito's midgut, the
  gametocytes develop into gametes and fertilize
  each other, forming motile zygotes called
  ookinetes.

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Malaria, Blood Picture
On a molecular level, the parasite damages red
blood cells using plasmepsin enzymes. Plasmepsins
are aspartic acid proteases which degrade
hemoglobin.
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Summary
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Diatoms

• Diatoms (Greek d?? (dia) "through" t?µ?e??
  (temnein) "to cut", i.e., "cut in half") are a
  major group of eukaryotic algae, and are one of
  the most common types of phytoplankton.
• Most diatoms are unicellular, although some form
  chains or simple colonies.
• A characteristic feature of diatom cells is that
  they are encased within a unique cell wall made
  of silica.
• These walls show a wide diversity in form, some
  quite beautiful and ornate, but usually consist
  of two symmetrical sides with a split between
  them, hence the group name.

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Diatoms

• The use of silicon by diatoms is believed by many
  researchers to be the key to their ecological
  success.
• In a new classic study, Egge Aksnes (1992)
  found that diatom dominance of mesocosm
  communities was directly related to the
  availability of silicate. When silicon content
  approaches a concentration of 2 mmol m-3, diatoms
  typically represent more than 70 of the
  phytoplankton community.
• Raven (1983) noted that, relative to organic cell
  walls, silica frustules require less energy to
  synthesize (approximately 8), potentially a
  significant saving on the overall cell energy
  budget.
• Other researchers (Milligan Morel, 2002) have
  suggested that the biogenic silica in diatom cell
  walls acts as an effective pH buffer,
  facilitating the conversion of bicarbonate to
  dissolved CO2 (which is more readily
  assimilated).

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Diatoms

• Planktonic forms in freshwater and marine
  environments typically exhibit a "bloom and bust"
  lifestyle. When conditions in the upper mixed
  layer (nutrients and light) are favourable (e.g.
  at the start of spring) their competitive edge
  (Furnas, 1990) allows them to quickly dominate
  phytoplankton communities ("bloom"). As such they
  are often classed as opportunistic r-strategists
  (i.e. those organisms whose ecology is defined by
  a high growth rate, r).
• When conditions turn unfavourable, usually upon
  depletion of nutrients, diatom cells typically
  increase in sinking rate and exit the upper mixed
  layer ("bust"). This sinking is induced by either
  a loss of buoyancy control, the synthesis of
  mucilage that sticks diatoms cells together, or
  the production of heavy resting spores.
• Sinking out of the upper mixed layer removes
  diatoms from conditions inimical to growth,
  including grazer populations and higher
  temperatures (which would otherwise increase cell
  metabolism).
• Cells reaching deeper water or the shallow
  seafloor can then rest until conditions become
  more favourable again. In the open ocean, many
  sinking cells are lost to the deep, but refuge
  populations can persist near the thermocline.
• Ultimately, diatom cells in these resting
  populations re-enter the upper mixed layer when
  vertical mixing entrains them. In most
  circumstances, this mixing also replenishes
  nutrients in the upper mixed layer, setting the
  scene for the next round of diatom blooms. In the
  open ocean (away from areas of continuous
  upwelling see Dugdale Wilkerson, 1998), this
  cycle of bloom, bust, then return to pre-bloom
  conditions typically occurs over an annual cycle,
  with diatoms only being prevalent during the
  spring and early summer.

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Golden algae

• Coccolithophores are single-celled algae, or
  phytoplankton, belonging to the haptophytes.
• They are distinguished by special calcium
  carbonate plates (or scales) of unknown purpose
  called coccoliths, which are important
  microfossils.
• Coccolithophores are exclusively marine and are
  found in large numbers throughout the surface
  euphotic zone of the ocean.
• Due to their microscopic size and broad
  distribution, coccoliths (calcareous
  nannoplankton) have become very popular for
  solving various stratigraphic problems,
• and many studies have been devoted to that end.
  Nanofossils are sensitive indicators of changes
  in the temperature and salinity of the ocean and
  sea surface water.
• Quantitative analysis of calcareous nanoplankton
  assemblages is being employed to reveal such
  changes.

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Brown Algae

• The brown algae are a large group of
  multicellular, mostly marine, algae.
• They play an important role in marine
  environments. For instance Macrocystis, may reach
  60 metres in length, and forms prominent
  underwater forests.
• Another notable example is Sargassum, which
  creates unique habitats in the Sargasso Sea
  (hence the name Sargassum).
• Many brown algae such as members of the order
  Fucales (the rockweeds) are commonly found along
  rocky seashores. Some members of the division are
  used as food.

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Green Algae

• The Green algae (singular Green Alga) are the
  large group of algae from which the embryophytes
  (higher plants) emerged.
• As such they form a paraphyletic group, variously
  included among the Plantae or with the Protista.
• The green algae include unicellular and colonial
  flagellates, usually but not always with two
  flagella per cell, as well as various colonial,
  coccoid, and filamentous forms.

A growth of the green seaweed, Enteromorpha on
rock substratum at the ocean shore. Some green
seaweeds, such as Enteromorpha and Ulva, are
quick to utilize inorganic nutrients from land
runoff, and thus can be indicators of nutrient
pollution.
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Red Algae

• The red algae (Rhodophyta, IPA
  ?r??d?(?)'f??t?, from Greek ??d?? (rhodon)
  rose f?t?? (phyton) plant, thus red plant)
  are a large group of mostly multicellular, marine
  algae, including many notable seaweeds. Most of
  the coralline algae, which secrete calcium
  carbonate and play a major role in building coral
  reefs, belong here. Red algae such as dulse and
  nori are a traditional part of European and Asian
  cuisine and are used to make other products like
  agar, carrageenans and other food additives.

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Red Algae

• The oldest fossil identified as a red alga is
  also the oldest fossil eukaryote that belongs to
  a specific modern taxon. Bangiomorpha pubescens,
  a multicellular fossil from arctic Canada,
  strongly resembles the modern red alga Bangia
  despite occuring in rocks dating to 1200 million
  years ago.1
• Red algae are important builders of limestone
  reefs. The earliest such coralline algae, the
  solenopores, are known from the Cambrian Period.
  Other algae of different origins filled a similar
  role in the late Paleozoic, and in more recent
  reefs.

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Red Algae

• Several species are used as food. Dulse (Palmaria
  palmata) and Porphyra are perhaps the best
  known4
• They have cell walls that are made out of
  cellulose and thick gelatinous polysaccharides
  which are the basis for most of the industrial
  products made from red algae.

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Summary
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Fungus-like protista
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Water moulds

• Water moulds or Oomycetes are a group of
  filamentous, unicellular protists, physically
  resembling fungi.
• They are microscopic, absorptive organisms that
  reproduce both sexually and asexually and are
  composed of mycelia, or a tube-like vegetative
  body
• The name "water mould" refers to the fact that
  they thrive under conditions of high humidity and
  running surface water.
• Their cell walls are composed of cellulose rather
  than chitin and generally do not have septations.
  
• Also, in the vegetative state they have diploid
  nuclei, whereas fungi have haploid nuclei.

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• Phytophthora cinnamomi (dieback) - this affects
  as many as 20001 of the 9000 native plant
  species in Southwest Australia, most notably
  jarrah (Eucalyptus marginata).

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• The water moulds are economically and
  scientifically important because they are
  aggressive plant pathogens (see plant pathology).
  The majority can be broken down into three
  groups, although more exist.

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• The Phytophthora group is a genus that causes
  diseases such as dieback, potato blight, sudden
  oak death

Potato blight
Infected oak It was first discovered in
California in 1995 when large numbers of Tanoaks
(Lithocarpus densiflorus) died mysteriously, and
was described as a new species of Phytophthora
in 2000
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Summary
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Plants and green algae has similar biochemical
characteristics

• Same biosynthetic pigment
• Same cell wall component
• Same carbohydrates storage material

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Plants and green algae share similarities in cell
division.
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What is different in plants?
Evolution of number of anatomical, physiological
and reproductive adaptations
Land colonization
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Plant features

• Plant cuticles are a protective waxy covering
  produced only by the epidermal cells
  (Kolattukudy, 1996) of leaves, young shoots and
  all other aerial plant organs.
• The cuticle is composed of an insoluble cuticular
  membrane impregnated by and covered with soluble
  waxes.

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Plant, stomata

• In botany, a stoma (also stomate plural stomata)
  is a tiny opening or pore, found mostly on the
  under-surface(epidermis) of a plant leaf, and
  used for gas exchange.
• The pore is formed by a pair of specialised cells
  known as guard cells which are responsible for
  regulating the size of the opening.
• Air containing carbon dioxide and oxygen enters
  the plant through these openings where it gets
  used in photosynthesis and respiration. Waste
  oxygen produced by photosynthesis in the
  chlorenchyma cells (parenchyma cells with
  chloroplasts) of the leaf interior exits through
  these same openings.
• Also, water vapor is released into the atmosphere
  through these pores in a process called
  transpiration.

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Gametangia

• is an organ or cell in which gametes are
  produced.
• Most plants produce multicellular gametangia with
  a protective jacket of sterile cells surrounding
  the gametes.

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Plant, Reproduction

• Antheridia are gametandia that produce SPERM
  cells
• Archegonia are gametangia that produce EGGS.

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Plant, Reproduction

• Mosses have motile sperm that swim in water and
  fertilize the egg

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Plant, transport system

• The vascular plants are plants in the kingdom
  Plantae (also called Viridiplantae) that have
  specialized tissues for conducting water.
  Vascular plants include the ferns, clubmosses,
  horsetails, flowering plants, conifers and other
  gymnosperms.

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Plant, transport system

• xylem is one of the two types of transport tissue
  in plants, phloem being the other one. The word
  xylem is derived from classical Greek ?????
  (xylon), "wood", and indeed the best known xylem
  tissue is wood, though it is found throughout the
  plant.
• The xylem transports sap from the root up the
  plant. Xylem sap consists mainly of water and
  inorganic ions, although it can contain a number
  of organic chemicals as well.

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Plants, alteration of generations

• plant life cycle has an alteration of
  generations in which they spend part of their
  life cycles as a muticellular haploid gaetophyte
  and part as a muticellular diploid sporophyte

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Seeds

• A seed contains the embryo from which a new plant
  will grow under proper conditions.
• Seeds also usually contain a supply of stored
  food and is wrapped in the seed coat or testa.
• In angiosperms, the stored food begins as a
  tissue called the endosperm, which is derived
  from the parent plant via double fertilization.
• The usually triploid endosperm is rich in oil or
  starch and protein.
• In gymnosperms, such as conifers, the food
  storage tissue is part of the female gametophyte,
  a haploid tissue.

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Seeds

• Endosperm is tissue produced in the seeds of most
  flowering plants around the time of
  fertilization. It surrounds the embryo and
  provides nutrition in the in the form of starch,
  though it can also contain oils and protein.
• Endosperm is formed when the two sperm inside a
  pollen grain reach the interior of an embryo sac
  or female gametophyte. One sperm fertilizes the
  egg, forming a zygote, while the other sperm
  usually fuses with the two female nuclei at the
  center of the ovary, creating endosperm (double
  fertilization). Thus endosperm cells are usually
  triploid (containing three sets of chromosomes)
  but can vary widely from diploid (2n) to 15n.

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Gymnosperms

• Gymnosperms (Gymnospermae) are a group of
  seed-bearing plants with ovules borne on the edge
  or blade of an open sporophyll, the sporophylls
  usually arranged in cone-like structures. The
  term gymnosperm comes from the Greek word
  gumnospermos, meaning "naked seeds" and referring
  to the unenclosed condition of the seeds, as when
  they are produced they are found naked on the
  scales of a cone or similar structure.

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Pinophyta Conifers

• Largest phylum of gymnosperms
• Woody plants
• Bear evergreen needles.
• Produce seeds on cones.
• Have separate male and female on separate cones
  on the same plant.

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Pinophyta Conifers
SAME PLANT MONOECIOUS
Fertilization
zygote
Embryo within the seed
Wind dispersal
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Cycadophyta - Cycads
Plant A
Plant B
TWO PLANTSDIOECIOUS
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Cycadophyta - Cycads
Female Cone

• Cycads are an ancient group of seed plants
  characterized by a large crown of compound leaves
  and a stout trunk. They are evergreen,
  gymnospermous, dioecious plants having large
  pinnately compound leaves.
• Some are renowned for survival in harsh
  semi-desert climates, and can grow in sand or
  even on rock. They are able to grow in full sun
  or shade, and some are salt tolerant.

Male Cone
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Cycadophyta - Cycads
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Gnetophyta

• The gnetophytes differ from other gymnosperms in
  having wood vessels as in the flowering plants
  (Angiosperms or Magnoliophytes), and on the basis
  of morphological data it has been suggested that
  Gnetophytes may be the group of spermatophytes
  most closely related to the flowering plants.
• Molecular data have suggested a closer
  relationship to other gymnosperms than to
  angiosperms, and the conflict between
  morphological and molecular data has not yet been
  resolved.

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Gnetophyta
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Flowering plants angiosperms

• Vascular plants
• Seeds enclosed within fruits
• Most diverse and most scceussful group of plants
• Why?

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Flowering plants, special features

• Flowers function in sexual production

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• Double Fertilization diploid zygote and triploid
  zygote Endosperm.

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• Ovule enclosed within the ovary.
• Ovule seed
• Ovary Fruit

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• Efficient water conducting cells called vessel
  elements in their xylem
• A vessel element is one of the cell types found
  in xylem, the water conducting tissue of plants.
  Vessel elements are typically found in the
  angiosperms but absent from most gymnosperms such
  as the conifers.
• Vessel elements are the building blocks of
  vessels, which constitute the major part of the
  water transporting system in the plants where
  they occur. Vessels form an efficient system for
  transporting water (including necessary minerals)
  from the root to the leaves and other parts of
  the plant.

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• Efficient carbohydrate conducting cells (sieve
  tube) members in their system.

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Various ways of fertilization

• Wind
• Water
• Insects
• Other animals
• All can transfer pollen grains.

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Floral parts multiples of four or five Seeds
two cotyledon Seeds Nutritive tissue cotyledons
Floral parts multiples of three Seeds one
cotyledon Seeds Nutritive tissue Endosperm
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Cotyledon

• A cotyledon (Greek ??t???d??) is a significant
  part of the embryo within the seed of a plant.
• Upon germination, the cotyledon usually becomes
  the embryonic first leaves of a seedling.
• The number of cotyledons present is one
  characteristic used by botanists to classify the
  flowering plants (angiosperms).
• Species with one cotyledon are called
  monocotyledonous (or, "monocots") and placed in
  the Class Liliopsida.
• Plants with two embryonic leaves are termed
  dicotyledonous ("dicots") and placed in the Class
  Magnoliopsida.

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Seed Plants, origin

• Theory
• Seed plants probably arose from seedless vascular
  plants Progymnosperms.
• Progymnosperms (have large leaves (megaphylls)
  and woody tissue.
• Amborella (dicot) nearest living to the ancestor
  of all flowering plants

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Mosses

• Mosses are small, soft plants that are typically
  1-10 cm tall, occasionally more.
• They commonly grow close together in clumps or
  mats in damp or shady locations.
• They do not have flowers or seeds, and their
  simple leaves cover the thin wiry stems.
• At certain times mosses produces spore capsules
  which may appear as beak-like capsules borne
  aloft on thin stalks.

No seeds no vessels
Cuticle, stomata multicellular gametangia
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Bryophytes

• The bryophytes are those embryophyte plants
  ('land plants') that are non-vascular they have
  tissues and enclosed reproductive systems, but
  they lack vascular tissue that circulates
  liquids. They neither flower nor produce seeds,
  reproducing via spores.

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