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Flashcards in deck_1141064 Deck (133):
1

Evolution

Changes in the genetic make-up of populations of a species over generations.

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Factors that cause evolution.

- Natural selection- Gene flow- Genetic drift- Bottlenecking- Non-random mating

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Use and disuse

Belief that the environment modifies traits.E.g., a giraffe's neck lengthens due to it stretching to reach leaves.

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Inheritance of acquired traits

Belief that acquired traits are passed on to offspring.E.g., the aforementioned giraffe passes on this trait to its offspring.

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Gene flow

The mixing of genes through immigration and emigration.

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Genetic drift

When random changes occur in the genetic make-up of a population. Most significant in small populations.

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Bottlenecking

When the original population has genetic diversity, but an event causes similar groups to be wiped out. The remaining population is very homogenous.

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Non-random mating

Occurs through:- Inbreeding- Sexual selection

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Hierarchy of biological order

- Atoms- Molecules- Organelles- Cells- Tissue- Organ- Organ System- Organism

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Atom (e.g.)

Oxygen atom

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Molecule (e.g.)

DNA

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Organelles (e.g.)

Cell nucleus

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Cells (e.g.)

Cardiac muscle cell

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Tissue (e.g.)

Cardiac muscle tissue

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Organ (e.g.)

Heart

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Organ system (e.g.)

Circulatory system

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Organism (e.g.)

Zebra

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What are the smallest units of life?

Cells

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Scientific method

- Observations- Question- Hypothesis- Prediction- Test (experiment or additional observation)If correct, retest. If incorrect, revise or replace hypothesis.

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Charles Darwin

Discovered the mechanism for evolution and developed the theory of evolution through natural selection.- Carapace shape in Galapagos tortoises- Marine iguanas adapted to eat algae- The Origin of Species- A. Wallace developed same theory

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Darwinian evolution

A gradual change in populations over time as a result of natural selection.

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Species survival relies on the abilities to...

- Obtain resources- Survive- Reproduce

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Modern synthesis of evolution

1. Individuals that make up a population are not identical.2. Some of this variability is heritable, passing in genes.3. In most generations, more offspring are produced than can survive.4. Survival and reproduction are not random effects, but those best able to obtain resources, survive, and reproduce will pass on their genes.

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Other causes of evolution

- Gene flow- Genetic drift- Bottlenecking- Non-random mating

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Gene flow

The mixing of genes through immigration and emigration.

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Genetic drift

Random changes in the genetic make-up of a population over time. These are most significant in small populations. E.g., eye color in people.Types:- Population bottleneck- Founder effect

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Founder effect

When a small population of a colony breaks off and the genetic diversity of this smaller colony is much more homogeneous, misrepresenting its founder.

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Non-random mating

- Inbreeding- Sexual selection

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Microevolution

Evolution that does not result in a new species, but changes the genetic make-up of existing populations. - Most common

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Macroevolution

Evolution that results in a new species. - Rare, requires special circumstances and a significant amount of time. - Also called "speciation."

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Artificial selection

Done by humans. E.g., crops and domestic animals.

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5 Kingdoms

- Plantae (eukaryotes)- Fungi (eukaryotes)- Animalia (eukaryotes)- Protista (eukaryotes)- Monera (prokaryotes)

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Spontaneous generation

Incorrect hypothesis that life originated from non-living things.

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Biogenesis

Synthesis of organic compounds from inorganic precursors.

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Inorganic compounds

Do not possess a carbon skeleton. May possess one carbon atom.

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Louis Pasteur

Conducted experiments to show that life comes from life, supporting his biogenesis hypothesis. - Chicken broth in flasks with straw

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The first life form was...

Anaerobic and prokaryotic

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Protobiont

Abiotically formed cell.

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Hypothetical steps to formation of the first cell

1. Assemble simple molecules into building blocks for complex polymers2. Assemble polymers that can store information and catalyze reactions.3. Add membranes and an energy source to make a living organism.

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Phospholipids

Form vesicles in water.

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Organic compounds found in cells

- Proteins (amino acids)- Sugars- Fats- Genetic material (DNA/RNA)

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Ribozyme

RNA molecule that was likely the first molecule to carry genetic information, replicate itself, and speed up chemical reactions.

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Steps to abiotically formed cells

1. Spontaneous formation of lipids, carbs, amino acids, proteins, and nucleotides.2. Formation of protein-RNA systems and lipid spheres.3. Self-replicating system enclosed in selectively permeable, protective lipid sphere.4. Membrane-bound protobionts5. Living cells (prokaryotic and eukaryotic)

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History of life on Earth summarized

1. Abiotic synthesis of small, organic molecules.2. Joining of molecules into polymers (chains of organic molecules)3. Origin of self-replicating molecules as genetic material.4. Packing of these molecules into protobionts, formed by many abiotically produced molecules.5. First cells anaerobic and prokaryotic, followed by aerobic and photosynthetic prokaryotic cells.6. Eukaryotic cells are formed, initially single-celled and then multicellular.

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Prokaryotic cell structure

- No interior membrane for nucleus- May have flagella for locomotion- Pili for grip- Gelatinous outer capsule - Cell wall - Plasma membrane - Cytoplasm - Nucleoid + Contains genetic material - Plasmid + Carries resistance to antibiotics - Ribosomes

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Prokaryote shapes

- Bacilli- Cocci- Spirochetes

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Bacilli

Rod shaped

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Cocci

Spherical

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Spirochetes

Spiral shaped

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Prokaryote

Single-celled (usually) organism that has neither a distinct nucleus with a membrane nor other specialized organelles such as mitochondria or chloroplasts.

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In what order did prokaryotes and eukaryotes evolve?

1. Heterotrophic prokaryotes2. Autotrophic prokaryotes (photosynthesis) a) Do not possess chloroplasts but may possess chlorophyll.3. Aerobic respiration4. Unicellular eukaryotes5. Multicellular eukaryotes

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Endosymbiotic theory

Origin of eukaryotic cells: - Ancestral prokatyote's plasma membrane unfolds to form the endoplasmic reticulum and nucleus.- This cell then engulfed aerobic heterotrophic prokaryote cells which developed into mitochondria. + These cells became heterotrophic eukaryotes. - Animals and fungi today.- Some of the cells also engulfed autotrophic prokaryote cells which developed into plastids, or chloroplasts. + These cells became photosynthetic eukaryotes. - Plants and algae today.

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Eukaryotic cell structure

- Contains a nucleus with DNA as well as mitochondria and other organelles. + These organelles are membrane-bound.- Autotrophic eukaryotes will also possess plastids, or chloroplasts.- Contains a plasma membrane, cytoplasm, and other structures found in prokaryotes.

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Monera

Prokaryotes- Bacteria- Archaea

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Protista

Eukaryotes, mostly unicellular

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Classification of life

- Domain + (Eu)bacteria, archaea, eukarya- Kingdom + Monera, protista, plantae, fungi, animalia- Phylum- Class- Order- Family- Genus- SpeciesMany biologists believe that kingdoms Monera and Prostista should be split into multiple kingdoms for different varieties of each.

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Taxonomy

The study of species identification.

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Binomial nomenclature

Invented by Linnaeus. Capitalized genus, lowercase species. Name must be underlined or italicized.

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Archaea

Domain of unicellular microorganisms that lack a nucleus or membrane-bound organelles. Similar to bacteria but possess a few different qualities and evolved differently as well. - Thermophiles - Halophiles - Methanogens

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Thermophiles

Heat-loving prokaryotes

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Halophiles

Salt-loving prokaryotes

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Methanogens

Methane-producing prokaryotes

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Why is bacteria dangerous?

A bacteria cell's metabolism allows it to release toxins.

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What are the most common prokaryotes?

Bacteria

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Autotrophs

Produce their own organic compounds from carbon dioxide. - Phototrophs - Chemotrophs

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Phototrophs

Use light energy to produce chemical energy (ATP) to be used by the cell. - E.g., cyanobacteria.

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Chemetrophs

Use energy from inorganic chemicals to produce chemical energy (ATP) to be used by the cell. - E.g., purple sulfur bacteria.

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Heterotrophs

Must consume organic molecules for energy and as a source of carbon to produce their own organic molecules.

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Oxygen requirements

- Obligate aerobes- Facultative aerobes- Anaerobes

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Obligate aerobes

Microorganisms that require oxygen to perform cellular respiration and cannot grow without it.

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Facultative aerobes

Microorganisms that grow in the presence of oxygen but will switch to anaerobe mode in the absence of oxygen.

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Anaerobes

Microorganisms that do not require oxygen to produce chemical energy (ATP). - May die when exposed to oxygen.

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Conjugation

Sexual reproduction in bacteria, accomplished by cell to cell contact or a bridge-like connection between cells to exchange DNA.

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(Eu)bacteria

Major ecological roles:- Symbiosis + Mutualism + Commensalism + Parasitism/Pathogens- Photoautotrophs + Cyanobacteria- Decomposers + Break down organic molecules and recycle nutrients.

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In eukaryotes, DNA is always found in the...

Nucleus

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Regarding their chromosomes, eukaryote cells may be either...

Haploid or diploid

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Haploid (n)

A cell with unpaired chromosomes, regardless of the number of chromosomes it has.

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Diploid (2n)

A cell with paired chromosomes.

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Mitosis

Process in which one cell splits to form two identical cells. - Haploid cell will produce 2 haploid cells and diploid cell will produce 2 diploid cells.

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Cytokenesis

Process in which the cytoplasm of a single eukaryotic cell is divided to form two daughter cells. It usually initiates during the late stages of mitosis or meiosis to ensure that chromosome number is maintained from one generation to the next.

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The cell wall of plants differs from other eukaryotes in that it is made of...

Cellulose

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The only haploid cells in the human body are..

Sperm and egg

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Meiosis

Necessarily for the reproduction of eukaryotes. Enables a diploid cell to split into 4 haploid daughter cells.

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Types of sexual reproduction

- Isogamy- Anisogamy- Oogamy

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Isogamy

Similar motile gametes

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Anisogamy

Dissimilar motile gametes

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Oogamy

One large, motile gamete (egg) and a smaller motile gamete (sperm).

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Reproductive life cycle of Laminaria (unicellular green algae)

- Mature algae is a 2n sporophyte. Contains sporangia that undergo meiosis to create haploid zoospores. - These zoospores develop into gametophytes that are either male or female, and come together as sperm and egg to create a 2n zygote that continues to be supported by its haploid female half.- This zygote matures into a new sporophyte.- Oogamy reproduction

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Meiotic types

- Zygotic- Gametic- Sporic

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Zygotic

Zygote (2n) undergoes meiosis to form 4 cells (n) - Used by most fungi and some algae.

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Gametic

Organism (2n) undergoes meiosis to form 4 gametes (n)- Used by animals

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Characteristics of Kingdom Protista

- Mostly unicellular, filamentous, colonial and multicellular organisms (with simple structure), eukaryotic cells- Polyphyletic origin, meaning that have distinct origins and are unrelated.

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Protists are grouped by...

Ecological role

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Ecological roles of protists

- Producer (autotrophic/plant-like)- Consumer (heterotrophic/animal-like)- Both

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Autotrophic protists

- Phylum Crysophyta- Phylum Phaeophyta- Phylum Rhodophyta- Phylum Chlorophyta

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Phylum Crysophyta

"Golden brown algae"- Diatoms are found in this phylum- Mostly unicellular or colonial- Chlorophyll A & C plus other pigments- Cell wall made of cellulose or pectin

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Diatoms

- Unicellular or colonial- Chlorophyll A & C plus other pigments- Cell wall made of silica or pectin- Limited locomotion- Significant source of oxygen- Great diversity of shells- Make up diatomaceous earth

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Phylum Phaeophyta

"Brown algae"- Kelp and sargassum found in this phylum- Mostly multicellular- Chlorophyll A & C plus other pigments- Structure: holdfast (roots it), stipe (stem), frond (leaf division), vessel cells

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Phylum Rhodophyta

"Red algae"- Mostly multicellular- Chlorophyll A & D and deep water pigments- Lack flagella- Cell walls of cellulose (deposits of calcium carbonate)- Coralline algae (looks like coral)/calcareous- Extracts: carragean and agar

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Phylum Chlorophyta

"Green algae"- Unicellular, colonial or multicellular- Chlorophyll A & B- Cell wall: celluse and pectin- Locomotion: flagella- Ancestor of land plants- Chlamydomonas (unicellular), Volvox (colonial), and Ulva (multicellular), Caulerpa

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Mixotrophic (autotrophic/heterotrophic) protists

- Phylum Euglenophyta- Phylum DinoflagellataFeed through photosynthesis as well as on other organisms.

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Phylum Euglenophyta

- Mostly unicellular- When present, chlorophylls A & B- 2 flagella- Lack cell wall- Stigma (eyespot) + Used for light detection- Euglena genus belongs to this phylum

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Phylum Dinoflagellata

- Unicellular- Possess 2 flagellum- When present, chlorophylls A & C and other pigments- Cellulose cell wall- Bioluminescent- Responsible for red tide and other toxins- Includes Pfiesteria (flesh eating bacteria) and zooxanthellae

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Heterotrophic protists

- Kingdom Diplomonadida (animal-like)- Kingdom Parabasalia (animal-like)- Phylum Choanoflagellida (animal-like)- Phylum Kinetoplastida (animal-like)- Phylum Apicomplexa (animal-like)- Phylum Ciliophora (animal-like)- Phylum Rhizopoda (animal-like)- Phylum Actinopoda (animal-like)- Phylum Foraminifera (animal-like)- Phylum Oomycota (fungus-like)- Phylum Myxogastrida (fungus-like)- Phylum Dictyostelida (fungus-like)

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Protozoans

Heterotrophic protists

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Kingdom Diplomonadida

- Mostly parasites of guts- Unicellular- Multiple flagella- No plastids- No mitochondria- E.g., Giaridia lamblia (internal parasite)

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Kingdom Parabasalia

- Mostly parasites or commensals of guts- Unicellular- No mitochondria- Multiple flagella- E.g., trichomonas vaginalis

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Phylum Choanoflagellida

- Unicellular or colonial- Single flagellum encircled by collar- Feeds by creating a current with its flagellum to bring food into its collar.- May have given origin to animals

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Phylum Kinetoplastida

- Contain a "kinetoplast" + Kinetoplast contains extra nuclear DNA- Single, large mitochondrium- Unicellular- Possess flagella- Symbiotic or pathogenic + Trypanosoma (African sleeping sickness, transmitted by the tse tse fly through protists in the bloodstream) + Chagas disease (bugs in mud houses) + Leishmania (feeds on cartilage)

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Phylum Apicomplexa

- All species are parasites- Non-motile adults- Malaria + Main symptom is fever + Caused by mosquito (Plasmodium sp.) which occurs in 3 stages: - Sporozoite - Merozoite (in the liver, Cryoptozoite) - Gametocyte

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Oocyst

A cyst containing a zygote formed by a parasitic protozoan such as the malaria parasite.

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Phylum Ciliphora

- Unicellular- Surface covered by cilia- Specialized organelles + Contractive vacuoles + Complex cytoskeleton- Mostly free-living (not a pathogen/parasite)- Two types of nuclei + Macronucleus - Chromosomes found here + Micronucleus - DNA for sexual reproduction found here- Use binary fusion for reproduction- E.g., Parameciums & Ciliates + Parameciums feed on anything smaller than them and release waste into surrounding water.

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Phylum Rhizopoda

"Amoeba"- Unicellular- No shell- Contain pseudopods + Lobed expansions of the body used for locomotion and feeding- Free-living or parasitic- E.g., Amoebas and Vampyrella

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Phylum Actinopoda

"Amoeba-like with silica shells"- Unicellular- Contain actinipods + Ray-like pseudopods- Typically plankton- E.g., Heliozoans and Radiolarians- Covered in holes

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Phylum Foraminifera

"Amoeba-like with calcium shells"- Unicellular- Chambered porous shells- Similar to Actinopoda but with chambers instead of holes

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Phylum Oomycota

"Water and slime molds"- Commonly known as "blights"- Marine, freshwater, and terrestrial (require water)- Reproduce asexually and sexually- Reproduce through zoospores

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Zoospores

Flagellated spores

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Life cycle of Oomycota

Asexual:- Completely diploid- Zoospore develops into a cyst- Cysts develops germ tube- This forms into a zoosporangium- Zoosporangium releases new zoosporesSexual:- Release of zoospores from zoosporangium- 2n zoospores undergo meiosis to create egg nucleus and sperm nuclei, contained in the oogonium.- Fertilization occurs and 2n zygotes, called oospores, are released from the oogonium.- Zygote germination occurs and oospores develop into zoosporangium.- Release of zoospores from zoosporangium

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Zoosporangium

A sporangium or spore case in which zoospores develop.

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Oogonium

Contains egg nucleus and sperm nuclei of Oomycota

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Oospores

Created by sexual reproduction of Oomycota

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Phylum Myxogastrida

"Plasmodial slime mold"- Plasmodium (2n) + Single mass of cytoplasm with several nuclei with amoeboid movement (no cell wall)- Reproduction + Sporangium with spores (n)- Terrestrial- Locomotion: pseudopodia

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Plasmodium

Single large cell with hundreds of nuclei that are all connected. - Grows sporangia in the absence of food or water. + Sporangia are reproductive structures that may release spores.

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Life cycle of Physarum (plasmodial slime mold)

- Mature plasmodium develops young sporangium.- Sporangium matures and mature sporangium has a stalk. Undergoes meiosis to release (n) spores.- Spores germinate and develop into either a flagellated cell or amoebic cell.- Cells reproduce, but only flagellated with flagellates and amoebic with amoebic.- Both result in a 2n zygote.- Zygotes undergo mitotis to form a larger, feeding plasmodium.- Feeding plasmodium develops into mature plasmodium, able to fruit.

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Phylum Dictyostelida

"Cellular slime mold"- Contain pseudoplasmodium + Similar to plasmodium but there is separation between cells.- Locomotion: pseudopodia- Sporangium- Utilize cAMP- Cell wall made of cellulose- May form multicellular colonies in the absence of food.- Colony grows "fruiting bodies" for the release of spores.

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Life cycle of Dictyostelida (cellular slime mold)

Asexual (completely n):- Solitary (feeding stage) amoeba cells aggregate (come together to form a whole)- Aggregate cells develop into migrating colony- Colony develops stalks with bulbs on the end called "fruiting bodies"- Fruiting bodies release spores- Solitary amoebas emerge from sporesSexual:- Amoebas (n) released from zygote (2n) through meiosis- Amoebas aggregate- Amoebas fertilize one another to create new zygote

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Feeding of fungus-like amoebas

Release enzymes outside of the body onto food source. Digestion takes place outside of the body and is then absorbed.

128

Three types of locomotion for heterotrophs

- Pseudopodia- Flagellum- Cilium

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Syngamy

The fusion of two cells, or of their nuclei, in reproduction.

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Pseudopodia

Cellular extensions used to move and feed.- Protists with these are usually amoebas.- Two types + Lobed - Short, bulbous lobes, typical of amoebas. - Called "lobopodia" - Found in Rhizopoda and Sarcodina + Thin - Long, thin pseudopods - Called "axopodia" or "actinopodia" - Found in Radiolaria and Heliozoa

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Flagellum

Whip-like tail(s) for locomotion. - Microorganisms with flagellum are called "flagellates."

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Cilium

Short, hair-like extensions used for feeding and locomotion. - Microorganisms that have cilium are called "ciliates."

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How do slime molds feed?

Fungus-like feeding mechanism