Zoology

hierarchy of biology organization

atoms → bio molecules → subcellular organelles → cells → tissues → organs → organ system → organism → group → population → community → ecosystem → biome → biosphere

emergent properties of systems

arise from interactions between components

H-Bs, spontaneous peptide folding

kingdoms

• bacteria

• archaea

• eukarya

  • plantae

  • fungi

  • animalia

  • protists

Darwin’s natural selection observations

1. individuals in a population vary in heritable traits

2. populations potentially produce far more than they can support

2 methods of classification

1. phenetic - species grouped by overall similarity

2. phylogenetic - classified by shared ancestors

agreement vs disagreement between phenetics and phylogenetics

• agree

  • constant rate of evolution

  • divergent evolution

• disagree

  • differential evolution rate

  • convergent evolution

cladistics

relationships determined by synapomorphies

synapomorphies

shared, derived characteristics

pleisiomorphic

primitive/original state

apomorphic

derived state

autapomorph

trait unique to a taxon

synapomorph

trait derived from nearest common ancestor

Symplesiomorph

trait derived from older common ancestor

monophyletic

clades sharing synapomorphies

Non-monophyletic clades

share symplesiomorphies, due to convergent evolution

paraphyletic group

a group containing a hypothetical common ancestor + some, but not all, of its descendants

polyphyletic

a group of taxa not including their hypothetical common ancestor

protist nutrition

• some aerobic

• some photoautotrophs

• some heterotrophs

• a few mixotrophs

euglena

a mixotrophic protists that absorbs organic material from the environment when no light is available

protozoa defining characteristics

• unicellular eukaryotes without collagenous and chitinous cell walls

• non-photosynthetic in primitive condition

plasmalemma

outer membrane of protists

protists cytoplasm components

• ectoplasm - gelatinous outer layer

• endoplasm - inner fluid region

spongiome

system of tubules and vacuoles that collects water in protists

contractile vacuoles

expel excess water from cytoplasm of protists (osmotic regulation)

galvanotaxis

electrical stimulus

geotaxis

gravity stimulus

thigmotaxis

touch stimulus

rheotaxis

currents stimulus

ciliates

• phylum ciliophora

• live solitary in fresh water

• externally ciliated body some point during life

• reproduce via binary fission

ciliary movement

power stroke followed by recovery stroke

Metachronal Rhythm

beat of cilia where wave moves through it one way and the organism is propelled the opposite direction

paramecium

• cilia used to draw in food along oral groove

• expel water via contractile vacuole

macronucleus

• 50+ copies of genome

• control everyday function by synthesizing RNA

• necessary for asexual reproduction

micronuclei

• 1-80 copies

• required during sexual process to create genetic variation

conjugation

sexual shuffling of genes in protists where micronucleus undergo meiosis and are exchanged

pseudopodia

cellular extensions used to move and feed

Sarcodinids

• amoeboid protozoans

• have pseudopodia

• most free-living

• 2% parasitic

Amoebozoa

• protozoans

• inhabit freshwater, marine, and soils

• most are free-living heterotrophs

• called amoeboid due to constantly changing body

• most naked, some have a test (shell)

• posses pseudopodia for movement/feeding

Class Archamoebae

phylum amoebozoa → protozoans (kingdom)

Class Mycetozoa

• phylum amoebozoa → protists

• cellular and acellular slime molds

Entamoeba histolytica

parasite that causes amoeboid dysentery via contaminated water/food/utensils

AMEBIASIS

amoeboid dysentery caused by Entamoeba histolytica

test (shell)

secreted by body or consists of small sand/particles

cytoplasmic streaming

pseudopodia emerges → anchor its tip → streams more cytoplasm into pseudopodia

involves transition between gel and solid form

mimivirus

• virus that infects ameboid

• larger genome than many bacteria - blurs barrier between viral and cellular world

• encodes a few proteins involved in protein synthesis that belong to a set of universally conserved genes in cellular life

• acquired genes from HGT from ameboid hosts

sputnik

grows in mimivirus-infected amoeba to decrease yield of mimivirus

slime molds classification

class mycetozoa → phylum protozoa

Mycetozoa

• slime molds → convergent role in decomposition of organic material

• feed and move via pseudopodia (like amoeba), but protein sequences close to fungi and animals

plasmodial slime molds classification

Myxogastrida → class mycetozoa → phylum amebpzpa → protists

plasmodial slime molds

• brightly pigmented heterotrophic organisms

• feeding stage is amoeboid mass, plasmodium

plasmodium

• single mass of cytoplasm with multiple nuclei

• diploid nuclei undergo synchronous miotic divisions thousands of times

• cytoplasmic streaming distributes nutrients/O2 in cytoplasm

• phagocytosis food from: moist soil, leaf mulch, rotting logs

• differentiates into stages for sexual reproduction when habitat dries/food disappears

cellular slime molds

• Dictyostelida → Mycetozoa → amebozoa → protozoa

• feeding stage - solitary

• form aggregate unit when food is scarce - pseudoplasmodium

pseudoplasmodium

• aggregate that forms when food is scarce in cellular slime molds

• each cell remains its identity

• aggregates of amoebas form fruiting bodies → produce spores in asexual reproduction

acrasin

cAMP in clime molds

phylum radiozoa

• radiolarians (7700 fossil, 3300 extant)

• acantharians (500 extant)

• perforated membrane separated in 2 zones

  • intracapsular - nucleus

  • extracapsular - food vacuoles and digestion

• axopodia - psudopodia supported by thin microtubules

• rigid exoskeleton

  • silica - radiolarians

  • strontium sulphate - acantharians

acantharians classifications

in phylum radiozoa → protozoa

radiolarians classification

phylum radiozoa → protozoans

axopodia

pseudopodia supported by thin microtubules, in radiozoans

Heliozoa

• protists

• sun animals, life in fresh water

• skeleton is unfused siliceous or chitinous plates

• distinct inner and outer region with no physical boundary

• reproduce via autogamy

foraminifera

• protists

• mostly marine and benthic (live in sand or attach to rock/algae)

• some abundant in plankton

• multichambered porous shells consisting of materials hardened by calcium carbonate

• shells referred to as tests since some forms the protoplasm covers exterior of shell

• pseudopodia (reticuopodia) extend through pores for

  • swimming

  • shell formation

  • feeding

• symbiotic with algae

reticulopodia

• pseudopodia that extends through pores in forams for swimming, shell formation, and feeding

flagellated protozoa

• pedicle and one+ flagella

• flagella longer and fewer than cilia + have hair like projections

Trichozoa

mostly symbiotic

hydrogenosomes instead of mitochondria

Trichomonadea classification

subphylum parabasal → phylum Trichozoa → flagellated protozoa

Trichomonas vaginalis

• infect vaginal lining if acidity is disrupted

• infect male urethrae without symptoms

• spread sexually

saccostomae

• kinetoplastids

• phylum euglenozoa → flagellated protists

• single large mitochondrion with unique organelle kinetoplast

• symbiotic and include pathogenic parasites

kinetoplast

housed extracellular DNA

found in saccostomae (kinetoplastids)

metamonada

• multiple flagella (2,4,8)

• lack mitochondria

• intestinal symbionts

• ex Giardiais

Giardiais

parasite that infects human intesine, in phylum metmonada

Dinoflagellates

• abundant components of phytoplankton

• foundation of food chains

• some heterotrophic

• most unicellular, some colonial

• characteristic shape reinforced by internal plates of cellulose

• 2 flagella sit in grooves of armor and spin it

• lead to blooms that produce toxins

  • deadly to fish and humans

• some bioluminescent driven by ATP

sporozoa / apicomplexa

• spore forming protozoa

• endoparasites of animals

• intricate life cycle with sexual and asexual stages

  • requires 2+ hosts for completion

• 2 major groups

  • gregarines - parasites of insects/invertebrates

  • coccidians - parasites of invertebrates (intermediate hosts) and vertebrates

subphylum coccidiomorpha

plasmodium, parasite that causes malaria

in phylum sporozoa

plasmodium falciparum life cycle

• malaria

• sexual cycle (in mosquito)

  • female mosquito bites human and ingest gametocytes oocyst → sporogony occurs → sporozoites develop in oocyte → migrate and released in salivary gland

Asexual cycle (in human)

• sporozoite released in saliva → migrate to liver → enter liver cells and undergo schizogony → merozoites released

in RBC

• → merozoites enter blood cells and undergo schizogony → macrogametocyte → microgametocyte → trophozoite → merozoites released and cycle continues

choanoflagellates

• metazoans

• 150 spp

• no fossil record

• smore secrete delicate Loricae

  • outer coverings of interwoven silica bars

• some are colonial for part of their life (proterospongia)

proterospongia

• choanoflagellates → metazoans

• colonial for part of their life

• cells embedded in jelly-like matrix

• primitive cell differentiation

  • flagellated cells with colors move colony through water

  • amoeboid cells on inside grow and divide to grow colony

protostome development

• spiral and determinate cleavage

• schizocoelous

  • solid masses of mesoderm spits to form coelom

• blastopore → mouth

deuterostomes development

• radial and intermediate cleavage

• enterocoelous

  • folds of archenteron forms coelom

• blastopore → anus

occluding cell junction

seal off intracellular space from environment

• septate junctions - all invertebrates

• tight junctions - vertebrates, tunicates, some arthropods

desmosomes cell junctions

used for adhesion

gap junctions

chemical and electrical communication → in hydrozoa and bilateria

acoelomate

• body covering from ectoderm

• tissue filled region from mesoderm

• digestive tract from endoderm

pseudocoelomate

• body covering from ectoderm

• muscle layer from mesoderm

• digestive tract from endoderm

coelomate

• body covering from ectoderm

• tissue layer lining coelom and suspending organs from mesoderm

• digestive tract from endoderm