Mod 2

• 3 domains of life

  Bacteria, Archaea, Eukarya
• Bacteria and Archae


  prokaryotes

  single-celled

  3 RNA polymerase (archaea)

  1 RNA Polymerase (bacteria)
• prokaryote vs eukaryote cells

  Eukaryotes= nucleus, membrane-bound organelles, cytoskeleton

  
  

  Prokaryotes= no genuine nucleus, no real cytoskeleton, no membrane-bound organelles
• Plant Characteristics


  autotrophs

  multicellular

  photosynthetic
• Fungi characteristics


  1. Heterotrophic

  2. Multicellular

  3. Carbon cycling
• Characterise organism as an animal


  central nervous system + muscle tissue

  collagen as 'cell wall'

  consume nutrients
• defining characteristics of sponges


  lack tissues + nervous system

  pores

  filter-feeding

  2 layer wall (ectoderm and endoderm)
• Define the term diploblastic

  2-layer germ layer

  give rise to tissues + organs of embryo

  lacks true symmetry + tissues (basal)
• Diplobastic layers


  Ectoderm (germ layer covering surface)

  Endoderm (innermost germ layer lines (archenton) digestive )
• triploblastic


  bilateral symmetry (right + left) (dorsal + ventral) (anterior + Posterior)

  coelom + digestive tract = 2 opening

  Ectoderm, mesoderm, endoderm
• characteristics of ctenophores


  100sp

  comb jellyfish

  diploblastic

  radially symmetrical

  8 combs of cilia (propellers)

  specialised cells in tentatives (nematocysts to entrap prey)

  true tissues
• Defining characterists of cnidarians


  Sessile (upright) polyp (adheres to substrate by aboral end)

  motile medusa (bell-shaped) (mouth on underside)

  Radially symmetrical

  diploblastic body

  gastrovascular cavity (mouth/anus)

  carnivores= cnidocytes (tentacles capturing)

  nematocysts= organelles within cnidocytes eject sting thread

  nerve net- sensory organs around medusa
• EUMETAZOA


  clade w real tissues (most bilateral)
• Radial symmetry


  round shape that is symmetrical

  jellyfish, starfish
• Bilateral vs radial


  all bilateral animals are triploblastic

  all radial animals are diploblastic
• Diplo vs Triplo


  sponges + other groups (lacking tissues)= lack symmetry.

  triploblastic = body cavity.

  diploblastic= no organs

  Diploblastic/ Triploblastic=tissues + nervous system.
• Types of tissues that derive from ectoderm, mesoderm and endoderm


  Ectoderm (epidermis, nervous system, lens, mammary glands)

  
  

  mesoderm (heart, blood, kidney, connective tissue)

  
  

  Endoderm (intestines, bladder, colon, liver, stomach, lungs )
• lophotrochozoans


  most diverse

  crown of ciliated tentacles (feeding)

  distinctive stage

  \within the protostomes= flatworms, annelid & Molluscs.
• acoelomate


  an animal that lacks a coelom, or body cavity
• Platyhelminthes


  free-living flatworms (planarians) ] live in marine/freshwater

  gastrovascular cavity

  high surface to volume ratio

  
  

  parasites, flukes and tapeworms

  acoelomates

  have a central nervous system
• (trematode) flukes:


  hermaphroditic

  human parasites - snail hosts

  produce surface protein (hirudin) as their host and manipulate the host's immune system
• blood fluke:


  reproduce sexually in the human host

  the fertilized eggs exit in host's faece

  eggs develop into larvae via faece in water, larvae infect snails (become intermediate host)

  asexual reproduction in snails + types of motile larvae produced, then escape from the snail host
• (Cestode) tapeworm:


  hermaphroditic

  parasites of vertebrates (pigs and cattle)

  have no mouth or gastrovascular cavity, they absorb nutrients directly from host's body

  have suckers and hookers for attaching to the host

  sexually produced fertilized eggs leave the host's body through faece
• molluscs


  snails, slugs, oysters, squids, clams....most are marine

  soft body, hard shell made of CaCO3

  squids, slugs have lost their shell completely during evolution

  body plan: muscluar foot, visceral mass, mantle

  Feed with a strip-like radula

  Many are hermaphrodites

  Many molluscs= ciliated larva stage(trochophore) (free-swimming larva)
• four classes of mollusc


  Polyplacophora (chitons)

  Gastropoda (snails, slugs)

  Bivalvia (clam, oyster)

  Cephalopoda (squid)
• polyplacophora (chitons)


  oval-shaped marine animals

  use foot grip= rock

  radula=scrape algae
• Gastropoda(snails, slugs):


  75% of molluscs

  move slowly= rippling motion of their foot or cilia

  most= shell against dehydration.

  most= herbivores

  musclar foot, visceral mass, mantle
• Bivalvia (clam, oyster):


  shell divided into halves joint together by muscles

  have eyes + sensory tentacles along mantle

  mantle cavity= feeding + gas exchange

  limited motlity
• cephalopoda (squids):


  immobilize prey with poison from their saliva

  foot =muscular excurrent siphon (part of the tentacles)

  closed circulatory system
• annelids (earthworm)


  repeating segments + fused rings (metameric)

  use setae for swimming

  coelomate

  setae/ chaetae) provide anchorage or used for swimming (not in leech)

  no eyes/tagmata
• two clades of annelids


  errantia (mostly motile marine predators)

  sedentaria (leeches, earthworm)
• functioning of the excretory system of an earthworm

  nephridia (pair of pores in each segment) contain absorption walls for the absorption of essential for absorbing nutrients

  ciliated tubules push the waste out of the body.

  Wastes are eliminated through the same opening as the digestive wastes.
• Ecdysozoans


  shed cuticle as they grow

  8 animal phyla

  more known species than all other groups combined
• nematodes (roundworm)


  non-segmented

  mostly aquatic habitats, soil, plant/animal parasite

  25,000 sp

  decomposition + nutrient cycling

  gas diffusion

  Alimentary canal

  pseudo-coelomic body cavity (organs suspended in fluid)
• arthropods


  metameric

  3 tagmata

  jointed legs (energy efficent)

  waterproof exoskeleton (polysaccharide chitin)

  moult

  bilaterial
• arthopod - annelid


  metamerism
• Arthopod growth + exoskeleton structure


  moulting

  exoskeleton secreted by epidermal (hypodermis below cuticle)

  upper part of the procuticle= be hardened sclerotization or CaCO3

  lower procuticle= flexible for joints
• Crustacean


  thorax 8 segment, abdomen 6 segment

  2 pair of antennae

  biramous limbs

  metameric

  3 tagmata

  compound eyes
• Insects


  1 pair antennae

  1 pair compound eyes

  thorax- 3 pair legs, 2 pair wings

  metameric

  3 tagmata

  waxycuticle
• millipede vs centipede


  Millipedes - Diplopoda

  • 2 pairs of legs per segment

  • Herbivores and detritivores

  
  

  Centipedes - Chilopoda

  • 1 pair of legs per segment

  • Carnivores