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BIOL371 Comparative Biology of Plants and Animals > Theme 2 > Flashcards

Theme 2 Flashcards

1
Q

Opisthokonts

A
  • Animals, fungi, choanoflagellates
  • single posterior (opisthios) flagellum (kontos)
  • Flattened cristae in mitochondria (but variable)
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2
Q

Choanoflagellates

A
  • opisthokont eukaryotes
  • sessile
  • closest to Animalia among opisthokonts
  • “collar” around the flagellum consists of contractile microfibrils
  • currents set up by flagellar action carry food particles into collar, trapped and carried down to cell – filter feeding
  • choanocytes in Porifera (sponges) strongly resemble individual choanoflagellates
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3
Q

Origins of Opisthokont ANIMALS

A

Likely originated from a colony of choanoflagellates

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4
Q

Opisthokont ANIMALS

A
  • Multicellular eukaryote
  • Chemoheterotrophic
  • Cell membranes contact adjacent cell membranes (no cell walls)
  • Motile (capable of self-directed movement at some life stage)
  • Oxidative Phosphorylation to supply ATP
  • Sense and respond to the environment rapidly
  • Extracellular digestion
  • Sexual reproduction featuring eggs and sperm
  • Sperm and eggs are single cells
  • Diploid is dominant (usually), haploid short-lived
  • 3 diagnostic characteristics, only found in animals: Develop from a blastula, Certain extracellular matrix molecules (e.g. the proteoglycan collagen), Certain cell-cell membrane junctions
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5
Q

Archaeplastida PLANTS

A
  • multicellular eukaryote
  • photoautotrophic (mostly) – fix inorganic carbon using light energy
  • Cell walls– cell membranes not in contact
  • Sessile
  • Alternation of generations life cycle
  • haploid (gametophyte) stage alternates with a diploid (sporophyte) stage
  • both are prominent/multicellular
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6
Q

Secondary endosymbiosis:

A
  • heterotrophic eukaryote cell engulfs symbiotic photoautotrophic eukaryote
  • photoautotroph evolves into chloroplast with four membranes
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7
Q

Opisthokonts and Archaeplastida Diverge

A
  • Cell Structures differ
  • In plants, we see: cell wall, large vacuole, chloroplasts
  • Photoautotrophs vs. chemoheterotrophs
  • Mobility (in Plants): don’t need to move to acquire energy and carbon, but move in different ways i.e growing
  • Mobility and motility (in Animals): Eat things to acquire energy and carbon, must be mobile (usually) to acquire food, many consequences of being mobile
  • Most animals are diploid as the dominant stage with haploid stage reduced to unicellular gametes
  • Alternation of Generations in land plants
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8
Q

Consequences of being mobile for animals:

A
  • Muscle
  • Well developed senses and cephalization
  • Nervous systems
  • Digestive system
  • Excretory system – eliminate nitrogenous wastes
  • Skeletal system – endo- and exo-, hydrostatic
    locomotory mechanism
  • High metabolic rate – cells; requires bulk flow and gas exchange systems
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9
Q

Classification of Plants and Animals

A
  • systematics is the science of classification of the living world (including fossil forms)
  • Organisms classified/grouped based on inferences of evolutionary relatedness: genetics, morphology, physiology, behaviour, heritable traits – shared derived characters
  • use cladistic principles to derive phylogenies for the groups that we are classifying
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10
Q

What is a clade?

A

a monophyletic group composed of taxa with a unique common ancestor and sharing synapomorphies (shared derived characters)

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11
Q

cladistic phylogenies are:

A

hypotheses, which estimate evolutionary relationships based upon distribution and congruence of synapomorphies
- can be used to make predictions about data not yet found (intermediate forms, fossil history)

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12
Q

the likeliest phylogeny is the one requiring the least amount of:

A

proposed evolutionary change in a character – the most parsimonious

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13
Q

History Of Animals – The Cambrian Explosion

A
  • Burgess Shale fauna – 525-515 Mya
  • first diverse fauna of large complex multicellular animals
  • first recognizable representatives of most modern animal phyla
  • first fauna with eyes and jaws
  • first fauna with bilaterian component
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14
Q

The Cambrian Explosion

A

sudden appearance of this diverse complex fauna, apparently without antecedents

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15
Q

Homeotic genes

A

Genes specifying the development of specific structures at particular locations during embryogenesis - responsible for symmetry, antero-posterior and dorso-ventral axes
Appear to be strongly conserved among Animalia

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16
Q

How do homeotic genes map onto phylogenies?

A

Predictions:

  • strong relationship between chronological order of appearance of major groups, morphological complexity and body size, and number of homeotic genes
  • unique body plans associated with unique homeotic genes
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17
Q

Hox genes

A
  • linear cluster of homeotic genes involved in embryonic pattern formation
  • number varies among taxa
  • number increases with phylogenetic position and complexity (with some losses - insects vs crustaceans, myriapods)
  • linear increase most parsimoniously explained by gene duplication
18
Q

Strong inference that Cambrian Explosion closely associated with:

A

Elaboration of hox clusters. However, morphological complexity not directly correlated with Hox cluster complexity.

19
Q

Most animal phyla was established in the:

A

Cambrian Explosion

20
Q

Changes in homeotic genes and in gene regulation enabled:

A

Rapid diversification of body form - Cambrian Explosion represents an adaptive radiation of Animalia

21
Q

Animal Classification: Tissue layers and Symmetry

A
  • Ectoderm, mesoderm, and endoderm
  • diploblastic (radial) have ecto/endoderm
  • triplovlastic (bilateral) have ecto/meso/endoderm
22
Q

Development of Bilateria

A
  • Protostome (mouth first)

- Deuterostome (anus first)

23
Q

Protostome

A
  • Spiral cleavage
  • Schizeocoelous coelom
  • Blastopore forms the mouth
  • Determinate cleavage
  • Ventral nerve cord that surrounds the digestive tract anteriorly
24
Q

Deuterostome

A
  • Radial cleavage
  • Enterocoelous coelom
  • blastopore forms the anus
  • Indeterminate cleavage
  • Dorsal nerve cord, brain does not surround digestive tract
25
Q

Protostomes are further divided into:

A
  • Lophotrochozoans (some have a trochophore larva, some have lophophore feeding structure)
  • Ecdysozoans (external cuticle that is shed to grow (ecdysis))
26
Q

Other cues to taxonomy

A
  • Body segmentation (metameric segmentation repeating: chordates, arthropods, earthworms)
  • Dorso-ventral orientation of C.N.S and main elements of circulatory system
  • Molecular evidence like DNA and proteins are now primary source of info about phylogenies
27
Q

Phylum Ctenophora: The Comb Jellies

A
  • Sister group to all other animals
  • Gelatinous body
  • “Combs” are rows of fused cilia that are used in locomotion
28
Q

Phylum Porifera (sponges)

A
  • Asymmetrical
  • para(beside)zoans - no true tissues - neither diploblasts or triploblasts
  • sessile as adults (no nerves, filter feeders)
  • choancytes’ coordinated flagellar action produces inward water currents
  • suspension feeders - choanocytes filter food particles out of water
  • very similar to choanoflagellates
29
Q

Phylum Cnidaria

A
  • Radial (or biradial/rotational) symmetry, diploblastic

- jellyfish, sea anemones, coral, hydra (cnidaria)

30
Q

Cnidocytes and Nematocysts

A
  • Harpoon-like nematocysts are microscopic structures found in epidermis of cnidarians
  • Contact triggers the ejection of nematocysts
  • nematocysts of some cnidarians inject toxins into predators or prey
  • some forms are colonial with specialized individuals
31
Q

Phylum Rotifera

A
  • 1mm, crown of cilia for feeding
32
Q

Bilaterally Symmetrical

A
  • Protostomes and Deuterostomes - all Triploblasts

- Protostomes - most diverse animal group

33
Q

Phylum Platyhelminthes

A

Platy = flat, helminthe = worm

- scavengers, predators, ectoparasites, liver fluke, tapeworms

34
Q

Phylum Mollusca

A
  • calms, oysters, scallops, mussels, snails, octopi, squid

- all have head/foot, visceral mass, mantle

35
Q

Phylum Annelida

A
  • segmented worms

- earthworms, marine/bristle worms, leeches

36
Q

Ecdysozoans

A
  • external cuticle of chirin protects animal, must be shed for animal to grow, this is shared derived morphological and developmental feature that is secreted by epidermal cells
37
Q

Phylum Nematoda

A
  • roundworms

- v important in agriculture, medicine, and research

38
Q

Phylum Arthopoda

A
  • largest animal phylum
  • arthro (joint), poda (feet), exoskeleton, segmented body
  • insects, spiders/mites, scorpions, crustaceans, centipedes and milllipedes
39
Q

Phylum Echinodermata

A
  • echino (spiny) dermata (skin)
  • starfish, urchins, sand dollars, brittle stars, sea cucumbers
  • bilaterally symmetrical larvae
  • pentaradiate (5) symmetry as adults
  • water vascular system and tube feet
40
Q

Phylum Hemichordata

A

Acorn worms

41
Q

Phylum Chordata

A
  • Supbphyla Urochordata, Cephalochordata, and Vertebrata

- notochord, pharyngeal gills silts, dorsal hollow nerve cord, segmented muscle/posr-anal tail

BIOL371 Comparative Biology of Plants and Animals (10 decks)

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