Unikonta Flashcards
Amoebozoa
includes lobose amoeba and slime molds
slime molds
type of amoebozoa
originally classified as fungi
individuals come together to form “supercell” with many nuclei
important role in nutrient recycling
amoeboid motion
amoeboid motion
sliding movement
extension of pseudopodia
rest of cell follows
requires ATP and coordination of actin and myosin in the cytoplasm
motion also used in phagocytosis feeding
fungi
oldest fossils 440 mya
unicellular (yeasts)
multicellular (mycelium)
-hyphae and mycelium
heterotrophs
- release digestive enzymes into the environment (extracellular digestion)
- absorb molecules through their cell walls
no locomotion
-grow and retract in response to resources in the environment
hyphae
slender filaments with high surface area for absorbing nutrients
mycelium
dense mats of hyphae
extracellular digestion
releasing digestive enzymes into the environment
fungi hyphae
long, narrow filaments with lots of branches
cell walls typically made of chitin
most have septa- cross walls
-contain pores that enable materials to be passed between compartments
others are coenocytic- without septa, have many nuclei
thinner than plant root hairs, so can access tighter spaces in soils
because hyphae are so thin, fungi have very high surface-to-volume rations
increases capacity for absorption
also increases evaporation of water
-most fungi live in moist habitats
chitin
what makes up the cell walls in fungi hyphae
septa
cross walls in fungi hyphae
contain pores that enable materials to be passed between compartments
coenocytic
the state of fungi hyphae that do not have septa and have many nuclei
fungi reproduction
mushrooms are the fruiting (reproductive bodies of mycelium species
made of dense hyphae
produce spores that are responsible for dispersal
nature’s recyclers
carbon cycle
- fixation by primary producers
- release by cellular respiration
fungi often responsible for linking these two parts of cycle breaking down dead plants
carbon cycle
fixation by primary producers
release by cellular respiration
decomposers
main role in ecosystem is decomposing organic material
saprophytic
recycle key elements like carbon, nitrogen, and phosphorus for plants and animals
requires ability to digest lignin and cellulose
-only fungi and a handful of bacteria can digest both
saprophyte
organism that feeds primarily on dead organic matter
lignin and cellulose digestion
plant cell walls contain strong polymers lignin and cellulose that makes them difficult to digest
without fungi the terrestrial habitats of Earth would be covered in dead trees
lignin peroxidase- breaks down lignin
-lignin is not infested, but needs to be broken down to expose cellulose
several cellulase enzymes
-cellulose broken down into monomer (glucose) for consumption
mutualistic relationship example
leaf cutter ants and fungi
mycorrhizal fungi
mycorrhizal fungi
mutualistic relationship between fungi and plant roots
fungi receives carbohydrates from plants
plants receive nutrients like phosphorus and nitrogen from fungi
fungi interactions with humans
penicillin: antibiotic derived from fungus
food, leavening agent, fermentation
also used in some detergents and pesticides
loss of food due to blights or spoilage
Humongous fungus
largest organisms on Earth
honey mushroom in eastern Oregon
about 3.5 square miles
confirmed with DNA testing
choanoflagellates
closest extant relatives of animals
unicellular protists
“collared flagellates”
common in freshwater and oceans
sessile: live permanently attached to substrate
many species form colonies
sessile
live permanently attached to substrate
animal characteristics
all are multicellular heterotrophs
all animals move under their own power at some point in their life cycle
all except sponges have neurons and muscle cells
usually invest food before digestion
oldest animal lineages
porifera (sponges)
ctenophora (comb jellies)
cnidaria (jellyfish, corals, sea anemones)
aceola (acoels)
porifera (sponges)
earliest animals in the fossil record
-635 mya; before cambrian explosion
primarily sessile
lack complex tissues, but have “tool kit” of genes related to complex process
e.g. specialization of cells, regulation of cell growth, cell-cell adhesion
choanocyte- specialized feeding cell
support achieved by:
- secreted exoskeleton of calcium carbonate
- spicules
- spongin fibers
- can be combinations of 3
choanocyte
specialized feed cell, in Porifera
beating flagella creates water current
organic debris collected
spicules
silicia or calcium carbonate
secreted exoskeleton
made of calcium carbonate
spongin fibers
collagen protein
ctenophora (comb jellies)
oldest fossils
-550 mya; before cambrian explosion
move via eight combs of cilia
- largest organisms to move using cilia
- range from few mm to 1.5 m
radial symmetry
capture food with sticky colloblast cells
decentralized nerve net
embryos for most species are diploblasts
two type of germ layer tissues
- ectoderm (outer)
- endoderm (inner)
History view: porifera-first hypothesis
favored based on parsimony evolution of morphological characters
also supported by some genomic studies
alternative view: ctenophore-first hypothesis
requires more steps (against parsimony)
some molecular evidence that Ctenophore neurons are not homologous to neurons of other animals
supported by most recent genomic studies
cnidaria
oldest fossils
-55 mya; before Cambrian explosion
variety of mostly marine species: anemones, corals, hydrozoans, jellyfish, box jellies
cnidocytes: specialized cells for capturing prey or defense
- usually on tentacles or near cavity opening
- eject a barbed, spear-like structure that may contain toxins
diploblast embryos
- in developed individuals:
- ectoderm and endoderm layer surround gelatinous mesoglea
- gastrovascular cavity with one opening
diffuse nerve net via hydra
jellyfish life cycle
includes a sessile polyp and a free-floating medusa
cnidaria- radial or bilateral symmetry
recent research shows that cnidarians genes related to bilateral symmetry
-Hox and app genes
while genes involved and complexity not as extensive, provides evidence that some genetic tools for bilateralism evolved early
Bilateria- traits of common ancestor
- bilateral symmetry
- complete digestive tract with mouth and anus
- cephalization
- central nervous system
- triploblast embryos
- coelom
cephalization
evolution of the head (anterior) region where feeding, sensing environment, and information processing is concentrated
central nervous system
neurons clustered into one or more tracts through body
contests the nerve net- diffusion of neurons in hydra
ganglia
a mass of neurons in a centralized nervous system
triploblasty
three germ layers:
ectoderm- skin and nervous system
endoderm- lining of the digestive tract
mesoderm- circulatory system, muscle, internal structures
ectoderm
skin and nervous system
endoderm
lining of the digestive tract
mesoderm
circulatory system, muscle, internal structures
lines the coelom
coelom
fluid-filled cavity between the inner and outer tubes
lined with mesoderm
‘tube-within-tube’ body plan
found in most bilateria
provides a hydrostatic skeleton
hydrostatic skeleton
gives support and allows movement for soft-bodied animals without limbs/fins
provided by the coelom
bilateria transitions to land
the oldest fossils: around Cambrian explosion and were marine
still abundant in aquatic environments, but also multiple transitions to land after Cambrian explosion (after land plants)
terrestrial selective pressures in transition to land
- gas exchange
- desiccation (dehydration)
- support of body weight
some adaptations in transition to land
respiratory structures inside the body to reduce water loss
reduced porosity of surface
better able to move, seek suitable environment
gastrulation
early developmental phase during which the three germ layers are formed
either protostome or deuterostome
protostome
“first-mouth”
pore becomes mouth
deuterostome
“second-mouth”
pore becomes anus
Lophotrochozoa
includes Platyhelminthes (flatworms) and Mollusca
Platyhelminthes (flatworms)
flattened, unsegmented body
found in marine, freshwater, and moist terrestrial environments
loss of coelom
digestive tract with only one opening
some are endoparasitic
e.g. tapeworms
Mollusca (mollusks)
- bivalvia (clams, mussels, scallops, oysters)
- cephalopoda (nautilus, cuttlefish, squid, octopuses)
- gastropoda (snails, slugs, nudibranchs)
- polyplacophora (chitons)
body with three major parts: foot, visceral mass, mantle
foot (mollusks)
large muscle at base of individual, usually used for movement
a type of muscular hydrostat
snails-waves of muscle contraction along foot allows individuals to “crawl”
bihalves- digging appendage
cephalopods - forms tentacles for crawling and grasping
visceral mass
region containing most of the internal organs as well as external gill
separates internal organs from the foot (hydrostatic muscle)
contains the radula
-specialized feeding structure with sharp plates that rasp/file food
mantle
outgrowth that covers the visceral mass
secretes a hard protective calcium carbonate shell in many species
may have evolved in response to selection pressures imposed by predation during Cambrian
shells are heavy
- trade-off between protection and mobility
- thick shells usually in marine species (water supports weight)
muscular hydrostat
type of hydrostatic skeleton giving support to the body
e.g. the foot of mollusks
radula
specialized feeding structure with sharp plates that rasp/file food
part of the visceral mass
lost in bivalves
Ecdysozoa
includes nematoda and arthropoda
Nematoda (nematodes)
round, unsegmented worms (roundworms)
molt during growth
widespread and can be abundant
-90,000 in single apple, ~1 billion per acre of rich farm soil
free-living and parasitic species
main athropoda lineages
pancrustacea (crabs, crayfish, shrimp, barnacles, insects)
myriapods (millipedes, centipedes)
chelicerata (horseshoe crabs, sea spiders, arachnids)
arthropoda characteristics
grow by molting an outer exoskeleton
- made primarily of the polysaccharide chitin
- provides protection
- structure for muscle attachment
movement possible due to jointed appendages
body is segmented into discrete regions (tagmata)
modular body plan
-gene expression patterns create a wide diversity of functions for different body parts
jointed appendages
makes movement possible for arthropoda
tagmata
the discrete regions that the body of arthropoda are segmented into
modular body plan
gene expression patterns create a wide diversity of functions for different body parts
Insecta metamorphosis
hemimetabolous metamorphosis
-juvenile nymphs are small, but are often adults in body plan and niche
holometabolous metamorphosis
- distinct large larval stage
- after growth, larva secretes pupa (protective case)
- body plan is completely remodeled
- emerges as adult
hemimetabolous metamorphosis
juvenile nymphs are small, but are often adults in body plan and niche
holometabolous metamorphosis
distinct large larval stage
after growth, larva secretes pupa (protective case)
body plan is completely remodeled
emerges as adult
homometaolous species are a monophyletic clade
hemimetabolous and holometabolous species
homometaolous species are a monophyletic clade
hemimetabolous- 130,000 holometabolous-850,000
hypotheses?
- reduced competition between stages
- increased specialization between stages
Deuterostomes
includes echinodermata and chordata
echinodermata characteristics
sea stars, sea urchins, sand dollars, sea cucumbers
“spink-skins”
larvae have bilateral symmetry
adults have pentaradial symmetry
-5 sided radial symmetry
loss of cephalization
-can interact with environment using all five sides at once
endoskeleton: internal skeleton for protection and support made of calcium carbonate
water vascular system
endoskeleton
internal skeleton for protection and support made of calcium carbonate
water vascular system
water moves via beating cilia
tube feet appendages
-used for capturing prey suspension feeding, deposit feeding
in echinoderms
main chordata lineages
chephalochodata (lancelets)
urochordata (tunicates)
vertebrata (jawless fish, shark/rays, bony fish, amphibians, reptiles/birds, mammals)
chordata characteristics
pharyngeal gill slits
- used for filter feeding in aquatic chordates
- only present in embryonic stages of tetrapods
hollow nerve chord is dorsal
-lost in adult urochordates
notochord
post-anal tail
vertebrata
includes jawless fish, sharks/rays, bony fish, lobe-finned fish, amphibians, reptiles/birds, mammals
notochord
in chordata
origin yet flexible
becomes intervertebrate discs in vertebrates
pharyngeal gill slits
- used for filter feeding in aquatic chordates
- only present in embryonic stages of tetrapods
Extracellular matrix
includes proteins specialized for cell-cell adhesion and communication
benthic
live at the bottom of aquatic environments
colonies
groups of individuals attached to each other
coelomates
bilaterians whose coelom is completely lined with mesoderm
acoelomates
bilaterians that have no coelom
e.g. Platyhelminthes (flatworms)
pseudocoelomates
bilaterians whose coelom is only partially lined with mesoderm
e.g. Nematoda (roundworms)
cephalothorax
“head-chest”
simple eyes
few to many clustered on the sides of the head
a compound eye
contains many lenses, each associated with a light-sensing, columnar structure
siphons
tubes formed by muscle that lines the mantle in bivalves and cephalopods
