Midterm 2 Flashcards
characteristics of eukaryotic cells
- presence of a nucleus
- dynamic cytoskeleton and membranes
endosymbiotic hypothesis (theory of endosymbiosis)
chloroplasts and mitochondria of eukaryotic cells were originally free-living bacteria that were incorporated into a host cell
- each have 2nd membrane and own DNA
- genes lost by transfer to nucleus
Eukaryotic kingdoms
animals, plants, fungi, protists
now 7 super kingdoms:
1) opsithokonts
2) amoebozoans
3) archaeplastids
4) stramenopila
5) alveolata
6) rhizaria
7) excavata
cytoskeleton
internal protein scaffolding – filaments of actin and microtubules
- can be remodeled quickly, enabling cells to change shape (not possible with cell wall)
- functional flexibility: movement to obtain food, vacuoles and organelles to store and digest
- enables endo/exocytosis
endo/exocytosis
membrane-lined vesicles transport through the cytoskeleton by molecular motors (much faster than diffusion) allows eukaryotes to grow in size
endomembrane system consists of:
nuclear envelope, ER, Golgi apparatus, cell/plasma membrane
phagocytosis
engulfing of food particles, even other cells
eukaryotic metabolism localized in:
mitochondria and chloroplasts
Eukaryotic DNA organization
–multiple linear chromosomes & multiple replication sites allow for rapid and simultaneous replication
(singular circular prokaryotic DNA harder for fast replication)
–non-coding DNA functions in gene expression
–more complex, different cell types, growth & development
eukaryotes w/ bacteria and archaeons
eukaryotes did not outcompete bacteria and archaeons but developed novel functions
sex promotes genetic diversity via:
1) meiotic division produces genetically unique daughter cells
2) recombination
3) independent assortment
4) fertilization – egg and sperm combinations
symbiont
organism that lives in closely evolved association with another species
protist diversity
algae - photosynthetic protists
protozoa - heterotrophic protists
some live in tests – “houses” constructed of organic molecules
Opsithokonts
- most diverse eukaryotic superkingdom (75% of all species 1.8 mil + species)
- flagellated cells - single flagellum
- (animals and fungi) heterotrophic, but some have photosynthetic symbionts
- includes choanoflagellates
- includes microsporidia: parasites inside animal cells; spores in external enviro
choanoflagellates
group of mostly unicellular protists within the superkingdom opsithokonts.
characterized by ring of microvilli: fingerlike projections that form a collar around the cell’s single flagellum
– close relationship to animals
Amoebozoans
group of eukaryotes with amoeba-like cells that move and gather food by means of pseudopodia
- more than 1000 species described
- plasmodial slime molds are coenocytic: multiple nuclei within one giant cell
- cellular slime molds aggregate into a multicellular “slug” for feeding
Archaeplastids
- 2nd most conspicuous and diverse group of eukaryotes
- includes land plants
- nearly all photosynthetic; direct descendants of protist that first evolved chloroplats from endosymbiotic cyanobacteria
- includes galucocystophytes: small group of single-celled algae found in freshwater ponds and lakes w/ more features of ancestral cyanobacterial endosymbiont than any other algae
- includes red algae
- includes green algae (viridoplantae)
red algae
- 5000+ species known, mostly marine enviro and multicellular
- principle photosynthetic pigment is chlorophyll a
- coralline algae secretes CaCO3 – live by corals – resist breaking waves
- nori, agar
green algae
from viridoplantae
- diverse assortment ~10,000 marine species, some coenocytic
- have chlorophyll a and b in chloroplasts
- unique attachment for flagella
Stramenopiles
- characterized by two flagella – one smooth, one hairy
- includes brown algae (giant kelps) and protozoa (free living cells & parasites)
- include diatoms
diatoms (stramenopiles)
- skeletons/cell walls of silica
- 1/2 of all primary production in the ocean
- 1/4 of all photosynthesis on earth (more than tropical rainforests)
- 10,000+ known species
Alveolates
cortical alveoli – small vessicles packed beneath the cell surface; in some store calcium ions for use by the cell
- dinoflagellates – photosynthetic, cellulose walls, red tide, bioluminescence
- ciliates – heterotrophic protists with two nuclei in each cell and numerous short flagella (cilia)
- apicomplexans, plasmodium species causes malaria
Excavata
- free-living, parasitic or symbiotic
- - includes euglenids (have chloroplats) and giardia (causes diarrhea)
eukaryotic lifestyle
alternation between sexual and asexual
alternation between haploid and diploid phase
animals – multicellular stage is diploid (dominates life cycle), only haploid phase is gamete
plants – 2 multicellular phases, 1 haploid, 1 diploid
advantages of sexual reproduction
- new combinations of alleles
- can produce new genotypes
- provides variation w/ new allel combos
- clears deleterious mutations
evolution of complex multicellularity
~550 MYA
– came with the rising O2 levels - oxygen necessary for multicellular life
arose six times in evolution - red algae, brown algae, green algae –> land plants, animal, fungi (twice)
bulk transport
means by which molecules move through organisms at rates beyond those possible by diffusion across a concentration gradient (i.e. pumping of blood)
– more effective than diffusion (from unicellular organisms)
Multicellular organism characteristics
1) adhesion (stick together)
2) specialized structures for communication
3) tissue and organ differentiation
4) small subset of reproductive cells
5) cell or tissue loss can be lethal to organism
6) 3-dimensional – presence of interior and exterior cells
epithelia
lining of tissues
secrete ECM
animals – cadherins, integrins, transmembrane proteins provide molecular mechanism for adhesion
plants – pectin (fruit jelly)
gap junctions
facilitate targeted transport of ions and molecules between adjacent cells in animals
plasmodesmata
facilitate targeted transport of ions and molecules between adjacent cells in plants
meristem
population of actively dividing cells at the tips of stems and roots
– permanently undifferentiated
gastrulation
movement of cells during embryogenesis that transforms the blastula –> gastrula
gastrula
brings cells into direct contact for signaling for growth and development throughout the body not just “meristem” area (in animals)
simple multicellularity
1) cell adhesion
2) little communication between cells
3) little/no differentiation of specialized cells
4) most cells have all functions and reproduction
5) every cell in contact with external enviro
selective advantages of multicellularity
1) avoid protozoan predators
2) better maintain position on a surface or in water
requirements for multicellularity
1) cell adhesion
2) communication (via gap junctions/plasmodesmata)
3) genetic program for development (network of genetic interactions for cell division and differentiation)
regulatory genes
genes that prompt expression/repression of another gene
– played important role in evolution of complex multicelluar organims
dessication
excessive water loss
vascular plants
have the ability to draw water from the soil and limit water loss from leaves
vascular plants
> 95% of all land plants today
1) ferns + horsetails
2) gymnosperms (seeded) - pine trees, conifers
3) angiosperms (seeded) - flowering plants: trees, grasses, sunflowers
4) lycophytes - forms sister group to all other vascular plants
dessication tolerance
suite of biochemical traits that allows cells to survive extreme dehydration without damage to membranes or macromolecules
- feature of bryophytes - resume photosynthesis w/ return of water
- vascular plants just draw from soil
shoot
composed of leaves, stem, and reproductive organs
roots
4th organ system
root apical meristem covered by root cap
leaf
main site of photsynthesis
- epidermis - upper and lower surface lining
- mesophyll - “middle leaf” photosynthetic cells
- veins - connects leaf to rest of the plant
CO2 and H20 exchange
CO2 diffuse in –> H20 diffuse out
hot day – water conc in mesophyll higher inside – several hundred H20 lost per CO2 for photsynthesis
transpiration
evaporative loss of water vapor from leaves
cuticle
waxy product secreted by epidermal cells to limit water loss – brought to surface by water loss (stimulation)
stomata
small pores in epidermis that regulate diffusion of gases between leaf and atmosphere
solute + H20 uptake –> opening stomata via guard cell swell
release solute + H20 –> closing stomata
fern vs. angiosperm stomataq
fern: guard cells grow and shrink independent of other epidermal cells
angiosperm: guard cell growth –> adjacent cell shrink via k+, cl- transfer, and vice versa
- increases opening, volume of guard cell up to 3x
stomatal stimulation
open: light
close: high CO2 in cell, dehydration, abscisic acid: hormone during drought–prevention
Roles of Plants
- produce oxygen
- contribute to soil (via decomposers)
- protect against erosion - hold soil together
- retain moisture in soil
- buffer local climate
human use of plants
1) agriculture - artificial selection
2) fuel sources - wood, coal
3) forestry - paper, construction
4) bio-prospecting - medicinal uses (taxol cancer drug, aspirin)
5) aesthetically pleasing
epiphytes
plants that grow high in canopy of other plants without soil contact
photoautotrophs
produce own carbon energy source (food) using sunlight
fix carbon
CO2 + H20 –> C6H12O6 + O2
parenchyma
thin walled cells enclosed by epidermis - photosynthesis
make up the mesophyll
phloem
transports carbohydrates from leaves to rest of plant
xylem
- transports water + nutrients from roots to leaves
- have pits, tracheids, and vessels
pit
circular/ovoid region in wall where water enters/exits xylem conduits
tracheid + vessel
tracheids more common in lycoophytes, ferns + horsetails, gymnosperms
- unicellular conduit, pills in secondary cell walls (transport)
vessels found in gymnosperms
- multicellular conduit (ends have gaps through 1st and 2nd wall (transport)
- individual = vessel element
evolutionary increase in vascular tissue
1) simple water-conducting cells
2) first vascular tissue (lignin)
3) tracheids (1st wall with cellulose and 2nd wall with lignin), have pills
4) vessel elements, ends have gaps through both walls
Root structures
Epidermis
- cortex: composed of parenchyma cells
- endodermis: surround xylem and phloem, controls most of nutrients into xylem
Casparian Strip
- thin band of hydrophobic material
- allows selective control of substance flow
- transport via ATP powered proteins
lots of respiration for ATP
mycorrhizae
symbioses between roots and fungi that enhance nutrient uptake
fungi “super root hairs” absorb phosphorous (phosphate ions) give phosphorous, receive carbhohydrates from roots from leaves, release enzymes that enhance PO3 motility
- consume 4-20-% of carbohydrate production
- > 85% of plant species have mycorrhizae
ectomycorrhizae
thick sheath of fungal cells surrounding root tip
endomycorrhizae
arbuscules protrude into root increases contact area
- higher C and nutrient exchange
root nodule
nitrogen fixing bacteria and root cells created when bacteria enter the root
–common in legumes, replenish nitrogen – crop rotation
phloem structures
sieve tubes, companion cell, phloem sap
sieve elements
individual cells that make up sieve tube
-linked by sieve plates - end walls w/ large pores
companion cell
carries out cellular functions (protein synthesis, etc) connected to sieve elements by plasmodesmata
phloem sap
sugar-rich solution that flows through sieve tube lumen and sieve plate pores
rhizosphere
the soil layer that surrounds actively growing roots
-rich in microbial populations that aid in decomposition
sieve tubes transport
sugars, ions, nitrogen, hormones, protein signals, RNA, moves raw material and signaling molecules
trends in plant evolution
- increase in vascular tissue
- gametophyte to sporophyte dominant life cycles (same with dependency)
- evolution of pollen: H20 independent fertilization
- evolution of the seed
bryophytes & life cycle
- mosses, liverworts, hornworts are small, simple, and tough
- many live on branches of trees or rocks (epiphytes)
- 2n zygote, 2n gametophyte, 1n spores, 1 n gametophytes, 1n gametes
- gametophyte photosynthesizes (g-phyte dependent)
- H20 dependent fertilization
- disperse via 1n spores
sporangium
structure that contains thousands of haploid spores
sporopollenin
complex mix of polymers resistant to environmental stress: UV & desiccation, that protects the zygote through the air
alternation of generations
gametophyte and sporophyte can live on their own
- one near ground for fertilization
- one above for dispersal
pollen
multicellular gametophyte within spore wall
liberated seed plants from need for swimming sperm
– allows for air dispersal
pines
ovule cones
- upper branches = female gametes
- lower branches = male gametes
- spores within pollen cones divide mitotically –> gametophyte inside cone
ovule
gametophyte and protection produced from haploid spores
pollination
when pollen reaches ovule
– pollen tube extends from sporopollenin coat and sperm travels through pollen tube
seed
fertilized ovule composed of 3 generations
1) 2n seed coat (product of diploid sporophyte)
2) 1n female gametophyte
3) 2n embryo
dormancy
delays germination until better conditions (smaller seeds)
- sometimes need to be digested in animal
- some require vernalization
- some need light simulation
flower parts
INNER WHORLS
- carpel - ovule producer, includes style, stigma, ovary
style = cylindrical stalk at the top
stigma = sticky/feathery surface at the top of style
- stamen - pollen producer, includes anther and filament
anther = contains sporangia for pollen production and opens for pollen exposure
OUTER WHORLS
- sepal : encases and protects flower during development
- petals : attract and orient animal pollinators, odors
self-compatible (flower reproduction)
pollen and egg from same plant can produce viable offspring
self-incompatible (flower reproduction)
self recognition of S-genes, if too similar, cannot reproduce
double fertilization (flower reproduction)
during pollination:
1 sperm fuses w/ egg
1 sperm fuses with 2n female gametophyte –> 3n endosperm
endosperm
triploid cell that undergoes mitotic division supplying nutrition to the embryo
formed by sperm and female gametophyte fusion
fruit
ripened ovaries–induced by fertilization of ovule
1) enhance seed dispersal
2) protect immature seeds from predators
photoperiodism
describes effect of day length on flowering
short-day plants
only flower when day < critical length
- flower late summer (germinated in spring)
long-day plants
only flower when day length > critical length
- flower in spring (germinated in summer)
photoreceptors
molecules whose chemical properties are altered when they absorb light
vernalization
flowering induced after experiencing a cold period (winter) so it will flower in the spring and not prematurely in the fall/late summer
phytochrome
switches been 2 forms
P fr- active form induced by red light
night resets –> Pr for sunlight day stimulation (circadian rhythm)
-helps detect overhead plants (plants living above another plant) by detecting less red light – avoids growing below it
far red inhibiting germination can be overcome by red light
vegetative reproduction (aspens)
asexual, produces genetically identical clones - grow to new location then produce new plants via horizontal stems
rhizomes - new shoots from horizontal stems
ex: aspen trees - new trees from roots –> stem develops up
thallus
flattened photosynthetic structure of some bryophytes. very thin, no air spaces or water system
peat bogs
wetlands in which dead organic matter accumulates
- store up to 65x the amount of C emitted from fossil fuels
- essential that there is slow decomp
- sphagnum moss slows decomp
lycophytes, ferns, and horsetails
- spore-dispersing vascular plants
- sporophyte dominated
- H20 required fertilization
Rhynie charts
fossils near Rhynie, Scotland provide best view of early vascular plants
- small w/ branches + hairlike rooting structures
- gametophytes not yet reduced
- plants began standing upright before vascular structures developed
gymnosperms
seed plants: cycads, conifers, ginkos, gnetophytes
- woody stems and roots
- sporophyte dominant
- pollen –> H20 independent fertilization
- disperse via seeds (2n)
cycads - large leaves and cones
ginkos - ginko berry female reeks
conifers - (pines, junipers, redwoods), tallest and older, evergreen– pine needles yr round, wind pollinated, some juniper seeds, mostly tracheids not vessels
ferns
- 40% epiphytes
- some have pinnae: smaller divisions of photosynthetic surfaces in ferns
- Azolla - aquatic fern w/ nitrogen fixing cyanobacteria symbiosis –> biofertilizer for rice
land plant phylogenetic tree
1) other green algae
2) coleochaete and chara (closest relative to land plants)
3) liverworts
4) mosses
5) hornworts
6) lycophytes
7) ferns and horsetails
8) gymnosperms
9) angiosperms
fern lifecycle
- 2n sporophyte –> leaf, 1n spores –> gametophytes –> fertilization back to 2n sporophyte
gymnosperm lifecycle
2n fertilized ovule –> seed, 2n sporophyte (tree), 1n gametophytes –> 1n spores, fertilization
advantages of gamete and seed dispersal
- outcrossing –> genetic diversity
- reduced competition for nutrient supply
- pathogen and parasite avoidance
angiosperm advantages
1) flowers - variation in shape color scent size communicates w animal pollinators (more effective than wind)
2) tiny female gametophyte reduces energy and resources needed
monocots
- 1 cotyledon
- vascular tissue scattered (no cambium)
- sexual organs in groups of 3
- parallel veins in leaves
eudicots (dicots)
- 2 cotyledons
- vascular tissue in circular arrangement
- sexual organs in multiples of 4 or
- branching veins in leaves
angiosperm lifecycle
1) pollination
2) fertilization
3) germination
4) meiosis
angiosperms
flowering plants w huge diversity (reason unknown)
- sporophyte dominant
- pollen = H20 independent fertilization
- disperse via seeds
primary growth (plants)
shoot apical meristem (tip) and elongation zone (upper part)
- increases height
secondary growth (plants)
lateral meristems - increase plant diameter
- formation of continuous vascular cambium that produces secondary xylem toward inside and phloem toward outside, cork cambium maintains protective outer layer
- growth rings: record annual age, past climatic conditions (temp, moisture, fire) based on size of ring
phototropism
growth toward light (shoots)
growth away from light (roots)
gravitropism
growth against gravity (shoots)
growth toward gravity (roots)
plant defenses
MECHANICAL
hairs, spines, thorns, minerals (silica), toughness
CHEMICAL
nervous system: bitter, nicotine, caffeine, morphine, quinine
growth&dev: oils: lemon peel, mint, sage, pine resin, taxadiene –> taxol cancer drug
digestion: tannins (unripe fruit)
plant animal interactions
caterpillars and milkweed – caterpillars avoid latex – prevent spread of latex
ants and acacia – symbiosis, nutrients and defense
parasitic plants
dodder – vines wrap around plant and take from vascular system of host
rafflesia – grow as thread-like strands of tissue completely embedded within and in intimate contact with surrounding host cells from which nutrients and water are obtained
mistletoe – attach to and penetrate the branches of a tree or shrub by a structure called the haustorium
fungi
heterotrophs of opisthokonta superkingdom- secrete enzymes for digestion then absorb the food/molecules (extracellular)
- movement via growth (hyphal extension)
saprophytic fungi decompose plant material
- high dessication, temp, light tolerance – sensitive to air pollution
hyphae
highly branched filaments that provide fungi with a large surface area for absorbing nutrients and help w/ finding food (extend)
can extend waaay out, demonstrated by fairy rings
mycelium
network of branching hyphae that grows when the fungus finds a rich food source
chitin
- polysaccharide that makes up the cell wall
- structural support for moving through dirt
- resistance to cell volume changes in wet environments (turgor pressure)
- same material in insect exoskeletons
bulk flow
driven by changes in turgor pressure along hyphae
carries materials obtained in nutrient-rich location so they can fuel hyphal elongation across nutrient poor locations (allows for dev of large reproductive structures: mushrooms)
septa
pored walls that partially divide the cytoplasm into separate cells
yeast
single-celled fungi in moist, nutrient-rich environments (lost hyphal development)
- most divide by budding
- plant surfaces
- animal skin and gut –> yeast infection
- fermentation, leavened bread
budding
small outgrowth increases in size and breaks off to form new cell
fungal symbioses
~90% of plants live in close association with fungi
mutualistic
- mycorrhizae
- glomeromycetes cannot live w/o plant
- lichens : fungi + algae/cyanobacteria (~15% of fungal species, 100 phosynthetic symbiont species)
ants = fungus farmers (grow for food)
parasitic
– fungal spores spread or fungi enter wounds or stomata
endophytes
endosymbiont fungus that lives within leaves – produces chemicals that deters pathogens and herbivorous insects
fungal phylogeny
1) chitinous walls
2) hyphae
3) regularly placed septa (earlier groups were coenocytic)
4) complex multicellular fruiting bodies
fungi & carbon cycle
fungi digest cellulose and lignin to obtain small organic compounds, also release CO2
life cycle (Fungi)
sexual and asexual
sexual - plasmogamy + karyogamy (fusion of cytoplasm, then nuclei), dispersal and germination
asexual - dispersal of spores
fungal mating types
determined by mating type gene
- can have 2+ mating type-alleles
- prevents self fertilization
fruiting bodies
compact + complex multicellular structures built from hyphae (mushrooms, stinkhorns, puffballs, truffles)
- facilitate the dispersal of spores
- grow aboveground to release spores from high up
- many forcibly eject spores up to 1m/s
dikaryotic fungi
heterokaryotic cells w/ 2 distinct haploid nuclei
make up 98% of fungi
- separation of plasmogamy + karyogamy = better/effective timing
- increase # of cells in which karyogamy with take place = more sexually produced spores
fungal groups
75,000 described species, may have up to 5 mil
1) chytrids
2) zygomycetes
3) basidiomycetes
4) ascomycetes
chytrids
ancestral fungi
- aquatic, unicellular, flagellated
- have rhizoids (anchor, absorb)
zygomycetes
- growth of mycelium
- production of aerial spores
- stalk and sporangia
- pilobus: light sensors orient sporangia
dikarya
- form regular septa
ascomycetes - nuclear fusion and meiosis take place in elongated saclike cell: ascus
basidiomycetes - nuclear fusion and meiosis take place in club-shaped cell: basidium
fungal genetic diversity
1) hyphae fuse to heterokaryotic cell
2) karyogamy forms diploid nucleus
3) crossing over - mitotic recombination, chromosome loss over time
4) nuclei w/ restored haploid chromosome count + novel gene combinations
humans and fungus
penicillium – helps cheese production, inhibits growth of gram-pos bacteria
- penicillin as antibiotic in 1930s
hydrostatic skeletons
support animals by muscles that act on a fluid-filled cavity
(cnidarians: anemones, jellyfish)
2 sets of muscles surround and control
circular = reduce diameter of cavity
longitudinal = reduce length of cavity
movement - clam burrows, earthworm, octopus tentacles, tongue
exoskeleton
protect from dessication - physical insults, support and protection
drawack; limits growth
-arthropods, mollusks (bivalves)
endoskeletons
muscles attach to skeleton by tendons of collagen
- tendons transmit muscle forces, redirecting over wide range of join motion
- store and recover elastic energy
axial/appendicular skeletons
axial: skull, jaws, vertebrae, ribs
appendicular: limb bones, shoulder, pelvis
extracellular matrix (ECM)
secreted by specialized cells, form connective tissue around cells (bone, tooth enamel, cartilage)
suspension filter feeding
water w/ food suspend in it passes through a sievelike structure
(scallops, whales, worms, bivalve mollusks - clams)
suction feeding
rapid expansion of fish’s mouth cavity draws water and prey into mouth
- 2nd set of jaws in throat
- “sit and wait” feeding
(fish, aquatic salamanders)
active swimming (feeding)
sharks, whales, dolphins
temporalmandibular joint
allows top and bottom teeth to fit together
incisor - bite
canine - pierce
molar - crush and shred
nitrogenous waste
ammonia - byproduct of nitrogenous waste
urea - mammals (less toxic)
uric acid - birds and reptiles (least toxic)
process of urine excretion
1) filtration - into excretory tubules
2) reabsorption - key ions and solutes
3) secretion - toxic compounds, excess ions
Animal Evolution
~550 yrs ago tons of diversification (cambrian explosion) from increase in O2
KEY TRAITS
1) multicellularity - lack cell walls, extensive ECM
2) heterotrophy - obtain necessary C compounds from other organisms, generally ingest
3) motility - move under own power at some pt in life cycle
4) nerve cells and muscle cells - except in sponges
cephalization
concentration of nervous system component at one end of the body (head)
- evolved indept. multiple times
- adaptation for forward movement and predation
choanoflagellates
closest living relative to animals
phlogeny
1) choanoflagellates
2) sponges
3) cnidarians
4) bilaterians
cnidarians
radial symmetry - bodies have axis from mouth to base w/ many planes of symmetry through axis
- allows for up and down movement, tentacle in all directions at once
- diploblastic 2 germ layers endo and ectoderm
bilateria
bilateral symmetry - bodies with distinct head and tail, front and back with single plane of symmetry between them at the midline
- movement in horizontal direction
- sensory organs at front
- appendages at sides for locomotion
- triploblastic 3 germ layers endo, ecto, mesoderm
benefits of body cavity
- cushions internal organs against hard blows to the ody and enables body to form w/o twisting the internal organs
- allows internal organ like the stomach to expand, enhancing digestive function
sponges
choanocytes - flagellated cells line interior surface of sponges, draw water in w/ flagella
- spicules - make up sponge skeletons
- mesohyl - gelatinous mass between interior and exterior
- intracellular digestion
- endocytosis - take in nutrients from nutrients form interior lining
- metabolize food inside cells
chemoreceptors
basis for senses of smell and taste
detect molecules such as O, CO2, glucose, AAs
role of pheromones
mating, territory, alarm, trail, social interactions
mechanoreceptors
respond to touch, stretch, pressure, motion, sound
- detection of motion and gravity
- hearing (sense vibrations)
- echolocation
photoreceptors
detect light
flatworms
houseflies - compound eye
single-lens eye
focuses light on retina and allows for high degree of acuity
- evolved independently in vertebrates and octopus and squid
thermoreceptors
nociceptors
electroreceptors
temperature stimuli
pain stimuli
electrical stimuli
sponge reproduction
asexual, totipotent cells
1) choanocytes migrate to mesohyl
2) meiosis in mesohyl, differentiation to sperm and egg
3) sperm released in water fus w/ eggs in mesohyl of other sponges
- sessile
- suspension filter feeders
- asymmetric
- no true tissues
protostomes
blastopore becomes the mouth “first mouth”
- mesoderm hollow to form coelom
- arthropods, mollusks, worms
deuterostomes
blastopore becomes the anus “second mouth”
- mesoderm pinches off to form coelom
- chordates and echinoderms
triploblasts
ectoderm –> skin and nervous system
endoderm –> digestive tract
mesoderm –> circulatory system, muscle, bone, most organs
- mesoderm important: complex muscle tissue for movement
cnidaria
radial body plan
jellyfish = medusa
sea anemone = polyp
1) epidermis
2) more differentiation - sophisticated function (muscle and nerve cells, light sensitivity)
3) capture prey w/ tentacles, nematocysts
4) some form colonies - “man ‘o war”, fire coral, reef forming coral
5) reproduction often asexual budding
- zooxanthellae symbiosis with photoautotrophs
cnidocytes
cells containing nematocysts - tiny harpoon-like organelle often tipped w/ powerful neurotoxin to aid in prey capture and defense
Ctenophores (comb-jellies)
- 8 rows of comb-like cilia line surface
- 2 long tentacles for feeding
- anal pore and mouth (front-back axis) axial symmetry
- rudimentary mesoderm
phylogenetic tree of animals
OG - choanoflagellates (closest relative not animal) 1) porifera 2) cnidaria (bilateria): protostomes: 3) rotifera 4) platyhelminthes 5) annelida 6) mollusca 7) nematoda 8) arthropoda deuterostomes: 9) echinodermata 10) chordata
Bilateria
1) bilateral symmetry
2) complex organs that develop from a triploblastic embryo
3) anatomical complexity allows for: locomotion types, feeding, gas exchange, behavior, reproduction (diff from earlier branches)
(everything past porifera and cnidaria)
lophotrochozoans
<1/2 of all animal phyla
- lophophore - tentacle lined organ for filter feeding
- trocophore - type of larvae
- zoan = animal
(platyhelminthes, annelida, mollusca)
platyhelminthes (flatworms)
- acoelomate
- gas exchange by diffusion
annelida (segmented worms)
- digestive tract –> mouth and anus
- cephalization –> “brain”
- closed circulatory system –> delivers O2 at higher rates
- gas exchange –> through skin (terrestrial) or via gills (aquatic)
- fluid-filled coelom - hydrostatic skeleton and paired muscled in each segment for movement
mollusks
bivalves, gastropods, chitons, cephalopods
- mantle : breathing, excretion, shell formation
- trochophore larvae (tuft of cilia at top)
bivalves (mollusk)
clams, muscles, scallops, oysters
- calcium carbonate shells secreted by mantle
gastropods (mollusk)
snails and slugs
- radula for feeding
- gills for gas exchange
- muscular foot for movement
- torsion (snails) – occurs during development, rotation of visceral mass, mantel and shell 180 with respect to head and foot of the gastropod
cephalopods (mollusk)
(octopus, squid, nautilus, cuttlefish)
- muscular tentacles - capture prey and sense environment (found on head)
- rapid locomotion - jet propulsion
- predator defense - jet of ink
- exceptional eyesight - most complex behavior of invertebrates
- reduced/absent shell (not chambered nautilus)
- highly intelligent
- beak - biting force
- sexual reproduction - spermatophores and lay eggs
bivalves (mollusk)
(clams, oysters, mussels)
- lost head
- 2 hard calcium carbonated shells (valves)
- food via filtering
chitons (mollusk)
- 8 plated shell
- herbivorous grazer
- marine intertidal
coelom
acoelomate - no cavity
pseudocoelomate - cavity does not completely surround internal organs
coelomate - body cavity surround internal organs
ecdyszoa
nematoda and arthropoda
- secrete cuticle of protein to cover body –> EXOSKELETON
- ecdysis = molting
nematodes (roundworms)
ecdyszoa
- unsegmented, pseudocoelomates
- gas exchange, nutrients, wastes move via diffusion
- thick, elastic cuticle –> molt to grow
- free living and parasitic
- found in every known habitat
- extremely abundant –> up to 9 bil in acre of farm soil
- sexual reproduction - internal fertilization then female lays eggs
water-to-land transition
adapt to:
1) exchange gases
2) avoid drying out
3) hold up bodies under own weight
arthropods (ecdyszoa)
1) segmented bodies (head, thorax, abdomen)
2) exoskeleton made of chitin - protection, structure (muscle attachment)
3) paired jointed appendages - gas exchange, sensory, feeding, locomotion
(chelicerates, myriapods, crustaceans, insects)
-grow by molting: molt, fluid causes body expansion, larger cuticle/exoskeleton forms
- appeared > 520 MYA
- > 1 mil extant species, millions more exist
Hox genes
- identify body part/segment during embryonic development
- small changes in timing and location of gene expression can result in novel shapes and sizes
chelicerates (arthropod)
6 pairs of appendages:
4 pairs of legs
1 pair of chelicerae by mouth: feeding, defense, copulation, movement, sensory reception
1 pair of pedipalps w/ diverse function
- spiders, daddy longlegs, scorpions - predators
- mites, ticks eat ectoparasites
- horseshoe crabs eat animals, algae, detritus
- secrete digestive enzymes into prey
- sexual reproductionw ith internal fertilization (pedipalps transfer male sperm)
- no larvae, no metamorphosis
myriapods (arthropod)
millipedes & centipedes
- paired appendages 1-2 legs/ body segment
- mouthparts bite and chew
- centipedes are predatory carnivores, use poison
- millipedes are detrivores
- sexual reproduction: internal fertilization, egg laying
crustaceans
- primarily in marine and freshwater enviros
- consumers, grazers, predators
- exoskeleton strengthened by calcium carbonate in crustaceans
1) 2 pairs of antennae
2) sophisticated, compound eyes
3) mouthparts bite/chew
4) highly variable limb structures: claws, paddle shaped, legs, feather structures
insects
> 1 mil known species, huge diversity and abundance
- sexual & asexual reproduction (copulation & parthenogenesis)
- metamorphosis
- spiracles - small pores in exoskeletons for gas exchange
- tracheae - internal system of tubes that direct air
metamorphosis
- drastic change from one developmental stage to another
- larvae different habitat, food, looks
- juveniles - post metamorphosis, look like adults, same habitat, food, sexually mature
tardigrades
“water bears”
- segmented bodies and limbs
- no exoskeleton or jointed appendages
- marine, freshwater, terrestrial environments
- eat dead organic matter, suck fluids from plants/animals
Vertebrates
1) vertebrae - series of hard segments that runs along the main axis of the body creating the jointed skeleton
2) cranium - protects well-developed brain
3) pair of eyes, distinctive mouth, internal skeleton
4) coelom, organs suspended, closed circulatory system
rhizomes
new shoots from horizontal stems
