Biology 2- OSU - Unit 4

Nuclear envelope

separates transcription and translation which allows alternative splicing and other forms of RNA processing, controls gene expression; the synapomorphy that defines the domain of Eukarya

Eukaryotic cells are…

larger than prokaryotes, have organelles, and a cytoskeleton

Multicellularity

being made up of multiple cells, evolved multiple times in eukaryotes

Protists

eukaryotes that are not fungi, green plants, or animals; a collection of lineages that are surrounded by water most of the time

Important evolutionary innovations in protists…

a nuclear envelope/ membrane, the mitochondria, the chloroplast

Endosymbiotic theory of mitochondria

proposed by Lynn Margulis; mitochondria evolved from an aerobic bacterium that was engulfed by an anaerobic eukaryotic cell; mutually beneficial- host supplied protection and carbon while bacterium produced more ATP for the host

Mitochondria

similar genes to alpha-proteobacteria, divide independently of the host via fission, have their own ribosomes, have a double membrane, have their own chromosomes

Endosymbiotic theory of chloroplasts

in all photosynthetic protists, originated when a protist engulfed a cyanobacterium, provides host with oxygen and glucose while host provided protection and light

Chloroplasts

similar genes to alpha-proteobacteria, circular genes like in cyanobacteria

Secondary endosymbiosis

in excavata, rhizaria, alveolata, and stramenopila the chloroplast is surrounded by more than 2 membranes (usually 4), when an organism engulds a photosynthetic eukaryotic cell and retains the chloroplasts as intracellular symbionts

Land plants evolved from _______ _______ that lived in freshwater

green algae

Land plants

live in water for water/ minerals, support, and reproduction; are monophyletic; evolved to resist drying out, absorb nutrients, stand upright, and reproduce without water

Embryo protection

nourish a multicellular embryo in the body of the female plant

Cuticle and stomata

cuticle is a waxy sealant that prevents water loss and inhibits the uptake of CO2, stomata are pores bounded by guard cells that allow the uptake of CO2 and control water loss, gas exchange done through pores

Non-vascular plants (Bryophytes)

simplest plants, lack roots and vascular tissue, water and nutrients move by diffusion, small, depend on water for reproduction; ex: mosses, liverworts, and hornworts

Roots

absorb water and key nutrients; made up of taproots and lateral roots; anchor plants, absorb ions and water, obtain energy from sugar, store material

Shoots

absorb light

Vascular tissue

what distinguishes vascular and non-vascular plants; made up of xylem and phloem; have tracheids to conduct water; increases structural support

Xylem

transports water and mineral from roots upward

Phloem

transports sugar, amino acids, hormones, and other substances from root to shoots and shoots to root; made up of sieve-tube elements to connect cytoplasm of cells and companion cells to support metabolic function

Wood

formed in stems and branches of some vascular plants, tracheids and vessels come together

Transpiration

water transport from roots to shoots due to different water potential; driven by evaporation of water from stomata of leaves

Conditions for transpiration

stomata are open, the air surrounding leaves is drier than the air inside of leaves

Cohesion-tension theory

open stomata create a water potential gradient between the interior of a leaf and its surroundings, water evaporates from the cell wall of plants, a negative force pulls water from root to leaf

Translocation

the movement of sugars through the plant by bulk flow from sources to sinks through the phloem

Sources

the tissue where sugar enters the phloem, high sugar concentration

Sinks

tissue where sugar exits the phloem, sugar concentration is low

Pressure-flow hypothesis

explains how sugars are moved through the phloem, water in phloem sap moves down a pressure gradient carrying sugars; high turgor pressure near source and low turgor pressure near the sink; moves sap toward sinks

Seedless vascular plants

first to evolve vascular tissue to move water and nutrients upward and dissolved sugar down leaves, use spores and the wind for reproduction

Pollen grain

in land plants, allows plants living in dry habitats to reproduce efficiently, can be exposed to air for longer periods of time, carried to female plants by wind or animals

Seeds

portable embryos that can disperse to new locations, allows for less competition between plants, distinguishes plants with seeds from seedless plants

Vascular seed plants (Gymnosperms)

first plant to evolve seeds, use seeds rather than spores, have naked seeds many times come in cones, do not need water and do not have flowers and fruit

Flowers

reproductive structures that attract pollinators and develop into fruit, distinguishes angiosperms from gymnosperms

Pollination

the transfer of pollen from one individual stamen to another individuals carpel

Directed-pollination hypothesis

natural selection favored structures that rewards an animal for carrying pollen directly from one flower to another

Flower variations

vary in size, structure, scent, and color in order to attract specific pollinators

Flowers attract pollinators by providing them with _______

food; either protein-rich pollen or nectar or sugar-rich fluid

Trickery

a strategy for achieving pollination, a plant deceives animals into transporting pollen

Bribery

a strategy for achieving pollination, a plant offers something of value to pollinator

Diversity of angiosperms resulted from __________ with animal pollinators

coevolution

Fruit

a structure derived from an ovary and encloses one or more seeds, a fertilized egg becomes a zygote, an embryo plus stored food grows into a fruit, allows for efficient seed dispersal

Animal-dispersed seeds/fruit

fruits are colorful and conspicuous, taste good, usually good for animals

Angiosperms

vascular plants with covered seeds, only plants to have flowers and produce fruit, highly diverse - great adaptive radiation

Adaptive radiation

single lineage produces large number of descendant species that are adapted to wide variety of habitats

Animalia

multicellular eukaryotes that move under their own power, have both nerve cells and muscle cells, ingest their food prior to digestion

Sponges

earliest animals to appear in the fossil record, do not have nerve or muscle cells, part of a paraphyletic group - some but not all descendants of a common ancestor

Diploblasts

animals whose embryos have two types of tissues or germ layers, consist on an ectoderm and an endoderm

Triploblasts

animals whose embryos have three germ layers, consist of the ectoderm, endoderm, and mesoderm

Ectoderm gives rise to ____________ and ____________ _____________ in triploblasts

skin; nervous system

Endoderm gives rise to the lining of the __________ __________ in triploblasts

digestive tract

Mesoderm gives rise to ____________ ____________, ___________, and _____________ ___________ in triploblasts

circulatory system; muscle; internal structures

Cilia

used by ctenophores to swim

ctenophores and cnidarians lack true ______________ ____________

mesodermal muscle

Contractile proteins

all animals share homologous genes for this, the proteins responsible for muscle

Epitheliomuscular cells

proteins in ctenophores and cnidarians used in contractile cells, similar to true mesodermal muscle cells but evolved independently

Radial symmetry

multiple planes divide the organism into mirror images

Bilateral symmetry

only one plane divides the organism into mirror images

Bilaterians

have diverse central nervous systems, tend to encounter their environments at one end

Cephalization

the evolution of a head where structures for feeding, sensing environment, and processing information are concentrated, where the brain is located and coincided with the evolution of the CNS

“Protostome”

develops mouth first, the gut develops from front to back

“Deuterostome”

mouth forms second, the gut develops from back to front

Cambrian explosion

marine animals evolved most of the basic body forms, lots of fossil evidence of relatives of todays species

Protostomes

make up atleast 22/ 30 known animal phyla, contains almost all animal species

Bilaterian body shape

inner tube of a gut with a mouth on one end and an anus at the other and an outer tube that forms the nervous system and skin, mesoderm forms muscles and organs

Coelom

an enclosed, fluid filled body cavity between the tubes in a bilaterian, provides space for oxygen and nutrients to circulate, enable the internal organs to move independently of each other

True coelomates

bilaterians whose coelom is completely lines with mesoderm

Acoelomates

bilaterians that have no coelom, such as flatworms

Pseudocoelomates

bilaterians whose coelom is only partially lined with mesoderm, like roundworms and rotifers

Molting

shedding an exoskeleton and replacing it with a larger one at regular intervals

Deuterostome

high diversity in bodies, feeding, movement, and reproduction

Echinoderms or spiny-skins

have spines or spikes, marine, very abundant especially in deep waters

Hemichordata

acorn worms and pterobranchs, burrow, deposit-feed or suspension-feed

Chordata

includes lancets, tunicates, vertebrates

Notochord

a rod of tissue from head to tail, stiffens when muscles contract during locomotion, sets chordates apart

Dorsal hollow nerve cord

a bundle of nerve cells that runs from brain to posterior, forms the central nervous system in vertebrates, sets chordates apart

Pharyngeal gill slits

gills, in aquatic chordates, separates type of chordate

Hagfish

have cartilage, lack jaws and vertebrae, have a notochord, swim like snakes, produce lots of slime

Vertebrates

monophyletic group distinguished by synapomorphies: the vertebrae and cranium

Vertebrae

protects the spinal cord, column of cartilaginous or bony structures, forms along the dorsal side of most species

Cranium

protects the brain and sensory organs; bony, cartilaginous, or fibrous case encloses the brain

Vertebrate brain regions

forebrain, midbrain, and hindbrain, key innovation in vertebrate evolution

Lamprey

a vertebrate, cartilage skeleton, jawless, parasitic, suck on other fish fluids

Paired fins

allow the fish to swim fast and straight

Jaws

enabled predators to capture prey and bite chunks

Fish

aquatic vertebrates with gills and fins, most diverse and largest group of vertebrates

Limbs from fins hypothesis

a series of species shows a gradual transition from a lobe-like fin to a limb that could support walking on land, problems included respiration, gravity, and egg desiccation

Amphibians

first terrestrial vertebrates, live in water and on land

Amniota

terrestrial vertebrates, lineage that includes all tetrapod’s other than amphibians, have an amniotic egg, reptiles and birds (lay eggs)

Amniotic egg

a protective covering that reduces the rate of drying

Reptiles

amniotes, have paired kidneys, skin covered in scales, ectothermic

Feathers

evolved before birds, in many species of dinosaurs, not used for flight but rather courtship, territorial displays, and insulation

Mammals

a monophyletic group of amniotes named for mammary glands, produce milk, have cheek muscles and lips, endotherms, have hair or fur

Thermoregulate

control body temperature

Conduction

the direct transfer of heat between two physical bodies that are in contact with each other

Convection

a special case of conduction in which heat is exchanges between a solid and liquid or gas rather than being two solids

Radiation

the transfer of heat between two bodies that are not in direct physical contact

Evaporation

is the phase exchange that occurs when liquid water becomes a gas

Endotherm

an animal that produces adequate heat to warm its own tissue, extremely high basal metabolic rates

Ectotherm

an animal that relies on heat gained from the environment, only generate small amounts of heat as a metabolic byproduct, need less food

Homeotherms

keep their body temperature constant