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UB / Biology / BIO 200 / What is horizontal gene transfer in bacteria?

What is horizontal gene transfer in bacteria?

What is horizontal gene transfer in bacteria?


School: University at Buffalo
Department: Biology
Course: Evolutionary Biology
Professor: C lindqvist
Term: Fall 2015
Cost: 50
Name: Bio 200 Study Guide for Exam 2
Description: Study guide for Exam 2, includes a condensed version of all notes, points stressed during lectures, and reoccurring topics on practice exams
Uploaded: 11/12/2015
25 Pages 29 Views 24 Unlocks

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Bio 200 Exam 2 Review Sheet:

What is horizontal gene transfer in bacteria?

Three-Domain Tree of Life-Each domain is monophyletic

Horizontal Gene Transfer-Movement of genetic material between distantly related  organisms & across typical mating barriers

-Endosymbiotic Theory

-Eukaryotes arose from horizontal gene transfer through symbiosis between  multiple microorganisms

All life shares certain traits, strongly indicating the existence of a Last Universal  Common Ancestor (LUCA):

What is endosymbiotic theory?

-All replicate DNA the same way (semiconservative)

-Encode proteins & use similar genetic codes to create proteins

-Transcription & translations

-All living thing process nutrients in a very similar way

Prokaryotes are fundamentally different

1.) Unicellular

2.) Binary Fission

3.) Un-enclosed DNA, circular chromosome

4.) No Organelles

5.) Asexual

Eukaryotes are:

1.) Multicellular

2.) Compartmentalized

3.) Sexual (mostly)


-Describes organisms that are small & didn’t fit in elsewhere on the tree -Some protists are more closely related to plants, fungus, or animals than to other protists

When does eukaryotes arise?

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Life has Two Characteristics

1.) Organized

2.) Replicates Itself


-Do not fit definition of life, though they are incredibly close

1.) Highly organized; use same kind of genetic storage as cells

2.) Replicate (with help), and mutate like other cells

-Protein coat (capsid) core, containing nucleotides

-DNA or RNA, Circular or linear genetic material

-No cytosol (plasma membrane)

-Do not perform metabolic functions

-Not cells (virions)

-Can respond to selective pressures & evolve to have higher fitness -Vary greatly in size

Virus Replications:

-Replication is parasitic: virus infects host cell & tricks cell into replicating it, often  destroying the infected cell

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-Transmission Vectors

-Not caused by virus, but rather by prions (contain no genetic material), infections  passed by proteins only

-When normal prion comes into contact with abnormal prion, it changes  configuration “Transmission of Infection”

Prokaryotes vs. Eukaryotes:

Horizontal Gene Transfer

-Gene transfer between bacteria & archaea significantly complicates our  understanding of evolution

Cell Walls

-Differ in Bacteria & Archaea

-Gram-positive or Gram-negative (Stain used to see various parts of the cell) -Archaea all considered Gram-negative  

-Thickness of peptidoglycan layer

Bacteria Classification before Genetic Analysis:

1.) Shape (rod, sphere, spiral)

2.) Metabolism

a. Aerobes (need oxygen) or Anaerobes (poisoned by oxygen)

b. Autotrophs (self feeders) or Heterotrophs (other feeders)

c. Chemoautotrophs- Make energy by breaking the bonds in organic  chemicals. Use Carbon dioxide to make sugars We also discuss several other topics like What are the three sections of stomach?

3.) Gram-positive vs. Gram-negative

a. Low-GC

i. More AT than GC bases in DNA sequence

ii. Very diverse group, not all have cell wall

iii. Endospore-heat resistant structures that can survive harsh  

conditions that would otherwise harm the parent cell

iv. Some may not be active for hundreds of years, can lead to  

highly noxious species

b. High-GC  

i. More GC than AT

ii. Provide us with most of our antibiotics-attack other bacteria

iii. Responsible of the mechanisms of composting

4.) Cyanobacteria are Critical Autotrophs

-Carry out complex photosynthesis

-Plant chloroplasts are derived from Cyanobacteria

5.) Can live as single cells or live in massive colonies




Typically unicellular

Uni- or multicellular

Internal Structure

No membrane bounded  organelles


compartmentalized, many  organelles


Single, circular DNA

Double membrane bound  nucleus with multiple  linear chromosomes

Cell Division

Binary fission

Mitosis & meiosis

Gene Transfer

Horizontal Transfer



Simple, single fiber

Very complex, 9 + 2  


Cell Wall

Ubiquitous (peptidoglycan  or psuedomurein)

In some organisms (no  peptidoglycan)

Size (can be misleading)

Typically small


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-Love hot, cold, or acidic environments

-Most common marine archaeans  


-Contains Methanogens (methane-producing), Halophiles (high-saline  environments), & extreme thermophiles

Origin of Eukaryotes & Protists:

Origin of the Eukaryotes

-Eukaryotes arise between 2.7 and 1.7 billion years ago

-Have cells much larger than prokaryotes, thicker walls, and an internal membrane Several events preceded the origin of the eukaryotic cell

-Flexible cell surface


-Nuclear envelope

-Digestive vacuoles


Eukaryotic Traits

1.) Multicellular

a. Allows for flexibility

2.) Sexual reproduction

a. Leads to increased genetic diversity (recombination)

3.) Compartmentalization

a. Organelles that carry out different functions in the cell

b. Requires several stages

Evolution to eukarya  

-Loss of the cell wall (endocytosis)

-Origin of the nucleus and ER (both the result of membrane enfolding) -Endosymbiosis “Living together in close association”-an ancestral eukaryotic cell  engulfed an aerobic energy producing bacteria, but did not digest it

-Over time this arrangement be came permanent, led to mitochondria -Endosymbiotic events are examples of horizontal gene transfer

Origin of Eukaryotes

-Began with ancestral protists (some scientists refer to them as microbial  eukaryotes)

-Protists are only unified by the fact that they all have organelles- highly  paraphyletic  

Variations in Protist Traits reveal lack of Unity in the Group

1.) Locomotion

2.) Cell Surfaces

a. Some protists have extracellular material to shield them from  negative aspects of the environment

3.) Nutrition  

a. Chemoautotrophy-only observed in protists, photosynthesis 4.) Reproduction

a. Both sexual and asexual protists

Protists Show the Development of Multicellularity

-Eukaryotic cells began living in close association

-Associations become colonies

-Individuals in colony take on different roles

-Colony begins to function as an individual

Protist Groups

-Alveolates are a diverse group identified by the presence of alveoli -3 types, have all developed very interesting types of nutrition - Apicomplexans -parasites with apical complex

-Dinoflagellates are photosynthetic & have 2 flagella (one short, one long)  within 2 grooves on their surfaces

-Can cause red tides, during which times they release toxins that kill  birds & other mammals

-Ciliate-move using cilia & are heterotrophic

- Stramenopila - characterized by the fine hairs extending from their flagella -Brown Algae-multicellular, include giant kelp

-Diatoms-Unicellular with unique double shell of silica

-Use both sexual & asexual reproduction

-Do not have flagella (except for male gametes)

-Important energy producers

-Oomycetes-not molds- use external digestion

-Most are harmless decomposers, but some can be serious plant  pathogens

-Rhizarians-All unicellular & aquatic

-Foraminiferans-fossilize easily

-Tiny organisms in shells

-Excavates-very diverse, includes organisms that do not even have mitochondria -Diplomonads & parabasalids-lack of mitochondria likely a derived trait -Euglenids-can be heterotrophs or photoautotrophs

-Reproduce solely through binary fission


-Amoebozoans-contain amoebas & the slime molds

-Loboseans- fit definition of “classic amoeba”

-All heterotrophic

-Plasmodial & cellular slime molds

-Can exist asexually so long as there is enough food

-Ooze over particles, engulfing food

-Opisthokonts-Contain fungi & animals

-Ancient choanoflagellates are ancestral to animals

Land Plants

Plants must overcome:

-Drying out

-Structural support



-Embryophytic- Need embryos to stay moist

-Cuticle- Keep moisture in

-Stomata-Small holes that open to let moisture in and close to keep plant from  drying out

-Pigmentation-Blocks UV radiation in absence of water

-Fungal relationship-Develop mutual relationship with fungi that help plants  absorb nutrients from soil

-Tracheid cells-Allow for transfer of water & nutrients throughout plant & allow  them to become larger

-Thick spore walls-Protect plant from drying out

-Seeds-Ultimate embryo protection

Notable differences from Animals:

-Diplontic life cycle-only diploid stage that’s multicellular or undergoes mitosis -Haplodiplontic life cycle: alteration of generations-gametophytic (multicellular  haploid organism) alternates with sporophytic (multicellular diploid organism)


-Meiotic event represents change from diploid to haploid

Gametophyte-produces gametes through mitosis

-When gametes fuse we call it syngamy, or fertilization

-Represents transition from haploid to diploid generation

-Everything below this point is 2N

-Major difference between plant and animal lifecycles is the length of gestation and  haplonic phase

Two Points:

-Spores & gametes both swim

-Makes a lot of sense in aquatic environment, but requires a lot of adaptation  for land plants

-Relative length of the diploid & haploid generation vary considerably between the  different plant groups

-Different life cycles for different plants

-Mosses-gametophytic stage is dominant phase, why sporophytic stage is  short

-Seed plants are just the opposite

-We believe this happens because haploid phases are very sensitive to  deleterious mutations, as these are not masked by a second allele, as they  would be in a diploid organism

Primary vs. Secondary Endosymbiosis

Primary-Eukaryotic Cell engulfs bacteria & codependence develops. A bacterium  takes on functions of the cell

-Chloroplasts result from Primary Endosymbiosis: a single event that gave  rise to red & green algae (two membranes)

Secondary-Eukaryotic cell that engulfed another eukaryotic cell, which had already  engulfed bacteria

-Brown algae is an example of a secondary endosymbiosis (engulfed red or green  algae to get their chloroplasts; three membranes)

Land plants all arise from green algae lineage & therefore are all photosynthetic,  using chlorophyll

Green Plants

-Include both land plants & all green algae


-Contain most species of green algae

-Flattened cell form  

-Contain both unicellular organisms & complex, mobile organisms -Stoneworts

-Thought to be most closely related to land plants

-All show branching apical growth (growth only from the tip of the organism,  common in all land plants)

Non-Seeded Land Plants

The transition to Land

-Moss is most ancestral land plant

-Land Plants are non-vascular, meaning that they have no tracheid cells

Non-Vascular Plants (Bryophytes)

1.) Embryotic

2.) Gametophyte dominant

3.) Sporophyte dependent on gametophyte

4.) Require water for sexual reproduction

-Includes mosses, liverworts, and hornworts

System of Transport

-Xylem-moves water & minerals upwards through the plant

-Phloem-moves sugar & nutrients down (phloem=flow down)

-Both provide structural support for the plant

Seedless Vascular Plants (Tracheophytes)

1.) Embryophytic

2.) Sporophyte dominant

3.) Free-living gametophyte

4.) Can grow to be very large

-Tracheophyte gametophytes are very small

Club mosses

-Simple leaf-like structures

-About 11-hundred species of club mosses

-Vascular plants (regular mosses are not vascular)


-Monophyletic group of vascular plants

-Sister group to seed plants

-First group to have more complex leaf veins (megaphils)

-Includes Horsetails (readily dividing set of cells at each segment), and Ferns

Seed Plants

Benefits of Seeds



-Dormancy-delay between development of embryo and dispersal of the seed -Allows time for dispersal-gives opportunity to find best growth conditions Gymnosperms

-Monophyletic group

Important facts about Seed plants

-All heterosporous  

-Allow for dispersal

-Allow for dormancy

-Dramatic reduction of gametophytic phase

-Sporophyte is the dominant form

Gymnosperm Lifecycle:



-Microspore-develop into pollen grain after mitosis

-Pollen Grain-male gametophyte (haploid)


The female gametophyte is enclosed in protective tissue and is dependent on the  sporophyte for nutrition


-Megasporangium-becomes nucellus



-Integument-covers sporangium, diploid

-Seed Coat

-Micropyle-opening in seed that allows the entrance of pollen  


-The seed is the mature ovule containing an embryo (product of fertilization) -End of dependence on water for reproduction

Gymnosperms are divided into Four Groups

1.) Cycads

a. Ancient lineage that was extensive during age of dinosaurs

b. Slow growing

c. Can reach heights of 15 meters

d. Resemble palms, though genetically they are nowhere close e. Do not flower, but bear cones

f. Motile sperm that will swim down pollen tube

2.) Ginkgos

a. Dioecious-has separate male & female individuals

b. Believed there are no wild ginkgos left

c. Males have cones, females do not

d. Motile sperm

3.) Gnetophytes

a. Only gymnosperms that share a form of tracheid cell-vessel cells or  elements

b. Once believed to be closer related to angiosperms than gymnosperms c. Gnetum, Welwitschia & Ephedra-Three types of Gnetophytes 4.) Conifers

a. Most common gymnosperms

Angiosperms-Flowering plants

-Most successful group of plants

-Have both flowers and fruit

Flower Structure

-Sepals-covering of flower

-Petals-Colorful to attract pollinators

-Anthers-Site of microspore pollen production  

-Filaments-hold up anthers

-Stamens-Comprised of anther & filament

-Ovary-Eventually becomes fruit, houses ovules

-Ovules-House megaspores (which produce eggs)

-Style-Where pollen must travel through to reach cell

-Stigma-Where pollen lands

-Carpel-Comprised of stigma, style & ovary

-Each microspore divides into a tube cell and a generative cell

-The generative cell divides to form two sperm cells

-Both sperm cells will fuse with parts of the female gametophyte -Sperm & egg=2N zygote

-Sperm and polar nuclei=3N endosperm

Angiosperms Differ from Gymnosperms

-Double Fertilization

-2N zygotes and 3N endosperm

-Flowers & fruit

-Reduced cell number in gametophytes

-Speed of pollen tube growth

-Triploid Endosperm

Angiosperm’s Success

-Vessel cells

-Rapid maturation



Touring the Angiosperms:

Fossils of Archaefructus

-Now extinct, but though to be a close ancestor to the first angiosperms -Dates back to 125 million years


-Male and female reproductive parts

-No petals or sepals

Angiosperm Origin

-Flowering plants became dominant ~90 million years ago -Previous fossil records suggest an origin in Early Cretaceous (~140 MYA) -New evidence pushes the origin back 100 million years

Amborella Trichopoda

-Thought to represent one of the most ancient living angiosperms -Represents sister group to all other living angiosperms

-Dioecious species


Nymphaeales: Water lilies

-80 species

-Comprised entirely of aquatic plants

-No vessel cells-live in water & therefore have no need for vessel cells


-Comprised of woody plants

-Star anise- dried fruit from a tree in China


Chloranthaceae and Ceratophyllum


-Large group of plants that with many economically important species -Cinnamon, avocado, black pepper

-Trimerous flowers- multiples of 3


-Represent 75% of all angiosperms

-Tomato, Venus fly trap, coffee, cocoa

-Multiples of 5

-Broad leaves with branching veins


-Together with the Eudicots, they represent 97% of angiosperms -Grains & grasses

-Corn, wheat, rice, palms, bananas, orchids, tulips, lilies, coconut, ginger,  onions, garlic

-Trimerous flowers

Two Main Types of Pollination


-Water Pollination

-Include most water species

-Pollen must be relatively impermeable by water, but still able to  pollinate

-Wind Pollination

-Small, greenish, odorless flowers that hang from the plant

-Wind rarely carries pollen more than 100 meters

-Biotic-Insects, beetles, bees, butterflies & moth pollinate flowers


-Make up a monophyletic clade  

-Branch off the clade with choanoflagellates & animals

-More closely related to animals than plants

Fungus Share 6 Traits

1.) Most fungi have a number of cell types

2.) Fungi have cell walls with Chitin

3.) Some fungi have dikaryon stages

4.) Fungi undergo nuclear mitosis

5.) Many fungi have both sexual and asexual reproduction

6.) Fungi are heterotrophs that absorb nutrients

Fungal Cell Types

-Unicellular (can be flagellated) or Multicellular

-Mycelium (fungus like) composed of long cell-like structures called hyphae -Hyphae can be septate (when septa separates structures) or coenocytic (without  septa)

-Most hyphae can be considered single, long, multinucleate cells -Groups of hyphae form complex structures: Mycelium

-Cell walls with chitin-what gives cell’s their structure

Dikaryons (2 nuclei)

-Form from the fusion of two haploid mating strains

-Though both nuclei are haploid, dikaryon cells are protected from lethal mutations  that would be masked in a true haploid organism

-Cannot self-fertilize

Nuclear Division

-The nucleus replicates and forms two copies, but the cell remains a single unit -Nucleus divides without breaking the nuclear envelope


-Can reproduce both sexually & asexually

-Sexual reproduction can be common is some groups while rare in others -Dikaryon stage-1N + 1N haploid nuclei function independently, they do not fuse -Spores develop into new haploid individuals

-Asexual reproduction is often done by spores in multicellular fungi


-Fungi uses External digestion-all are heterotrophs

-Completely dependent on water

-Can feed in 3 different ways

-Mutualists-exchange nutrients in a mutualistic manner

-Saprophytes-Eat dead matter

-Parasites-Eat living organisms

Fungal Groups

1.) Microsporidia

-Obligate parasites of animals, especially common in insects, crustaceans and  fish

-Host cells are penetrated by a tube inserted by Microsporida  

-Lack true mitochondria, has mitosome instead

2.) Chytrids- likely paraphyletic


-Unicellular life stages

-Flagella present

-May be killing amphibians-becomes pathogenic at lower temperatures

3.) Zygomycetes

-Bread molds

-Do not have any septa, Zygospores

-Grow completely asexually

4.) Glomeromycota

-Mycorrhizal and coenocytic fungi-form mutual or beneficial relationships with  most plants

-Cannot live without host plants

-Monophyletic group  

-Do not form mycelia with hyphae

5.) Ascomycota


-Dikaryon forming

-Bear spores in sacs (asci)

Group Contains:

-Cup fungi, Yeast, common molds (Penicillin), Truffles, morels, Cheese molds, Plant  pathogens (chestnut blight & Dutch Elm)

-Cordyceps-genus of parasitic ascomycetes that infects insects and other arthropods

6.) Basidiomycota


-Dikaryon forming

-Basidiocarp- houses the basidia that produce spores (can produce up to 40 million  spores in an hour)

Plant Review:

Heterosporous Spore Production


-Microsporangium????microspore????microgametophyte (pollen)????sperm

Homosporous spore production

-Sporangium???? single spore type???? gametophyte (bisexual)???? eggs & sperm  

Double fertilization in Angiosperms:

-One sperm cell fertilizes with the egg cell ???? 2N zygote

-The other sperm cell fuses with the central cell (2N)???? 3N endosperm (triploid)


What Makes an Animal?

1.) Multi-cellularity

2.) Heterotrophy

3.) Lack Cell Walls

4.) Motility

5.) Sexual Reproduction

6.) Characteristic embryonic development

7.) Specialized Tissues

All are part of a monophyletic group


-The first form of symmetry to evolve was radial

-Radial symmetry leads to body designs where parts around are arranged around a  central point

-Generally circular or spherical

-Bilateral Symmetry-Where right & left halves are mirror images -Bilaterians-have top (dorsal) and bottom (ventral) portions

Embryonic Development

-Sponges have undifferentiated tissues & no symmetry

-Diploblastic animals have two layers & radial symmetry



-Most animals have three layers of embryonic tissue (triploblastic) & bilateral  symmetry


-Outer body covering

-Nervous system





-Digestive organs


-Tissues allow for increased specialization

Bilaterians are further divided

-Protostomes and Deuterostomes:

-Protostome mouths develop before their anuses: “first mouth” -Deuterostome anuses develop before their mouths “second mouth”

The body cavity (coelom) influence movement

-Roundworms have fluid filled cavity-hydrostatic skeleton-gain rigidity due to fluid -Movement is more efficient than on Acoelomate (flatworm)

Segmentation: segments allow for redundancy of function and specialization

Changes in the animal body plan

1.) Symmetry

2.) Embryonic tissue layers

3.) Specialization of tissues and cell types

4.) Coeloms

5.) Segmentation

The Basal Animals

-Choanflagellates are the ancestors to all animals

-The most basal lineage of animals is the sponges

-Free swimming, though adults are anchored to rocks

-Sponges have highly specialized cells called choanocytes

-Choanocytes collect food as they pass by

-Can reproduce either asexually or sexually

-The Cnidarians have radial symmetry and tissues

-Includes marine predators

-Two body forms: Polyps & Medusae

-Polyps-cylindrical & usually attached to something

-Medusae-free-swimming, umbrella shape with tentacles surrounding the  mouth

-The Placozoans & Ctenophora (comb jellies) are small groups



Bryozoans and entoprocts are marine colonial animals

-The Flatworms (Platyhelminthes) are acoelomates with a true head and one  gut opening

-Flat because they lack organs to transport oxygen through the body -Hermaphroditic but do not self-fertilize

-Rotifers are tiny, pseudo-coelomates with complex organs

-Ribbon worms-acoelomates characterized by their proboscis

-Similar to flatworms, though have mouth & anus

-Can grow up to 20 meters long

Annelids-segmented worms

-Segmentation allows for Specialization of different parts







-Annelid segments are a stack of hollow rings that can expand and contract  independently, allowing for much more control that a single unit -Sensory organs are in the anterior segments-likeness to brain

Two Classes of Annelids:

-Earthworms and leeches

-Polychaetes-often have one or more pairs of eyes or tentacles


-Three body part plan:

-Foot-Used to direct movement & capture prey

-Visceral mass-holds the organs

-Mantle-covers dorsal portion of all mollusks & typically secretes a shell -Mollusks have specialized mouthpart called the radula-used to scrape algae off  rocks, some have modified this radula into drill to drill through shells -Cross-fertilization is common among mollusks

Four Groups of Mollusks

1.) Polyplacophora: The Chitons (~1000 species)

-Bodies with eight dorsal plates


-Typically live in shallow water

2.) Gastropoda:  Snails & slugs (40,000 species)

-Some creep & others free swim

-Tentacles common (eyes and chemo- or mechanosensing)

-Nudibranch (sea-slug)-very brightly colored to signify toxicity

3.) Bivalvia: Bivalves (30,000 species)

-Ligament holds shells closed

-Most filter feed

-Have incurrent and excurrent syphons

-Sedentary adults

-Free swimming larvae

4.) Cephalopoda: Octopus, squid, and nautilus (~800 species)

-Marine predators with arms and tentacles

-Jet propulsion-forcibly eject water to produce movement

-Color & texture changing for excellent camouflage

-Highly intelligent-developed nervous system & eyes (better eyes than vertebrates  because there are no blind spots)


-Grow by molting

-Monophyletic group

-Horsehair worms have no mouth & guts are thought to have no purpose-eat only as  larvae

-Nematodes (roundworms) are species rich

-World Health Organization (WHO) suggests that 1/3rd population is at risk  for infection by nematodes, with 1/6th already infected

-C. Elegans -model organism for lab research

-Tardigrades: called Water Bears-less than half a mm in size

-Live in sand-once they dry they remain dormant until rehydrated -Onychophorans: Velvet worms are terrestrial and closely related to arthropods


Four Major Groups:

1.) Arachnids-spiders, ticks, scorpions

-Mouthparts are chelicera

-Four pairs of legs

2.) Myriapods-Centipedes & millipedes

-Mouthparts are mandibles

-Bodies consist of head, one pair of antennae and repeated segments 3.) Crustaceans- Lobsters, crabs, pill bugs, barnacles

-Mouthparts are mandibles

-Two pairs of antennae

-Five pairs of appendages

4.) Hexapods (Insects)-Beetles, ants, butterflies

-Grouped together based on body design

-Mouthparts are mandibles

-Bodies have three regions

-One pair of antennae

-Three pair of legs

Trilobites: had jointed appendages

-Became extinct ~250 MYA

-Body plans dominated by jointed appendages

-Have exoskeletons-Grow their new skeleton under the old one Echinoderms & Hemichordates:

Deuterostome: second mouth that develops into anus  


-Echinoderms are first Deuterostome

-Pentaradial symmetry means there are 5 axes of symmetry-special type of radial  symmetry

-This Pentaradial symmetry makes Echinoderms are very diverse animals, as does  their Deuterostome development & triploblastic tissue layering -Internal skeleton made of hard plates (acts similar to a cell)

-Covered by a very thin layer of skin-neurosensory cells that allow the animal to experience the world around them

-Pump water into specialized structures through tubes-water vasculature system -Water enters the body through a small hole or pore and flows into structure called  ring canal

-Characterized by their oral and aboral surfaces (as they lack a head) -Reproduce both sexually and asexually

-There are 20 extinct classes of Echinoderms, but only 3 extant groups:  -Crinoids

-Sea lilies and feather stars

-Sea lilies attach to rock-main body is a cup that contains water  vascularate system

-500-700 arms that radiate from the cup containing tubes  


-Sea urchins, sand dollars, and sea cucumbers

-No arms, hard to see pentaradial symmetry

-Can be toxic


-Sea stars & brittle stars

-Among the most important predators in most marine habitats

Hemichordates: Acorn worms

-3 Part Body Plan: Proboscis, collar, and trunk

-Can be up to 2m long & live in sandy or muddy marine environments


-Our phylate

-Three Chordate Groups: Lancelets, tunicates, and vertebrates (most are  vertebrates)

What Makes a Chordate?

-Hollow nerve cord-Differentiates during development into brain and nerve cord -Notochord

-Pharyngeal slits/pouches-Connect pharynx to external environment -Postanal tail-At some stage in development all chordates had a tail -All chordates are segmented

Lancelets vs. Tunicates

-Only non-vertebral chordates

-Fairly small groups

-Most chordate traits are absent in adult tunicates

-Lancelets clearly show chordate traits

Invasion of Land

What Makes a Vertebrate?  

1.) Heads

2.) Endoskeletons supported by vertebrae

3.) Internal organs suspended in a coelom

4.) Circulatory system with a muscular heart

Deuterostome Tree

-Tunicates may not be our sister Taxa; we may be closer to the hagfish

Vertebrate Groups

1.) Fish

a. Not a monophyletic group

b. Five Unifying Traits

i. Jaws & teeth

ii. Paired appendages

iii. Internal gills

iv. Single loop blood circulation

v. Nutritional deficiencies (unable to synthesize certain amino  acids)

c. Jawed fishes: Anterior gill arches became jaws and greatly improved  feeding efficiency

d. Sharks have lightweight, strong skeleton & up to 20 rows of teeth e. Bony fish have heavy, strong skeleton

i. Swim bladder provides buoyancy-fish can increase or decrease  the amount of air in the bladder  

2.) Amphibians

a. Land animals evolved from Lobe-fin fish- have muscular lobe  surrounding a core of bones which form joints

b. Challenges of Land invasion:

i. Moving heavy bodies

ii. Replacing gills

iii. Increasing oxygen intake and delivery to larger muscles  

required for walking

iv. Preventing drying out of eggs

v. Preventing body from drying out

c. Amphibia means “double life”-they spent time in both environments  to ensure bodies did not dry out

d. Ichthyostega was one of the first amphibians-strongly built with  ribcage & developed lungs

e. Amphibian Traits

i. Legs

ii. Lungs

iii. Cutaneous respiration

iv. Pulmonary veins

v. Partially divided hearts

f. Three modern amphibians:  

i. Frogs & toads-amphibians without tails, dependent on water  fro reproduction

ii. Salamanders-Long bodies & tails

iii. Caecilians-burrowing worm-like group with jaws & teeth

3.) Reptiles

a. Four Defining Reptile Traits

i. Amniotic Eggs-internal fertilization

ii. Dry Skin

iii. Thoracic breathing-Makes reptile lungs more efficient than  amphibian lungs

iv. Improved Kidneys

b. Reptiles are ectotherms-they can control their temperatures by  moving in and out of the sun, rather than an internal heating system c. First Reptiles were Synapsids

i. Pelycosaurs-dominant early synapsid

ii. Therapsids evolved from early synapsid groups

d. Diapsids contain crocodilians, dinosaurs, and birds-Also called  archosaurs  

i. Skulls that allow the jaw to open much wider

ii. Dinosaurs improved on early archosaurs body plan, giving  

them highly increased speed

e. Four Extant Groups of Reptiles

i. Lepidosaurs, includes Tuataras-very rare

ii. Squamates-Includes Lizards & snakes

iii. Turtles & tortoises-have sharp beaks in place of teeth

iv. Crocodilians are large predators, have nests & parental care  4.) Birds-Evolved from the Dinosaurs

a. Distinguished from other reptiles by four traits

i. Feathers

ii. Flight skeletons

1. Large breast muscles stretch from wing to prominent  

breast bone to power flight

iii. Lung design

1. Consumes radically more oxygen than ground animals,  

need efficient oxygen intake

2. Fully separated pulmonary systemic circuits, 4-

chambered hearts

3. Lungs always receive blood with highest oxygen content

iv. Endothermy  

1. Between 40-42º C body temperatures-higher than most  


b. Beaks & feet tell us a lot of bird habitats

i. Filtering vs. probing beaks, swimming vs. perching feet

c. Large flightless birds are likely the earliest birds (Ostrich)

d. Passeriformes-Most successful group of birds  

5.) Mammals

-Smallest class of invertebrates

-Mammals likely survived the extinction of the dinosaurs due to endothermy

Unified by Five Traits:

1.) Hair

2.) Mammary glands

a. Milk is calorie and fat rich, allowing for the development of the baby’s  brain

3.) Endothermy

a. 4-Chambered heart

b. Higher metabolic rates

c. Homoplasious in mammals and birds (has evolved separately) 4.) Sweat glands

a. Cool mammals via evaporation

5.) Placentas

a. Most mammals have internal gestation

b. Placenta allows developing baby’s blood to come into close enough  contact to mother’s blood to absorb nutrients, but bypass waste

Two Groups of Mammals

1.) Prototherians (Monotremes)- movie

2.) Therians (Marsupials and Eutherians)

a. Marsupials often have pouches

b. Though they have amniotic eggs, no shell develops

c. Most species of mammals are eutherians (Includes humans) i. Much more developed babies than Marsupials

ii. Huge size range

iii. Diverged quickly after the mass extinction of dinosaurs

iv. Diverged as the continents broke apart during the late  



Defined by Two Traits:

-Grasping fingers & toes

-Binocular vision (gives us depth perception), important for hunting

Two Main Groups of Primates we usually recognize

1.) Prosimian-before the apes

a. Paraphyletic group

b. Strepsirrhini (Wet-nosed)  

2.) Anthropoids-includes apes

a. Haplorrhini (dry-nosed)

Hominidae (Hominids):

-Comprised of the great apes and humans

-Humans and their direct ancestors are hominins

Hominids vs. Hominins

Traditional Classification

Family: Pongidae (great apes)

Family: Hominidae (modern humans and our close extinct relatives)

New Classification

Family: Hominidae (Great apes AND humans)

Subfamily: Homininae (gorillas, chimpanzees, and humans)

Tribe: Hominini (humans & our close extinct relatives)

Strepsirrhini (wet-nosed)- most ancient primates

-Includes Lemurs, bush baby, Loris

-Some lemurs do not act like other Strepsirrhini; some are diurnal (awake during  the day), very social and live in matriarchal societies

Haplorrhini (dry-nosed) primates

-Have developed color vision to adapt to daytime living

-Extended parental care allows for longer learning time & more brain development Platyrrhines (New World Monkeys)

-Live in South & central America

Catarrhines gave Rise to two groups:

1.) Old World monkeys

a. Tailless, include Rhesus macaque and Olive baboons

2.) Apes (hominids)

a. Gibbons

b. Hominids (great apes and humans)

c. Asian apes & orangutans diverged first, though neither group is  especially closely related to humans

d. African apes and humans evolved most recently

Where did we come from?

1.) Bipedalism is the only trait that distinguishes humans from other apes a. Allow for us to grasp other things not used for support

b. Ardipitithecus may have been mostly arboreal

i. Bipedal, allowing her to walk upright (though not for very long  periods)

c. Australopithecines is the first hominin group we have many fossils from  

i. Earliest Australopithecines were gracile

1. They could walk upright, but had much smaller brains

2. Lucy was an Australopithecus, her feet & leg bones were  

almost identical in function to those in humans  

ii. Second group of Australopithecines was most robust:  


d. All members of the genus Homo are called humans

i. Australopithecus sebida may be the lineage Homo evolved  


ii. First Homo species we recognize is Homo habilis

1. Much larger brain chamber than ancestors, but still only  

~50% the size of modern humans

2. Short with long arms

iii. Homo erectus

1. Longest lived human species

2. Nearly the height of an average modern male with 75%  

brain size of modern humans

3. Hunter-gatherers, first species to master fire, and first  

to leave Africa

iv. Modern humans originated around 600,000 years ago

1. Short & stocky, moved to Europe & developed complex  


2. Homo sapiens come to dominate around 34,000 years  


2.) Where did Homo neanderthalensis go?

a. Assimilation Hypothesis

i. Excessive hybridization led to single population

b. Out of Africa theory (Currently supported)

i. Separate lineages evolved & competition determined current  population

ii. Genomic data from archaic hominins suggest that our  

development may be more complex than this theory:  

Neanderthals and Denisovans

Photo Sources:

Tree of Life: http://philschatz.com/biology-concepts


Protist Tree: http://philschatz.com/biology-book/resources/Figure_23_03_01.jpg 

Gymnosperm Life Cycle:  


Angiosperm Life Cycle: http://image.slidesharecdn.com/unit3biodiversityofplants 130606053334-phpapp02/95/biodiversity-of-plants-51-638.jpg?cb=1370496915

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