Tree of LifeTree of Life

Planet Earth is about 4.6 billion years old.Planet Earth is about 4.6 billion years old. Oldest known rocks are about 3.8 billion Oldest known rocks are about 3.8 billion

years old.years old. Oldest fossils (prokaryotes) are about 3.5 Oldest fossils (prokaryotes) are about 3.5

billion years old.billion years old.

Tree of LifeTree of Life

All living organisms on this planet share a All living organisms on this planet share a common ancestor.common ancestor.

The tree of life reflects the branching The tree of life reflects the branching pattern of speciation (phylogenetic history pattern of speciation (phylogenetic history of life) that has occurred since the origin of of life) that has occurred since the origin of life.life.

Tree of LifeTree of Life

There is an excellent Tree of Life website There is an excellent Tree of Life website in which you can trace the branching in which you can trace the branching pattern of the history of life and explore pattern of the history of life and explore classification.classification.

http://tolweb.org/tree/http://tolweb.org/tree/

Tree of LifeTree of Life

There is a hierarchichal classification of There is a hierarchichal classification of life in which organisms are progressively life in which organisms are progressively nested within larger and larger categories nested within larger and larger categories as more distant relatives are included in as more distant relatives are included in the classification (we will explore the classification (we will explore classification shortly).classification shortly).

The highest level of classification is the The highest level of classification is the Domain of which there are three.Domain of which there are three.

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Domains Bacteria and ArchaeaDomains Bacteria and Archaea

Domain BacteriaDomain Bacteria Domain ArchaeaDomain Archaea

The domains Bacteria and Archaea are The domains Bacteria and Archaea are both prokaryotes (they have no nucleus both prokaryotes (they have no nucleus and the DNA is not arranged in and the DNA is not arranged in chromosomes). Prokaryote derived from chromosomes). Prokaryote derived from the Greek the Greek ProPro meaning before and meaning before and karyon karyon meaning a kernel [i.e. a nucleus]meaning a kernel [i.e. a nucleus]

Domain BacteriaDomain Bacteria

Includes most of the bacteria people are Includes most of the bacteria people are familiar with including disease-causing familiar with including disease-causing species (species (SalmonellaSalmonella; ; VibrioVibrio cholerae cholerae which which causes cholera), nitrogen-fixing causes cholera), nitrogen-fixing ((NitrosomonasNitrosomonas) and parasites () and parasites (BorreliaBorrelia burgdorferiburgdorferi which causes Lyme disease). which causes Lyme disease).

Domain BacteriaDomain Bacteria

Bacteria play a major role in Bacteria play a major role in decomposition and many live symbiotically decomposition and many live symbiotically with other organisms including humans with other organisms including humans helping to break down or synthesize foods helping to break down or synthesize foods needed by the host.needed by the host.

Domain ArchaeaDomain Archaea

The Archaea include many extremophiles, The Archaea include many extremophiles, organisms that live in extreme environments.organisms that live in extreme environments.

Includes thermophiles which tolerate extreme Includes thermophiles which tolerate extreme heat (e.g. live in geysers and hot springs where heat (e.g. live in geysers and hot springs where temps may reach 90 degrees celsius) and temps may reach 90 degrees celsius) and halophiles (salt lovers, which live in very saline halophiles (salt lovers, which live in very saline environments (e.g. Great Salt Lake, Dead Sea)environments (e.g. Great Salt Lake, Dead Sea)

Archaea in hot springs

Bacteria and ArchaeaBacteria and Archaea

Bacteria and Archaea are both Bacteria and Archaea are both prokaryotes and their DNA is arranged in prokaryotes and their DNA is arranged in circular structures called plasmids. circular structures called plasmids.

However, they have substantial However, they have substantial differences in their biochemistry, cell wall differences in their biochemistry, cell wall structure and other molecular details.structure and other molecular details.

Bacteria vs. ArchaeaBacteria vs. Archaea

Bacteria are inhibited by antibiotics Streptomycin Bacteria are inhibited by antibiotics Streptomycin and Chloramphenicol but Archaea are not.and Chloramphenicol but Archaea are not.

Archaea in common with Eukarya have histone Archaea in common with Eukarya have histone proteins associated with their DNA, have introns proteins associated with their DNA, have introns in their DNA, and have several kinds of RNA in their DNA, and have several kinds of RNA polymerase. Bacteria lack these features. polymerase. Bacteria lack these features.

Archaea and Eukarya thus are members of a Archaea and Eukarya thus are members of a clade.clade.

Domain EukaryaDomain Eukarya

Domain Eukarya contains the eukaryotic Domain Eukarya contains the eukaryotic organisms (from Greek organisms (from Greek eueu true and true and karyon karyon aa kernal) which have a true nucleus and kernal) which have a true nucleus and DNA arranged in chromosomes.DNA arranged in chromosomes.

Eukaryotic cells are much larger and Eukaryotic cells are much larger and complex than prokaryotic cells and contain complex than prokaryotic cells and contain organelles such as mitochondria, organelles such as mitochondria, chloroplasts, and lysosomes. chloroplasts, and lysosomes.

Domain EukaryaDomain Eukarya

Domain Eukarya includes three kingdoms Domain Eukarya includes three kingdoms the Plantae, Fungi and Animalia. the Plantae, Fungi and Animalia.

There are also a number of unicellular There are also a number of unicellular eukaryotes that may form as many as five eukaryotes that may form as many as five other kingdoms. These were formerly other kingdoms. These were formerly grouped in the paraphyletic group the grouped in the paraphyletic group the Protista.Protista.

Domain EukaryaDomain Eukarya

Plantae, Fungi and Animalia are mostly Plantae, Fungi and Animalia are mostly multicellular, but plants are autotrophic multicellular, but plants are autotrophic (produce their own food by (produce their own food by photosynthesis) whereas the fungi and photosynthesis) whereas the fungi and animals are heterotrophic (consume other animals are heterotrophic (consume other organisms).organisms).

PlantsPlants

Unlike animals, plants remain in one place Unlike animals, plants remain in one place and produce food through photosynthesis. and produce food through photosynthesis. They trap the energy in sunlight and store They trap the energy in sunlight and store it in chemical bonds.it in chemical bonds.

The energy stored in chemical bonds can The energy stored in chemical bonds can then be used to fuel metabolic processes.then be used to fuel metabolic processes.

Figure 10.2

PlantsPlants

To carry out photosynthesis plants must To carry out photosynthesis plants must obtain water and minerals from the soil, obtain water and minerals from the soil, COCO22 from the air, and light from the sun. from the air, and light from the sun.

The structure of plants reflects their need The structure of plants reflects their need to carry out these tasks. to carry out these tasks.

Basic structure of plantsBasic structure of plants

Plants have three basic organs:Plants have three basic organs: RootsRoots StemsStems LeavesLeaves

These organs are organized into two These organs are organized into two systems: the largely below-ground systems: the largely below-ground root root systemsystem and the above-ground and the above-ground shoot shoot systemsystem (stems and leaves). (stems and leaves).

35.2

FungiFungi

Fungi are heterotrophs and feed by Fungi are heterotrophs and feed by absorption.absorption.

They secrete enzymes outside their They secrete enzymes outside their bodies (exoenzymes) which break down bodies (exoenzymes) which break down complex molecules to simpler ones which complex molecules to simpler ones which the fungus can absorb.the fungus can absorb.

FungiFungi

Some fungi are unicellular (yeasts), but Some fungi are unicellular (yeasts), but most are multicellular.most are multicellular.

Body of multicellular fungi made up of tiny Body of multicellular fungi made up of tiny filaments called hyphae. filaments called hyphae.

The hyphae form a mass called a The hyphae form a mass called a mycelium that penetrates the medium the mycelium that penetrates the medium the fungus is feeding on.fungus is feeding on.

31.2

FungiFungi

Mushrooms and toadstools are the familiar Mushrooms and toadstools are the familiar reproductive structures of fungi.reproductive structures of fungi.

Fungi produce spores which may be Fungi produce spores which may be sexually or asexually producedsexually or asexually produced

FungiFungi

Fungi and Animalia share a more recent Fungi and Animalia share a more recent common ancestor (about 1.5 billion years common ancestor (about 1.5 billion years ago) than they do with Plantae.ago) than they do with Plantae.

Fungi are believed to have evolved from Fungi are believed to have evolved from flagellated single-celled protistans, which flagellated single-celled protistans, which suggests multicellularity arose suggests multicellularity arose independently in Fungi and Animaliaindependently in Fungi and Animalia

AnimaliaAnimalia

Since zoology is the study of animals, the Since zoology is the study of animals, the kingdom Animalia is the focus of this kingdom Animalia is the focus of this semester although we will briefly discuss semester although we will briefly discuss the single-celled protozaon groups.the single-celled protozaon groups.

AnimaliaAnimalia

Animals are heterotrophic eukaryotes. Most are Animals are heterotrophic eukaryotes. Most are multicellular. multicellular.

Except for sponges all animals have tissues Except for sponges all animals have tissues which are specialized collections of cells which are specialized collections of cells separated from other tissues by membranes. separated from other tissues by membranes.

Tissues are arranged together to produce Tissues are arranged together to produce organs and organs are organized into organ organs and organs are organized into organ systems (e.g. digestive system).systems (e.g. digestive system).

AnimaliaAnimalia

Most animals are bilaterally symmetrical Most animals are bilaterally symmetrical and form a large clade called the Bilateria.and form a large clade called the Bilateria.

Bilateral animals have a left and right side, Bilateral animals have a left and right side, top and bottom, as well as front and rear top and bottom, as well as front and rear ends.ends.

A smaller number are radially symmetrical A smaller number are radially symmetrical (e.g. jellyfish).(e.g. jellyfish).