SB 3 Students will derive the relationships between
SB 3. Students will derive the relationships between single-celled and multicelluar organisms and the increasing complexity of systems b. Compare how structures and function vary between the six kingdoms LEQ 2: How do the structures and functions vary between the six kingdoms?
Organisms can be classified based on similarities.
Linnaeus developed the scientific naming system still used today to classify organisms. Taxonomy is the science of naming and classifying organisms. White oak: Quercus alba A taxon is a group of organisms in a classification system.
Binomial nomenclature is a two-part scientific naming system. – uses Latin words – scientific names always written in italics if typed, underlined if written – two parts are the genus name and species descriptor
A genus includes one or more physically similar species. – Species in the same genus are thought to be closely related. – Genus name is always capitalized. A species descriptor is the second part of a scientific name. – always lowercase Tyto alba – always follows genus name; never written alone
• Scientific names help scientists to communicate. – Some species have very similar common names. – Some species have many common names.
Linnaeus’ classification system has seven levels. • Each level is included in the level above it. • Levels get increasingly specific from kingdom to species.
The Linnaean classification system has limitations. • Linnaeus taxonomy doesn’t account for molecular evidence (DNA comparisons). – The technology didn’t exist during Linneaus’ time. – Linnaean system based only on physical similarities.
• Physical similarities are not always the result of close relationships. • Genetic (DNA) similarities more accurately show evolutionary relationships.
The current tree of life has three domains.
The three domains in the tree of life are Bacteria, Archaea, and Eukarya. • Domains are above the kingdom level.
HISTORY Classification is always a work in progress. • The tree of life shows our most current understanding. • New discoveries can lead to changes in classification. – Until 1866: only two kingdoms, Animalia and Plantae – 1866: all single-celled Animalia organisms moved to Protista kingdom Protista – 1938: prokaryotes moved to kingdom Monera – 1959: fungi moved to own kingdom Monera Fungi Archaebacteria Eubacteria
DOMAIN BACTERIA Kingdom: Eubacteria/Bacteria • Unicelluar • Prokaryotic • Have thick cell walls – Peptodoglycan • Both Heterotrophic or Autotrophic • Classified by shape, need for oxygen, and diseases cause – Coccus – Bacillus – Spirillum • Examples: e. coli True Bacteria – one of largest groups on Earth
DOMAIN ARCHEA Kingdom: Archaebacteria • • Unicellular Prokaryotic organisms Both Heterotrophic or autotrophic NOT the same as Eubacteria but resemble them – Differences exist in the DNA of Eubacteria and Archaebacteria – Cell walls not made of peptidoglycan • Live in harsh environments – Anaerobic environments • Examples: methanogens, halopiles, and thermophiles
DOMAIN EUKARYA Kingdom: Protista • • Most unicellular, some multicelluar Autotrophic or heterotrophic May or may not have cell wall and chloroplasts Have characteristics similar to plants, animals, and fungi (but are none of the above) – Very diverse • Examples: – Protozoa, amoeba, paramecium, and euglena resemble animals – unicellular algae resembles plants – slime molds have some characteristics of fungi
PROTISTA PICTURES AMOEBA VOLVOX COLONY EUGLENA Thought to be an important link in early evolution Evolving from prokaryotes and giving rise to the entire line of eukaryotes PARAMECIUM
DOMAIN EUKARYA Kingdom: Plantae • Eukaryotic organisms • Multicellular • Autotrophs (photosynthesis) – Use sunlight to make food – Produce oxygen • Have cell walls made of cellulose • Link to energy and survival of all organisms • Examples: – Multicellular algae, mosses, ferns, flowers trees
DOMAIN EUKARYA Kingdom: Fungi • Eukaryotic • Multicellular and unicellular organisms • Heterotrophs – Obtain nutrition by feeding on dead or decaying matter • Decomposer • Have cell walls made of chitin, no chloroplasts • Examples: Mushroom (multi), yeasts (uni)
DOMAIN EUKARYA Kingdom: Animalia • Eukaryotic organisms • Multicellular • Heterotrophic – Obtain nutrient by eating plants or other animals • Release energy from food by process of respiration • NO cell wall • Examples: – sponges, worms, insects, fish, amphibians, reptiles, birds, and mammals – Have interior digestive tracts, body symmetry and nerve tissue
SB 3. Students will derive the relationship between single-celled and multicelled organisms and the increasing complexity of systems. c. Examine the evolutionary basis of modern classification systems. LEQ 3: How is evolutionary history used to classify organisms?
In addition to classifying organisms scientists attempt to understand the evolutionary relationships among organisms They do this to find clues of how life has changed or diversified over time
Cladistics is classification based on common ancestry. Phylogeny is the evolutionary history for a group of species. (Phylogenetics) – evidence from living species, fossil record, and molecular data (DNA) – shown with branching tree diagrams
• Cladistics is a common method to make evolutionary trees. – classification based on common ancestry – species placed in order that they descended from common ancestor
• A cladogram is an evolutionary tree made using cladistics. – A clade is a group of species that shares a common ancestor. – Each species in a clade shares some traits with the ancestor. – Each species in a clade has traits that have changed.
• Derived characters are traits shared in different degrees by clade members. – basis of arranging species in cladogram – more closely related species share more derived characters – represented on cladogram as hash marks 1 Tetrapoda clade 2 Amniota clade 3 Reptilia clade 4 Diapsida clade 5 Archosauria clade FEATHERS & TOOTHLESS BEAKS. SKULL OPENINGS IN FRONT OF THE EYE & IN THE JAW OPENING IN THE SIDE OF THE SKULL OPENINGS BEHIND THE EYE EMBRYO PROTECTED BY AMNIOTIC FLUID FOUR LIMBS WITH DIGITS DERIVED CHARACTER
• Nodes represent the most recent common ancestor of a clade. • Clades can be identified by snipping a branch under a node. CLADE 1 Tetrapoda clade 2 Amniota clade 3 Reptilia clade 4 Diapsida clade 5 Archosauria clade FEATHERS AND TOOTHLESS BEAKS. SKULL OPENINGS IN FRONT OF THE EYE AND IN THE JAW OPENING IN THE SIDE OF THE SKULL OPENINGS BEHIND THE EYE EMBRYO PROTECTED BY AMNIOTIC FLUID NODE FOUR LIMBS WITH DIGITS DERIVED CHARACTER
Molecular evidence reveals species’ relatedness. • Molecular data may confirm classification based on physical similarities. • Molecular data may lead scientists to propose a new classification. • DNA is usually given the last word by scientists.
Molecular clocks provide clues to evolutionary history.
Molecular clocks use mutations to estimate evolutionary time. • Mutations add up at a constant rate in related species. – This rate is the ticking of the molecular clock. – As more time passes, there will be more mutations. Mutations add up at a fairly constant rate in the DNA of species that evolved from a common ancestor. DNA sequence from a hypothetical ancestor Ten million years later— one mutation in each lineage Another ten million years later— one more mutation in each lineage The DNA sequences from two descendant species show mutations that have accumulated (black). The mutation rate of this sequence equals one mutation per ten million years.
• Scientists estimate mutation rates by linking molecular data and real time. – an event known to separate species – the first appearance of a species in fossil record
Mitochondrial DNA and ribosomal RNA provide two types of molecular clocks. • Different molecules have different mutation rates. – higher rate, better for studying closely related species – lower rate, better for studying distantly related species
Due to mutations and natural selection over time SPECIATION can occur. • Speciation: – Process whereby a population of interbreeding individuals is split into separate populations. Over time these separate populations evolve independently of each other and become separate species • They are no longer capable of interbreeding
E C I T C A R P Common Ancestor
1. Using the phylogenetic tree determine which of the following lizard species are most closely related: A. C. tigris and U. scoparia B. C. draconoides and U. scoparia C. D. dorsalis and C. draconoides D. C. tigris and D. dorsalis
Continued…. . 2. Which species of lizard was the first to evolve from the common ancestor? 3. Which lizard is most like the common ancestor that gave rise to all of the species of lizard shown?
SB 3. Students will derive the relationship between single-celled and multicelled organisms and the increasing complexity of systems. d. Compare and contrast viruses with living organisms LEQ 4: How are viruses different from living organisms?
What are Viruses? • A virus is made of DNA or RNA and a protein coat. – non-living pathogen – can infect many organisms • NOT considered to be a living organism
Why are viruses NOT considered to be a living organism? • Living things are made up of cells and are able to live independently of other organisms • By this definition viruses are NOT alive • They share many characteristics of living things but cannot function without infecting a living cell
Characteristics • Viruses do share many characteristics of living things • Can reproduce – Only after infecting a host cell • Uses host cell to replicate itself multiple times • Control gene expression • Evolve (change over time)
Cells Viruses Reproduce through cell Reproduce only inside of division (sexual/asexual) host cell Genetic code is DNA Genetic code can be DNA or RNA Use energy Do not use energy Respond to environment Do not respond to environment Change with time (evolve) Develop and Grow Do not develop or grow
Viruses differ in shape and in ways of entering host cells. • Viruses have a simple structure. – genetic material – capsid, a protein shell – maybe a lipid envelope, a protective outer coat enveloped (influenza) capsid nucleic acid lipid envelope helical (rabies) Surface proteins capsid nucleic acid surface proteins lipid envelope polyhedral (foot-and-mouth disease) surface proteins capsid nucleic acid
Bacteriophage • Most common virus • Infect bacteria cell by attaching their “legs” to the bacterium • Injecting their genetic material into it • Virus takes control of cell and produces more viruses. • New viruses are released when the cell bursts and then they are free to infect other cells
Bacteriophages infect bacteria. capsid DNA tail sheath PROTEIN COAT tail fiber
Viruses enter cells in various ways. – bacteriophages pierce host cells colored SEM; magnifications: large photo 25, 000; inset 38, 000 x
viruses of eukaryotes can fuse with membrane
What happens next? Two different processes that occur once genetic material of the virus is inside the host cell – Lytic infection – Lysogenic infection
Lytic Infection • Injects DNA directly into the cell. • Host cell is unable to tell the difference between viral DNA and its own. • Host cell begins to make viral m. RNA – Translated into viral proteins that destroy the cell DNA • Cell them make thousands of copies of virus’s DNA • Cell bursts and releases the new virus’s
• A lytic infection causes the host cell to burst. host bacterium The bacterophage attaches and injects it DNA into a host bacterium. The host bacterium breaks apart, or lyses. Bacteriophages are able to infect new host cells. The viral DNA forms a circle. The viral DNA directs the host cell to produce new viral parts. The parts assemble into new bacteriophages. The virus may enter the lysogenic cycle, in which the host cell is not destroyed.
Lysogenic Infection • Does not destroy host cell right away • Insert DNA into host’s DNA – Called a prophage • Exists in cell for many generations without becoming active • Once active it enters in to the lytic cycle and behaves just like lytic infection
• A lysogenic infection does no immediate harm. The prophage may leave the host’s DNA and enter the lytic cycle. The viral DNA is called a prophage when it combines with the host cell’s DNA. Many cell divisions produce a colony of bacteria infected with prophage. Although the prophage is not active, it replicates along with the host cell’s DNA.
Cycles of Virus
VACCINES • Vaccines have been developed for viruses such as measles, mumps and polio. • Usually a piece of the antigen (the foreign substance or part that the body reacts to) is injected into the body. • The immune system then produces antibodies against it. That way if you later come in contact with the pathogen, your body will have a defense against it.
Key Questions: 1. How do viruses reproduce? A. They copy their own genetic material inside a protein coat. B. They kill a cell and reproduce in it. C. They invade a living cell and use the cell’s function to replicate their genetic material. D. They do not reproduce because they are not technically living things.
Key Questions: 2. What is the capsid of a virus? A. the disease it causes B. the receptors to which it binds C. its genetic material D. its protein coat
Key Questions: 3. What is one way that a lysogenic infection differs from a lytic infection? A. A lysogenic virus does not act on a bacteria as a lytic virus does. B. A lysogenic virus can remain in the host DNA for a longer period without becoming active. C. A lysogenic virus contains RNA instead of DNA. D. A lysogenic virus does not affect a cell but does direct the production of new viruses.
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