Dichotomous Keys

• A tool used that allows users to determine the identity of unknown species

• Keys consist of a series of choices, where the user selects from a series of connected pairs

• Each pair of choices contains contrasting traits (most of which are observable)

Dichotomous Keys

• A tool used that allows users to determine the identity of unknown species

• Keys consist of a series of choices, where the user selects from a series of connected pairs

• Each pair of choices contains contrasting traits (most of which are observable)

Creating a Dichotomous Key• Choose a single feature that enables you to divide your group into

two smaller groups• Take each smaller group and repeat the previous step• Be sure to indicate to your key users (those using the key) where to

go next…similar to a “Choose Your Own Adventure” novel• Repeat each step until each species is alone in its own group• Number each dividing feature and assign the the letters “a” and “b”

to the options for that feature• Assemble into a flow chart…of sorts

Comparative Biochemistry

• Analyzing DNA to determine the percentage of relationship

• DNA fingerprinting is used to compare relatedness

• The more base pairs two living things have in common the closer their evolutionary history

Comparative Biochemistry

• Can also mix single strands of DNA from two different species

• The greater the bonding between complimentary base pairs, the more closely related the two species are

Comparative Biochemistry

• Can also mix single strands of DNA from two different species

• The greater the bonding between complimentary base pairs, the more closely related the two species are

Phylogenetic Tree

Cladistics• Classification scheme based on phylogeny• Based on the idea that each group of related

species has one common ancestor• Cladogram – diagram similar to a phylogenetic

tree, that can be used to test evolutionary history

• Not a phylogenetic tree because it does not show how ancestors are related to descendants or how much they have changed

Viruses• Viruses consists of little

more than DNA/RNA surrounded by protective protein coat – capsid

• They do not:– Have cell structure– Have cytoplasm– Respire

• They are not classified in kingdoms of living things

• They can however replicate, but depend on a host cell

Viral Reproduction – Lytic Cycle● 5 step process:

1. Attachment

● Virus attaches to a specific receptor site on the host cell membrane

2. Entry

● Virus injects its DNA/RNA into the host cell

● Cell could also engulf the virus

3. Replication

● Virus uses host cell metabolism to copy its DNA/RNA and its proteins

4. Assembly

● New virus particles are assembled inside the host cell

5. Lysis and Release

● Host cell breaks open, releasing new viruses

Viral Reproduction – Lytic Cycle

http://www.dnatube.com/video/4086/Life-cycle-of-virus-lytic

Viral Reproduction – Lysogenic Cycle

• After entry, viral DNA becomes part of host cell’s chromosomes as a provirus

• Host cell divides, it replicates the provirus along with its own DNA

• Process can occur for years without harm

• Only when it enters the lytic cycle will the damage be done

• Viral dormancy of sorts…think Cold Sores

• http://www.dnatube.com/video/2312/Provirus-animation

Other Points about Viruses• Many viruses are retroviruses

– Viruses containing RNA

– They use an enzyme, that causes the host cell to copy RNA into DNA

– When copied into DNA, retrovirus become a provirus

– Ex: HIV (Human immunodeficiency virus)

• Mutations occur frequently

– DNA/RNA – new varieties or strains of virus are produced

• Viruses are often used as vectors

– Genetic engineers, using recombinant DNA technology, can splice or transfer a gene into the genome of a virus, so it can replicate itself quickly

– Viral vaccines

Kingdom Monera

• Aka. Eubacteria

• Prokaryotic and unicellular

• No organized structure

• Use cilia, flagella, or pili as locomotive organs

• Nutrition obtain in a variety of ways

– Photosynthetic

– Heterotrophic

– Chemosynthetic

Kingdom Monera

• Classified based on shape:1. Spherical: coccus

2. Rod-Shaped: Bacillus

3. Spiral-shaped: Spirillum

Kingdom Monera

• Reproduction is most often asexual by Binary Fission

• However reproduction can also be sexual via Bacterial Conjugation

Kingdom Monera

Kingdom Monera

• Examples:1. Escherichia coli

2. Streptococcal pharyngitis

3. Mycobacterium tuberculosis

Kingdom Archaea

• Most primitive

• Unicellular, prokaryotic

• Heterotrophic

• Found in extreme environments

– Hot springs

– Deep sea vents

• Reproduce asexually

• Use cilia, flagella, or pili as locomotive organs

Kingdom Archaea

• Examples:1. Thermacidophiles

• Hot, acidic water

2. Halophiles• Extremely salty

solutions

3. Thermophiles• Hot conditions, hot

springs

Kingdom Protista

• Simplest of the eukaryotes

• Divided into three groups:

1. Protozoa

• Animal-like protists

• Heterotrophs

• Ex: Amoeba

2. Algae

• Plant-like protists

• Autrotrophs

• Ex: Euglena and Diatoms

3. Slime and water molds

• Fungus-like protists

• Heterotrophic

Kingdom Protista

• Mostly unicellular and aquatic

• Use cilia, flagella, or amoeboid movement

• Reproduction is often asexual – Binary Fission

• Sexual reproduction also occurs

Kingdom Protista

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• Show cases the life cycle of Plasmodium vivax – i.e. What causes Malaria

• Has both asexual and sexual parts to its life cycle