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)
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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