Summary of Biology 2e by Openstax

Bullet point summary of chapters 20-29. It is concise but it has all important information from the chapters.

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Summary of biology 2e
Online version: https://openstax.org/books/biology-2e/
Chapter 20: phylogenies and the history of life
20.1 Organizing Life on Earth
● A phylogenetic tree reflects evolutionary relationships among organisms or groups
of organisms → like a map of evolutionary history
○ Rooted trees: show a common ancestor
○ Unrooted trees: do not show a common ancestor
● Taxonomy: internationally shared classification systems with each organism placed
into increasingly more inclusive groupings
20.2 Determining Evolutionary Relationships
● Homologous structures: features that overlap morphologically (in form) and
genetically
○ Organisms that share homologous structures are more closely related than
those that do not
○ e.g., the bones in bat and bird wings
○ Share a similar embryonic origin
● Analogy or homoplasy: similar characteristics that occur because of environmental
constraints and not due to a close evolutionary relationship
○ E.g., insects use wings to fly like bats and birds, but the wing structure and
embryonic origin is completely different
○ Analogous organs have a similar function
● Homologous traits are organized into cladistics
○ It sorts organisms into clades: groups of organisms that descended from a
single ancestor
● Maximum parsimony: events occurred in the simplest, most obvious way
○ E.g., if a group hikers entered a forest, most would hike on established trails
rather than forge new ones
20.3 Perspectives on the Phylogenetic Tree
● Horizontal/lateral gene transfer: transfer of genes between unrelated species
● Standard phylogeny: genes pass between distantly related species
● HGT in Prokaryotes
○ Transformation: bacteria takes up naked DNA
○ Transduction: a virus transfers the genes
○ Conjugation: a hollow tube, or pilus transfers genes between organisms
● HGT in Eukaryotes
○ Rarer and has a much smaller evolutionary impact than in prokaryotes
○ In plants, gene transfer in species that cannot cross-pollinate by normal
means
○ Transposons or “jumping genes” have shown a transfer between rice and
millet plant species
○ Fungal species feeding on yew trees, from which the anti-cancer drug TAXOL®
is derived from the bark, have acquired the ability to make taxol themselves
● Web of life:
○ Some individual prokaryotes transferred the bacteria that caused
mitochondrial development to the new eukaryotes
○ Other species transferred the bacteria that gave rise to chloroplasts
● Ring of life: all three domains of life evolved from a pool of primitive prokaryotes
Key terms: https://openstax.org/books/biology-2e/pages/20-key-terms
Chapter 21: viruses
21.1 Viral Evolution, Morphology, and Classification
● Viruses are tiny, noncellular entities - can only be seen with an electron microscope
● Their genomes contain either DNA or RNA - never both
● Replicate by using the replication proteins of a host cell or of the viral genome
● Viruses are diverse → infect archaea, bacteria, fungi, plants, and animals
● Many viruses use some sort of glycoprotein to attach to their host cells via
molecules on the cell called viral receptors
○ Adenovirus (non-enveloped animal virus that causes respiratory illnesses in
humans) uses glycoproteins
● Capsids of viruses are classified into four groups
○ Helical capsids: long and cylindrical → many plant viruses (e.g. TMV)
○ Icosahedral: roughly spherical, e.g. poliovirus or herpesviruses
○ Head-and-tail infect bacteria and have a head that is similar to icosahedral
viruses and a tail shaped like helical viruses
○ Enveloped: membranes (from the host cell) surrounds the capsids
■ Animal viruses, such as HIV

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Specificaties

Niveau: Universiteit
School: University College Roosevelt
Opleiding: Liberal Arts & Sciences
Vaknaam: Introduction to biodiversity
Vakcode: SCIENVI102
Studiejaar: 2020
Boek
Naam boek: Biology 2e
ISBN: ISBN-10: 1-947172-52-2 & ISBN-13: 978-1-947172-52-4
Hoofdstukken: 20, 21, 22, 23, 24, 25, 26, 27, 28, 29
Druk: 2nd
Auteur: Mary Ann Clark, Matthew Douglas, Jung Choi
Document
Rubriek: Samenvattingen
Gemaakt op: 02-02-2021
Type: .pdf
Pagina's: 64
Taal: English
Tags
biodiversity ecology biology openstax 2e summary bullet points environment science