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Lecture 13

BIO SCI 94 Lecture Notes - Lecture 13: Deuterostome, Body Plan, Bilateria

Biological Sciences
Course Code
Robin Bush

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An Introduction to Animals
~The beginning of the animals:
a group of multicellular Eukaryotes that differ from their protist ancestors in numerous ways.
~Photosynthetic eukaryotes then evolved via the endosymbiosis of a photosynthetic protist by
a predatory protist.
~Next came the evolution of the eukaryotes (nuclear membrane) and at some point in here (~2
BYA) the mitochondria originated through the endosymbiosis of a bacteria by a eukaryotic cell.
~The Earth's atmosphere didn't contain enough oxygen to support aerobic respiration until the
evolution of the cyanobacteria, around 2.5 BYA.
~Photosynthetic cells evolved soon afterwards.
~The first evidence of life on earth has been dated to about 3.5 BYA.
~Photosynthetic cells evolved soon afterwards.
~The first evidence of life on earth has been dated to about 3.5 BYA (there was a typo (MYA) on
previous versions of this slide).
~The origin of the earth was estimated to have occurred 4.5 billion years ago.
~All of the animal phyla appeared during the Cambrian explosion.
Define what makes an animal an animal.
Fungi vs. Animals
~Fungi and animals are both heterotrophs, but unlike fungi, animals usually ingest their food
before they digest it.
~Fungi cells have cell walls, animal cells do not.
~Many fungi are multicellular, but their cells are not held together, by an extracellular matrix
(ECM) composed of proteins and polysaccharides, as is the case with animals.
~Fungi never move under their own power.
The Animals
Animalia: A major lineage
of eukaryotes that typically:
have complex, large, multicellular bodies;
eat other organisms (are heterotrophs),
are mobile, under their own power, at some point in their life cycle,
and (except for sponges), have neurons and muscle cells.
The developetal took kit is thought to have ee preset i the aestor of the aials. It
includes the genes necessary for all basic molecular processes required by animals:
Cell specialization
Regulation of cell cycling and growth
Adhesion among cells, and between cells and ECM
Recognition of self and non-self
• Iate immunity
Developmental signaling and gene regulation
Programmed cell death
The Evolution of Animals:
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