BIOL 111 Lecture Notes - Dinoflagellate, Mechanoreceptor, Lophotrochozoa

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Published on 26 Jun 2012
School
McGill University
Department
Biology (Sci)
Course
BIOL 111
Professor
Bio 111 Alanna Houston
October 18, 2007
SPONGES
Asexual Reproduction:
-Fragmentation:
oNot self-induced
oWaves, predators
-Budding:
oClone of parent
Sexual Reproduction:
-Hermaphroditic
oSperm and eggs develop inside single cells
oBroadcast sperm
oFilter in different sperm
oEggs fertilized, develop in jelly layer (mesohyl)
oLarvae released
oSettle on suitable substrate
oDevelop in sessile adult
Sponge Origins:
-Evolved ~ 700 MYA
-Ancestor – coanoflagellate (protists) cells are similar to
choanocytes of modern sponges
Limitations of Sponges:
-Very successful group, but
-Unable to feed on larger prey than choanocytes
oDigestion is intracellular
-Unable to achieve high level organization or coordination between
body parts
oCellular level of organization
oNo tissues etc. cannot respond to stimulus and do not have
muscles to move
When in time first displayed a gut: C (look at phylogeny)
Evolutionary innovations:
-Gut
oEnables extracellular digestion
-Tissues
oEnable body organization
ANIMALS
Which is not a characteristic of animals:
-D: a haploid multicellular life stage
-Their multicellular life stage is diploid
Characteristics of Animals:
-Eukaryotic
-Heterotrophic
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Bio 111 Alanna Houston
-No cell walls
-Motile at some life stage
-Multicellular
-Have tissues
-Life cycle mostly diploid
-Unique embryonic development
Embryonic Development
-Embryo: a young animal or plant contained within a protective
structure (seed, egg or uterus)
-Zygote: multicellular organism
-2 major processes during embryonic development
oCleavage: cell division – process forming many cells from
one cell
oGastrulation: infolding – process forming embryonic tissue
layers (2-3) from one layer of cells
o
oZygote – cleavage morula (solid ball) blastula (hollow
ball) – Gastrulation early gastrula and blastopore
(opening) late gastrula forming a higher bigger
blastopore
o
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Bio 111 Alanna Houston
-Gastrula:
oLayers of embryonic cells = germ layers
oGerm layers: ectoderm (epidermis, nervous system) – outer
layer, endoderm (lining of digestive and respiratory
systems) – inner layer
-Animals with two germ layers are diploblastic (simpler animals)
o3rs layer is called mesoderm (inside) – most internal organs:
muscles, skeletal system, heart, stomach
-Animals with three germ layers are triploblastic (us)
-Blastopore turns into mouth of anus
-Archenteron is the digestive space (gut cavity – one opening)
-A tract has an in and an out whereas a cavity only has one
opening
-
-Triploblasts start after cnidarians
CNIDARIANS
Challenge One: Obtaining Energy
-Heterotrophic
-Sometimes sessile during life
-Multicellular – how get nutrients to all cells? (Cells have to be
small) Must be another way other than simple diffusion
-Capture food with cnidocytes (stinging cells)
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Document Summary

Fragmentation: not self-induced, waves, predators, clone of parent. Hermaphroditic: sperm and eggs develop inside single cells, broadcast sperm, filter in different sperm, eggs fertilized, develop in jelly layer (mesohyl, larvae released, settle on suitable substrate, develop in sessile adult. Ancestor coanoflagellate (protists) cells are similar to choanocytes of modern sponges. Unable to feed on larger prey than choanocytes: digestion is intracellular. Unable to achieve high level organization or coordination between body parts: cellular level of organization, no tissues etc. cannot respond to stimulus and do not have muscles to move. When in time first displayed a gut: c (look at phylogeny) Tissues: enables extracellular digestion, enable body organization. Embryo: a young animal or plant contained within a protective structure (seed, egg or uterus) Gastrula: layers of embryonic cells = germ layers, germ layers: ectoderm (epidermis, nervous system) outer layer, endoderm (lining of digestive and respiratory systems) inner layer.

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