BIOL10004 Chapter Notes - Chapter 4: Phagocytosis, Cycloheximide, Purple Bacteria
29 Jun 2018
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Primary Endosymbiosis and the origin of organelles
(Chapter 4)
Protists are a diverse group of eukaryotes
Protists once grouped in two
oAutotrophic - able to produce food by photosynthesis
oHeterotrophic - consumers of organic substances or other organisms
Photosynthetic protists - algae
Smaller protists - protozoa (simple animals)
Nutrient absorbing protist - fungi
System far too simplistic and a new system has been devised
oBased on classification based on morphological, biochemical and molecular features
oGene sequences
Where did eukaryotic cells come from?
Eukaryotic organisms did not appear until 1.4 billion years ago
Prokaryotes appeared 3.5 billion years ago
Origin of the nucleus
Two major distinction between eukaryotic nucleus and prokaryotic nucleoid
oProkaryotes
Lacks a nuclear envelope
Single circular chromosome
oTransformation from circular to linear chromosomes due to break in circle and
duplication of linear chromosome
Origin of nuclear envelope explain by accumulation of vesicles from infolding (invagination)
of cell membrane and prokaryotic nucleoid
If vesicles flatten around nucleoid, forms double envelope complete with gaps or nuclear
pores
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Document Summary
Primary endosymbiosis and the origin of organelles (chapter 4) Protists once grouped in two: autotrophic - able to produce food by photosynthesis, heterotrophic - consumers of organic substances or other organisms. System far too simplistic and a new system has been devised o. Based on classification based on morphological, biochemical and molecular features: gene sequences. Eukaryotic organisms did not appear until 1. 4 billion years ago. Two major distinction between eukaryotic nucleus and prokaryotic nucleoid o. Transformation from circular to linear chromosomes due to break in circle and duplication of linear chromosome. Origin of nuclear envelope explain by accumulation of vesicles from infolding (invagination) of cell membrane and prokaryotic nucleoid. If vesicles flatten around nucleoid, forms double envelope complete with gaps or nuclear pores. The endomembrane system: extension of the nuclear envelope. Forms channel from nuclear envelope to subcellular compartments and exterior of cell via plasma membrane. Evolved as means of sorting and transporting proteins and glycoproteins.
