BIOL10004 Lecture Notes - Lecture 1: Cambrian Explosion, Semipermeable Membrane, Extraterrestrial Life
28 Jun 2018
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BIOL10004 – Biology of Cells
MODULE 1: CELL BIOLOGY
LECTURE 1 – WELCOME TO BIOLOGY
Generalisations:
1. Evolution through natural selection accounts for the animal kingdom’s diversity – both the
similarities and differences
o Evolution = Unifying theory in biology
§ Earth has a long history
§ All living organisms arose from earlier, more primitive forms
§ Hence, all organisms share a common ancestor
o Natural selection:
§ Individuals in a species show a wide range of variation
§ Fitter individuals with characteristics best suited to the environment are more
likely to survive and reproduce to pass the genes on à DIFFERENTIAL
REPRODUCTION
§ Over time, species will evolve (differential reproduction)
o Origin of life is unknown but there are several theories:
§ Extra-terrestrial life – life from another planet
§ Special/spontaneous creation by supernatural forces – i.e. reducing
environment facilitated organic molecule formation (i.e. RNA)
2. Unity of Biochemical Processes – all organisms share a common ancestor
o Hence, all organism shares certain biochemical reactions
o I.e. All organisms have genetic material (DNA) that contains instructions for how
organisms develop
o Organisms have proteins to carry out these specified instructions
3. The Cell theory – all organisms consists of cells
o The cell is a bag/closed domain where the chemical reactions for life are carried out
o Surrounded by semi-permeable membrane
§ Allows movement of molecules in/out of cell (i.e. toxins out)
o Cell theory:
§ All living organisms are composed of cells
§ All cells come from pre-existing cells (no spontaneous generation of cells)
§ The cell = smallest organisational unit
Darwin’s Dilemma – objections to his theory of evolution
• Where were the first cell(s) in the fossil record?
o Stromatolites – referred to as “living fossils”
o Has cyanobacteria on their surface à looks almost identical to modern day bacteria
o Complex cell types appear more recently
§ How did eukaryotic cells evolve from prokaryotic cells?
o Photosynthetic due to cyanobacteria within.
• How to explain the Cambrian explosion?
Document Summary
Generalisations: evolution through natural selection accounts for the animal kingdom"s diversity both the similarities and differences, evolution = unifying theory in biology. All living organisms arose from earlier, more primitive forms. Hence, all organisms share a common ancestor: natural selection: Individuals in a species show a wide range of variation. Fitter individuals with characteristics best suited to the environment are more likely to survive and reproduce to pass the genes on differential. Over time, species will evolve (differential reproduction: origin of life is unknown but there are several theories: Extra-terrestrial life life from another planet. Special/spontaneous creation by supernatural forces i. e. reducing environment facilitated organic molecule formation (i. e. rna: unity of biochemical processes all organisms share a common ancestor, hence, all organism shares certain biochemical reactions. Allows movement of molecules in/out of cell (i. e. toxins out: cell theory: All living organisms are composed of cells. All cells come from pre-existing cells (no spontaneous generation of cells)
