MMED1005 Lecture Notes - Lecture 1: Great Oxygenation Event, Molecular Genetics, Mendelian Inheritance
7 Jun 2018
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From chemistry to living organisms:
- Formation of new molecules from ongoing flow of chemical energy
- Their self-assembly into macromolecules (*without anything predesigned, self-
assembly)
o Spontaneous binding of molecules to form supramolecular structures (forces
between molecules)
o Macromolecules show many new properties:
▪ Catalysis: facilitate chemical reactions
▪ Autocatalysis: facilitate their own chemical reactions
▪ Replication: e.g. RNA and DNA molecules
▪ Form sheets (membranes)
• Assembly of membranes and vesicles: membrane vesicles
provide compartmentalisation of chemical reactions
- Their segregation in separate compartments that facilitate dynamic stability
Appearance of life and evolution:
- Life appeared around 3.8 billion years ago
- Early cells, prokaryotes, were formed by compartmentalisation of chemical reactions
- Energy flowing into cells transformed to produce and maintain order (reduction of
entropy)
- Cells are described as dissipative systems
- Energy sources for living organisms:
o For cyanobacteria and plants: solar energy (light, photosynthesis)
▪ Photosynthesis uses sun light to create small electrical current that
drives chemical reactions that form energy-rich chemical bonds
(involves chlorophyll)
▪ Uses water and carbon dioxide and releases oxygen while making
glucose
▪ 6H2O + 6CO2 + photons → C6H12O6 + 6O2
▪ Glucose has high energy bonds and is a way of storing energy than
can subsequently be used. These bonds can be broken to release
energy through cellular respiration (burning), which converts the
energy of glucose into ATP (another high-energy chemical) (energy
currency of ALL cells)
o For animals: eat plants and other animals
Nonliving and living systems both replicate, but the DNA-based living network allows
information propagation, evolution, and error correction.
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Document Summary
Formation of new molecules from ongoing flow of chemical energy. Their segregation in separate compartments that facilitate dynamic stability. Early cells, prokaryotes, were formed by compartmentalisation of chemical reactions. Energy flowing into cells transformed to produce and maintain order (reduction of entropy) These bonds can be broken to release energy through cellular respiration (burning), which converts the energy of glucose into atp (another high-energy chemical) (energy currency of all cells: for animals: eat plants and other animals. Nonliving and living systems both replicate, but the dna-based living network allows information propagation, evolution, and error correction. Bacteria begun to pump oxygen into atmosphere, initially absorbed into rocks (rusting of the earth, 1. 7-2 billion years ago) ~2 billion years ago: surge of oxygen atmosphere (the great oxidation event) Oxygen: destructive, break down organic molecules into h2o and co2. Some bacteria survived surge of oxygen atmosphere and oxygen-based metabolism appeared. Transition from prokaryotes (no nucleus) to eukaryotes (with nucleus)
