A2.1 Origin of Cells

A2.1.1 Conditions of early earth

No O₂, UV (no atmos), High T, Much CO₂, frequent storms w lightnin

Planet formed of smaller particles → larger masses;more grav:attract

Caused spontaneous reactions with carbon.

A2.1.2 Functions of life

Metabolism: all chemical reaction in organism

Homeostasis: maintaining constant internal environment

Growth: becoming bigger, any form

Nutrition: using nutrients for supporting functions

Reproduction: produce fertile offspring

Excretion: get rid of waste/harmful stuff

Response: adapt to stimuli

Mr. H. Gren

Virus is not living: cant self-sustain: reproduce, metabolize: host cell

A2.1.2 Cell theory

1. All organisms composed of 1 or more cells

2. Cells are smallest unit of life

3. All cells come from pre-existing cells

A2.1.3 Evolution of a cell

All cells com from pre-existing cells!!! First “cell” = protocell; prebiotic/non-living environment.

First cells: catalysis, self-replication of molecules, self-assembly, compartmentalisation

A2.1.3 Claims in science

Claims, theories, hypotheses, etcetc… especially abt early earth conditions difficult to test and stuff…

A2.1.4 Miller Urey

Evidence for origin of (organic) carbon compounds.

H₂O/CH₄/NH₃/H₂ through sparks (lightning) → condensor →analyse

Found hydrocarbons and amino acids;

evidence life originated in primordial soup;water soup;simple org.mol

A2.1.5. Spontaneous forming of vesicles

Vesicle: membrane bound comparment allowing internal chemistry

Form spontaneous from hydrophil head + hydrophob tails of phos.lip.

A2.1.6 First genetic material

DNA needs enzymes, enzymes need DNA; chicken/egg

RNA was first: replicated individually, catalytic function, spontaneous from nucleotides.

A2.1.7 LUCA

Last Universal Common Ancestor.

Evidence: universal genetic code, >300 common genes to all cells, same nucleotides, replic/transc/translat same, same transport type

A2.1.8 Dating <3

Use radioactivity/half lives…. fossils, genome info…

Humans 1 sec before midnight on clock of 4.5 bil years earth exists.

A2.1.9 Hydrothermal vents

Probably where LUCA comes from; hot place in sea, LUCA comes from here bc. eg. anaerobic respir etc, many minerals here, and some of the oldest fossils are found here, H and CO₂ present