Abiogenesis

What do you think this word means?

• Abio

• Genesis

• Abiogenisis

Aim Outline key theories and evidence for how life

started on earth

D1 – Abiogenisis (a theory)

Emergence of Life from the Primordial Soup

http://www.slideshare.net/jasondenys/ib-option-d1-origin-of-life?ref=http://www.slideshare.net/slideshow/embed_code/8168926

The Origins of Life on Earth

Homework

See website for instructions (30 minute activity)

Test Tuesday after school – 5:35 prompt

HW

What is Life?

http://www.youtube.com/watch?v=5OfIsNPZm8w

How did it start?

How did it start? (In abiogenesis theory) Sort the cards

1. Non-living (abiotic) synthesis of simple organic molecules 2. Assembly of these simple organic molecules into polymers 3. Origin of self-replicating (organic) molecules that make

inheritance of information possible 4. Packaging of self replicating molecules into membranes with

an internal chemistry different from their surroundings (homeostasis)

Spontaneous generation… Abio or biogensis

http://www.slideshare.net/jasondenys/ib-option-d1-origin-of-life?ref=http://www.slideshare.net/slideshow/embed_code/8168926

Muller-Ruey: A Working Hypothesis for Abiogenisis

http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter26/animation_-_miller-urey_experiment.html

http://www.youtube.com/watch?v=iahBQolXQH8

• Recreating the ‘primeval soup’ • In a lab 1953 • ‘Chemical evolution’ • Simulated atmosphere, volcanic activity, lightning….. • 15/23 amino acids….

Muller-Ruey: A Working Hypothesis

Origins of a Self Replicating Molecule

2 Key properties of a self replicating molecule: • Ability to self replicate • Catalytic activity (self enzyming)

Can you think of a molecule that is not DNA but can self replicate?

DNA replicates, but it cant self replicate, it needs biological catalyst….

RNA has ‘Ribozyme’ activity!

RNA World (hypothesis)

Biogenesis: Comets?

Simulation & Quiz http://bcs.whfreeman.com/thelifewire/content/chp03/0301s.swf

EXTRA: http://www.youtube.com/watch?v=51V363V1bkI

Heavy bombardment 4000 million years ago • Organic molecules only? • RNA?

Possible Locations

Problem: Water in Miller-Urey experiment tends to hydrolyse….. Ocean conditions couldn’t have produced life!

• Hydrothermal vents (dissolved sulphides crystallize around vent)

• Volcanoes (Higher levels of fixed nitrogen NH4)

• Extraterrestrial locations (organic molecules are out there! Could account for how life has moved around, not how formed)

http://www.youtube.com/watch?v=IcJlmpen4A0

Protobionts – What does it mean?

• Proto- • Bio – Before Biological-living

• Ultimately it means…. A pre ‘cell’, with living properties but not alive

http://exploringorigins.org/protocells.html

Aim Outline theories for how complex life may have

origonated

Protobionts

Coacervates & Microspheres

• Internal environment different from surrounds.

• Can absorb, concentrate substrates and divide

into two

• Can catalyse some reactions

• Can grow (divide) but cannot reproduce

• Non-living

• May contain RNA

• RNA that got encapsulated in one of these

structures may have gained the ability to form a protein

http://exploringorigins.org/protocells.html

Cyanobacteria (Prokaryotes) The Oxygen Revolution

• Little free oxygen early on

• Small amounts made by

lightning/hydrolysis

http://www.youtube.com/watch?v=fXADhz6JjWw

Endosymbiosis

Complex Life: Endosymbiosis http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter4/animation_-_endosymbiosis.html

Evidence in support: Discuss the evidence in support of evolution

with the person next to you! 1. Mitochondria & Chloroplasts -

circular DNA 2. DNA analysis shows some

organelle is now present in nuclear DNA & protein is transported to organelle (lost ability)

3. Choloroplast structure similar to that of cyanobacteria

4. Self replication (similar to binary fission)

5. Double membrane resembles prokaryote structure

6. Small ribosomes (70s)

3.8 billion yrs - Evolution of Life Create an illustrated timeline (dates not required) from the creation

of the earth through to the formation of complex life. Include both evidence & uncertainties surrounding each event on your

timeline. (TBC as homework)

http://www.bbc.co.uk/nature/history_of_the_earth http://www.youtube.com/watch?v=H2_6cqa2cP4

Further info & evidence on the theory of ‘Evolution’

Evolution: https://www.youtube.com/watch?feature=player_embedded&v=5NdMnlt2keE Timeline of the evolution of life: http://exploringorigins.org/timeline.html http://www.newscientist.com/article/dn17453-timeline-the-evolution-of-life.html?full=true Evolution & oxygen: http://www.youtube.com/watch?v=DE4CPmTH3xg Evidence for evolution: http://www.youtube.com/watch?feature=player_embedded&v=GnR5kQG6qBU

Endosymbiosis Resources

Activity: http://www.sumanasinc.com/webcontent/animations/content/organelles.html

http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter4/animation_-_endosymbiosis.html

http://blogs.discovermagazine.com/notrocketscience/2010/10/20/the-origin-of-complex-life-%E2%80%93-it-was-all-about-energy/#more-2905