What are the 3 parts to the cell theory?
1) All living things are composed of one or more cells
2) Cells are the smallest units of living things
3) New cells only come from pre-existing cells by division
How old is the earth?
4.55 billion years old
When is it thought that life has begun on earth?
between 4 and 3.5 billion years ago
Bacteria existed for over _________ years before eukaryotes came along
1.5 billion years
As the Earth formed and cooled, the atmosphere was much different than today.. How?
There was no oxygen
What was the early atmosphere made up of? (4)
1) NH3 (amonia)
2) CO2 (Carbon dioxide)
3) CH4 (methane)
4) H2O (water)
**Observe, no molecular oxygen**
In the 1920s Aleksander Oparin and John Haldane suggested that …
In the 1920s Aleksander Oparin and John Haldane suggested that the chemicals in the early atmosphere could react to produce simple organic compounds
Who started the Reducing Atmosphere Hypothesis? And what was it?
Oparin and Haldane
The key was the ‘reducing environment and lack of a protective ozone layer
What was the Miller-Urey Experiment in 1953?
They tried to mimic the early atmosphere (early earth) to determine if organic compounds could be produced
What did the Miller- Urey Experiment produce?
Produced simple and complex organic molecules
1) Cyanide (HCN)
2) Formaldehyde (H2CO)
3) Amino acids
4) Sugars
How did the Miller-Urey experiment work?
They put the compounds of the early atmosphere (CH4, NH3, H2O, H2) which went through a condenser (water in and out) which formed water containing organic compounds… then boiled what and got organic molecules (HCN,H2CO, amino acids, sugars)
What was the conclusion of the Miller- Urey experiment?
The conclusionn was that simple organic molecules could form under the conditions of the primitave Earth
Do the results of the Miller-Urey Experiment prove that organic molecules came about this way?
No, but it did demonstrate that chemical evolution could occur and that it could be tested in the lab under controlled conditions
_______ provide many ofthe same characteristics as early earth atmosphere plus high pressure
Hydrothermal (deep sea) Vents
The high temperatures and pressures of Deep-sea vents can also promote the production of _______
Complex organic molecules
It is thought that the diverse _______ emitted by the vent, the gradient of _______ and the immense ______ could result in organic compounds being produced
It is thought that the diverse chemicals emitted by the vent, the gradient of temperatureand the immense pressure could result in organic compounds being produced
Comets and Meteors often contain ______ compounds and may have contributed to the _____ present on Earth
Comets and Meteors often contain carbon compounds and may have contributed to the carbon present on Earth
Simple biomolecules:
How did they become more complex?
Initial ideas suggest that clays may have acted as a polymerization catalyst
Polymers of atleast ________ are required for a simple genetic system
Polymers of atleast 30-60 units are required for a simple genetic system
Clay particles tend to be _____ charged and thus attract _________ ions which will interact with _______ charged organic molecules
Clay particles tend to be negatively charged and thus attract positive ions which will interact with negatively charged organic molecules
Clays could give rise to _______________
Clays could give rise to stable nucleic acid polymers
Protibionts:
Next a compartment was needed… what could have formed a primitive cell membrane?
Amphipathic molecules (lipids or even proteins)
Which are made up of hydrophobic (inside-hate water) and hydrophilic (outside- like water) ends
What did Dr. Jack Szostak’s lab at Harvard University study?
They looked at in vitro vesicle formation and RNA synthesis
*In vitro = “in glass”- outside and organism*
Protobionts?
It is also suggested that particles of _____ and ______ may have attracted water to form compartments, essentially providing a_________
It is also suggested that particles of protein and carbohydrate may have attracted water to form compartments, essentially providing a surface for reactions
In experiments these simple compartments supplied with modern enzymes, took in _______ and made _______
In experiments these simple compartments supplied with modern enzymes, took in glucose-phosphate and made starch
What is the track of the enzymes in a protobiont?
Glucose-1 phosphate -> (enters the protobiont as Glucose-1 phosphate)
*In the compartment*
Glucose-1 phosphate-> Starch
(Using the enzyme Glycogen phosphorylase)
Starch -> Maltose
(Using the enzyme Amylase)
Maltose -> (leaves the protobiont as Maltose)
To become a living cell, these particles (compartments) needed to become ________
self-replicating
One theory suggests that RNA molecules inside of a primitive compartment may have randomly achieved the ability to enhance the rate of______________
One theory suggests that RNA molecules inside of a primitive compartment may have randomly achieved the ability to enhance the rate of adding one RNA nucleotide onto another
*Clay particles inside a protocell may have helped accelerate this process*
_____ provides an RNA molecule with the enzymatic ability to synthesize new RNA molecules from pre-existing RNA molecules
Mutation
What is the chemical selection of a mutation?
The amount of this mutant RNA with enzymatic function increases because it can self replicate
______ provides an RNA molecule with the enzymatic ability to synthesize ribonucleotides
A second mutation
What happens at the chemical selection of a second mutation?
After many generations the protobionts have 2 enzymatic functions - self replication and ribonucleotide synthesis
What is one catalytic RNA molecules possible sequence of events?
Catalytic RNA - learning to catalyze the synthesis of proteins from amino acids
Catalytic RNA molecules:
Later, ____ may have replaced ____ as the information storage molecule because it is more stable
Later, DNA may have replaced RNA as the information storage molecule because it is more stable
Once the ________ could speed up their own production, it was probably only a matter of time (LOTS of time) until simple bacteria evolved
Primitative particles
Do the first cells look like the cells today?
Do nothing and look nothing like a cell today
What are Stromatolites?
They are mineral deposits left by Cyanobacteria
Some are over 3 billion years old
*Shark Bay, Australia*
Define Endosymbiotic Theory
It is based on a number of observations scientists proposed that chloroplasts and mitochondria originated as bacteria
What are the five parts of the Endosymbiotic Theory?
1) Morphology (development of Eukaryotes)
2) Reproduction
3) DNA - sequence and organization
4) Transcription and Translation
5) Metabolism
What type of life was on the early earth?
Life was anaerobic (no oxygen)
T or F:
As O2 levels increased it stressed some bacteria, while others adapted to use O2
True
_______ bacteria would die in the presence of oxygen, if they lived in _______________ they would be protected
Anaerobic bacteria would die in the presence of oxygen, if they lived in close contact with areobic bacteria they would be protected
… Eventually the membrane of the anaerobic bacteria might __________
Eventually the membrane of the anaerobic bacteria might encapsulate the aerobic bacteria
Original prokaryotic host cell:
Is thought to have resulted in the formation of _______
The ____ and __________ formed perhaps to help protect the ‘host’
Is thought to have resulted in the formation of mitochondria
The ER and Nuclear Envelope formed perhaps to help protect the ‘host’
In a second step primitive _______ may have associated with some of the new eukaryotic cells with the end result being the formation of ______
In a second step primitive cyanobacteria may have associated with some of the new eukaryotic cells with the end result being the formation of chloroplasts
See slide 42
We can also see the transfer of genetic information between the ________ and the ______
Endosymbionts and the nucleus
*We see this same process between bacteria*
What can be immuned to bacteria ?
Penicillium
What are the 3 benefits of Endosymbiosis?
1) Compartmentalization of metabolism
2) Many acient cells were sensitive to oxygen; “mitochondria” use oxygen
3) Chloroplasts provided a continuous source of energy
What is the difference between reducing atmosphere and an oxidizing atmosphere?
Reducing - no oxygen and doesnt break down
Oxidizing - has oxygen and complex things break down
What pieces of evidence do scientists think support the endosymbiotic theory of organelle development?
There are two organismes that share resources and living space
Mitochondria have their own DNA
What was an outcome of horizontal gene transfer?
a) Import of proteins into mitochondria
b) Increase in size of the chloroplast genome
c) Genes localized to the mitochondria were relocated to the nucleus
d) Decrease in the number of proteins in the chloroplast
a or c