[WEEK10] How did life start on Earth?

PPT

 

 

 

 

How easy is it to make the molecules required for life?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

First life on Earth

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Eukaryote Evolution

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The Fossil Record

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mass Extinctions

 

 

SPQ

 

1. Darwin finches suggested that the diet differntiate the species. Depending on the finches diet, their beak shaped different.  

These different birds are seemed to evolved from a single common finch ancestor but their difference in niches diverged their specoies 

(Cactus -> long sharp / Insect -> sharp pointy / Seed -> strong large)

 

2. Survival of the fittest indicates that depending on the environmental condition, more adaptable individual survive better and have more chance to reproduce so they leave more desecendants

3. Darwin's idea of evolutionary was affected by the fossil and continental changes. 

The fossil found closer to the surface had similar appearance to nowdays organism

 

 

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Within six months of effectively using methicillin to treat S, aureus infections in a community, all new infections were caused by MRSA. How can rhis result best be explained?

-> Some drug-resistant bacteria were present at the start of treatment, and natural selection increased their frequency 

NOT MAKING WHOLE NEW VERSION

ADAPTION, SURVIVAL, 

SIX MONTHS IS NOT ENOUGH TO CHANGE THE GENE/ EXPRESSION / FUNCTION

 

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Natural selection is based on the fact that ... 

1) There is heritable variation among individuals

2) Species produce more offspring than the environment can support (so then the competition occurs)

3) Individuals whose characteristics are best suited to the environment generally leave more offspring than those whose characteristics are less well suited

4) Only a fraction of an individual's offspring may survive

 

HERITABLE VARIATION

MORE OFFSPRING THAN ENVIRONMENT CAN AFFORD -> COMPETITION

MORE FITTED, MORE ADJUSTABLE INDIVIDUAL CAN REPRODUCE MORE OFFSPRING

 

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Natural selection changes allele frequencies because some individuals survive and reproduce more successflly than others

 

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No two people are genetically identical, except for identical twins. The main source of genetic variation among human individual is the reshuffling of alleles in sexual reproduction

 

Changes the allele frequency in the population 

1) mutation

2) natural selection

3) gene drift

4) gene flow 

 

Changes the genetic variation in human

1) random fertilisation between sperm and egg

2) Rule of segregation (homologous choromosome seprate into the gamete randomly)

3) mutation

4) crossing over

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From the space we could source CHON, and as the early stage of earth, there were full of energy, 

 

 

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Earth is first formed apprx 4.5 BYA

The first life on earth was unicellular prokaryote, cyanobacteria found in the stromatollite about 3.5BYA

 

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Vesicle seperates the inner mass from the environment.

Proto-cells are composed of vesicles containing DNA inside

As vesicle can arise spontaneously ( catalysed by the clay) + self reproduce + can contain RNA,

It is regarded as having same role as cell membrane

 

 

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RNA can self replicate (ribosomal RNA produce polypeptides)

RNA act as a catalyst (ribozymes)

DNA is more stable so then it can store genetic information more stable

 

RNA once the replication process had begun by chance, this process had no option but to assemble

 

 

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Mammals and life started to diverged 

 

 

 

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Fossilised stromatolites resemble sturctures formed by bacterial communities that are found today in some warm, shallow, salty bays

Stromatolites release oxygen as a byproduct.

Other organism can use oxygen and produce ATP (aerobic metabolises -> allowed more complex life forms)

 

21. 

The oxygen revolution changed Earth's environment dramatically. Which of the following took advantage of the presence of free oxygen in the oceans and atmosphere?

-> The evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules