UNIT 2 ORIGINS OF LIFE Flashcards
What are the 7 characteristics that all forms of life share?
- They have a display order (cell being the fundamental unit of life)
- Harness and utilize energy
- Reproduce
- Respond to stimuli
- Do homeostasis
- Grow and develop
- They evolve
What are the 3 main ideas of the cell theory?
- All organisms are composed of one or more cell
- Cell is the smallest unit that has the property of life
- Cells are from growth and division of preexisting cells only.
What was the type of atmosphere in early atmosphere?
Reduced atmosphere
What is a reduced atmosphere?
Lack of oxygen or other oxidizing gases, leads to the production of complex organic molecules.
Early atmosphere constitutants?
Large amount of water, hydrogen sulphide, carbon dioxide, ammonia and methane.
What is an oxidizing atmosphere?
02 rich atmosphere that oxidizes surface compounds.
What is the atmosphere we have today?
Oxidizing atmosphere
Miller-Urey experiement?
Confirmed the reducing atmosphere created building blocks for the creation of life.
How did the mille-Urey experiment worked?
They placed the components of a reducing atmosphere in a closed environment and exposed them to an energy source. After a week they found lots of organic compounds in water.
What are protobionts?
The first cell. Are abiotic.
What is the Oparin-Haldane hypothesis?
Earth was a reducing atmosphere having a lot of electrons that can easily be donated.
What are ribozymes and what do they do?
They are a group of RNA molecules that can catalyze reactions on the precursor RNA molecule that leads to their own synthesis.
What did RNA served for in primordial earth.
Both the information and the catalyst
First energy releasing reaction in primitive cells?
Oxydation-reduction reactions.
Exemple of an oxidation-reduction reaction.
We oxidize food molecules to release energy and reduce other molecules like those needed for protein synthesis.
What is panspermia?
The hypothesis that simple forms of life are present in space and could have seeded early earth.
Panspermia points?
- too little of a window to create life between the cooling of earth and first evidence of life.
- The presence of extremophiles
Prokaryotes are 2 organisms?
Archea and bacteria
What are the properties of prokaryotes?
They have a plasma membrane and a cytoplast consisting of cytosol. Organelles, electron transport chain, chromosomes and DNA in nucleoid.
Are prokaryotes 10 times smaller than eukaryotes?
Yep
Prokaryotes have a high metabolic flexibility meaning that:
They can use a variety of substances as a source of energy and carbon source and they synthesize almost all their organic molecules from raw inorganic materials.
The evidence of atmospheric increase in CO2 about 2.5 million years ago is shown by what?
Banded iron.
How is banded iron formed?
In the sediments of lakes and oceans as dissolved oxygen reacted to dissolved iron which formed rust.
What causes our atmosphere to have CO2 now?
Cyanobacteria. Could harness electrons from water and by doing so was forming CO2 that was released. With time the CO2 accumulated in the atmosphere.
What is oxygenic photosynthesis?
Photosynthesis that relies on oxydation of water and releases CO2.
Ho does eukaryotes distinguish from prokaryotes?
They have a nuclear enveloppe, cytoplasm has membrane bound compartiments with specialized functions (mitochondria, chloroplasts, endoplasmic reticulum, Golgi complex) they also have motor proteins to move cells.
What is an endomembrane system?
Collection of internal membrane sacs that divides the cell into functional compartments called organelles.
The endomembrane system is derived from the plasma membrane how?
Pockets of plasma membrane extended inwards and surrounded the nuclear region, forming the nucleus. The remaining of those membranes formed ER and the Golgi complex.
What is the endoplasmic reticulum?
interconnected network of channels and vesicles.
What is lumen
the space inside a vesicle
Rough ER.
Contains many ribosomes on it’s outer surface.
Smooth ER.
Doesn’t contain any ribosome on its surface.
Where is the Golgi complex located?
Between the rough ER and the plasma membrane.
What is the theory of endosymbiosis?
That mitochondria and choloroplasts evoked from ingested prokaryotes.
Evidences of the theory of endosymbiosis?
- Morphology, mitochondria ressembles aerobic prokaryotes while chloroplasts resemble cyanobacteria.
- Reproduction, Only derived from preexisting.
- They both have DNA
- Generates ATP from electron transport chains.
Cytoskeleton
system of protein, fibers and tubes that extend through the cytoplasm
Function of cytoskeleton?
reinforces the plasma membrane and helps the cell stay in shape and maintain their internal organization. Also gives mechanical support to carry division and movement.
3 structural elements of cytoskeleton?
-microtubules,
-Intermediate fillamanents
-microfillaments
All interlinked.
Plant cytoskeleton contains only
microtubules and microfillamanet
Structure of motor protein
one end is attached to the cell, the other end walks along a microtubule or microfilament and then releases. It Neds ATP.
Cytoplasmic streaming
Active flowing motion of cytoplasm
What is a flagella?
La queu. Helps in movement of the cell.
Flagella in prokaryotes
Made of a protein called flagellin
Flagella in eukaryotes
Constitute of microtubules.
Analogous structures
same functions but not the same evolution history
Homologous structures
same evolutionary history
Why eukaryotic cells are larger than prokaryotes?
The size of the cell is determined by the surface being able to supply it’s volume with necessary metabolic requirement. They have a large area of internal membrane structures.
Multicellular eukaryotes
Cells are not identical in structure and function, they help each other to benefit the entire organism.
Cell colony
group of cells that are only one type
How long did it take for eukaryotes to develop from prokaryotes ?
1.3 billion years.
Approximate age of planet?
4.6 billion years
What is RNA
Ribonucleic acid. translate the genetic code to proteins from DNA with the help of ribosomes.
What is DNA
The molecule that contains the genetic code of an organism.
