The orgin of life and evolution - Biodiversity
What is life
Water is the most important solvent for dissolvijg nutrients needed for life to
The 3 ataomic building blocks are Carbon , Nitrogen and Phosphorus
What was discovered in the Europa moon of Jupiter
It is covered in ice with 10 Km of water below the ice that form an ocean so there is major tidal effects on the moon and can lead to hydrothermal vents and volcaninc activity
Also there are carbon sources on the surface of Europa so there is CO2 and may be evidence for life potential
What are the characteristics of life
Reproduction and Inheritnace
Cellular organisation
Growth and development
Energy use via metabolic activity
respond to environment changes
Homeostasis
Evolutionary adaptation
What is the bionomial naming system
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
When was earth formed
Was formed 4.5-5 billion years ago but there was no life for millions of years after due to rock bodies from the solar system bonmbared the earths surface to so life was impossible, life developed on earth 4 billion years ago
The evidence for this was fossils found in australia that date back 3.8 billion years ago and resembled early bacteria
This was due to water cooled to allow prokaryotes to evolve
Stromatolites are rich sources for early prokaryotes fossils that show the bacteria was metabolically doberse 3 years billion years ago
How is life a continuum
It is always evolving via phylogentic branches to form great organsim variety and this started 3.8 billion years ago
Prokaryotes have dominated evolution from 3.5 - 2billion years in 2 forms = Bacteria and Archaea
Single cell eukaroyotes didnt evolve till 2billion years ago
How did life start
Non replicating molecules --> Replicating molecules --> celles go from simple to complex --> Get cell collections forming
How did earth change to allow life to grow
The atmosphere conatined many molecules like N2, H2, H20, CO, Co2, CH4 ands NH3 with very limited O2 4 billion years ago
Our seas formed due to the cooling of water temperarture as less UV entered through atmosphere
Energy from lightening and UV radiation combined woith volcanic activty gave energy for life to start
What is spontaenous generation
Life is able to arrive from non-living matter and was believed tobe hwo life started orginally
However now thought life started from non-living matter became orderded to agregate that then were able to self-replicate and be metabolic
What is the priciniple of biogenesis
All life exist today on earth due to the reproduction of pre-existing life on earth
How did early atmosphere favoured early life formation
No evidenve for sponatenous generation today, the early conditons of high UV and extreme volcanic activity favoured the systhesis of organic compounds from inorganic precursors
Cant happen today due to too much oxygen that attack chemcial bonds and also lower extreme energy sources
What is chemical evolution
Build up of small molecules -> Monomer go to polymer --> Polymer + Monomer go to Protobionts that then lead to replication and heriditary
What was the Oparin and Haldane experiment
They created an atmosphjere of H2,CH4,NH3 and CO2
They created and added lightening sparks and made a sea from condensation to mimic ealry earth atmosphere
They found after 1 week amino acids were detected as well as organic compound called liposomes that form lipids to alow li;id bilayer to form
What is the alternative to Oparin Haldane
Hypothermal venst that can catalyse reaction due to provide more energy and prokaryotic fossils came from hypothermal venst 3.2 billion years ago
What are Protobionst
Aggregate of abiotci monomers and polymers surrounded by a membrane like structure
If ezymmes are incorperted then the protobionst can absorb surrounding substrate and release products of enzyme reactions
Howeverr protobionst in ancient times dont have enzymes but abiotically made enzymes to allow rudimental metabolic activity by modfying substances over their membrane
What did Cech and Altmann do
They had ribsomes in term of RNA with catalytic properties
RNA can store info and self replicate if necassary nucleotides are present
Early life may have been RNA based = RNA world hypothesis
How can ribonucleotide polymers be made
Polymer are added to solution of ribonucleotide that then sequence 10 bases that are copied from template and not by base pairing rules
If zinc added then can copy up to 40 bases with 1% error chance
Evidence for the RNA world hypothesi
Life is defined as partly inheritance
Cells today have DNA for genetic info storage and use translater exons to RNA for protein synthesis
RNA was first hereditary materila is believed as RNA can act as an emzyme
What are chemoautotrophs and chemoheterotrophs
Chemoautotrophis get carbon from inorganic carbons sources
Chemoheterotrophs get their carbon from breakdowon of organic compounds
What is Darwin evidence for evolution
Plant and animal breeding
Palaeontology
Embryology
Biogeography
Comparitive anatomy
What is natural selection
This is what can lead to natural selection due to a change in allele frequency that then leads to the development of favourable characteristics that lead to an increase chance of favourable, causing to then greater reproduction, so then greater number of that allele passed to future generation leading to a change in allele frequency in the population. Allows the organisms to become very adapted for their environment to increase the chance of survival.
What are mutuation pressures
Certain parts of the genome are prone to muations meaning more mutation in later generations that then chabge gene frequency
Mutational presssure are diversifying
Stablising pressure are stabilisers
What is gene flow
Exchange of genetic material between 2 close populations due to to migration of sexual reproduction between fertile individual across populations
What is random genetic drift
Lead to fewer allele frequency and so less genetic variation in small population
What is evolution
A change in the gene frequency in a population from 1 generation to another generation that lead to change in phenotype traits displayed
What is glycolysis
Where ATP can be generated by the breakdown of organic compounds and was the first metabolic pathway to happen in anaerobic environments and is first stage of respiration
How did chemohetertrophs change the environment
They were able to carry out glycolysis and so depleted the earths supply of organic molecules so eventually ran out of food, whereas the chemoautotrophs were uneffected by this
This means natural selection would have favoured the prokaryotics that could harness energy from the sunmto drive ATP sythesis and genertae power to make organic compounds from CO2
When did photosynthesis evolve on earth
In early life in prokaryotic and within first billion years on earth including anoxygenic photosynthesis that came before oxygenic photosynthesis
Cyanobacteria 2.7 billion years ago sho photosynthetic evidence and oxygen liberation from deep sea vents started 3.5 billion years ago in iron rust deposit
How have prokaryotes evolved
Evolved for 2 billion years before eukaryotes and they still dominate the biosphere
The collectable biomass outweigh all eukaryotic biomass by tenfold
Some may aggregate or form true colonies that show divison of labour between cell types
Most common shape are helices, spheres and rods
Why are all prokaryotic cells not unicellular
Due to cell adhesion where they stick together
Cell communication - In multicellular bodies they must stay together and communicate and change in repsonse to changing conditons
Dependency - Cell must depend on surrounding cells for survivla otherwise just large colony not multicell body
Differentitaion - Cells of the body can carry out different jobs due to terminal differentiation meaning that can redifferentiate after gettting a job
Certain bacteria can carry out nitrogen fixing
How are Prokaryotic cells motile
About half of all prokaryotic cells are able to move due to the action of a flagella that spin around a circle on the membrane to propel the prokaryotic cell in a direction
Flagelle made uo of basal apparatus, Hook and Filament
How does cellular and genomic organisation in prokaryotic cells differ
The genetic material is single stranded DNA that is bonded to the cell membrane where it is looped and stored in plasmids
Also lack other endomembrane organelle but some may have thylakoids for photosynthesis
Most bacteria have an innner and outer plasma membrane so are gram negative '
Gram positive only have 1 cell membrane
What are examples of common bacteria
E.coli - Found in the gut and can be pathogenic
Human Pathogens - Salmonella and Staphylococcus
Cyanobacteria - Syenchocytsis is the model bacteria for oxygenic photosynthesis
Alphaproteobacteria -
What are the 2 prokaryotic domains
Archaea and Bacteria
They both diverged from each other in early life so are fundamentally different and yet both have prokaryotic organisation
How have archaee branched on the tree
rRNA allow to show that archaea are a seperate domain and that eukaryotes are more closely related to them than bacteria s they branched off from the archaea branch to form new domain
Where are archaea found
Primarily from extreme environments and the oceans in early life
Asgard archaea have homologous genes and are found in tge north sea
They have a different chemical make up due to extreme conditions so different phospholipid in the plasma membrane
What are Viruses
These depend on a host cell in order to be able to replicate
They can be enveloped or non-envelopoed by the lipid bilayer of another cell
They have RNA, Capsid, Glycoprotein cell surface receptors
Why are virsues not on the tree of life
This is as they are not alive as they dont have key traits of life such as, lack of metabolism, cannot self replicate, ,lack own translation machinary
No anscestor lineages
They are gene robbers not inventors
Lack structural continuity
What are the common characteristcs of eukaryotic cells
Membrane enclosed nucleus
The endomembrane system
Have mitochondria and sometimes chloroplast
Have cytoskeletom
Multiple chromosome and linear DNA with histones
How did eukaryotic cells occur
Eukaryotic and multicellular beings unfolded during the evolution of protists
The firstb eukaryotic cells were unicellular
They date back to 2.1 billion years ago and for about 2 billions years they were only small microorganism called Protists
The origin of eukaroyic organelle
Endomembranes =- The ivagination of the plasma membrane caused this to form that is needed for phagagcytosis and also needed for endosymbiosis that lead to mitochondria formation and plastids
How did the eukaryotic cytoskeleton and flagella occur
Microtubules for cell shape, ciliar and flagella movement and organell movement and are made of Tubulin
Microfilaments of actin made for muscle contraction, cytoplasmic reticulum and cell mobility
Intermediate filament for cell anchoring
How is the Eukaryotic flagella organised
They are the same thing as the cilia and is an extension of the cytoplasm with support of the 9+2 microtubule system
What did endosymbiosis lead to the evolution of
Mitochondria and plastids evolved from endosymbipotic bacteria by endosymbiosis
What did plastids evolve from
Endosymbiotic cyanobacteria only once
Primary cyonabacterial plastid is in green alage and plant and red algae
What is the evidence that bacteria and mitochondria/chloroplast are related
They are a similar size, simialar enzymes and transport system
Replication of chloroplast and mitochondria similar to Binary fission
Nuclear genome from the host cell
What did secondary endosymbiosis do in algae
Algal groups with 2 membranes as every event leads to another membrane
It occured when heterotropphic protist engulf an algae containin plastid
The new membrane derived from the vacuole membrane of the host cell
How have eukaryotes evolved
3 free living prokaroic cell at the time
The there was the evolution of the nucleus and endomembranes + chromosome and cytoskeleton
Evolution of mitochondria from aerobic prokaryotic endosymbiont
Evolution of chloroplast in some eukaroytic cells from photosynthetic endosymbiont
What are Protists
They are Eukaryotic and the emergence of multicellularity from the evolution of protists
There are 4 main eukaryotic super groups
Excavata - Protist
SAR- protists
Archaeplastida - Protist + land animal
Unikonta - Protist + Animal and fungi
How are protist defined
Structural level as most are uncellular
Exclusion from the definiton of plant animal and fungi
DNA analysis
most are aerobic
there are a mix of photoautotrophs and hetertrophs and very few mixotrophs
What are the Excavata
Characterised by its Cytoskeleton and made of 3 sub groups
Diplomonads, parabasalids and euglenozoans
What are the Diplomonads
They have multiple flagella and 2 seperate nuclei with a simple cytoskeleton and no plastids
What are the Parabasalids
These have no plastids and a reduced mitochondria and some can infect the vagina by sexual transmission
What are the euglenozoans
Seperated by a spiral or crystalline rod in the flagella that is used for locomotion
Include
Kinetoplastids - have single large mitochondrion that is associated with kinetoplast that house extracellular DNA
Euglendis - Have an anterior pocket where 1 or 2 flagell come from as well as unique glucose polymer called paramylon
What is the SAR group- S part
They have flagellum with many fine hairs that induce diatoms, golden alage and brown algae
Plastids of these evolved by secondary endosymbiosis
What are the Diatoms
They are unicellular, have glass like walls of hydrated silica on an organic matrix and wall is in 2 parts divided
What is golden and green algae
Golden is named for yellow and brown carotene and have 2 flagella
Brown is the largets and nost complex algae as they are multicelled and marine
What is the A part of SAR group
Dinoflagellates - many are unicellular but some colonies and have abundant phytoplankton components with 2 flagella that sit in the armour grooves, experince large explosive population blooms in coastal waters
Apicomplexans - Parasite of animal and human disease causers as they are specialised for penetrating host cells have intricate life cycle of both sexual and asexual stages that need 2 or most hosts
Ciliates - Use of ciliair to move and feed and have a macro and micro nuclei
What is the R part of SAR
Rhizarians have thread like pseudopia for movement and feeding made of 3 groups:
Foraminfierans - Calcium carbinate shell and symbitoic with algae in water of both fresh and marine
Radiolarians - Have a ray foot and silica skeleton reinforced by microtubules
Cercozoans - Ameoboid and flagellated protists
What is Red algae
Part of Archeplastida and have no flagalla ever in their life
Red colour due to Phycoeryhtrin and have evolved from primary endosymbiosis plastid
What is green algae
Chlorophyte and charophytes due to green chloroplast
Evolved from common anscestor that had chloroplast from cyanobacteria by primary endosymbiosis
Charophtes closely related to land plants
What are the Unikonta
include animals, fungi and plants
there are 2 clades of amoebozoans and opisthokonts
What are the amoebozoans
Are amoeba that have lobe or tube shaped including slime molds, tubulinids and entamoebas