Unit 5 Diversity of life Flashcards
7 characteristics of life?
- Display order, but does not maintain
- Harness and utilize energy
- Reproduce
- Respond to stimuli (react to changes in environment etc.)
- Exhibit homeostasis (homeo-life, stasis-stand still, regulation ex: running but body temp stays the same)
- Grow and develop
- Evolve (better adapt to the environment)
Basis of life?
The cell
Life is e—–
emergent
What do we mean when we say life is emergent?
Life is not planned, things emerge rather than being planned
Meaning of Archaeon
Archaeon = beginning, origin
How was the earth suitable for the development of life?
- Size and gravitational pull facilitated an atmosphere, was sufficient to hold said atmosphere
- Lies within the habitable zone around the sun (region around sun where water would exist in a liquid state)
- Red: no oxygen (mars for example), high CO2, Nitrogen, Hydrogen, etc.
- No ozone= no protection from UV light
What are macromolecules? Examples?
- Macromolecules (carbohydrates, proteins, lipids, nucleic acids) = necessary components of life derived from simpler organic molecules (saccharides, amino acids) their assembly requires input of energy
-What was Stanley Miller’s experiment?
Stimulated earth’s early atmosphere (assortment of organic molecules like urea, amino acids, lactic, formic, and acetic acids)
First experiment to demonstrate abiotic formation of molecules critical to life
what does abiotic mean?
abiotic (physical rather than biological; not derived from living organisms)
what was the deep-sea vent hypothesis?
Origin Hypothesis: deep sea vent hypothesis
o Nutrient rich waters
o Methane, ammonia, hydrogen sulfide
o Deep ocean cold, vents are hot (300 degrees Celsius combination of hot and cold creates = ambient temperature for life)
What was the extraterrestrial origin hypothesis?
- Origin hypotheses: extraterrestrial origins hypothesis (some data supporting mostly theoretical)
a. Meteorites rich in organic, key molecules
What were two major early hypotheses about early life?
Deep sea vent and extraterrestrial
How do we go from simple sugars to complex proteins?
Polymerization.
o Today cells use enzymes to lower the amount of activation energy
Unlikely to have occurred in ocean
Monomers to polymers via dehydration synthesis
Why is clay efficient in dehydration synthesis?
• Clay as catalyst for polymerization, provides reaction sites, undergoes dehydration, and continues to bond
layers of minerals separated via levels of H2O
allowed molecular adhesion forces to bring monomers together
clay stores potential energy used for energy requiring polymerization formation
What does modern life need? (hint 3 key conditions)
o Macromolecules of life: evolution of three things
- A membrane – defined compartment
- A system to store information and use this to guide protein synthesis
- Mechanisms to harness energy from the surroundings to sustain life (energy-harvesting pathways)
Condition 1:
- allowed primitive metabolic reactions to occur in environment diff. to external surroundings
- higher concentration of ley molecules
- greater complexity maintained in close space
Early protobiont:
- similar to liposome
- self assemble of phospholipids into membrane similar to bilayer (vesicle) isolating organic molecules
DNA and RNA
- All organisms contain deoxyribonucleic
acid (DNA) – Large, double-stranded, helical molecule – Information in DNA copied onto
molecules of ribonucleic acid (RNA) • Directs production of protein molecules - living cells require development of system based on nucleic acid that could store and pass on info to make proteins
process:
DNA: provide cell with genetic info to RNA : DNA copied into RNA which directs protein synthesis on ribosomes (translated into proteins) to Protein
what is a protobiont?
Protobiont – abiotically produced organic molecule
Is a virus alive?
No, viruses’ straddle line between abiotic and biotic since they display many properties of life i.e reproduce
Most consider them dead due to their dependency on other cells to reproduce
Viruses contain RNA and DNA but cannot make their own proteins
The foundation of earth was … years ago
4.6 billion
What was the approximate time line of evolution?
3.5 - prokaryotic cells 2 billion - eukaryote cell 525 million -animals, land plants 65 million years - extinction of dinos 150 thousand years - homo sapiens
True or false, biologically important molecules can be synthesized outside living cells?
True
What are the four classes of essential Macromolecules?
True or false, these are all derivative of simpler molecules like amino acid?
- nucleic acid
- proteins
- lipids
- polysaccharides
What are nucleic acids?
DNA and RNA made up of nucelotides which are made up of nitrogenous base, 5 carbon sugar and phosphorus atoms bonded to 4 O atoms
Difference between DNA and RNA
RNA= carries instructions for assembling proteins from DNA to the ribosome
DNA = stores hereditary info
What are proteins?
Polymers of amino acids
role: support, increase rate of bio reactors, produce cellular movements, defense against invading molecules, hold amino acids in stored form
What are lipids?
Non polar molecules
organic compound containing H,C, O atoms
forms framework for structure of function of living cells
contains polar head and non polar tails
What are polysaccharides?
long chains formed end-to-end linking of monosaccharides through dehydration synthesis reactions
Provide structural support, string energy, sending cellular communication signals
Ex: glycogen, cellulose, plant starches
Simple forms of macromolecules produced in early life via abiotic synthesis: what are the three major hypotheses to explain?
- Reducing atmosphere
- primordial atmosphere contained water vapour, high quantities of H2, CO2, NH3, CH4, complete lack of O2
What was the Oparin, Haldane hypothesis?
early atmosphere: reducing atmosphere b/c of presence of large concentrations therefor these elements reacted w. each other to form complex organic molecules
earth had no ozone, energetic ultra-violet light provided activation energy
4 examples of monomers and their corresponding polymers?
- simple sugars = starch, cellulose
- amino acid= proteins
- nucleotides = nucleic acid
- fatty acids = lipids
What is polymerization? What is the difference between today’s polymerization and early life?
formation of polymers via dehydration synthesis
Today: requires enzymes to lower activation energy
early: (think early bacteria) lack of polymerization in ocean more likely to have occurred on solid surfaces
Condition 2: Central Dogma
- flow of info from DNA to RNA to proteins
Ribozymes:
- RNA molecule that act as catalyst = where solely the RNA provides catalytic activity (leads to own RNA synthesis)
- fold into specific conformations due to specific H bonding (similar to functioning conformations of proteins)
- system no longer requires DNA - RNA -Protiens, just RNA
Cond. 2
Why don’t we solely use RNA?
- efficiency: proteins better catalyzed than ribozymes giving organisms with DNA-RNA-protein combos an evolutionary advantage
- Versatility: proteins are more versatile than RNA due to:
- increased catalytic powers
- typical cell contains a huge amount of proteins vs. RNA which is limited
- 20 amino acids to 4 nucleotides, amino acids interact with each other in formations not possible between nucleotides
- increased catalytic powers
in early life, why was RNA favoured over DNA?
RNA:
- ribose sugar easier to synthesize than deoxyribose
- DNA too structurally complex
As time progressed, which was favoured and why DNA or RNA?
DNA
- more chemically stable and less likely to degrade
- uracil (base in RNA) not found in DNA (replaced with base thymine) cytosine to uracil in DNA common mutation that gets repaired
- DNA double stranded: info is duplicated and in case of mutation complementary strand to the rescue with proper info
Condition 3: Energy Harvesting
earliest life forms = energy from life geo-chemical activity
Hydrothermal vents are sources of free energy • Rich in H2 , CH4 , low concentration of H+ compared with the ocean. • Concentration gradient of H+ can synthesize ATP (Adenosine triphosphate) • Energy coupling reactions – Oxidation/Reduction (Explored later) • These reactions occur without oxygen = Anaerobic • Still used by many microorganisms today
Why is life dependant on energy?
to work biosynthetic reactions
where does most energy come from today?
from sun via photosynthesis to fuel photosynthesis
