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Life in the Precambrian
Prelude to Us
LifeA Short
Summary
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Slime Mold
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Tardigrade
What is Life?• Composed of organic compounds• Resistance to entropy (disorder)
– Requires energy (must be able to gather and process (metabolize) energy)
• Ability to maintain a controlled environment– Requires ability to be isolated from environment
• Information storage• Self replication
– Including ability to pass on information
• Ability to adapt to its environment– Undergoes biological evolution
Life on Earth:Organic Compounds
HumanHuman AlfalfaAlfalfaBacteriaBacteria
•Oxygen(O) 62.8% 77.9% 73.7%•Carbon (C) 19.4% 11.3% 12.1%•Hydrogen (H) 9.3% 8.7% 9.9%•Nitrogen (N) 5.1% 0.8% 3.0%•Phosphorous (P) 0.6% 0.7% 0.6%•Sulfur (S) 0.6% 0.1% 0.3%
Carbon is found in all organic compounds
Important Elements
Life on Earth:Organic CompoundsTypes of Organic Compounds
1. Lipids - (H,C (hydrocarbons)) Fats and Oils
cell membranes & energy storage
2. Carbohydrates - (C, H, O) Sugars, Starches and Cellulose
energy storage & structure
Life on Earth:Organic CompoundsTypes of Organic Compounds
3. Amino Acids Proteins - (C, H, O, N, S) Enzymes - catalysts for chemical reactions also Hair, silk, fingernails, etc.
4. Nucleic Acids - (C, H, O, N, P) DNA (Deoxyribonucleic Acid) RNA (Ribonucleic Acid)
store & transfer genetic information
Organic Compounds
Cells
Organisms
Not Alive
Alive
Life on Earth:Controlled Environment
Cell
Eukaryote
Prokaryote
Prokaryote - E. coli
• Small (<5m)• No nucleus• Unicellular
Eukaryote- Frog & Ameba
• Larger (> 10 m)• Nucleus• Organelles• Cytoskeleton• Uni- and multi-cellular
Life on Earth:Controlling Entropy
Gathering Energy
Photosynthesis
Carbon Dioxide + Water + Sunlight --> Sugar + Oxygen
Chemosynthesis
Hydrogen Sulfide + Carbon Dioxide + Water + Oxygen+ Geothermal Heat --> Sugar + Sulfuric Acid
Chloroplasts
Life on Earth:Controlling Entropy
Releasing Energy
Respiration
Sugar + Oxygen --> Carbon Dioxide + Water + Energy
Mitochondria
Life on Earth:Information
Storage
DNA - Deoxyribonucleic Acid
RNA - Ribonucleic Acid
Chromosomes
Human Chromosomes
Chromosome Numbers
Life on Earth:Information
Storage
DNA - Deoxyribonucleic Acid
RNA - Ribonucleic Acid
DNA
RNA
Protein
Replication
Transcription
Translation
The Universal Genetic Code
AUG - UGC - CAU - AAA - UGAStart - Cysteine - Histidine - Lysine - Stop
DNA TranslationInstructions: How to make proteins from amino acids
Genetics Produce Variety
Life on Earth:Self
Replication
Life on Earth:Self Replication
Cloning (Mitosis)
Life on Earth:Self Replication
Sexual Reproduction(Meiosis)
Sperm & Egg
Fertilization(Combination of genes
from 2 parents)
CompleteOrganism
Life (as we know it)
• Made of organic compounds• Organized into cells (controlled environment)• Cells interacts with environment to collect
nutrients/energy and remove waste• Has a mechanism (DNA) to store information• Can replicate itself & pass on information• Can evolve and adapt to changing environment
Causes of Diversity and Evolution of Life on Earth
Charles Darwin Alfred Russell Wallace
Causes for Diversity of Life
1. All populations have the potential to increase in size2. Many populations retain a constant size
• Many individuals die young
3. Individuals in a population differ in their abilities• Some of these abilities affect survival
4. Best adapted individuals are most likely to survive and produce offspring (Natural Selection)
• “Abilities” are passed on to offspring (Genetics)
5. Over time the “abilities” of the population shift to include advantageous traits (Evolution)
Note:
Natural Selection Affects Individuals
Evolution Affects Populations
Net Result:
Populations change with time to become better adapted to their environment (Evolution)
Example: Microbe Resistance
Apply Antibiotic
Survivor’s with Resistance Reproduce
How does it Work?Variation in the Gene Pool of a Population
How does it Work?Variation is a result of (1) Mutations and (2) Sex
Errors occur in DNA Replication
On average 1:10,000-100,000genes per individual per generation
Increased by exposure to radiation, etc.
Most Mutations are bad or at least neutral
What is “good” depends on environmental conditions
Evidence for Evolution
Evidence for Evolution: Fossils & Faunal Succession
Evidence for Evolution: Analogous Structures
Evidence for Evolution:Homologous Structures
Evidence for Evolution:Embryology
Evidence for Evolution:
Biochemistry of Life
Evidence for Evolution:
Gene Sequencing
Evidence for Evolution:Artificial Selection
Evidence for Evolution:Artificial Selection
Evidence for Evolution:Modern Examples
Some InterestingEffects of Evolution
Evolution & Psuedoextinction
Species A Species B
Through time Species A evolves into Species B
In effect, Species A goes extinct
Extinction
Species A
Sometimes a species cannot adapt fast enough to environmental change or competition
Moa
No moa, no moa,In old Ao-tea-roa.Can’t get ‘em.They’ve et ‘em.They’ve gone and there ain’t no moa!
Extinctions through time
Evolution & Speciation
Species A
Species B
Species C
Species A is separated into 2 isolated populations, each affected by different environmental conditions
In effect, Species A goes Extinct
Speciation of Hawaiian
Honeycreepers
Diversity Increases
Convergent Evolution
Coevolution:Plants and Pollinators
Coevolution:Predator/Prey
Life (as we know it)
• Made of organic compounds• Organized into cells (controlled environment)• Cells interacts with environment to collect
nutrients/energy and remove waste• Has a mechanism (DNA) to store information• Can replicate itself & pass on information• Can evolve and adapt to changing environment
Origins?
• Where did organic compounds come from?How did they form?
• How did cells form? What formed the first membrane?• How did the machinery of cells (ability to perform
respiration and photosynthesis) come about?• Where did DNA come from? Was it the first form of
information storage?• How were the first cells able to replicate?• How did they adapt to changing environment?
Major Steps in the Precambrian Evolution of Life
1. Origin of Life (3.8-3.5 Gyrs)
2. Photosynthesis (3.5 Gyrs)
3. Aerobic (Oxygen-based) Respiration (3-2 Gyrs)
4. Eukaryotes / Endosymbiosis (2.1-1.5 Gyrs)
5. Sex / Death (1 Gyrs)
6. Multicellular Life (800 Myrs)
7. Skeletons & Shells (600 Myrs)
* All dates are approximate
Evolvovision(Ray Troll)