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)