What is life

Tardigrade

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Life
A Short
Summary

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Slime Mold


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
Important Elements

•Oxygen(O)
•Carbon (C)
•Hydrogen (H)
•Nitrogen (N)
•Phosphorous (P)
•Sulfur (S)

Human

Alfalfa Bacteria

62.8%
19.4%
9.3%
5.1%
0.6%
0.6%

77.9%
11.3%
8.7%
0.8%
0.7%

0.1%

Carbon is found in all organic compounds

73.7%
12.1%
9.9%
3.0%
0.6%
0.3%


Why Carbon?
• Small and Abundant
• 4th most abundant element in the Solar System
• Bonds with a lot of different atoms
• Forms lots of different organic compounds
• Forms long chains (polymers)
• Forms very strong bonds
• Hard to destroy (Stable)
• Bonds “store” a lot of energy
• Forms compounds that are
water soluble


Life on Earth:
Organic Compounds
Types 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 Compounds
Types 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
Not Alive
Cells
Organisms

Alive


Life on Earth:
Controlled Environment

Cell

Eukaryote
Prokaryote


Prokaryote - E. coli

• Small (<5µm)
• No nucleus
• Unicellular


Eukaryote
- Frog &
Ameba
• Larger (> 10 µm)
• 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


Replication

DNA
Transcription

RNA
Translation

Protein


The Universal Genetic Code

AUG - UGC - CAU - AAA - UGA
Start - Cysteine - Histidine - Lysine - Stop


DNA Translation
Instructions: How to make proteins from amino acids

Genetics Produce Variety


Life on
Earth:
Self
Replication