Natural Science 3 Second LE Lecture Notes Bangga_05480
Lecture 2.1: The Biosphere
Life’s Origin
- Life first appeared about 3.5 to 3.9 Bya
- “Primordial Soup” by Charles Darwin
o warm water with right combinations of
chemical compounds with the right sources of
energy which could produce proteins
- Early environment:
o No free oxygen
o Nitrogen, Carbon dioxide, Methane, Ammonia
o High temperature
- Miller and Urey: Conducted experiments that replicated
the early conditions of the earth to produce amino acids
o set up: continuous sealed loop of tubes with all
the air removed
o introduced an atmosphere rich in CO2,
Nitrogen, ammonia, methane and water (but
no free oxygen)
o ocean flask that was being heated to generate
steam and to start the circulation of the
atmosphere
o used sparks to simulate lightning as the energy
source
o once the ammonia-methane-nitrogen- laden
steam moves through the lightning, they move
into a condenser which turns the steam back
into liquid and is moved back into the “ocean”
o in a few days, the ocean turned into an organic-
rich “soup” and contained 4 of the 20 amino
acids used to create proteins
o experiments proved that it is easy to create
amino acids in nature
Essential Components of Life
- Proteins
o Strings of simple organic molecules – amino
acids
o Fundamental building blocks of living things
o Functions:
1. Tissue formation
2. Provide patterns for laying down mineral
structures
3. Acts as enzymes
- Nucleic Acids
o Carry the genetic code necessary for making
copies of the cell
o Two types:
▪ RNA
▪ DNA
- Organic Phosphorus compounds
o Transform light energy or chemical fuel into the
energy required for cell activities
- Cell membrane
o A container
o Keeps the cell components together so they
can interact.
Simplest forms of Life
1. Prokaryotes
o Organisms that have their nucleic acids genes
floating in a cell without a nucleus
o E.g. Bacteria
- earliest known fossils: cyanobacteria (incorrectly known
as “blue green algae”), 3.4-3.5 Ga
- traces: stromatolites which form when cyanobacteria
formed sticky mats in shallow areas of the ocean and
are eventually covered with sediment. these sediment-
covered mats
- eventually build up and form mounds
2. Eukaryotes
o Cells contain a nucleus which contain the
nucleic acid genes
o Have additional structures: organelles
- the organelles were once free-living prokaryotes that
had come to live symbiotically within another cell and
eventually became a part of it (by Lynn Margulis)
Cell Theory
1. All living things are composed of one or more cell
2. The chemical reactions of living cells take place within
cells
3. All cells originate from pre0existing cells
4. Cells contain hereditary information, which is passed
from one generation to another.
- Each cell is self-contained and self- maintaining,
meaning it can take in nutrients, convert these nutrients
into energy, carry out specialized function and
reproduce
Taxonomy
- Naming and grouping of organisms
- From general to specific
Domain – general grouping
Kingdom
Phylum
Class
Order
Family
Genus
Species – specific grouping; organisms
that can interbreed to produce a fertile
offspring
Phylogenetic Trees and Cladograms
- Phylogenetic Tree
o Shows the relationship between different
organisms with respect to the evolutionary time
and the amount of change with time
- Cladograms
o shows only the relationship between different
organisms with respective to a common
ancestor
- The Domains:
1. Domain Archaea
2. Domain Bacteria
3. Domain Eukarya
a. Kingdom Protista
b. Kingdom Plantae
c. Kingdom Animalia
d. Kingdom Fungi
Domain Bacteria
- Prokaryotes
- Unlock organics from corpses and waste products
- Most dominant life form on earth
- Example:
o Cyanobacteria
▪ Can photosynthesize and produce its
own food
- hard to find stromatolites because the older the rock, the
larger possibility for it to have been eroded long ago
- no evolutionary changes from 3.5 to 1.75 billion years
ago
- first eukaryotes appeared 1.75 bya
- first multi cellular life appeared 600 million years ago
- for 2 billion years (60% of life history), there was nothing
on Earth more complicated than a bacterium
- for 3 billion years (85 % of life history), there were only
single celled organisms
Domain Archaea
- extremophiles
- commonly found in deep-sea volcanic vents that spew
superheated, sulfur-rich water
- genetically simplest forms of life
- individual archaeans range from 0.1 to 15 micrometers
- and occur in various shapes (spherical, rod-shaped,
spiral, lobed or rectangular)
- since light does not reach these deep-sea vents,
archaeans rely on chemosynthesis instead of
photosynthesis
- Examples:
1. Pyrococcus furiosus
o “the rushing fireball”
o Found in marine sand surrounding sulfurous
volcanoes
o Anaerobic – does not depend on oxygen
o Capable of living in temperatures ranging from
70 to 103oC and pH ranging from 5 to 9.
2. Halobacterium
o 5 microns
