BIOL1108 STUDY GUIDE TEST 2
Microbes
Evolution of the Earth in Context
●The earth is 4.5 billion years old
●Life started 4 billion years ago
●Photosynthesis began 3.2 billion years ago.
Cambrian Explosion:
➢540 MYA (million years ago)
➢Explosion of diversity- several different species emerged at the same time
➢Sudden increase in marine animal life
➢All in the ocean: there was no life on land yet
Extinction
Bumps in the line graphs represent mass extinctions; Pinching in the graphs also represents
extinction.
Mass Extinction: A profound loss of life. Mostly caused by “rapid” (20,000 -200,000 years)
climate change which alters atmospheric or ocean chemistry.
There are FIVE major mass extinction events (within the last 550 million years):
(We are only focusing on two)
1. Permian Extinction
➢252 million years ago (MYA)
➢The largest one
➢A loss of over 95% of the life on earth
➢Possible causes: asteroid impact, volcanic activity
2. Cretaceous Extinction
➢66 MYA
➢75% of life lost
➢The most likely cause is asteroid strike (discovered in the 1980s by the KT boundary)
➢KT boundary : A layer of rock that can be seen all around the world. It draws the line
between the cretaceous and Triassic periods. This rock was high in the element Iridium
which is commonly found in asteroids)
➢Started the Age of Mammals
The Sixth Extinction?
Anthropocene Extinction: new era in which humans played an enormous role in different things
Background extinction: the standard rate of extinction in earths geological and biological
history before humans became a primary contributor to extinctions. (Wikipedia)
Basics
,Eukaryotes (Carrie Pucko’s slide)
●Presence of a nucleus
●Membrane enclosed organelles
●Chromosome pairs
●Larger ribosomes (80s)
●Cell division by meiosis
●Cellulose in cell walls in plant cells
●Cytoskeleton
●Digestive vesicles (vacuoles)
●Internal membranes (Endoplasmic reticulum and Golgi Apparatus)
Prokaryotes (Carrie Pucko’s slide)
●Absence of a nucleus (circular strand of DNA)
●No membrane enclosed organelles
●Single chromosome
●Cell division: binary fission
●Smaller ribosomes (70s)
●No cellulose in cell walls
Domains: a taxon in the highest rank of organisms
●Archaea PROKARYOTES
●Bacteria PROKARYOTES
●Eucarya ( Animals, Fungi, Plants, Protista) EUKARYOTES
Note: Archaea & Eucarya arose from the same common ancestor which arose at least 2 billion
years ago.
What is LUCA?
L.U.C.A. (Last Universal Common Ancestor) - The common ancestor of all the life on earth.
Existed 3 billion years ago
Did life exist before LUCA? Most likely. In order for a split/speciation to occur and LUCA to go
extinct, some other sign of life had to exist.
Where did LUCA live? Probably in deep sea thermal vents (discovered using Genomics). They
relied on the natural creation of ions and amino acids in the water.
Genomics: the study of comparing the entire genomes of different species instead of looking at
individual genes. This was used for microbial research, sequencing technology and determining
what genes LUCA most likely had.
●Scientists compared genes shared between 1800 bacterial genomes and 843 Archaean
genomes. They found 355 common genes, assumed to be those of LUCA.
● Some include: Ion exchange, DNA repair, no genes to create an ion gradient (an ion
gradient is needed for respiration therefore LUCA probably didn’t carry out respiration).
, The SEVEN requirements for LIFE:
1. Reproduction
2. Response; sensitivity to external environment
3. Metabolism
4. Adaptation
5. Growth & Development
6. Cells
7. Homeostasis: a self-regulating process by which organisms tend to maintain stability
and balance while adjusting to conditions that are optimal for survival. Example: the pH
of our blood and our body temperature must be within a certain range.
Metabolism: The chemical processes that drive life
“Photo” – light energy provides energy for metabolism.
“Chemo” - chemical energy provides energy for metabolism.
“Auto”- the carbon used in metabolism comes from carbon dioxide (inorganic carbon).
“Hetero” – the carbon used in metabolism comes from organic substances.
Types + Examples
Photo-autotrophs: cyanobacteria, plants, brown algae
Photo-heterotrophs: purple sulfur bacteria
Chemo-autotrophs: deep sea vent bacteria, methanogens. LUCA was most likely a
chemo-autotroph!
Chemo-heterotrophs: most organisms on earth.
Aerobic Metabolism vs Anaerobic Metabolism (Carrie Pucko’s slide)
Aerobic Anaerobic
Requires Oxygen Without Oxygen
Glycolysis + respiration (CO2 + water as Glycolysis + fermentation (lactic acid as a
byproducts) byproduct)
38 ATP per glucose molecule 2 ATP per glucose molecule
Where does the ETC take place in Bacteria?
Electron Transport Chain in bacteria happens in the outer cell membrane as they don’t have
mitochondria like eukaryotic cells.
Timeline
4.5 BYA - Earth created
4.0 BYA- Life started (prokaryotes)
3.0 BYA - LUCA existed
3.2 BYA- Photosynthesis started + Oxygen revolution
2.2 BYA -eukaryotes
Microbes
Evolution of the Earth in Context
●The earth is 4.5 billion years old
●Life started 4 billion years ago
●Photosynthesis began 3.2 billion years ago.
Cambrian Explosion:
➢540 MYA (million years ago)
➢Explosion of diversity- several different species emerged at the same time
➢Sudden increase in marine animal life
➢All in the ocean: there was no life on land yet
Extinction
Bumps in the line graphs represent mass extinctions; Pinching in the graphs also represents
extinction.
Mass Extinction: A profound loss of life. Mostly caused by “rapid” (20,000 -200,000 years)
climate change which alters atmospheric or ocean chemistry.
There are FIVE major mass extinction events (within the last 550 million years):
(We are only focusing on two)
1. Permian Extinction
➢252 million years ago (MYA)
➢The largest one
➢A loss of over 95% of the life on earth
➢Possible causes: asteroid impact, volcanic activity
2. Cretaceous Extinction
➢66 MYA
➢75% of life lost
➢The most likely cause is asteroid strike (discovered in the 1980s by the KT boundary)
➢KT boundary : A layer of rock that can be seen all around the world. It draws the line
between the cretaceous and Triassic periods. This rock was high in the element Iridium
which is commonly found in asteroids)
➢Started the Age of Mammals
The Sixth Extinction?
Anthropocene Extinction: new era in which humans played an enormous role in different things
Background extinction: the standard rate of extinction in earths geological and biological
history before humans became a primary contributor to extinctions. (Wikipedia)
Basics
,Eukaryotes (Carrie Pucko’s slide)
●Presence of a nucleus
●Membrane enclosed organelles
●Chromosome pairs
●Larger ribosomes (80s)
●Cell division by meiosis
●Cellulose in cell walls in plant cells
●Cytoskeleton
●Digestive vesicles (vacuoles)
●Internal membranes (Endoplasmic reticulum and Golgi Apparatus)
Prokaryotes (Carrie Pucko’s slide)
●Absence of a nucleus (circular strand of DNA)
●No membrane enclosed organelles
●Single chromosome
●Cell division: binary fission
●Smaller ribosomes (70s)
●No cellulose in cell walls
Domains: a taxon in the highest rank of organisms
●Archaea PROKARYOTES
●Bacteria PROKARYOTES
●Eucarya ( Animals, Fungi, Plants, Protista) EUKARYOTES
Note: Archaea & Eucarya arose from the same common ancestor which arose at least 2 billion
years ago.
What is LUCA?
L.U.C.A. (Last Universal Common Ancestor) - The common ancestor of all the life on earth.
Existed 3 billion years ago
Did life exist before LUCA? Most likely. In order for a split/speciation to occur and LUCA to go
extinct, some other sign of life had to exist.
Where did LUCA live? Probably in deep sea thermal vents (discovered using Genomics). They
relied on the natural creation of ions and amino acids in the water.
Genomics: the study of comparing the entire genomes of different species instead of looking at
individual genes. This was used for microbial research, sequencing technology and determining
what genes LUCA most likely had.
●Scientists compared genes shared between 1800 bacterial genomes and 843 Archaean
genomes. They found 355 common genes, assumed to be those of LUCA.
● Some include: Ion exchange, DNA repair, no genes to create an ion gradient (an ion
gradient is needed for respiration therefore LUCA probably didn’t carry out respiration).
, The SEVEN requirements for LIFE:
1. Reproduction
2. Response; sensitivity to external environment
3. Metabolism
4. Adaptation
5. Growth & Development
6. Cells
7. Homeostasis: a self-regulating process by which organisms tend to maintain stability
and balance while adjusting to conditions that are optimal for survival. Example: the pH
of our blood and our body temperature must be within a certain range.
Metabolism: The chemical processes that drive life
“Photo” – light energy provides energy for metabolism.
“Chemo” - chemical energy provides energy for metabolism.
“Auto”- the carbon used in metabolism comes from carbon dioxide (inorganic carbon).
“Hetero” – the carbon used in metabolism comes from organic substances.
Types + Examples
Photo-autotrophs: cyanobacteria, plants, brown algae
Photo-heterotrophs: purple sulfur bacteria
Chemo-autotrophs: deep sea vent bacteria, methanogens. LUCA was most likely a
chemo-autotroph!
Chemo-heterotrophs: most organisms on earth.
Aerobic Metabolism vs Anaerobic Metabolism (Carrie Pucko’s slide)
Aerobic Anaerobic
Requires Oxygen Without Oxygen
Glycolysis + respiration (CO2 + water as Glycolysis + fermentation (lactic acid as a
byproducts) byproduct)
38 ATP per glucose molecule 2 ATP per glucose molecule
Where does the ETC take place in Bacteria?
Electron Transport Chain in bacteria happens in the outer cell membrane as they don’t have
mitochondria like eukaryotic cells.
Timeline
4.5 BYA - Earth created
4.0 BYA- Life started (prokaryotes)
3.0 BYA - LUCA existed
3.2 BYA- Photosynthesis started + Oxygen revolution
2.2 BYA -eukaryotes
