Origins of Life
Plant evolution
first algae-1.6 bya
first land plants before 600 mya
seed plants 350 mya
flowering plants 150 mya
Cells
Energy currency-ATP :
Common genetic code-RNA and DNA
Tree of Life
Similarity of ribosomes
Bactieria
Archaea
Eucarya
Carbon
C-12
C-13
C-14
99% abundance
1% abundance
extremely small abundance and decays
EVIDENCE
CONDITIONs
Early conditions
chemical reactions could have made life possible
Water cycle
ocean-->evaporation-->condensation-->precipitation (repeat)
RNA
Simple while also complicated
self replicating
Before RNA was PNA
can direct formation of RNA
information rich
with time evolution introduced division of labor
DNA and Proteins
with time life went from simplicity to complexity
Natural selection
gene duplication
lateral transfer
EARLY METABOLISM
Chemosynthesis
occurs in lower clades in tree of life
metabolism may have predated biological macromolecules
Energy from inorganic minerals used to drive metabolism
reducing power
Electron movement provides impetus for energy production
oxidation is loss of electrons
reduction is gain of electrons
NADH
Nicotinamide adenine dinucleotide
electron carrier
strong reducing agent
ATP
Adenosine Triphosphate
high energy bond
photophosphorylation-Light-driven electron flow linked to existing machinery for making ATP
Glycolysis
uses 2 ATP
Produces 4 ATP
Begins with glucose
C6H12O6
Ends with Pyruvate C3
NAD+-->NADH and then recycled back into NAD+
Does not require oxygen
Making sugars
Activation engery
Energy required to drive the creation of sugars
Glycolysis requires 2 ATP to get started
Glucose
C6H12O6
Alpha and Beta glucose
Starch
Amylose
Amylopectin
angular
1,4 bonds
linear
1,6 bonds
CELLS
Bubble world
Arose in a prebiotic soup containing most of necessary molecules
Growth & energy supply available
contains information molecule
divide
interact
fuse
Plasma Membrane
Phospholipid bilayer
hydrophilic head
hydrophobic tail
embedded proteins
facilitate metabolism
receptors
Membrane Bubbles
as cells increase nutrients decrease resulting in selection
Eukaryotes
originated 2.7 bya
endomembrane system
Plasma membrane
Golgi body
endoplasmic reticulum
nuclear envelope
Differences of Prokaryotes
Membrane-bound genetic material
Circular DNA vs chromosomes
Genome size
Cytoskeleton
Ribosome size
Microfilaments
Important for vesicle movement near membrane
Intermediate filaments
More permanent, fix things in place
Actin
Dimers→ tetramers
Microtubules
trackway for long-range movement of transport vesicles
Endosymbiotic Theory
have own circular DNA
Similar in size to bacteria
self replicate by binary fission
can only be made if there is a pre-existing one
double membrane
beta has OH group going up instead of down on C 1
Mitochondria and Plastids
inner membrane
intermembrane space
outer membrane
cristae
oxidative phosphorylation
citric acid cycle
plastids
chloroplasts
etioplastst
chromoplasts
leucoplasts
amyloplasts
elaioplasts
proteinoplasts
outer membrane
inner membrane
grana
stack of thylakoids
stroma
Cell Wall
additional protection
composed primarily
Cellulose→𝛃-glucose
Hemicellulose
Pectin
beta glucose
beta has OH group going up instead of down on C 1
major building block of cellulose
cellulose microfibrils
made of glucose beta monomers through dehydration synthesis
hydrogen bonds=very strong
small number of organisms can break it down
RESPIRATION
Aerobic Respiration
Major Steps
Glycolysis
Pyruvate oxidation
Citric acid cycle
Oxidative phosphorylation
starts with glucose
2 net ATP
ends with pyruvate
2 net NADH
C6H12O6
C3
4 total
moves into mitochondria
moves into mitochondria
add coenzyme A to get acetyl CoA
NAD+-->NADH
release of CO2
C2 joins C4 to make C6 (citrate)
2 steps of rearranging
NAD+-->NADH and release CO2
NAD+-->NADH and release CO2
ADP-->ATP
FAD-->FADH2
1 more step of rearranging
NAD+-->NADH
SUBSTRATE LEVEL PHOSPHORYLATION
The players
NAD+ is the oxidizing agent and accepts electrons
NADH is the reduced form and gives up electrons
FAD is the oxidizing agent and accepts electrons
FADH2 is the reduced form and gives up electrons
stronger proton motive than FADH2
Chemiosmotic, electrochemical gradient
Only way down concentration gradient is through special protein complex
ATP synthase
Catalyzes formation of ATP from ADP + Pi
Driven by energy from chemiosmotic, electrochemical gradient across membranes
Electron Transport Chain
Electron transport chain
Mitochondrial ETC consists of 4 large protein complexes
The Process
NADH and FADH2 drops off electrons
electrons move through the ETC
The protons are pumped across through the protein complexes
oxygen receives the electrons that pass through the ETC and is the final electron acceptor
Chemiosmotic electrochemical gradient runs ATP synthase
Most of ATP produced comes from this process
