Lecture 5 Microbes 2 Flashcards
2 links between information and metabolic pathways are
Transcription and translation
Transcription is (1) and its process (2)
mRNA synthesis. RNA polymerase synthesizes mRNA from antisense strand of DNA, producing a copy of “working” strand. It stops at termination sequence.
What does ribosome consist of? (4)
Large 50S subunit, small 30S subunit; ribosomal RNA and protein.
Does bacterial genome contain a single copy of ribosomal gene?
No. 1-15.
Translation process (6)
Two theories for why there are 20 kinds of amino acids utilized
A “frozen accident” theory by Crick; optimal biochemistry for versatility and cost of synthesis
Genetic (3) and physiological (1) attributes of organisms to distinguish between rocks and life
Genetic: self-replication, heritability for sake of evolvability
Physiological: metabolism causing complexity.
Two theories of origins of life
Panspermia and Spontaneous generation (and Special Creation)
Background of panspermia
Genome size and complexity increase over time, size doubles every 400 million yrs. The begining stage of life took a “jumpstart” in genomes.
Three types of panspermia
- Undirected: dispersal of microbes among planets.
- Directed: deliberate seeding by aliens
- Misdirected: pollution by spacecraft
What are evidence and objections to undirected panspermia (2+1)
Pro: Relates to short interval between appearance of permanent oceans and first signs of life.
Bacteria could be transported by meteors.
Con: low local star density, low probability of capture
What are evidence and objections to directed panspermia (1+3)
Pro: solves means of dispersal
Con: time scale, no evidence of intelligent life, why only bacteria?
What is evidence to misdirected panspermia
NASA spacecraft has 300,000 spores
Background of spontaneous generation (2)
Flies, lice, mice were thought to arise from putrefaction. Simple creatures could be reproduced.
Two premises for spontaneous generation to happen
complex bacteria arise by natural self-organization.
Or, continuous series of entities linking chemicals with evolution through natural selection take over self-assembly
Three stage processes of spontaneous generation
Growth - exergonic material available
Reproduction - fraction that continues to grow.
Inheritance - reproduction results similar to parents over random members.
Two branches of spontaneous generation
Genetics first or metabolism first
Background of Genetics first theory (3) and example
RNA is both capable of replicating and metabolizing.
With raw materials and replicase, it can replicate itself.
Can act as enzymes called ribozymes to modify other RNA
Ex: self-splicing introns.
Thus, theory states that early ocean with RNA leads to organisms now.
Background of metabolism first theory
Metabolism evolves from photosynthesis to cyanobacteria (oxidizing atmosphere) to respiration.
Energy source of metabolism for early metabolism
hydrothermal vent (CO2 reduced by H2 to form organic mcls, anoxic)
Bacterial metabolism is based on
Redox reactions
How does the redox chart work
Oxidation side on top left and reduction on bottom right
Explain first stage of metabolism of metabolism first theory (3)
General fermentation: sugar to alcohol/acids + ATP under lightning/UV
Glycolysis: glucose into two 3-C pyruvate + ATP + NADH (reducing power)
Fermentation: When anoxic, pyruvate oxidize NADH into NAD+ and ethanol, do not produce energy.
Explain second stage of metabolism of metabolism first theory (5)
Oxidation of pyruvate into acetyl group attached to CoA.
Citric acid (TCA, Krebs) cycle gives off 1 ATP and 3 NADH.
Electron transport chain: energy of electrons into work. Electropositive to negative
When aerobic, electrons from NAD+ to NADH to eventually O2 into H2O, or eventually to (what’s in the chart).
Chemiosmotic energy storage by membranes:
Lipid bilayer membranes separate charges produced redox from ETC pumping H+ from inside to outside.(ETC created electrochemical gradient)
When H+ return through ATP synthase channel, ADP into ATP (a water mill)
Third, fourth, and fifth stages of metabolism
- Photosynthesis
- Oxygenic photosynthesis (cyanobacteria) boost atmospheric oxygen to 21%
- Aerobic respiration
What does winogradsky column do
separating and visualizing metabolic systems of prokaryotes
